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BIOLOGY IS THE STUDY OF LIFE CHARACTERISTICS OF LIVING ORGANISMS: 1. All living organisms are composed of cells. 2. All living organisms maintain their structure by taking chemicals and energy from their environment. (autotrophs/heterotrophs) 3. All living organisms respond to their external environment. (tropism-a growth response to a stimulus) 4. Living organisms adapt to change or migrate or die. 5. All living organisms reproduce. HOW SHOULD BIOLOGISTS STUDY LIFE? _________________________________ The steps to the scientific method are as follows: 1._______________________________ 2._______________________________ 3._______________________________ 4._______________________________ 5._______________________________ 6._______________________________ The ______________ is defined as the basic structural and functional unit of life. It is the smallest unit that can maintain life and reproduce. Any components below the cellular level are nonliving. WRITE IN THE MULTICELLULAR ORGANIZATION OF ANIMALS BELOW. Atoms should be at the bottom and organism should be at the top. 1 DISCOVERY OF THE CELL There are 4 basic parts to the cell theory, and many scientists are credited with contributing to it. We sometimes call these parts propositions. 1. All living organisms are composed of cells. 2. Cells are the site of all metabolic reactions in an organism. 3. Cells arise from pre-existing cells. 4. Cells contain the hereditary information. Several men are credited with the first proposition. 1.__________________________________________________________ 2.__________________________________________________________ 3.__________________________________________________________ Two others had a great influence in forming proposition 2. 1.__________________________________________________________ 2.__________________________________________________________ Two men had much input in forming proposition 3. 1.__________________________________________________________ 2.__________________________________________________________ What about the following guys? Spallanzani--_________________________________________________ Redi--_______________________________________________________ Proposition 4 is more recent in comparison to the others. 1.____________________________________________________________ 2.____________________________________________________________ 2 ON THE BASIS OF STRUCTURE, THERE ARE 2 MAIN TYPES OF CELLS: PROKARYOTIC Examples—bacteria and archaea EUKARYOTIC Examples—plant, animal, fungi, protists Characteristics: 1. Characteristics: 1. 2. 2. 3. 3. 4. 5. 4. 5. PLANT AND ANIMAL CELLS ARE BOTH EUCARYOTIC CELLS, HOWEVER. THERE ARE SEVERAL DIFFERENCES BETWEEN THE TWO. Animal Plant 1. 1. 2. 2. 3. 3. 4. 4. 5. 5. WHAT ARE THE 3 BASIC PARTS OF ALMOST ALL EUKARYOTIC CELLS? _____________________________,_____________________,_____________________ Remember, all cells are surrounded by a plasma membrane, but not all cells have a cell wall. Understand that cells that do have a cell wall, also have a plasma membrane; the cell wall is outside the plasma membrane. 3 STRUCTURES OF A CELL I. Plasma Membrane A. Structure: composed of a bilayer of _________________________and randomly scattered globular proteins. Phospholipids contain a phosphate head and 2 lipid tails. The phosphate is said to be ______________________(attracted to water). The lipid tails are ________________________(not attracted to water). In most cells, the plasma membrane also contains cholesterol molecules. Also, carbohydrates are attached to many of the proteins. DRAW THE FLUID MOSAIC MODEL OF A PLASMA MEMBRANE BELOW: B. Function: This thin membrane isolates the cell from the external environment. It also controls which substances are allowed to pass in or out and transfers chemical messages from the external environment to the cell’s interior. Proteins within the plasma membrane fall mostly into 3 categories:___________, _______________________________, and ______________________________. II. Cytoplasm A. Membranous canals and vacuoles 1. Endoplasmic reticulum a. Structure__________________________________ b. Function__________________________________ c. Types____________________________________ Rough____________________________________ Smooth___________________________________ 4 2. Ribosomes a. Structure___________________________________ b. Function___________________________________ c. Location___________________________________ 3. Golgi a. Structure___________________________________ b. Function___________________________________ c. Location___________________________________ HOW DOES SECRETION DIFFER FROM EXCRETION?____________________ ____________________________________________________________________ 4. Vacuoles a. Structure___________________________________ b. Function___________________________________ c. Types_____________________________________ 5. Lysosomes a. Structure___________________________________ b. Function___________________________________ c. Additional__________________________________ ___________________________________________ ___________________________________________ 6. Peroxisomes a. Structure___________________________________ b. Function___________________________________ B. Energy related organelles 5 1. Mitochondria a. Structure___________________________________ b. Function___________________________________ GENERAL AEROBIC CELLULAR RESPIRATION CHEMICAL EQUATION: _____________________________________________________________________ 2. Plastids a. Location___________________________________ b. Types: 1)__________________________________ 2)__________________________________ 3)__________________________________ GENERAL, OVERALL PHOTOSYNTHESIS CHEMICAL EQUATION: C. Cytoskeleton 1. Microfilaments (actin) a. Structure___________________________________ b. Function___________________________________ 2. Intermediate filaments a. Structure___________________________________ b. Function___________________________________ 3. Microtubules a. Structure___________________________________ b. Function___________________________________ D. Centrioles and related organelles 6 1. Centrioles a. Structure___________________________________ b. Function___________________________________ 2. Cilia and flagella a. Structure___________________________________ b. Function___________________________________ III. Nucleus A. Nucleoplasm 1. Chromatin (become chromosomes) a. Structure____________________________________________ b. Function____________________________________________ _____________________________________________ _____________________________________________ 2. Nucleolus a. Structure____________________________________________ b. Function____________________________________________ B. Nuclear envelope a. Structure___________________________________________ b. Function___________________________________________ DRAW A TYPICAL ANIMAL CELL BELOW AND LABEL THE 3 MAIN PARTS. 7 Eukaryotic Organelles Simplified Name Plasma membrane Structure Function Bilayer of phospholipids and scattered proteins Controls passage of molecules or ions into and out of the cell similar to cell membrane Controls passage of substances into and out of nucleoplasm Nucleolus Concentrated area of RNA and protein in the nucleus Ribosome formation Chromatin material composed of DNA and protein Endoplasmic reticuli flattened channels Rough Studded with ribosomes Transport of proteins Smooth Have NO ribosomes Lipid synthesis and detoxification of harmful substances Ribosomes Protein and RNA in 2 subunits Protein synthesis Nucleus: Nuclear envelope Golgi Stack of membranous sacs Differentiation, reproduction, and all metabolic processes Intracellular transportation Packaging and secretion of proteins Vacuole and vesicle Membranous sacs Storage Lysosome Membranous container of digestive enzymes Intracellular digestion of worn out cell parts or germs Mitochondrion Inner membrane (forms cristae) outer membrane; enzymes and DNA present Cellular respiration Chloroplast Inner membrane (grana) within outer membrane Photosynthesis 8 Microtubules Thickest protein filaments Movement of organelles and shape of cell Microfilaments Thinnest protein filaments Muscle contraction, pseudopods, cytokinesis Centrioles Made of 9 + 0 microtubule triplets Forms spindle fibers, cilia, and flagella Peroxisomes Membranous sacs; contain Synthesis of bile acids, breakdown of lipids, degradation of rare biochemicals peroxidases and catalase 9 MOLECULAR STRUCTURE The matter of the universe is composed of a limited number of basic substances called elements. Definition: Elements important in biology 4 major elements: carbon, hydrogen, oxygen, and nitrogen 7 major mineral elements: potassium, phosphorus, sodium, sulfur, chlorine, calcium, magnesium There are also many elements needed by the body in minute amounts. These are referred to as trace elements or microminerals. Subatomic structure Each atom has three types of subatomic particles: Protons-__________ Neutrons-_________ Electrons-_________ The number of protons equals the number of electrons, thus giving the atom a neutral electrical charge as a whole. Atomic number - the number of protons within an atom Atomic weight - the relative weight of the subatomic particles within an atom; relative because it is based on the weight of carbon Atomic mass - found by adding the protons and neutrons together Isotope - atoms of an element with the same number of protons but with a different number of neutrons; an example would be deuterium and tritium, both isotopes of hydrogen 10 Energy levels There are 7 energy levels or electron shells possible within an atom, depending on the number of electrons the atom has. 1 2 3 holds 2 electrons 8 8 In biology, we work only with the the first 3 levels. IMPORTANT NOTE: 8 electrons represent a stable configuration for any electron shell except the first. Diagram the subatomic structure of oxygen, hydrogen, carbon, sodium, and chlorine. Chemical bonding: valence Valence describes how an atom will react in a chemical reaction with another atom. It depends on the number of electrons in the outer energy level. 11 1. Oxygen Atomic number - _____ Has ____ electrons in its outer energy level Valence of _______ 2. Sodium Atomic number - _____ Has _____ electrons in its outer energy level Valence of _______ 3. Chlorine Atomic number-______ Has _____ electrons in its outer energy level. Valence of_______ 4. Hydrogen Atomic number -_____ Has _____ electrons in its outer energy level Valence of ______ Chemical reaction Atoms interact with each other by the taking, giving, or sharing of electrons. Atom with more than 4 electrons in its outer energy level tends to ________ electrons. Atom with less than 4 electrons in its outer energy level tends to __________electrons. Compounds Definition: Most of the substances in living organisms exist in the form of compounds. Draw the following compounds: water, carbon dioxide, oxygen, sodium chloride 12 Types of Compounds I. Organic Contain the element, carbon, in a HC chain What is the significance of C? The sharing of electrons forms a covalent bond. Organic compounds form covalent bonds. Classes of organic compounds important in biology: II. Inorganic Do not contain the element, carbon, in a HC chain The transfer of electrons forms an ionic bond. Inorganic compounds form ionic bonds. Classes of inorganic compounds: The atom that gives up electrons becomes positively charged. The atom that receives electrons becomes negatively charged. The molecule as a whole is neutral. Ionization When inorganic compounds with ionic bonding are placed in water, they dissolve and separate into charged particles called ___________or _______________________. The electron transfer that occurred to make the bond is permanent, and when the bond is broken, ions are produced. This happens when the compound dissolves and is known as dissociation. 13 EXAMPLES: An ion is an ___________ with a _____________or a charged particle. Polarity of Water Inorganic compounds can also form covalent bonds. Examples include the following: In forming a covalent bond, the sharing of electrons is usually equal between the 2 atoms, however, this is not the case with water. Water is a molecule with covalent bonding but is also a polar molecule. Why? ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ The larger oxygen atom has a partial __________ charge and the smaller hydrogen atom has a partial _______________ charge. Hydrogen bond Definition: Only another polar molecule will dissolve in polar water. A nonpolar molecule will not. Example: 14 Chemical Composition of Cytoplasm 75 - 90% water remainder - solid components _________________________compounds dissolve when placed in water, forming _______________, also known as __________________________. This is a true solution. ____________________ compounds (with one exception) do not dissolve when placed in water. They form a colloidal suspension. Why don’t they dissolve? One type of organic compound will dissolve when placed in water--________________. The most prevalent substance in a cell next to water is ______________. 15 HYDROCARBONS These are compounds formed of __________________ and _______________ atoms. 1. Examples: Methane Series (covalent bonds and hydrogens must be added) Name Molecular Formula Structural Formula methane CH4 H-C-H ethane C2H6 H-C-C-H propane C3H8 H-C-C-C-H butane C4H10 H-C-C-C-C-H pentane C5H12 H-C-C-C-C-C-H hexane C6H14 H-C-C-C-C-C-C-H heptane C7H16 H-C-C-C-C-C-C-C-H octane C8H18 H-C-C-C-C-C-C-C-C-H nonane C9H20 H-C-C-C-C-C-C-C-C-C-H 16 2. Other features of carbon and its bonds: a. Can bend and form various geometric shapes. Molecule Molecular formula benzene C6H6 acetylene C2H2 Structural Formula b. Can double or triple bond. double bonding-2 pairs of electrons are shared between the carbon atoms. (4 electons in all) triple bonding-3 pairs of electrons are shared between the carbon atoms. (6 electrons in all) c. Can be saturated or unsaturated. Saturated compounds are single bonded such as the list of hydrocarbons of the methane series. No H atoms can be added at the bonds between the carbons. Unsaturated compounds contain double or triple bonded such as acetylene or benzene. 3. So, there are at least 3 reasons why there are so many thousands of carbon compounds: 1. 2 . 3. WHAT ARE ISOMERS? ________________________________________________________________________ ________________________________________________________________________ Example:________________________________________________________________ 17 PLASMA MEMBRANE PERMEABILITY 1. Size of the entering molecule substance must be less than 7 angstroms in order to enter through the pore examples: water, urea, chloride ions (Cl-) 2. Solubility in lipids substance must be lipid soluble to pass through the phospholipid layer examples: fats, alcohols, carbon dioxide, oxygen gas 3. Electrical charge neutral substances pass through membrane more easily 4. Presence of a carrier molecule for the entering molecule These carriers are enzymes or coenzymes. examples: glucose and amino acids The plasma membrane has 2 main functions--it acts a barrier, keeping some substances out and as a gateway, allowing some substances to come in. 18 MOVEMENT OF MATERIALS THROUGH THE PLASMA MEMBRANE Four Methods 1. Diffusion 2. Osmosis 3. Active Transport 4. Pinocytosis and Phagocytosis All plasma membranes are semi-permeable. Diffusion Definition--The random movement of molecules from an area of higher concentration to an area of lower concentration until an equilibrium is reached on both sides of the membrane. A substance diffuses down its concentration gradient. The difference between the high concentration and the low concentration is its concentration gradient, and the steeper the gradient, the faster the diffusion. Examples of substances that diffuse through the pores or channels of the plasma membrane: ____________________________________________________________________ Examples of substances that diffuse through the phospholipid layer of the plasma membrane: _____________________________________________________________________ Facilitated Diffusion The substance combines with a carrier molecule and is transported from high to a low concentration until an equilibrium is reached. Examples of substances that typically diffuse through the plasma membrane by facilitated diffusion: _______________________________________________________________________ 19 Osmosis The passage of water only through a semi-permeable membrane from an area of high concentration to an area of lower concentration (in reference to the solvent). Osmosis is a special type of diffusion; the diffusion of water only because the plasma membrane is permeable to the water but less permeable to the solute. Terminology: 1. solvent - the fluid in which the substance is dissolved 2, solute - the substance which dissolves Together these make a solution. Examples of osmosis include the following: ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ Osmosis always results in osmotic pressure. One solution gains water but loses nothing. (Remember the solute cannot easily permeate the plasma membrane). Osmotic pressure develops in the solution or in the cells in which water _______________. WATER TENDS TO MOVE TOWARD THE ________________ SOLUTE. There are 3 types of solutions with reference to their strengths or tonicity. Define and determine which water moves in the following solutions: 1. isotonic: _______________________________________________________________________ _______________________________________________________________________ 2. hypertonic: ________________________________________________________________ ________________________________________________________________ 3. hypotonic: ________________________________________________________________________ ________________________________________________________________________ DEFINE CRENATION AND PLASMOLYSIS. 20 ________________________________________________________________________ ________________________________________________________________________ Active Transport The substance combines with a carrier molecule and is transported from low to high concentration. This movement is against its concentration gradient. Examples of substances that are typically transported by active transport include the following:_____________________________________________________________ ENDOCYTOSIS: Pinocytosis Invagination of the plasma membrane, resulting in the ingestion of substances within a liquid. Vesicles are produced. Examples of substances that move through the plasma membrane by pinocytosis include the following:___________________________________________________________ Sometimes receptors are found in the invaginated pit that forms by the entering substances. The substances attach to these receptors and enter the cell. This process is termed receptor-mediated pinocytosis. Examples of substances that enter cells typically by receptor-mediated pinocytosis: ______________________________________________________________________ Phagocytosis Surrrounding and engulfing of solid material by the plasma membrane This process is similar to pinocytosis, but the entering substances are larger. Examples of substances moving into a cell by phagocytosis include the following: A cell capable of phagocytosing is the ______________; it is loaded with which organelle that contains digestive enzymes for degrading the entering substance? ___________________ 21 Filtration Movement of molecules from an area of higher pressure to an area of lower pressure Filtration occurs across a ___________________________. DRAWING OF KIDNEY TUBULE BELOW 22 METABOLISM Definition: 2 types of metabolism: 1) Anabolism - Examples 2) Catabolism - Examples What does endergonic and exergonic mean?____________________________________ EVERY CHEMICAL REACTION THAT OCCURS IN THE BODY REQUIRES AN ENZYME. Definition of enzyme: Characteristics: 1) 2) 3) 4) 5) 6) Enzymes usually end in what 3 letters?________; they are named for their substrates. 23 Coenzymes: ATP: Definition: 3 molecular parts of ATP: 1) 2) 3) 3 Types of Energy Carriers Dependent Upon the Number of Phosphates: (How ATP is recycled). 1) 2) 3) When ATP breaks down into ADP, the energy released is used to start anabolic reactions. Uses of ATP: 1) 2) 3) 4) 24 ACIDS AND BASES: Acid definition: Examples: ACIDS ARE PROTON DONORS. Base definition: Examples: BASES ARE PROTON RECIPIENTS. The pH scale measures the concentration of ________. The pH scale goes from _____to ________. Acids are ______________7 on this scale;bases are _______________7 on this scale. 7 is neutral. This means that the number of H+ and OH- (ions) are equal. ______________________ help resist the change in pH by taking up or releasing of H ions (H+). An example of a protein buffer is hemoglobin. The carbonic acid - bicarbonate buffer system works the following way: This is an example of homeostasis. WHAT IS A SALT? Example: ________________________________________________________________________ 25 PROCESS OF PHOTOSYNTHESIS Organisms which undergo photosynthesis must have chlorophyll, a green pigment. Chloroplasts, located in the cytoplasm, contain chlorophyll. Chlorophyll has the ability to absorb certain wavelengths of light. absorbs red, blue, and violet wavelengths allows yellow and orange wavelengths to pass through reflects green wavelength back to the eye A Characteristic of Light The shorter the wavelength, the more energy it contains. Red has the longest wavelength and represents the least energy. Violet has the shortest wavelength and represents the most energy. Photosynthetic Reactions Photosynthesis can be divided into light dependent and light independent reactions. I. The Light Reactions (Light-dependent) Require the presence of light May require the participation of two light-gathering units called photosystem I and photosystem II (different wavelength peaks absorbed) Take place in the thylakoid membranes of the chloroplast Solar energy is absorbed and funneled to chlorophyll a, which sends energized electrons to an electron-acceptor molecule. Electrons have two pathways: Cyclic After solar energy is absorbed, electrons travel from PSI and enter an electron transport system (ETS). As electrons travel from one carrier to the next, energy is released and stored in the form of a hydrogen gradient (H+). As these H+ flow down the electrochemical gradient, ATP is made. Electrons return to PSI. Noncyclic Electrons move from water through PSII to PSI and then on to NADP+ Water splits and releases oxygen. It is water that supplies the replacement electrons after electrons move to PSI. ATP is made as well as NADPH when NADP+ receives electrons and then a H+ . II. The Light Independent Reactions (the Calvin Cycle) 26 Light is not used. Take place in the stroma, the fluid-filled region surrounding the thylakoids The energy used to start the light independent reactions is ATP which is supplied by the light reaction. CO2 is taken up by a 5-carbon sugar, ribulose biphosphate (RuBP). This 6-carbon compound immediately breaks down into 2 phosphoglycerate (PGA) molecules which are reduced to phosphoglyceraldehyde (PGAL) or glyceraldehyde 3 phosphate (G3P) molecules. RuBP is recycled. Fate of PGAL: 1. 2 PGAL’s combine to form 1 glucose molecule 2. PGAL transforms into amino acids, fatty acids, and other carbohydrates Fate of glucose: 1. usually converted into starch and stored in roots of plants 2. may be converted into another carbohydrate such as sucrose 3. may be cellularly respired. C4 plants such as corn and sugarcane carry on the Calvin Cycle in different cells than the C3 plants--bundle sheath cells rather than mesophyll cells. These C-4 plants use a different enzyme to fix carbon dioxide to a different compound, resulting in oxaloacetate. In hot, dry weather, C4 plants have an advantage over C3 plants. (No photorespiration--See text). CAM (Crassulacean-acid) plants are succulent desert plants which carry on carbon dioxide fixation at night when the stomates(openings on surfaces of leaves are open allowing the passage of water to the outside and CO2 into the plant. 27 CELLULAR RESPIRATION Four Stages I. Glycolysis Occurs in the cytosol of all cells Is anaerobic Breaks down glucose into 2 molecules of pyruvate Yields 2 ATP’s per glucose Yields 2 NADH II. Transition Reaction Pyruvate is oxidized to acetate which combines with coenzyme A forming acetyl Coenzyme A. NADH is produced. Carbon dioxide is released. III. Kreb's Cycle (Citric Acid Cycle) Occurs in the matrix of the mitochondria Is aerobic The 2-C acetate group of acetyl coenzyme combines with a 4-C compound, oxaloacetate to form citric acid. In the course of the cycle, citrate is recycled to oxaloacetate and carbon dioxide is released as waste. Energy is captured as ATP and the reduced, high-energy compounds, NADH and FADH2. With 2 turns of the Kreb's Cycle, 2 ATP's are produced. WHY IS KREB’S CYCLE KNOWN AS THE FINAL COMMON PATHWAY? _______________________________________________________________________ ________________________________________________________________________ ________________________________________________________________ IV. Electron Transport System (ETS) and Chemiosmosis Occurs in the cristae of the mitochondria The H’s are removed in the ionized state. The electrons are handed down a series of carriers and lose energy; this energy is used to pump H ions across the inner mitochondrial membrane, forming a H ion gradient. By chemiosmosis, H ions flow through ATP synthase. This energy is used to produce 32 ATP molecules. Oxygen is the final recipient in the ETS. When it receives electrons and H ions, water is produced. The total number of ATP’s produced from 1 glucose molecule is ________. 28 FERMENTATION Definition: Kreb’s cycle only occurs if adequate oxygen is present. After glycolysis, without oxygen, pyruvic acid is converted into lactic acid in animal cells. Lactic acid in our cells causes the following symptoms: soreness in muscle cells a lowered pH fainting Lactic acid is toxic to our cells and must be converted so that the Kreb’s cycle can take place inside the mitochondria of our cells for a high energy yield. Fermentation also occurs in plant, yeast, and bacterial cells producing CO2 and alcohol as a result. 29 ORGANIC RADICALS Organic radicals are a few basic building blocks that give dissimilar compounds a similar property. These groups of atoms, also called functional groups, can substitute for a single H. 1. Hydroxyl (also called the alcohol group) -OH All alcohols, carbohydrates, and triglycerides contain this radical. 2. Carboxyl (known as the acid group) This radical is found in amino acids and fatty acids. 3. Aldehyde 4. Amino group (acts as a base) This group is found in all amino acids. 5. Sulfhydral -SH This radical is found in all enzymes (which are proteins formed from amino acids ). 30 DIGESTION Digestion includes the following processes: 1. 2. 3. 4. _______________________ - bringing food into the mouth (usually) _______________________ - physical breakdown of food _______________________ - accomplished by exposure of food to enzymes _______________________ - transport of small molecules out of digestive tract into bloodstream and to the cells 5. _______________________ - expulsion of wastes from the body In some animals, digestion occurs in a sac with a single opening for ingesting food and ejecting wastes. Examples: _______________________________________________ Humans have a ________________ digestive tract with several compartments. Chemical digestion occurs through a process called ______________________ which means________________________________________________________________. Monomer water energy enzymes water energy enzymes ________________ Process? __________________ Process? Polymer or Macromolecule Carbohydrate Digestion: 31 Carbohydrates contain the elements, carbon, hydrogen, and oxygen. Carbohydrates include sugars and starches. The ratio of H to O is 2:1. The general molecular formula for sugars is (CH2O)n. The sugars include simple sugars called _________________________ and double sugars called ____________________. Examples of simple sugars include the following: 1) 2) 3) Examples of double sugars include the following: 1) 2) 3) GLUCOSE, FRUCTOSE, AND GALACTOSE ; AND MALTOSE, SUCROSE, AND LACTOSE ARE __________________ BECAUSE THEY HAVE THE SAME MOLECULAR FORMULA BUT DIFFERENT STRUCTURAL FORMULAS. See the structural formulas below. Good carbs refer to those which contain fiber and typically cause proper amounts of insulin to be released into the bloodstream. High fiber diets are needed to reduce the risks of colon cancer. The U.S. government advocates an increase in consumption of fruits, vegetables, and whole grains and a decrease in refined sugars. A third type of carbohydrate is the polysaccharide. Examples include the following: 32 ____________________________ - how glucose is stored in liver and muscle cells ____________________________ - found in cell wall of plants ____________________________ - how glucose is stored in roots and underground stems of plants ____________________________ - found in exoskeleton of arthropods ____________________________ - found in fruit peeling The enzymes which break down carbohydrates include the following: _____________________,_______________________,__________________ ____________________,and__________________________. The enzymes maltase, sucrase, and lactase are present in intestinal juice. Starch + H2O ----------maltose + H2O-----------glucose C12H22011 + H2O--------------------C6H12O6 + C6H12O6 + ENERGY Maltose breaks down into 2 molecules of glucose. Sucrose breaks down into 1 molecule of glucose and 1 molecule of fructose. Lactose breaks down into 1 molecule of glucose and 1 molecule of galactose. CARBOHYDRATES CONTAIN THE ORGANIC RADICALS, HYDROXYL AND SOMETIMES ALDEHYDE AND OTHERS. 33 FAT DIGESTION Fats also include carbon, hydrogen, and oxygen like carbohydrates but in a ratio of >2:1 (H to O). Fat molecules contain the _________________ and __________________ organic radicals or functional groups. Another name for a fat molecule is___________________________. The enzymes that digest lipids are __________________. Triglycerides + H2O ------------------ 3 fatty acids + glycerol. Fats are a more concentrated source of energy than carbohydrates. They supply over twice the amount of Calories as carbohydrates or proteins. Types of Triglycerides: 1) Saturated contain single bonds; can lead to build up of cholesterol, therefore are associated with high blood pressure and heart disease; contain the maximum number of hydrogen atoms possible; solid at room temperature, usually; generally animal in origin but also include cocoa butter and coconut oil. 2) Unsaturated contain double bonds; not associated with heart disease but high doses are linked to cancer; do not contain the maximum number of H atoms possible; liquid at room temperature, usually; plant in origin such as olive oil, soybean oil, safflower oil, peanut oil, etc. What are trans-fatty acids? _____________________________________________ There are essential and non-essential fatty acids. What is the difference between these 2 terms? ____________________________________________________________________ LDL - LOW DENSITY LIPOPROTEIN - THE BAD TYPE These lipids are taken to arteries and tissues. HDL - HIGH DENSITY LIPOPROTEIN - THE GOOD TYPE These lipids are taken out of the tissues to the liver. 34 Types of Lipids: 1) Triglycerides - 3 fatty acids + glycerol 2) Phospholipids - 2 fatty acids + glycerol + phosphate 3) Waxes - 3 fatty acids + a different alcohol than glycerol examples include beeswax and paraffin 4) Steroids - 4 interlocking C rings - examples include aldosterone, testosterone, cholesterol, estrogen, progesterone, cortisol Write the Triglyceride structural formula below. A steroid can be drawn as follows: The U.S. government advocates a decrease in consumption of fats, especially saturated fats. It also advocates a decrease in high cholesterol foods such as butter and eggs. 35 PROTEIN DIGESTION Proteins contain the elements, carbon, hydrogen, oxygen, and nitrogen always. Sometimes phosphorus and sulfur make up proteins as well. Draw a typical amino acid below. Notice the 2 organic radicals above. These are found in all amino acids. Proteins consist of repeating units of ________________________. Amino acids make up peptides which make up polypeptides which make up proteins. These repeating units are joined by ___________________ bonds. The enzymes that digest proteins collectively are known as ________________________. Enzymes are proteins which contain the sulfhydral radical . Protein + H2O ------------ peptides Peptides + H2O ------------------ amino acids A good source of protein would be lean meat, poultry, fish, or egg white. There are essential and nonessential amino acids: Essential means that we must obtain these amino acids from the food we eat. A vegetarian must eat a variety of vegetables to get all 9 of the essential amino acids that he or she needs. Nonessential means that our bodies can make these. Protein deficiency can cause a variety of debilitating conditions, including kwashiorkor, which is seen in some poverty-stricken countries. Remember that most enzymes are proteins and that almost every organelle of a cell that we discussed contains protein. 36 ORGAN Mouth FUNCTION digestion of starch FEATURES teeth; tongue FUNCTION chewing food; formation of bolus; a ball of food Esophagus passageway peristaltic action; rhythmic, wavelike contractions that move materials through tract Stomach digestion of proteins gastric glands; gastric juices and chyme is made; thick, semi-liquid mixture of partly digested food and secretions Small intestine digestion of all foods intestinal glands release intestinal juices absorb nutrients villi; fingerlike projections that increase surface area Large intestine absorption of water Anus defecation What are the 3 parts of the small intestine?______________, _______________, ____________________. How do recombined fats leave the small intestine? Through lymphatic vessels called _________________ and then into the bloodstream to the liver and then to all parts of the body How do monosaccharides and amino acids leave the small intestine? Through blood vessels called _______________________, to the liver, and to all parts of the body. (See drawing in text). See the drawing in text and trace the path of food from the mouth to the anus, and note the placement of the accessory organs of digestion, the liver and the pancreas. 37 FUNCTIONS OF THE LIVER: destroys old red blood cells produces bile which emulsifies fats stores glucose as glycogen produces urea from breakdown of amino acids makes blood proteins detoxifies the blood converts hemoglobin into bilirubin and biliverdin BILE CONTAINS NO ENZYMES. IT DOES CONTAIN BILE SALTS FROM CHOLESTEROL AND PIGMENTS FROM HEMOGLOBIN. PANCREATIC JUICE CONTAINS SEVERAL ENZYMES INCLUDING THE FOLLOWING: LIPASE which breaks down __________________. TRYPSIN which breaks down ___________________. AMYLASE which breaks down ___________________. BILE AND PANCREATIC JUICE TRAVEL THROUGH THE COMMOM BILE DUCT INTO THE DUODENUM FOR THE COMPLETE DIGESTION OF ALL FOOD TYPES. HORMONES PLAY A ROLE IN DIGESTIVE GLAND SECRETIONS: After eating a protein-rich meal, the hormone, gastrin, produced by the lower part of the stomach, enters the bloodstream and then stimulates the upper part to produce more digestive juices. Chyme, from the stomach, causes the duodenum to release the hormones, secretin and CCK. These stimulate the pancreas to secrete digestive juices. Secretin causes the release of bicarbonate and the CCK stimulates the gallbladder to release bile. What are gallstones?___________________________________________________ 38 REPRODUCTION Two Types 1. Sexual - cells from 2 parent cells fuse The male gamete, called sperm, unites with the female gamete, called egg or ovum, to produce a single celled zygote when the nuclei fuse . Occurs in many different types of organisms Meiosis describes the events occurring in the nucleus to produce gametes or meiospores (in plants) so that sexual reproduction can occur. 2. Asexual - two new cells arise from a single parent cell Mitosis describes the events occurring in the nucleus so that cells can produce daughter cells exactly like themselves. In some organisms, mitosis is a means of asexual reproduction. There are many types of asexual reproduction in addition to mitosis. Three types are mentioned below. a) budding b) binary fission c) asexual spore formation MITOSIS One cell divides to form 2 new cells, each identical to the parent cell This process accounts for the following: a) asexual reproduction in some less complex organisms b) growth c) repair and replacement The stages of mitosis include - prophase, metaphase, anaphase, and telophase. Interphase occurs first. I. Interphase This stage occurs before mitosis begins. It is sometimes called the resting stage, but it is busy metabolizing -building RNA, protein etc. Chromatin is present instead of chromosomes. The genetic material has not shortened and coiled yet. The nuclear envelope and nucleolus are present. Replication of the genetic material and organelles occur during the S subdivision. 39 II. Prophase a) begins with the coiling and thickening of chromatin into recognizable chromosomes b) nuclear membrane and nucleolus disappear c) two centrioles migrate to opposite ends of the nucleus and establish spindle fibers between them Each chromosome has 2 parts - each called a chromatid The 2 chromatids are joined in the middle by the centromere. Why is a chromosome composed of two parts?__________________________________ III. Metaphase The chromosomes line up along the middle of the cell, which is called the equitorial plate. IV. Anaphase The centromere divides and one chromosome (formally called a chromatid) moves to one pole and the other chromosome moves to the opposite pole. 40 V. Telophase a) Chromosomes become the dispersed chromatin again. b) The nuclear envelope and the nucleolus reappear. c) Spindle fibers disappear. d) The plasma membrane constricts around the equator dividing the cytoplasm into 2 parts, each receiving a nucleus. This constriction or indentation of the plasma membrane is called a cleavage furrow and occurs in animal cells but not plant cells. Plant cells divide into 2 cells by a division plate, also called a cell plate, which forms on the inside of the cell. The process of the division of the cytoplasm is referred to as cytokinesis. DUPLICATION OF THE GENETIC MATERIAL OCCURS IN ___________________. DIVISION OF THE GENETIC MATERIAL OCCURS IN________________________. DIVISION OF THE CYTOPLASM OCCURS IN_______________________________. 41 STAGES OF MEIOSIS ( Reduction Division) Interphase Prophase I Metaphase I Anaphase I Telophase I Interkinesis no replication of the genetic material occurs ProphaseII Metaphase II Anaphase II Telophase II Prophase I 1) 2) 3) 4) 5) (same 3 points as in prophase of mitosis plus 2 more) chromatin condenses to form recognizable chromosomes nuclear membrane and nucleolus disappear centrioles migrate to opposite ends of the nucleus and form spindle fibers between them synapsis occurs, resulting in the formation of a tetrad or bivalent crossing over occurs in nonsister chromatids Definition of synapsis: the pairing up of homologous chromosomes side by side which produces a four part structure called a tetrad Definition of homologous chromosomes: chromosomes from each parent that are alike-- they contain the same genes which control the same type traits. Metaphase I tetrads line up along the middle along the equitorial plate Anaphase I division of the homologous chromosomes; tetrads separate and each homologous chromosome (dyad) moves towards opposite pole Telophase I nuclear envelope and nucleolus reappear; chromatin is present again; 2 daughter cells are produced as a result of cytokinesis. Prophase I nuclear envelope and nucleolus disappear; spindles and chromosomes return 42 Metaphase II dyads line up in the middle of each of the 2 cells Anaphase II Telophase II 1) 2) 3) 4) dyads divide in each cell, and each monad (sister chromatid) moves toward opposite poles of each cell (same 4 points as in telophase of mitosis) chromosomes become the dispersed chromatin nuclear envelope and nucleolus reappear spindle fibers disappear cytokinesis occurs Four daughter cells are produced, and because the chromosomes separated twice, and cytokinesis occurred twice, each daughter cell contains half the number of chromosomes as the parent cell. REMEMBER, IN ANIMAL CELLS, CYTOKINESIS OCCURS BY THE FORMATION OF A CLEAVAGE FURROW. IN PLANT CELLS, IT IS ACCOMPLISHED BY A DIVISION OR CELL PLATE. Two important principles of meiosis: These cause variation in the gametes. 1) The final number of chromosomes in a gamete is only half (haploid) of the parent cell number. 2) There is random or independent assortment in this reduction so that each gamete receives either one or the other of the homologous pairs of chromosomes; not both. The way that one chromosome pair lines up during metaphase I has no effect on how another pair of homologous chromosomes line up. DIFFERENCES BETWEEN MITOSIS AND MEIOSIS Mitosis one division occurs in all body cells produces 2 cells identical to parent cells produced have diploid # of chromosomes Meiosis two divisions occurs in sex cells produces 4 cells unlike parent cells have haploid # of chromosomes What is a karyotype?_______________________________________________________ ________________________________________________________________________ What does differentiation mean? _____________________________________________ 43 From Fertilization to Implantation to Early Development A. Activation – the penetration of an egg by a sperm B. Fertilization – the process of the fusion of the egg and sperm nuclei C. Sperm 1. formed in testes continually throughout life 2. spermatogonial cells----primary spermatocytes---secondary spermatocytes-----spermatids----sperm 3. production occurs in seminiferous tubules 4. teardrop shaped: 3 parts—head, mid-piece, and tail D. Egg 1. formed in ovaries and released after puberty until menopause 2. oogonial cells----primary oocytes----secondary oocytes----ootid---ovum 3. by fifth month of development, human oocyte number is determined; regresses greatly by adolescence 4. At ovulation, the secondary oocyte is released from its follicle and is drawn by fimbriae into the oviduct. 5. If the secondary oocyte is penetrated by the sperm, it continues meiosis and develops into the ovum or egg. E. Conception - period of time from fertilization until implantation 1. Fertilization will occur in upper third of oviduct. 2. A zygote is produced when the nucleus of the sperm and egg unite. It migrates down toward the uterus, beginning mitotic divisions called cleavage along the way. There is little or no growth during this time because with each division, the cells become smaller and smaller. The zygote divides into a 2-celled stage, which divides into a 4-celled stage, which divides into an 8-celled stage, etc. F. Animal Development 1. The 16-32 celled stage morula enters the uterus in 4 or 5 days. 2. The 1024 celled stage blastocyst begins to burrow into the uterine wall. This is referred to as implantation. This starts around day 7 and is completed around day 12. 3. Gastrula stage results in 3 germ layers, eventually Ectoderm - becomes skin, sense organs, nervous system Mesoderm - becomes muscles, bones, circulatory, reproductive, excretory organs Endoderm - becomes lining of digestive and respiratory tracts, lungs,liver,etc. 4. Gradually the germ layers rearrange themselves into organs and other body structures that will be present in the adult. 5. The heart is beating by the 4th week; by 40 days, most of the brain has formed. 44 DEOXYRIBONUCLEIC ACID DNA’S structure was discovered by ________________and_______________ in 1953. DNA is a double helix with ___________________ and ____________________ on the outside and paired nitrogen bases on the inside. Complementary base-pairing rules are as follows: Adenine pairs with _____________________ (double H bond) Cytosine pairs with _____________________ (triple H bond) Adenine and guanine are known as purines. (double-ringed structures) Cytosine and thymine are known as pyrimidines. (single-ringed structures) The two strands of DNA are anti-parallel to each other. This means that the sugars have a different orientation (are right-side-up on one strand and upside-down on the complementary strand). Why is this important?_____________________________ __________________________________________________________________ See the drawing on the next page. Points of Interest: The length of DNA is 2.36 meters in almost every cell of our body. Our DNA is composed of around 3 billion base pairs. Translation occurs at a rate of about 4 proteins per minute. Everyone has the same 4 base pairs of DNA but no 2 people (with the exception of identical twins) have the same DNA fingerprint. Completed DNA strands contain possibly about one mistake in one billion base pairs (spontaneous mutations). Induced mutations have a much higher rate. Replication of DNA occurs at a rate of about 50 to 5000 nucleotides per second. 45 ANTIPARALLEL STRUCTURE OF DNA Notice how a phosphate is at the top (5’) of one strand, and a sugar is at the top of the other strand (3’). One strand runs in a 5’to 3’direction and the complementary strand runs in a 3’to 5’ direction. 46 A nucleotide consists of a ____________________,_______________,and___________. If a strand of DNA were C C G T T G T A A G C T , what would its complementary strand be? ________________________ DNA Replication: (watch video) Many enzymes are involved in the replication of DNA. ___________ unwinds a portion of DNA which forms a bubble. __________ forms primers so that the DNA polymerases can begin their jobs. DNA polymerases synthesize new complementary strands of DNA in a 5’ to 3’ direction. One new strand is made continuously (the leading strand), but the other new strand is synthesized in short fragments (the lagging strand). ____________glues the discontinuous fragments together. This replication process takes place in the ________________ of eukaryotic cells. DNA replication is said to be ____________________________ because one parent strand is conserved in the replication process. Transcription: The process which forms RNA from DNA is known as ___________________. For this process to begin, an enzyme known as __________________________must bind to the promoter site of the DNA molecule. This process ends when RNA polymerase reaches the termination signal where both the enzyme and the new strand of RNA detach. Three ways that RNA differs from DNA: RNA _________________________________ _________________________________ _________________________________ DNA ________________________________ ________________________________ ________________________________ Where is mRNA made?__________________________________________________ Translation: The encoding process that produces proteins after transcription occurs is known as ______________________________. Where does this process occur?____________________________________________ The steps involved in this process are as follows: 1. The mRNA breaks away from the nucleus and travels to the small ribosomal subunit where tRNA will also join. 2. tRNA (transfer) contains free bases called anticodons which attach to codons of the mRNA. 3. Amino acids are brought to the ribosomes by the tRNA (called in by codons). Codons are triplet bases of mRNA. 47 Methionine is the first amino acid brought in by tRNA. The codon, AUG calls it in. The anticodon ,UAG, pairs with the codon, AUG. The large subunit of the ribosome is assembled which contains 2 binding sites and a catalytic site. 4. Amino acids are joined by peptide bonds to form polypeptides or proteins. 5. When a stop codon is reached, the protein is released from the ribosome. See drawing below. The ribosome moves along the mRNA. Notice that there are 2 binding sites as well as a catalytic site on the ribosome. We typically refer to the translation process as having 3 main steps: initiation, elongation, and termination. There are 64 codons and only 20 amino acids typically found in cells. More than one codon can call for the same amino acid. This is referred to as degeneracy or redundancy of the genetic code. Why is this important?__________________________________ _____________________________________________________________________ The genetic code is as follows: DNA-----------RNA---------------Proteins If a mutation occurs at the base pairs of the DNA level (in protein-coding DNA), there will be a mix-up in the mRNA made, thus an incorrect amino acid called in, thus an incomplete or incorrect protein made. Most mutations occur in what is called junk DNA. 48 BIOTECHNOLOGY Genetic engineering is the use of technology to alter the genome of organisms for medical or industrial purposes. Biotechnology includes genetic engineering and other techniques that make use of natural biological systems to produce a desired product. Human DNA and plasmid DNA (from a bacterium) are cleaved by a specific type restriction enzyme and spliced together by the enzyme, ligase. The host cell takes up the recombined plasmid and as the host cell reproduces, the plasmid does also. Multiple copies of the recombinant DNA are made in a short period of time. This new DNA may make a desired protein such as the following: insulin tPA interferon erythropoetin HGH interleukin-2 factor VIII TNF Draw the process of cloning of a human gene (gene splicing) below: 49 DNA FINGERPRINTING 1. DNA from blood, hair, other body fluids, etc. is isolated and purified. 2. Restriction enzymes cut the DNA sample into fragments or RFLPS (Restriction Fragment Length Polymorphisms). 3. DNA fragments undergo electrophoresis, which means they are placed in a tray of agarose gel and given an electrical charge. This separates the different fragments according to size. Larger fragments, due to resistance, move to the positive pole slower than the shorter ones. (Negatively charged phosphates in DNA cause the molecule to be attracted to the positive pole). A bar code similar to those found in supermarkets is produced. 4. This bar code can then be dyed and viewed for comparison. However, at this point, Southern blotting can be done. This is accomplished by placing a nylon membrane over the DNA that has been in a cellulose gel and adding a blotting paper. The DNA is absorbed into the nylon membrane by capillary action. This nylon membrane with DNA can then have radioactive probes added. These probes are single stranded DNA fragments found at several common sites on chromosomes and are referred to as VNTR’S. Where the DNA sample on the nylon matches the probes, they join, and the emission of radiation shows up on film when x-rayed. If there is an insufficient amount of DNA in the sample, it can be greatly duplicated by a process known as PCR (polymerase chain reaction). The enzyme, polymerase, is added along with a primer and millions of copies of the DNA can be made in a short period of time. DNA fingerprinting is used in the following ways: paternity cases forensic science identifying heredity relationships identifying patterns of inheritance of conditions such as cystic fibrosis, Huntington’s disease, Alzheimer’s disease, and many others. 50 GENETICS Father of Heredity - Gregor Mendel When Mendel crossed tall pea plants with short pea plants, all of the offspring were tall. When he crossed the tall offspring with themselves, the outcome was a 3:1 ratio of tall to short. He first realized that plants have 2 factors for each trait which we now call genes. (except for the gametes) Draw the Punnett squares below. Mendel’s Law of Segregation states that genes separate in the formation of gametes. Each gamete receives only one factor from each pair of factors. Terminology 1. 2. 3. 4. 5. 6. 7. 8. Parental generation (P) - original organisms that were crossed First filial generatin (F1) - offspring of P generation Second filial generation (F2) - offspring of F1 generation Phenotype - physical appearance of an organism Genotype - genes actually present on the chromosome Dominant gene - gene that will always be expressed; ( a capital letter) Recessive gene - gene that is masked by a dominant gene; ( a small letter) Homozygous - 2 genes for the same trait that are identical; Examples would be represented by TT (both dominant genes) or tt (both recessive genes) 9. Heterozygous - 2 genes for the same trait are different Example would be a genotype of Tt; the phenotype would be tall. 10. Monohybrids - heterozygous for only 1 pair of genes 11. Dihybrids - heterozygous for 2 pairs of genes See handout for one and two-trait genetic crosses. The expected ratios are given. 51 Genetic Disorders Some disorders are dominant. Examples: NEUROFIBROMATOSIS - tan spots, benign tumors HUNTINGTON DISEASE - progressive degeneration of brain cells Some disorders are recessive. Examples: TAY SACHS DISEASE - lack of a lysosomal enzyme; blind, helpless, seizures, “cherry red spot” in eyes CYSTIC FIBROSIS - mucus build-up in bronchial tubes and pancreatic ducts PHENYLKETONURIA - lack of a specific enzyme which breaks down phenylalanine----- mental retardation possible Some disorders are caused by variations in the sex chromosomes; not the autosomes. Examples: TURNER SYNDROME - an XO female KLINEFELTER SYNDROME - an XXY male JACOBS - AN XYY male Some disorders are X-linked (carried on the X chromosome). Males only have 1 X chromosome so these recessive genes are expressed. Examples: COLOR BLINDNESS - 1 gene affects green-sensitive cones; another affects red HEMOPHILIA - free-bleeder’s disease MUSCULAR DYSTROPHY - muscle weakness------wheelchair confinement Chromosome mutations cause disorders. Examples: Inversion - a segment is turned completely around Translocation - a segment moves to another non-homologous chromosome Deletion - a segment breaks off (Cri du chat syndrome) Duplication - a segment occurs more than once in the same chromosome Incomplete dominance of genes can cause disorders. Example: SICKLE-CELL DISEASE - abnormal hemoglobin causes misshaped rbc’s 52 VIRUSES Characteristics 1. noncellular 2. composed of DNA or RNA surrounded by a protein coat called a capsid 3. protein coat may be covered by a lipid envelope 4. cannot reproduce outside a living cell 5. are specific - they often attack specific cells at specific receptor sites 6. most are seen only with electron microscopes 3 Major Classes 1. Bacteriophages - attack bacteria only 2. Plant - move in through pores in cell wall 3. Animal - 50% or more have envelopes which fuse with host’s cell membrane Viruses are responsible for many diseases or infections. A few are mentioned below: Category Disease Sexually transmitted diseases AIDS, genital warts, genital herpes Childhood diseases mumps, measles, chicken pox, German measles Respiratory diseases common cold, influenza Skin diseases warts, fever blisters, shingles Digestive tract diseases gastroenteritis, diarrhea Nervous System diseases poliomyelitis, rabies, encephalitis Other diseases cancer, hepatitis There are numerous significant bacterial diseases or infections in humans. A few are mentioned below. Category Disease Sexually transmitted diseases syphilis, gonorrhea, chlamydia Respiratory diseases strep throat, scarlet fever, tb, pneumonia Skin diseases boils, carbuncles, impetigo, wound infections Digestive tract diseases gastroenteritis, food poisoning, dysentery, cholera Nervous system diseases botulism, tetanus, spinal meningitis, leprosy Systemic diseases plague, typhoid fever, diphtheria Other diseases gas gangrene, toxic shock syndrome, Lyme disease Anti-viral drugs are few in comparison to antibiotics; antibiotics have no effect on viruses. What are prions? ________________________________________________________ Examples of conditions caused by prions- _____________________________________ What are viroids ?________________________________________________________ Examples of conditions cause by viroids- ____________________________________ 53 2 Types of Viral Infections: 1) Lytic--usually destroys bacterial cells 2) Lysogenic--the viral DNA is incorporated into the host cell DNA and becomes a part of the cell; this DNA is passed on generation to generation and is called a prophage; may cause exotoxin production in bacterial cells Steps of Lytic Infections in Animal Cells: 1) Adsorption--The virus attaches to a specific receptor on the host cell membrane. 2) Penetration--The envelope fuses with the cell membrane and the virus goes in or is engulfed by pinocytosis; uncoating of the virus occurs. 3) Biosynthesis--This step is referred to as the latent period because no new viruses are made yet--just the viral parts--the DNA replicates and proteins are encoded. 4) Maturation or assembly--The viral parts are put together--virions are produced. 5) Release--The host cell may burst or budding of host cell may occur and virions are released to attack other cells if not phagocytosed by macrophages in the bloodstream. There are a few differences in the lytic cycle of bacterial cells. 1- Only the viral DNA enters the cell. 2- The host cell typically bursts. 3- Fewer virions are released. However, the steps are very similar. See next page of syllabus to view this lytic cycle. About 50% of human diseases are viral related. 54 PROCARYOTES Bacteria and archaea are examples; these are referred to as domains. Bacteria are ubiquitous--one pinch of dirt contains as many as 200 million bacteria. Gross Morphology of Bacteria: (refers to size, shape, and arrangement as can be observed with a light microscope) Size--the average length of a bacterial cell is from 2 to 8 micrometers Shape--the characteristic by which most bacteria are classified 1) coccus (round) 2) bacillus (rod-shaped) 3) spirillum (helical) The Spirillum genus has flagella for locomotion. These bacteria are rigid. The spirochete group is thinner and has axial filaments instead of flagella. The Vibrio genus is comma-shaped and is often considered to be rod shaped. Arrangement 1) as single cells 2) pairs--diplo 3) chains--strepto 4) clusters--staphylo 5) a group of 4--tetra 6) a group of 8--sarcina Fine Structure of Bacteria 1) cell wall--composed of layers of peptidoglycan (simple sugars joined by cross- bridges of amino acids) [not present in archae] The cell wall of some bacteria is thicker than others and has a lower lipid content. These bacteria are referred to as Gram-positive. The bacteria with thinner peptidoglycan layers and a higher content of lipids are referred to as Gram-negative. Gram-positive bacteria generally respond to penicillin but Gram-negative usually do not. 2) cell membrane--composed of phospholipid and protein 3) capsule or glycocalyx--composed of polysaccharide or polypeptide and may function in attachment of polysaccharide fibers, protection, or nourishment 4) genetic material--DNA a) chromosome--contains an average of 4000 genes; only one present in cells b) plasmid--contains from 5 to 100 genes; can be transmitted to other cells 55 Endopores: Some bacteria produce dormant bodies called endospores which contain genetic material and a few enzymes encased within a thick protective coat. These spores can withstand extreme temperatures, irradiation, drying, various chemicals, etc. They have the ability to change back into the original cell when environmental conditions become more favorable. Almost all Bacillus bacteria produce endospores. Growth Curve: Bacteria reproduce at different rates. If one bacterial is isolated, it does not immediately reproduce; it first must metabolize (build protein,etc.) This period of time is known as the lag stage of growth. After this stage, rapid reproduction begins. This period is known as the log stage of growth. Eventually, the number of cells dying equals the number of cells living. This is referred to as the stationary stage of cell growth. Then, there is a massive dying of cells known as the death stage. The bacterial cells are depleted of nourishment and/or toxins accumulate. Draw below. Prokaryotes reproduce by binary fission. They may be anaerobic or aerobic. Some are able to ingest materials that are toxic to us, including petroleum and methane. Some prokaryotes are able to capture nitrogen needed by plants. They play a crucial role in recycling waste. Most prokaryotes are harmless, but some are pathogenic or disease-causing. 56 THE PROTISTA KINGDOM The protists may be classified as follows: The chromists--_______________________________________________________ Diatoms--______________________________________________________ Brown algae-___________________________________________________ The alveolates--_______________________________________________________ Dinoflagellates-_________________________________________________ Apicomplexans-_________________________________________________ Ciliates-_______________________________________________________ What are slime molds?__________________________________________________ Other protists: Amoebas-_______________________________________________________ Foraminiferans-__________________________________________________ Radiolarians-____________________________________________________ How do these move?____________________________________________________ Green algae include the following : Unicellular:____________________________________________________________ Multicellular:___________________________________________________________ Protozoa are mostly microscopic. Also, most can form cysts (multi-layered ball stages) and are transmitted in this stage as a means of survival . 57 See pictures in text. ALGAE ARE AUTOTROPHIC LIKE PLANTS. MOST ARE AQUATIC. PROTOZOA ARE ANIMAL-LIKE. THEY ARE USUALLY HETEROTROPHIC. 58