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Transcript
Unit 1 1a. Scientific Method 1b.Life Characteristics 1c. Microscopes 1d. Cell Structure 1e. Osmosis 1f. Cell Energy Unit 1a Scientific Method I. The Scientific Method a. PHEOC 1. Problem -What is wrong, or what you are interested in understanding 2. Hypothesizing (An “If . . . then . . .because. . . ” statement) i. ii. 3. . explanation for a question educated guess Experimenting – The physical steps you take (The Requirements) i. ii. Control = The condition(s) that is kept the same Independent Variable = Condition that is changed – The different/new thing you are testing. iii. Dependent Variable = The condition that results from changes in the independent variable – What you want the Independent variable to do 4. 5. Observing – Data Conclusion – If your hypothesis is correct or not and why. 1. Talk about your data and how you can improve the experiment II. How Do We Write a Hypothesis? a. Three Requirements 1. If…,then… because statement 2. Can be tested 3. Be Specific! How to write Hypotheses Examples: 1. Incorrect: Chocolate may cause pimples Correct: If chocolate causes pimples, then people who eat lots of chocolate will get pimples, because chocolate leaves toxins in the intestinal tract. 2. Incorrect : Salt in soil may affect plant growth. Correct: If salt affects plant growth, then plants with exposure to excessive amounts of salt will not grow, because the salt sucks the water out of the soil. 3. Incorrect: Plant growth may be affected by the color of light Correct: If light color affects plant growth, then plants will grow the tallest in white light, because the light is a mixture of all colors. 4. Incorrect: Bacteria growth may be affected by temperature Correct: If temperature affects bacterial growth, then bacteria will not grow if the temperature gets to 0 C because the temperature is too cold for bacteria to reproduce. 5. Incorrect: Ultra violet light may cause skin cancer Correct: If skin cancer is caused by ultraviolet light , then people with a high exposure to uv light will have a higher frequency of skin cancer, because ultra violet light will mutate skin cells. 6. Incorrect: Temperature may cause leaves to change color Correct: If leaf color change is related to temperature , then exposing plants to low temperatures will result in changes in leaf color, because the low temperatures cause the chlorophyll to break down. Ex. Scientific Method • Problem/Observation: – The flashlight doesn’t work • Hypothesis #1: – If the batteries are dead, then replacing them will cause the flashlight to work • Test Hypothesis #1 in Experiment #1: – Replace batteries • Results observed in Experiment #1: – After replacing batteries: flashlight still doesn’t work • Conclusion: – The batteries were not the problem • New Hypothesis: – If the bulb is damaged then replacing the bulb will cause the flashlight to work. • Test New Hypothesis in Experiment #2: – Replace bulb • Results observed in Experiment #2: – After replacing bulb, flashlight now works • Conclusion: – The bulb was burnt out and the flashlight needed a new one to function properly. III. What is the difference between hypothesis, theory & law? 1. 2. 3. Hypothesis - “an educated guess”; a tentative explanation of phenomena. Theory - a widely accepted explanation of natural phenomena; has stood up to testing. Law - a statement of what always occurs under certain conditions. IV. Kinds of Information a. Quantitative = numerical data i. There were 7 blue birds after 3 months. b. Qualitative = observational data (no numbers) i. A Red and Yellow bird couple gave birth to all blue birds. c. SI = International System of Measurements i. Base Units 1. 2. 3. 4. Length = meter Mass = gram Volume = liter Time = second Unit 1b. Life Characteristics I. Characteristics of Life a. What makes something living? i. ii. iii. iv. v. vi. Has an orderly structure Produce offspring Grow and develop Requires energy Expels waste / Respiration Made of at least one cell i. A cell in and of itself is considered a living thing because it performs all of these functions. vii. Adjust to change in the environment involves. . . 1. Responding to Stimuli a. Ex. Getting a shot (the stimulus) makes you flinch 2. Homeostasis = Regulation of organism’s internal environment to maintain conditions suitable for survival. a. Ex: humans sweating and shivering 3. Adaptation = Inherited from generations (over time) that enables an organism to survive & reproduce Living or NonMule? Living? Liger? • Characteristics of life are subjective to human reasoning. II. All living things share common chemical compounds that help them to survive – Carbohydrates • are sugars and starches that provide energy for humans and animals • Carbohydrates are made up of simple sugars known as mono(one) saccharides: – Ex. Glucose • di- (two) saccharides = two monosaccharide joined together – Ex. Sucrose • poly- (many), saccharides, = many monosaccharides linked – Ex. Glycogen (in animals), Cellulose (in plants) – Lipids • These are fats, oils, and waxes • The three major purposes of lipids are 1. 2. 3. energy storage cell membrane development serving as a component of hormones and vitamins in the body. • Lipids don’t dissolve (non-soluble) in water. – – One part is hydrophobic = fear of water Other part is hydrophilic = loves water – Proteins • Required for the structure, function, and regulation of the body’s tissues (hair, nails, etc.) and organs. • They do most of the work inside and outside cells – Ex. Enzymes are proteins that do jobs for the cell and they regulate the body’s tissues and organs. – Ex. Antibodies are used to target viruses and bacteria for destruction. – Without certain proteins we wouldn’t be able to move around. • Proteins are made up of hundreds or thousands of smaller units called amino acids. – Nucleic acids • Is the genetic information that can be passed from parent to offspring. Composed of Nucleotides that are made up of three parts • – – – • Nitrogenous Base Monosaccharide Phosphate group Ex. are DNA and RNA Unit 1c. Microscopes I. Microscopes a. Compound Light Microscopes i. Magnify objects 1500 times b. Electron Microscopes i. Uses electrons instead of light to magnify structure up to 500,000 times 1. SEM= Scanning Electron Microscope a. Scans the surface of cells to learn 3-D shapes Electron Microscope Images Anatomy of a Microscope Unit 1d. Cell Structure and Function II. Two Types of Cells 1. Prokaryotes i. ii. iii. iv. NO NUCLEUS- DNA is floating freely inside cell! Smallest cells / unicellular – made of one cell No cellular organs (organelles) Ex: bacteria 2. Eukaryotes i. DNA is held in the nucleus ii. Contains organelles iii. Eukaryotic cells are MUCH BIGGER then Prokaryotic cells. iv. Can be multicellular or unicellular v. Ex: animals, plants, fungi, protist III. Discovery of Cells 1. Robert Hooke i. British scientist who first observed and named cells ii. studied bark of trees in 1665 2. Virchow i. Russian Scientist came up with the Cell Theory: 1. All organisms are composed of one or more cells 2. The cell is the basic unit of organization 3. All cells come from preexisting cells IV. What are Organelles? I. II. Tiny organs of a Eukaryotic cell Most organelles have an outer membrane layer. i. ii. Membranes are made of lipids The lipid membranes keep the inside of the organelle separate from the outside. (like a wall) III. Each Organelle has a job to do. IV. There are a lot of different organelles. 1. Plasma membrane i. Structure and Security ii. Surrounds the entire cell iii. Made of Phospholipids and Proteins 2. *Cell Wall- (Plants Only) i. Used for structure (Helps plants stand up) ii. Surrounds the entire cell (even the plasma membrane) iii. Like a solid wall 3. Cytoplasm- Work Area (Not really an organelle) i. ii. The fluid that makes up the inside of the cell. Organelles and proteins work in this space. 4. Nucleus- main office i. Where the DNA is kept. a. DNA is the blueprint for making proteins ii. Ribosomes are made in the nucleolus. 5. Ribosomes- worker-bees i. They help make proteins 6. Endoplasmic Reticulum (ER) i. Two Types a. Rough ER- Finishes protein- Specialized proteins are completed here and shipped off to other parts of the cell. i. Located next to the nucleus. ii. Where ribosomes are located. b. Smooth ER- Makes Lipids / Breakdown toxins 7. Golgi Complex i. Package & ships proteins to other parts of the cell. a. Golgi receives and sends proteins in objects called Vesicles. 8. Lysosomes i. recycling & waste removal a. b. Can break up food particles into smaller parts for cell to use. Can break down old useless organelles 9. *Chloroplast (Plants Only) i. Converts light into Carbohydrates. a. Carbohydrates are used by the cell for energy! 10. Mitochondria i. Provides cell with energy! a. Does this by breaking down Carbohydrates. 11. Vacuole i. ii. Stores water and waste/toxins In plants, puts pressure against the cell wall to keep cell rigid. 12. Cilia & Flagella i. ii. Cillia - catches particles Flagella - used for movement. Comparison of Animal and Plant cells Lysosome Vesicle Fungus-like Plant-like Animal-like Unit 1e. Osmosis V. How stuff gets into and out of the cell 1. Passive Transport i. Particles can enter and exit the cell without the use of energy. 1. Carrier Proteins move small particles into the cell. 2. Diffusion moves very small particles from an area of high concentration to an area of lower concentration. 2. Active Transport i. Particles can enter and exit the cell with the use of energy 3. Endocytosis (“in to” the cytoplasm) a. The process where a cell will take in foreign substances. 1. This is done by the cell wrapping its cell membrane around a substance and literally “taking it in.” 4. Exocytosis (“exit” the cytoplasm) a. The process where a cell will release substances from itself. 1. This is done by vesicles fusing with the cell’s cell membrane. VI. How water moves in and out of a cell. a. There must first be a Concentration gradient! i. ii. b. Difference in concentration of stuff across a space Diffusion will continue until there is no concentration gradient - - equilibrium has occurred. Osmosis i. ii. The diffusion of water. Water molecules moving from an area of high concentration to an area of low concentration VII. Three types solutions 1. Isotonic = a. Concentration of non-water molecules outside the cell is the same as the concentration of non-water molecules inside the cell. (i.e. equal water inside and outside of cell) b. Water will move in and out of cell at same speed. c. Cell keeps its shape 2. Hypotonic = a. High concentration of non-water molecules inside the cell (i.e. less water inside) b. Low concentration of non-water molecules outside of the cell (i.e. more water outside) c. Osmosis will cause water to move into the cell d. Cells will get bigger . . . and explode!!! 3. Hypertonic a. High concentration of non-water molecules outside of the cell (i.e. Less water outside) b. Low concentration of non-water molecules inside the cell (i.e. More water inside) c. Osmosis will move the water out of the cell d. Cell will shrink VIII. Osmosis in Plant cells 1. Turgor Pressure a. Pressure that builds inside of a cell as the result of osmosis b. Helps plant cells to keep the plant “standing up.” 2. Plasmolysis a. Loss of water resulting in a drop in turgor pressure b. Causes plant cells to wilt Unit 1f. Energy in a cell IX. Cell Energy – ATP – ATP is the energy source used by cells • • Ex.: Powers the creation of proteins and used to maintain homeostasis. In order to get ATP cells need carbohydrates Photosynthesis – Creates Carbohydrates – – Plant cells use sun’s energy to split water into separate Hydrogen and Oxygen atoms. Freed Hydrogen combines with CO2 to make carbohydrates and oxygen is released Cellular Respiration – Breaks down Carbohydrates – the process by which mitochondria use oxygen to break down food molecules (carbohydrates) to produce ATP, CO2, and water