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a short review of biology I 1. what does it mean to be alive 2. basic chemistry 3. what goes on in a cell 4. basic genetics 5. cell division (mitosis & meiosis) Carol is a college student Carol eats pizza all college students eat pizza Is this always true – NO this is INDUCTIVE REASONING BUT all men are mortal Tom is a man Tom is mortal is this always true = YES this is deductive reasoning Carol is a college student Carol eats pizza all college students eat pizza Is this always true – NO this is INDUCTIVE REASONING BUT the thousands of pages written by Darwin can be summarized in a simple statement the rearrangement of genes that takes place every time an egg and sperm are made can result in an advantage for survival and reproduction which over time will spread through a population and can change a population so that it no longer looks like it’s ancestors Darwin concluded that what he was seeing was 1)the result of an animal from one environment moving into a new environment and 2)changing slowly over time through sexual reproduction to become 3) more adapted to the new environment and 4) more sexually successful in the new different environment the changes in color, anatomy, size, physiology, and more over time produced a very different organism or an organism can change in its present environment to become more successful (pass on its genes= have more sex) when protons are equal to electrons - neutral atom when protons do not equal electrons – atom is an ion if there are more protons than electrons – positive cation if there are more electrons than protons – negative anion electrons determine the chemical behavior of atoms how when the outer electron shell of an atom is not full it will give away electrons, or get electrons from other atoms, or share electrons with other atoms in order to have the outer shell filled carbon has 4 electrons in its outer shell two carbons share their outer 4 electrons making an outer shell in each atom with 8 electrons thus each has a full outer shell with 8 electrons forming a covalent bond the electrons travel so fast that it is as if the 8 electrons are in both atoms at the same time the ability of atoms to form chemical bonds is influenced by - temperature (2x for every 10C) - concentration -catalysts (enzymes) - pressure (keeps atoms closer together) I will on many occasions mention the shape of a molecule why because molecules cannot talk to each other molecules cannot use a phone to tell you something so molecules react according to their shape they fit together like pieces of a puzzle message to cell – membrane carries message to cytoplasm - series of chemical changes take place in cytoplasm (transduction) - changes carry message to nucleus - in nucleus message cause 1 gene to unwind - DNA of gene makes a copy of the gene - the copy is known as messenger RNA (mRNA) -mRNA leaves the nucleus -mRNA stimulates RER to make a protein (enzymes and more) - enzyme tells cell what work to do at every step chemicals fit together like pieces of a puzzle if the pieces do not fit the process stops DEHYDRATION when 2 molecules are joined together to form a larger compound a H is removed from 1 reactant and an OH is removed from the 2nd reactant resulting in the formation of a molecule of water the reactants were dehydrated water was removed from the reactants and is now free in the cell HYDROLYSIS when a large molecule is being split by an enzyme then water is split to H and OH the H is added to one part and OH is added to the other part water was split and the subunits were added to the hydrolyzed compound resulting in the loss of a water molecule from the cell proteins have many functions -as enzymes-tell the cell what work to do -defense-fight infection and disease -transport-oxygen, hormones, through membranes -support-hair, skin, bone, muscle, -motion-muscles, tendons, ligaments, mitosis, meiosis -regulation-hormones, enzymes, gene activation -storage- calcium, iron, oxygen Proteins can be enzymes hormones transporters immune modulators receptors structural energy storage motion the cell theory 1. all living things are made up of one or more cells 2.cells are the basic building block of all organisms 3. cells come from other cells cells are small because of the ratio between surface area compared to volume surface area is represented by the cell membrane volume is represented by the cytoplasm (liquid in the cell) and it’s contents as a cell grows the surface area increases but not as fast as the cytoplasm inside the cell eventually the cell becomes too big and the cell membrane can no longer keep up with the needs of the inside of the cell and this becomes the stimulus for the cell to divide and become two smaller cells prokaryotes primitive cells - a simple but effective structure - one (1) strand of DNA some have a second - cell membrane and cell wall - move by pili and flagella - pili also used for attachment and gene exchange - have free ribosomes - no membrane bound organelles - no nucleus scavengers, carnivores, photosynthetic, decomposers eukaryotes advanced cells compartmentalized organelles nucleus protects genetic material internal endomembrane system internal transport system you have eukaryotic cells in your bodies DNA contains the genetic code(for many genes) one gene makes one kind of RNA mRNA goes to the cytoplasm and a protein is made many of the proteins are enzymes there are thousands of mRNAs rRNAs form ribosomes in the cytoplasm (protein factories) tRNAs bring amino acids to ribosomes to make up a protein the enzymes then link up with other cell components and cause the chemical reactions of those components to work millions of times faster then when the enzymes are not present in other words enzymes tell the cell what work to do when done the enzymes are recycled completed products from the RER, SER or free ribosomes are secreted as transport vesicles which fuse with the Golgi apparatus materials enter the Golgi apparatus from the RER and the SER as transport vesicles are rearranged and are packaged (made ready for delivery to where they are needed) these products are pushed out of the Golgi at the ends of the membranes (cisternae) in the from of secretory vesicles the vesicles which leave the Golgi can be used outside of the cell or in the cell many secretory vesicles combine with the cell membrane and by exocytosis are moved out of the cell in order to survive a cell needs energy mitochondria produce a high energy phosphate molecule known as ATP adenosine tri phosphate which produces the energy used by cells to do work the inside of a cell is a thin Jello-like cytoplasm the cell membrane is a thin layer of phospholipid if this was all that a cell had the cell would collapse but a cell has a cytoskeleton a series of actin filaments, microtubules, and intermediate filaments which allow a cell to retain a circular shape many of the cells components are organized into functional complexes organelles, enzymes, microbodies, molecular motors and more are in close proximity to each other so that all of the things needed to do work are right next to each other a cell membrane is much more than a simple skin animal cells secrete an extracellular matrix which is made up of fibrous proteins (collagen) glycoproteins (receptors, transporters) elastin (membrane strength & shape) integrins (chemical & mechanical signals) which cover the outside of the cell membrane -a chemical is floating in the liquid outside a cell -a membrane projection links up with the chemical -causes change in shape of a membrane chemical -cause chemical change in cytoplasm -change eventually causes chemical change in nucleus -one gene is opened up and copied as mRNA -mRNA leaves nucleus links up with ribosome -ribosome makes proteins and enzymes -enzyme stimulates 1 chemical reaction to work very fast -product goes to Golgi for rearrangement and packaging -Golgi releases vesicle which is moved by molecular motor -vesicle use in cell or is moved out of cell cell junctions cells that are next to each other interact with each other adhere to each other communicate with each other see fig. 6.30 page 120 tight junctions = two cell membranes glued together desmosomes = rivets or screws holding two cell membranes close to each other allowing some movement gap junctions = connects the cytoplasm of adjacent cells allowing material to move between the cells cell membrane protein functions are very important -transport (in & out of cell) -enzymes (many reactions on & in membrane) -surface receptors (chemical puzzle pieces) -surface identifiers (shows who the cell is) -adhesion (temporary & permanent attachments) -cytoskeleton (intra & inter connections) end result of diffusion is always equilibrium when the molecule concentration is equal on both sides of a membrane molecules move in and out at same rate so once equilibrium is reached the concentration remains the same which way water will move is determined by the concentration of water as a solvent and various chemicals as solute for example water will move across the membrane from an area of higher water concentration to an area of lower water concentration until the concentration of water is equal on both sides of the membrane isotonic = solute concentration the same on both sides hypotonic = side with less solute concentration hypertonic = side with more solute concentration active transport can move molecules against a concentration gradient the end result of diffusion is equilibrium but active transport can concentrate material on one side of a membrane active transport can move molecules from an area of low concentration to an area of higher concentration movement of material in and out of the cell is referred to as -endocytosis -exocytosis -phagocytosis -pinocytosis -receptor mediated endocytosis phagocytosis refers to taking in particulate matter pinocytosis refers to taking in liquid receptor mediated endocytosis refers to a process whereby membrane receptors are concentrated in an area and when bound to a target molecule the membrane folds inwards into a vesicle transporting the target molecule into the cell anabolic = use energy to build up catabolic = use energy to breakdown heat = energy moves from one item to another chemical energy = potential energy available from chemical reactions pathways = steps from raw material to finished product metabolism = chemical reactions of an organism ATP has 3 phosphate bonds each is a positive functional group to keep a 2nd group in place requires some energy but to keep a 3rd positive bond attached requires a large amount of energy when the energy of the 3rd bond (high energy bond) is released it is used to do work enzymes are not destroyed when they are used to do work they are used over and over until they are not needed then they are recycled in order to make the chemistry of cells more efficient enzymes needed to accomplish a specific task are part of a multienzyme complex all of the enzymes needed for one job are right next to each other so that the individual steps needed to form a product take place right next to each other remember that most biological reactions involve oxidation or reduction oxidation = loss of an electron reduction = gain of an electron electron donor = reducing agent electron acceptor = oxidizing agent aerobic = in presence of oxygen anaerobic = without oxygen glycolysis is a three step process which takes place in the cytoplasm of ALL cells it starts with glucose and ends with 2 molecules of pyruvate (acidic) 2 ATP 2 molecules of NADH 2 H+ (acidic) and 2H20 pyruvate also known as pyruvic acid must not be allowed to build up in a cell in primitive organisms pyruvate is broken down by fermentation to produce products which will not harm the cell in eukaryotic cells pyruvate enters mitochondria and pyruvate is oxidized in a multienzyme complex to acetyl coenzyme A and CO2 and NADH are produced (see fig. 9.11) pyruvate + NAD++ CoA acetylCoA + NADH + CO2 + H+ we have 46 chromosomes 23 from mom 23 from dad the only time that we can actually get to see the 46 chromosomes is during cell division we have 46 chromosomes 23 from mom 23 from dad the only time that we can actually get to see the 46 chromosomes is during cell division the cell cycle consists of 1. interphase (not part of mitosis) 2. prophase 3. metaphase 4. anaphase 5. telophase 6. cytokinesis gametes = eggs and sperm eggs and sperm = haploid (half a set) somatic cells = diploid (full set) what do you inherit? – genes what are genes = messages for what a cell should do where are genes located? – on chromosomes what do we pass on to the next generation? genes mutations variations of combinations it is as if you took a few thousand genes which occur as pairs and you rearranged them randomly and for the fun of it you see what happens 1. double the chromosomes (4 become 8) 2. form tetrads 3. exchange genes 4. line up at midplate 5. pull apart chromosomes so sister chromatids are intact 6. cell becomes 2 cells(each with 4 chromosomes) 7. sister chromatids in 2 cells line up at midplate 8. sister chromatids pulled apart 9. 2 cells become 4 cells each with 2 chromosomes dominant = if gene is present trait will be seen recessive = dominant gene must be absent for trait to be seen pure = both genes for a trait are identical hybrid = 2 genes (alleles) for the same trait homozygous = same as pure heterozygous = same as hybrid genotype = combination of genes for a trait phenotype = result of a genotype P = parent organism F1 = first generation after the P generation F2 = result of cross of F1 with F1 Gregor Mendel is called the Father of genetics because he came up with the idea that organisms carry a pair of “something” for each trait and that we only pass on 1 of these “somethings” to our offsprings here is what Mendel did 1. he chose specific traits in pea plants 2. he took plants which he knew were pure breeding 3. then he crossed them with other pure breeding plants 4. and he saw what the F1 generation looked like 5. then he crossed F1 with F1 and saw what the F2 looked like 6. but unlike others he did it quantitatively 7. he was lucky that all of the traits he chose were controlled by a single pair of genes 1. he made sure he had pure breeding plants 2. he crossed pure with same pure 3. he crossed pure with different pure 4. he crossed non pure with non pure 5. most important he recorded the numbers and here is what he got what he concluded was that whatever was controlling the traits came in pairs that each parent gave one of the pair to its offsprings that a parent can have an identical pair or a parent can have a non-identical pair he concluded that whatever was passed on was discrete (it was a thing) although he had no idea what it was Mendel’s 5 element model 1. parents pass on “factors” to their offsprings 2. each offspring gets one copy of the “thing” from each parent 3. the “things” come in 2 different forms 4. the “things” remain separate and do not affect each other 5. presence of a “thing” does not guarantee it’s expression Principle of Segregation two alleles for a gene/trait segregate during gamete formation and are rejoined at random one from each parent during fertilization there is no plan which controls which one of the two “things” will end up in an egg or sperm it is random