Term
|
Definition
| the number of protons in an atoms nucleus |
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Term
|
Definition
| the weight of protons and neutrons together. |
|
|
Term
|
Definition
| the degree to which an atom attracts electrons. atoms that gain electrons are more electronegative than atoms that lose electrons. |
|
|
Term
|
Definition
| the outermost orbital or electron shell of an atom. can only contain 8 electrons; once full an atom is stable and doesn't interact as well with other atoms. |
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|
Term
| how are ionic bonds formed? |
|
Definition
| ionic bonds are formed when an atom of high electronegativity (wants e-) interacts with an atom of low electronegativity (gives e-). the final charge of the molecule is neutral and both atom's valence shells are satisfied. |
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|
Term
| how are covalent bonds formed? |
|
Definition
| covalent bonds are formed between atoms that are very similar in electronegativity interact. they share electrons to fill their valence shells and neither atom attracts the electron more. |
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|
Term
| how are polar covalent bonds formed? |
|
Definition
| polar covalent bonds are formed when atoms that differ slightly in electronegativity interact. in water, oxygen attracts the shared electrons slightly more than the hydrogen atoms do due to differences in electronegativity, giving the oxygen end of the molecule a weak negative charge and the hydrogen end of the molecule a weak positive charge. |
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Term
|
Definition
| one oxygen + two hydrogens. polar. molecules connect oxygen-hydrogen with hydrogen bonds. |
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|
Term
| high specific heat of water |
|
Definition
| hydrogen bonds absorb lots of heat |
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Term
|
Definition
| molecules at the surface tend to be pulled inwards, while molecules inside are pulled in all directions. this results in a membrane on the surface of water. (attraction between molecules is very strong) |
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Term
| solvent properties of water |
|
Definition
| water is polar, which means it dissolves polar compounds very easily. |
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Term
|
Definition
| water becomes more dense as it cools, but when frozen it's less dense. this is because the hydrogen bonds become rigid and permanent between molecules as there is no energy left to break them. |
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|
Term
| capillary and imbibition of water |
|
Definition
| water molecules are cohesive (they stick together to a certain degree) allowing them to climb up surfaces like paper towel |
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|
Term
| high heat of vaporization of water |
|
Definition
| because water has a high specific heat, therefore takes a lot of energy to change state. |
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Term
| condensation/dehydration reactions |
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Definition
| the process of removing a H2O molecule from a compound, forming a chemical bond in the process. this is useful for forming polymers out of two or more monomers. |
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Term
|
Definition
| the process of adding a H2O molecule to a polymer and breaking a chemical bond to produce two or more monomers. produces energy. |
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Term
| carbohydrate structure and disaccharide/polysaccharide formation. |
|
Definition
| carbs have the general formula (CH2O)n. monosaccharides take on a ring shape in solution. disaccharides are 2 monosaccharides and polysaccharides are 2 or more monosaccharides. formed by condensation/dehydration synthesis, creating a glycosidic bond. |
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|
Term
| amino acid structure and protein formation |
|
Definition
amino acids have 2 functional groups, COOH- and NH2, as well as an R group.
H H O
| | ||
N-----C------C
| | |
H R O-H
peptide bonds are formed in proteins by dehydration/condensation synthesis where the H+ is removed from one amino functional group of one acid and and OH- is removed from the carboxylic functional group of another acid. this links them together in a peptide bond. |
|
|
Term
| primary protein structure |
|
Definition
| a long chain of amino acids linked by peptide bonds. -> polypeptide chain. |
|
|
Term
| secondary protein structure |
|
Definition
| forming the alpha helix or the beta pleated sheet. hydrogen bonding between functional groups NH+ and CO-. |
|
|
Term
| tertiary protein structure |
|
Definition
globular shape. created by the folding of the chain in 3D. Disulfide brigdes are strong covalent bonds between amino acids.
This structure determines the protein function. |
|
|
Term
|
Definition
extremes in pH and temperature change the structure of a protein.
pH changes the charges on substrates and enzymes, resulting in a change in shape and inability to function.
temperature breaks hydrogen bonds and ionic interactions cease, changing structure.
heavy metals are attracted to the strong covalent disulfide bonds in the tertiary structure and break them, resulting in denaturation. |
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|
Term
| fatty acids (saturated/unsaturated) |
|
Definition
straight chain monocarboxylic acids, have a terminal group of COOH-.
saturated fatty acids: no double bonds between carbons. straight chain, packed together tightly, solid @ room temp.
unsaturated fatty acids: bent chain, double bonds between carbon, not packed tightly, liquid @ room temp. |
|
|
Term
|
Definition
3 fatty acid monomers and 1 glycerol molecule: triglyceride. ester linkage.
formed by condensation synthesis creating ester links. |
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|
Term
|
Definition
| key component of cell membrane. polar, with hydrophilic head and hydrophobic tail. 2 fatty acids + glycerol + phosphate group. |
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|
Term
| diffusion and free energy |
|
Definition
| the diffusion of a solute from one place to another is due to the free energy of the molecules on either side of a membrane. the molecules with a higher free energy will diffuse faster across the membrane, meaning that the net transfer of solute will tend to one side of the membrane. |
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|
Term
|
Definition
| the diffusion of water from one place to another is due to the free energy of the molecules on either side of a membrane. the molecules with a higher free energy will diffuse faster across the membrane, meaning that the net transfer of water will tend to one side of the membrane. water molecules that are concerned with a solute will have less free energy and the net transfer of water will tend to the side with the solute. |
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|
Term
| facilitated diffusion and free energy |
|
Definition
| the solute is carried across the membrane by a carrier protein, moving along the concentration gradient. this is due to free energy being higher on the side with a higher concentration, meaning the net transfer is towards the side with lower free energy. |
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|
Term
| active transport and free energy |
|
Definition
| active transport moves solute against the concentration gradient with the use of a carrier protein operated by ATP. ATP adds free energy to molecules of solute, allowing them to move in the direction desired. |
|
|
Term
|
Definition
|
|
Term
|
Definition
| the amount of energy in a system available to do work. |
|
|
Term
|
Definition
| the measure of degree of chaos or disorder in a system. |
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|
Term
|
Definition
| the same osmotic pressure (concentration of water molecules) is present on either side of a membrane (no net water transfer occurs) |
|
|
Term
|
Definition
| the same concentration of solute on either side of a membrane (no net transfer of water occurs) |
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|
Term
|
Definition
| if a solution is more concentrated than the cell contents, the solution is said to be hyperosmotic to the cell. this causes lysis. |
|
|
Term
|
Definition
| a solution of lesser concentration to the cell contents is said to be hypo-osmotic to the cell. this causes crenation. |
|
|
Term
|
Definition
| when the cell contents are more concentrated than the solution, a net transfer of water into the cell occurs. the cell increases in volume and explodes, |
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|
Term
|
Definition
isotonic is a similarity in solute concentrations on either side of a membrane.
iso-osmotic is a similarity in free energy of water molecules on both sides of a membrane |
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|
Term
| cell membrane structure and function |
|
Definition
| cell membrane is composed mainly of a bilayer of phospholipids, studded with proteins. the lipid bilayer means that lipids can move across very easily, as can small nonpolar molecules. proteins act as transporters for moving particles across the membrane through active or facilitated transport. |
|
|
Term
|
Definition
| the cell is the basic structural unit of all living matter and is capable of performing all functions necessary to life. All living organisms are composed of one or more cells. All cells must arise from pre-existing cells. |
|
|
Term
|
Definition
| they are not confined to a nucleus. they are arranged in a circular DNA helix arrangement. they have no histone proteins associated with them. they occur singularly (not paired with any other chromosome). |
|
|
Term
|
Definition
| they are enclosed in the nucleus. they have a linear DNA helix arrangement. they are associated with histone proteins. they occur in pairs. |
|
|
Term
| structure of DNA - what is a nucleotide? |
|
Definition
| DNA is composed of many nucleotides. each nucleotide is composed of a 5 carbon sugar, deoxyribose with a phosphate group attached to the carbon-5 position and a nitrogen base attached to the carbon 1 position. |
|
|
Term
| structure of DNA - what are the 4 nucleotide types and why are the different? |
|
Definition
| nucleotides are differentiated by which nitrogenous base they are attached to; guanine, adenine, cytosine and thymine. adenine and guanine are purines, and composed of 2 carbon rings. thymine and cytosine are pyrimidines and composed of 1 carbon ring. |
|
|
Term
| structure of DNA - shape. what does antiparallel and complimentary mean? |
|
Definition
DNA occurs in a double stranded helix. the strands are complimentary and antiparallel.
antiparallel means that one strand has the carbon 5 facing up and the carbon 3 facing down, and the other strand has carbon 3 facing up and carbon 5 facing down. complimentary means that the bases on each side match up, A with T and G with C. |
|
|
Term
|
Definition
| the process by which DNA copies itself in preparation of mitosis. |
|
|
Term
| what does semi-conservative mean in terms of replication? |
|
Definition
| each new strand of DNA replicated is complimentary to a strand of parental DNA. |
|
|
Term
| in which direction is the DNA template read? |
|
Definition
|
|
Term
| in which way is the new DNA strand synthesized? |
|
Definition
|
|
Term
| what is the function of helicase? |
|
Definition
| helicase unwinds the DNA helix and separates the strands. |
|
|
Term
| what is the function of helicase? |
|
Definition
| helicase unwinds the DNA helix and separates the strands. |
|
|
Term
| what is the function of single-strand binding proteins? |
|
Definition
| they prevent the strands of DNA from rejoining after helicase separates them. |
|
|
Term
| what is the function of RNA primase? |
|
Definition
| it creates an RNA primer for DNA pol III to bind to. |
|
|
Term
| what is the function of DNA polymerase III? |
|
Definition
| it attaches via RNA primer, and as it reads the strand it adds complimentary nucleotides. it covalently bonds these together and then proofreads for errors. |
|
|
Term
| what is the function of DNA polymerase I? |
|
Definition
| it removes RNA primers and replaces them with DNA nucleotides. |
|
|
Term
| what is the function of DNA ligase? |
|
Definition
| it joins the Okazaki fragments on the lagging strand together. |
|
|
Term
| why is there a lagging strand? |
|
Definition
| DNA pol III only reads in a 5'-3' direction. one strand is 3'-5', and gets read in chunks (okazaki fragments) |
|
|
Term
| what is the leading strand? |
|
Definition
| the strand that is being read 5'-3' continuously. |
|
|
Term
| what is the central dogma of molecular biology? |
|
Definition
| information flows in cells from DNA to RNA to protein. |
|
|
Term
|
Definition
| mRNA is a template for protein synthesis. Depends on the gene that was transcripted. |
|
|
Term
| what is the function of RNA polymerase? |
|
Definition
| RNA pol opens up the DNA helix and unzips the strands, forming a single replication bubble. |
|
|
Term
|
Definition
carries amino acids to the ribosome for protein synthesis once mRNA is in place.
codons of mRNA are matched by anticodons on the middle loop of a tRNA molecule, carrying an amino acid. |
|
|
Term
|
Definition
| rRNA forms the ribosome when combined with proteins. |
|
|
Term
| what is the structure of a ribosome? |
|
Definition
| a large and small subunit join together and read the mRNA. the large subunit has 3 spaces, A, P and E. tRNA enters the A site, passes to the P site to add its AA, and then exits through the E site. |
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|
Term
protein synthesis: initiation steps?
hints: initiation complex |
|
Definition
small ribosomal unit attaches to mRNA close to the 5' end.
large unit attaches forming initiation complex.
tRNA molecule enters through A site. |
|
|
Term
| protein synthesis: elongation steps? |
|
Definition
| A site reads codons, the corresponding tRNA binds to the A site, moving into the P site and adding its amino acid to the chain. The tRNA occupying the P site previously moves to the E site and is ejected. the process is repeated til the end. |
|
|
Term
| protein synthesis: termination steps? |
|
Definition
| when the stop codon is reached, a protein called a release factor binds to the stop codon instead of tRNA. this makes the ribosome separate and lets go of the polypeptide chain. |
|
|
Term
| what are restriction endonucleases and what do they do? |
|
Definition
| they are special bacteria enzymes that recognize specific nucleotide sequences on DNA. |
|
|
Term
| how are restriction endonucleases used in recombinant DNA? |
|
Definition
| by cutting a plasmid and foreign DNA strand with the same restriction enzyme, we can insert a chunk of foreign DNA into the plasmid, which will be reproduced by the bacteria, giving many copies of the foreign DNA. |
|
|
Term
|
Definition
| when a restriction enzyme cuts DNA, L shaped 'sticky ends' are produced. these connect very easily with complimentary nucleotides from any DNA present. |
|
|
Term
what is the polymerase chain reaction used for?
why is it useful? |
|
Definition
PCR generates numerous copies of small amounts of DNA in a very short time.
this is useful for generating rare DNA for use in crime solving or labs. |
|
|
Term
| in PCR, what does the solvent DNA is placed into contain? |
|
Definition
| it contains a mix of all the nucleotides, DNA polymerase, and a mix of chemically synthesised primers from the lab. |
|
|
Term
| what is the first step of PCR? what is the result? |
|
Definition
| heating the mixture of DNA, DNA pol/nucleotides and primers so that the DNA strand separates into two strands. |
|
|
Term
| what is the second step of PCR? what is the result? |
|
Definition
| the mixture cools, and primers attach to the unzipped DNA. DNA pol steps in and replication begins. at the end double the amount of DNA is made. |
|
|
Term
| how long does one cycle of PCR take? |
|
Definition
|
|
Term
what are RFLPs? why are they caused?
what do they generate? |
|
Definition
restriction fragment length polymorphisms arise when the same restriction enzyme is used to cut 2 pieces of DNA, but the restriction site of one DNA is not available.
Results in different sized fragments. |
|
|
Term
| how can riflips be separated? |
|
Definition
| using gel electrophoresis. |
|
|
Term
| how does gel electrophoresis work? |
|
Definition
| DNA is a negative polar molecule. a charge is run through the gel and the molecule is pulled towards the positive pole, but at varying speeds due to the different sizes of DNA |
|
|
Term
| part one of gel electrophoresis |
|
Definition
| DNA samples are all cut with the same restriction enzyme, ending up with different lengths. |
|
|
Term
| part 2 of gel electrophoresis |
|
Definition
| the mixture of DNA fragments is placed on the gel plate and separated by electrophoresis. |
|
|
Term
| part 3 of gel electrophoresis |
|
Definition
| the gel is treated with an alkaline solution, causing the DNA to separate into single strands. the DNA can then the transferred to paper like an inkblot. |
|
|
Term
| what is energy of activation? |
|
Definition
| Ea is the energy required for a reaction to occur or 'activate'. Enzymes catalyse this reaction and lower the Ea to make it easier to cet over the 'hill'. |
|
|
Term
| enzymes are nearly all __________. |
|
Definition
|
|
Term
| enzymes are biological __________. |
|
Definition
|
|
Term
| an enzyme _______ the activation energy of a reaction. |
|
Definition
|
|
Term
| enzymes ________ initiate _____________ reactions. |
|
Definition
| initiate; energetically unfavourable |
|
|
Term
| enzymes _______________ at the end of the reaction. |
|
Definition
|
|
Term
| all enzymes possess an _________ where the __________ binds during a reaction. |
|
Definition
|
|
Term
| enzymes are ______ ________ and can only catalyse _________ chemical reaction. |
|
Definition
| substrate specific; one particular |
|
|
Term
| enzyme-substrate activity can be modified by ____, _______, _______ and _________. |
|
Definition
| temperature; pressure, pH, chemical inhibitors |
|
|
Term
| enzyme activity can be _______. |
|
Definition
|
|
Term
| define exergonic reaction. |
|
Definition
| the final energy of the products is higher than that of the reactants. ex, energy is a product. |
|
|
Term
| define endergonic reactions. |
|
Definition
| the final energy of the products is higher than that of the reactants. ex, energy is required for the reaction to proceed (it's a reactant) |
|
|
Term
| what happens when enzyme concentration is increased in a reaction? |
|
Definition
because the reaction rate is direction proportional to the concentration of enzymes in the solution, the graph of this reaction will be a linear graph, with reaction rate increasing as enzyme concentration increases.
there are more active sites for the substrate to bind to. |
|
|
Term
| what happens when the enzyme concentration is held steady and the substrate concentration is increased? |
|
Definition
| the enzyme has a maximum productivity where the product is being formed at maximum rate. this shows in the graph as a plateau after an increase in reaction rate, where there are no more active sites for more substrate to bind to and increase the rate. the enzymes are at maximum capacity. |
|
|
Term
| what does temperature change do to enzymes? |
|
Definition
| because enzymes are proteins, a large increase in temperature will cause them to denature. a decrease in temeperature will lower the reaction rate to a very small amount but the protein will not denature. |
|
|
Term
| what does pH change do to enzymes? |
|
Definition
| pH change causes a change in the charges of active sites and substrates, which means they do not match up properly. this change in charge (either H+ or OH- in soln) can also affect the hydrogen bonds of the protein, changing its shape. |
|
|
Term
| explain competitive inhibition? |
|
Definition
| the inhibitor molecule competes for the active site with the substrate. if the substrate concentration is increased the inhibitor is no longer effective. |
|
|
Term
| explain noncompetitive inhibition? |
|
Definition
| the inhibitor binds to a site other than the active site and changes the shape of the enzyme, making it impossible for the substrate to bind no matter how much of it there is. |
|
|
Term
1. Which statement below is false?
(a) Biosynthesis involves condensation/dehydration reactions.
(b) Oxygen is more electronegative than carbon.
(c) Polar covalent bonds are formed between atoms of equal electronegativity.
(d) Molecules with hydroxyl and amino functional groups are polar.
(e) Sucrose is table sugar. |
|
Definition
| c is false. polar covalent bonds are formed between atoms with slightly different electronegativity. |
|
|
Term
1. Which statement below is false?
(a) Biosynthesis involves condensation/dehydration reactions.
(b) Oxygen is more electronegative than carbon.
(c) Polar covalent bonds are formed between atoms of equal electronegativity.
(d) Molecules with hydroxyl and amino functional groups are polar.
(e) Sucrose is table sugar. |
|
Definition
| c is false. polar covalent bonds are formed between atoms with slightly different electronegativity. |
|
|
Term
2. With reference to Figure 1,
(a) Compounds A and C are fatty acids. Compound A is saturated and compound C is unsaturated.
(b) Compound B is found in seeds of peas.
(c) D represents the secondary structure of a protein.
(d) More of compound E is found in plant than in animal cells.
(e) Only (a) and (b) are true. |
|
Definition
|
|
Term
3. Which of the following statements is false?
(a) CH2O is the general formula for carbohydrates.
(b) The tertiary structure of a protein is its functional shape. It is held in place entirely by disulfide bridges.
(c) All steroids are structurally similar in having four carbon rings in their molecules.
(d) The polarity of phospholipids is directly caused by the phosphate functional group.
(e) Fatty acids and amino acids have a -COOH functional group. |
|
Definition
| b is false. in addition to disulfide bridges, tertiary structure is also held together by hydrogen bonds and ionic bonds. |
|
|
Term
Two test tubes are prepared with the following contents:
Tube A 2 ml distilled water and 2 drops of blood.
Tube B 2 ml 0.85% NaCl and 2 drops of blood.
1. Which one of the following statements is most correct about these two tubes?
(a) 0.85% NaCl is hypertonic to blood cell contents.
(b) The free energy of water molecules in distilled water is higher than that of water molecules in the blood cell.
(c) The blood cells in tube A will lose salts to the external fluid and their ionic contents will equilibrate with the outside solution.
(d) 0.85% saline will cause the blood cells to shrink.
(e) None of the above is true. |
|
Definition
|
|
Term
2. Which statement is false about the pea experiment to separate out subcellular contents?
(a) The order of sedimentation of structures from the most dense to the least dense is : mitochondria, chloroplasts, nuclei, starch grains.
(b) Only starch grains stain purple with iodine solution.
(c) Neotetrazolium chloride acts as an electron acceptor.
(d) Ribosomes remain in the supernatent.
(e) Nuclei appear between the green and white sediment layers. |
|
Definition
| a is false, mitochondria are the least dense. |
|
|
Term
3. Which statement is true?
(a) 0.3M urea solution is isotonic and isoosmotic with red blood cells.
(b) Polar molecules pass through the cell membrane faster than lipid soluble ones.
(c) The lipid molecules in a cell membrane have all their polar heads in contact with the external aquatic medium of the cell.
(d) The addition of salt to water elevates its melting point and depresses its boiling point.
(e) None of the above is true. |
|
Definition
|
|
Term
1. Which statement is not true of DNA?
(a) The two strands of DNA are complementary and antiparallel.
(b) The 5' end of a DNA strand has a phosphate group attached to the C5 position of deoxyribose and the 3' end has no phosphate.
(c) Different organisms have different relative amounts of the 4 nucleotides in their DNA. However, for each organism, the ratio of A to T and of C to G is approximately 1:1.
(d) DNA is found only in the nucleus in eukaryotes but in prokaryotes it occurs in the chromosome and in smaller plasmids.
(e) Prokaryotic chromosomes contain no histone proteins associated with DNA. |
|
Definition
|
|
Term
2. In DNA replication, which does not happen?
(a) Replication bubbles are formed by the action of helicases.
(b) RNA primers are necessary for the initiation of replication.
(c) The leading strand is continuously synthesized in a 5'-3' direction by DNA polymerase I.
(d) Okazaki fragments require DNA ligase to join them together.
(e) DNA polymerase III proofreads and edits new DNA strands. |
|
Definition
| c is false. synthesis occurs from 3'-5'. |
|
|
Term
3. Which is not true about protein synthesis?
(a) It can begin after mRNA completely leaves the nucleus.
(b) It requires association between two subunits of the ribosome.
(c) It requires binding of the mRNA strand to the ribosome smaller subunit and recognition of the 'start' codon AUG.
(d) There are fewer than 61 tRNA molecules to match the 64 codons in the genetic code.
(e) “Stop” codons have their own particular matching tRNA molecules. |
|
Definition
|
|
Term
1. With reference to Figure A
(a) The rising part of the graph indicates saturation of enzyme active sites.
(b) At the plateau of the graph, enzyme active sites are still available.
(c) At the plateau of the graph, the enzymes are operating optimally.
(d) At the plateau of the graph, all enzymes are operating at maximum capacity.
(e) Enzymes are being destroyed as the graph reaches the plateau. |
|
Definition
|
|
Term
With reference to Figure B
(a) This represents the pH graph for all enzymes in humans.
(b) Low pH provides excess [OH-] ions which compete for hydrogen bonding sites.
(c) pH affects charges on the active site and on the substrate.
(d) pH changes destroy peptide bonds in the enzyme protein.
(e) pH affects disulfide bridges which stabilize enzyme tertiary structure. |
|
Definition
|
|
Term
3. Photosynthesis
(a) always requires the input of electrons from water to produce ATP.
(b) produces G3P, all of which goes into synthesis of sugars.
(c) increases in rate indefinitely with increases in light and CO2 levels.
(d) can only occur if light is present.
(e) does not require intact thylakoid membranes. |
|
Definition
|
|
Term
|
Definition
| the range of wavelengths that stimulates photosynthetic action |
|
|
Term
|
Definition
| the range of wavelengths a compound absorbs |
|
|
Term
| the point of photosynthesis |
|
Definition
| to make sugars for storage and carbon fixation |
|
|
Term
| how does P680 regenerate its lost electrons? |
|
Definition
| from the splitting of water |
|
|
Term
| light is absorbed by ________, which get energized. electrons travel _____ the ____________ and get transferred to P680. this excites the _________ in P680 to a ______________, and they then get transferred to the ___________________. |
|
Definition
| pigments; down the free energy gradient; electrons; higher energy state; primary electron acceptor |
|
|
Term
| from the primary electron acceptor, electrons travel down the ___________, passing through the _____________ to __________, down the gradient. the _______ energy released will be used indirectly to generate ____. |
|
Definition
| electron transfer chain; cytochrome complex; photosystem I; free; ATP. |
|
|
Term
the calvin cycle takes _____ and adds it to an existing ________ (________) using the enzyme _______.
this process is ___________. |
|
Definition
| CO2; carbon chain; RuBP; rubisco; carbon fixation |
|
|
Term
| ATP is generated from electron transfer chain indirectly because the free energy released is used to ______ _______ across the ________ membrane. the resulting _______ gradient drives ATP synthesis by ________. |
|
Definition
| pump H+ ions; thykaloid membrane; proton; chemiosmosis |
|
|
