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carbs & metabolism
biol 1210
| Question | Answer |
|---|---|
| what are carbs & function of carbs? list term for monomers & polymers of carbs, and the 3 elements carbs are mostly made of | carbs = sugars & sugar polymers, used as fuel, building blocks & cell identity markers. monosaccharides, polysaccharides, commonly incl. C, H & O |
| give general chemical formula & describe structure of monosaccharides | carbon hydrate: (CH2O)n, n is # of C. Contain carbonyl group, hydroxyl groups & many C-H bonds -> carbonyl & hydroxl polar, so hydrophilic. Each has unique structure & function , classified by R group & # of C's |
| aldose sugars v. ketose sugars | sugars containing an aldehyde group (carbonyl at the tip of the molcule) v. sugars containing a ketone group (carbonyl in middle of molecule) |
| describe asymmetric carbon & difference btwn glucose & galactose | each carbon chain is different from another, if u change one u change the molecule. Glucose has -OH on 4' facing R group, galactose has -OH on 4' facing away from R group |
| what happens to most sugars in aqueous solutions? | they form rings |
| difference between a-glucose and b-glucose structure | the ring can close in different orientations. a-glucose has -OH group on 1' facing away from O at top of ring, b-glucose has -OH group on 1' facing towards O |
| disaccharide structure & 2 examples | two sugars linked together when dehydration synthesis reaction occurs btwn 2 hydroxyl groups, forming a covalent bond. Sucrose: glucose + fructose (table sugar), Lactose: galactose + glucose |
| describe glycosidic linkage & 2 common types | covalent bond formed btwn any 2 hydroxyl groups btwn monosaccharides. a-1,4-glycosidic linkage has the 6' groups on the same plane, in b-1,4-glycosidic linkage one monosaccharide is flipped w one 6' group up, one 6' group down |
| animal v plant sugar storage | plants store sugar as starch, animals store sugar as glycogen |
| structures of starch v. glycogen | both are long chains of glucose. Starch incl. 2 molecules bonded together: Amylose (unbranched helix, a-1,4 linkages) + amylopectin (longer, sparsely branches, some a-1,4 linkages). Glycogen is branched helices w tighter, shorter branches n mostly a-1,4 |
| Describe cellulose | Structural polymer of plant cell walls, forms fibres or sheets consisting of long strands of b-1,4-glycosidic linked glucose w bonds in between adjacent strands |
| Differences btwn a-glucose and b-glucose | a-glucose makes a-1,4-glycosidic linkage, easy to disgest, used as energy. b-glucose makes b-1,4-glycosidic linkage, hard to digest, used structurally |
| Why are b-1,4-linkages hard to digest? What is dietary fibre? | Not easy to hydrolyze - fibres that lack water. Most organisms lack enzymes to hydrolyze them. Dietary fibre formed by carbs is important for digestive health |
| What is fuel for metabolism? List 5 biological processes requiring energy | ATP is universal energy fuel. Metabolism (reactions), movement, growth, cell division, action potentials |
| Where does energy come from? What is it used for and how is it lost? | Living organisms can’t create energy but need it for metabolic reactions, so must obtain it from environment (photosynthesis or feeding). Energy is lost in form of heat during metabolism |
| Principle of conservation of energy | 1st law of thermodynamics: energy is constant; no energy is created or destroyed, only transferred & transformed |
| 2nd law of thermodynamics | Every energy transfer or transformation increases the disorder (entropy) of the universe (in relation to structure). In biology, entropy is heat (energy that is lost during every transfer/transformation) |
| Describe 4 steps of energy flow | 1. Energy enters ecosystem from sun, captured by photosynthesis 2. Photosynthesis makes O2 & other molecules 3. Cells use chemical energy in organic molecules to regenerate ATP thru cellular respiration 4. ATP powers cell work, energy leaves as heat |
| Describe chemical (potential) energy | Related to the position of shared electrons in covalent bonds - molecule’s potential to form stronger bonds is energy in potential state. Electrons farther from nucleus = larger amount of potential energy |
| Potential energy of covalent bonds | shared electrons far from both atoms’ nuclei = large amount of potential energy & vice versa. Organic molecules w many non-polar covalent bonds carry lots of potential energy |
| Define metabolism | The totality of an organism’s chemical reactions |
| What is a metabolic pathway? | A multi-step reaction that begins with a specific molecule and ends with a final product, with intermediate substances used in-between. Each step is catalyzed by a specific enzyme |
| Anabolic pathway | Consumes energy to build complex molecules from simpler ones for energy storage or structure (proteins), generally dehydration synthesis reactions |
| Catabolic pathway | Releases energy by breaking down complex molecules into simpler ones to produce energy & building blocks, generally hydrolysis reactions |
| Overview of metabolism + diagram? | |
| Traits & draw graph of exergonic reaction | Delta G < 0, spontaneous, no input of energy, catabolic, favoured reactions. See notes for graph |
| Traits & draw graph of endergonic reaction | Delta G > 0, non-spontaneous, needs input of energy, anabolic |
| Why r exergonic reactions spontaneous & how do cells do endergonic reactions? | No energy required, can happen at any time if conditions r right (?). In order to do endergonic reaction, need an exergonic reaction to produce the energy required |
| Coupled reactions & draw simple diagram w arrows + building blocks | Reactions that occur together, where energy released from catabolic process is used to power anabolic process. See notes for diagram |
| Energetic coupling | Free energy from one reaction is used to drive another. Cells do this by transferring phosphate group (from/to ATP, aka phosphorylation) or transferring electrons (redox reactions) |
| What is ATP and why is it used for energy? | Adenosine triphosphate, a nucleus acid: adenine + ribose + 3 phosphate groups. It provides energy in readily available form - contains a large amount of potential energy in the bonds between the phosphate groups |
| ATP & water reaction | ATP is hydrolyzed, this is exergonic (spontaneous & releases energy). Forms ADP and P_i, increasing entropy |
| Phosphorylation | Chemical attachment of a phosphate group to a molecule, used to control energy transfer & regulate biological processes |
| ATP synthesis & 2 mechanisms | synthesized by phosphorylation, either substrate phosphorylation or oxidative phosphorylation |
| Substrate phosphorylatin | Few ATP molecules synthesized during glycolysis & citric acid cycle. Phosphate group removed from reactant & free energy used to add 3rd phosphate to ADP -> ATP |
| Oxidative phosphorylation | Many (almost 90%) of ATP generated thru cellular respiration is from redox reactions |
| Describe redox reactions | Oxidation-reduction reactions, involve transfer of electrons btwn reactants (change electron sharing in chemical bonds). Oxidizing agent = substance loses electrons = is oxidized, reducing agent = substance gains electrons = is reduced |
| Electron carrier | Any molecule that readily accepts electrons from & donates electrons to other molecules |
| Describe the 2 electron carriers during cellular respiration | Act as oxidizing agents (take electrons). FAD, flavin adenine dinucleotide -> takes 2e- & 2H+ -> FADH2 (reduced). NAD+, nicotinamide adenine dinucleotide -> takes 1e- + 1H+ -> NADH + H+ (reduced). *reaction can go either way! |
| Describe cellular respiration briefly - how is energy released | Energy processing occuring mostly in mitochondria. Chemical energy is stored in reduced molecules like carbs & lipids, this energy is released gradually in a series of reactions and used to add phosphate group to ADP -> ATP |
| Stages of cellular respiration & where they occur | Glycolysis- cytoplasm, pyruvate oxidation - mitochondria matrix, citric acid cycle - mitochondria matrix, electron transport chain reactions - mitochondria inner membrane (in cristae) |
| Describe structure of mitochondria | Organelle w double membrane - outer membrane, intermembrane space & inner membrane which is highly folded into cristae that have ribosomes embedded. Matrix is fluid between cristae containing free ribosomes & mitochondrial DNA |
| Summarize glycolysis. Where does it happen, what happens to carbons + electrons, what is energy yield? | Occurs in cytoplasm, carbon atoms r split from 6’ glucose into 2 3’ pyruvate, 2 electrons r lost to NADH & energy yield of 2 ATP |
| Explain 3 phases of glycolysis | Energy-investment: glucose re-arranged to be symmetrical, using 2 ATP & making 2 ADP. Cleavage: glucose is split. Energy-payoff: 2NADH removes 2H+ & 2e- -> 2P replaces missing H -> 2P removed to make 2ATP -> lose 2H2O -> 2P removed for 2ATP -> 2 pyruvate |
| Regulation of glycolysis | Feedback inhibition - high levels of ATP inhibit 3rd enzyme, phosphofructokinase which has 2 binding sites for ATP: if bind to active site -> catalyze 3rd step of glycolysis, if bind to allosteric site -> inhibited |
| Important features of glycolysis | 2ATP used at beginning to destabilize glucose, 4ATP produced = net 2ATP. After the glycolytic step (4th, split of glucose), everything x2. Produces no CO2 & little ATP, hence pyruvate still has large amount of energy & glycolysis is anaerobic |
| Describe pyruvate processing | In presence of O2, pyruvate enter mitochondrion. Must be converted to acetyl CoA - NADH removes 1e-, destabilizing pyruvate & causing it to drop 1 C as CO2 -> acetyl, which binds to coenzyme A -> acetyl CoA |
| Summarize pyruvate processing. Where does it happen, what happens to carbons + electrons, what is energy yield, how many CO2 released during processing from 1 molecule glucose? | Occurs in mitochondrial matrix, 1 carbon is lost as CO2, 1 electron is lost to NADH, no ATP produced. 2CO2 released from 1 glucose (2 pyruvate) |
| summarize citric acid cycle. Where does it happen, what happens to carbons + electrons, what is energy yield? | occurs in mitochondrial matrix, old carbons (from previous cycle oxaloacetate) r released as CO2, acetyl is oxidized (loses electrons), net energy yield/glucose is 2 ATP |
| how much of ATP, NADH & FADH2 is generated per turn of the citric cycle? Per molecule of glucose? what do electron carriers do with their gained electrons? | 1ATP, 3NADH, 1FADH2 per turn, 2ATP, 6NADH, 2FADH2 per glucose. NADH & FADH2 relay electrons to the electron transport chain |
| steps of the citric acid cycle | 8 total steps, each catalyzed by a different enzyme. 1st the acetyl group of acetyl CoA joins cycle by combining w oxaloacetate (4') to make citrate (6'), then the next 7 steps decompose citrate back to oxaloacetate, making it a cycle |
| important features of citric acid cycle | a cycle due to the regeneration of oxaloacetate. Does not directly use O2 but can't work under anaerobic conditions - FADH2 can only be re-oxidized when O2 is available. CoA is used at 2 steps of cycle - both times acting to drive an anabolic step forwar |
| is the citric acid cycle catabolic or anabolic? | 1st step is anabolic and the step where 1ATP is produced, but the rest of the steps are catabolic and overall, the cycle is catabolic |
| draw mitochondrion, label: cristae,, inner membrane, intermembrane space, matrix & outer membrane | see notes |
| summarize oxidative phosphorylation. Where does it happen, what happens to carbons + electrons, what is energy yield? | in the cristae, no carbon used, electrons are transported along the chain to power proton pumps, ideally 28 ATP produced |
| describe electron transfer in ETC | e- transferred from NADH/FADH2 to ETC & pass thru protein complexes I-IV, dropping in free energy as they go down chain; energy released from e- movement powers proton pumps. e- passed to O2 at end of ETC, forming H2O |
| function of the ETC | generates no ATP - breaks the large free-energy drop from food to O2 into smaller steps that release energy at a manageable rate by regulating the force that drives ATP synthase |
| describe proton-motive force | the flow of H+ from mitochondrial matrix to intermembrane space, formed by the pumping of H+ by the complexes in ETC. Energy stored in the H+ gradient couples redox reactions of ETC to ATP synthesis & powers ATP synthesis |
| describe chemiosmosis in oxidative phosphorylation | H+ moves back across membrane along its concentration gradient thru ATP synthase, which spins the protein motor & thus uses flow of H+ to drive the phosphorylation of ATP |
| describe role of complex I-IV and protein Q & C in ETC | complex I, III & IV r proton pumps. Complex I receives electrons from NADH, complex II receives electrons from FADH2, complex III & IV transfer electrons & pump H+ ions. Protein Q shuttles electrons from I & II to III and protein C from III to IV. |
| compare energy yields of NADH & FADH2 & why | NADH passes its electrons to beginning of ETC (complex I) -> yields 2.5 ATP. FADH2 passes its electrons later down the chain (complex II) -> yields 1.5 ATP bc less energy is released from the electron's movement down the chain |
| # of ATP produced from cellular respiration & describe how this is calculated | theoretically 32 ATP, often doesn't reach this # due to ATP use for transporting NADH or Pi - ATP synthesis isn't perfectly efficient. 4 ATP from substrate phosphorylation + (2.5 ATP x 10 NADH) + (1.5 ATP x 2 FADH2) = 32. |
| describe energy/electron flow during cellular respiration | glucose -> NADH -> ETC -> proton-motive force -> ATP. Electrons are taken from food throughout substrate phosphorylation and brought to the ETC by electron carriers, where they power the proton-motive force before finally joining O2 to form H2O |
| Products per molecule of glucose for: 1. Glycolysis, 2. Pyruvate processing, 3. Citric acid cycle, 4. ETC, 5. Chemiosmosis | 1) 2 ATP, 2 NADH, 2 pyruvate. 2) 2 NADH, 2 CO2. 3) 2 ATP, 6 NADH, 2 FADH2, 4 CO2. 4) 10 NAD+, 2 FAD, 6 H2O. 5) 25-28 ATP |
| Describe fates of pyruvate | Depends on whether oxygen is present/absent. O2 present -> aerobic cellular respiration, O2 absent -> anaerobic cellular respiration or fermentation depending on the organism |
| Contrast aerobic respiration, anaerobic respiration & fermentation | Aerobic: most effective (most ATP produced), O2 as final acceptor of e-. Anaerobic: only in prokaryotes, pyruvate enters Krebs cycle then bacterial ETC that has non-O2 final electron acceptor. Fermentation: pyruvate is not fully oxidized, least effective |
| Describe fermentation & name 2 types | Uses only glycolysis - Glucose & 2 NAD+ must be regenerated for glycolysis to cycle, done in 2 different ways - alcoholic or lactic acid fermentation. Makes 2 ATP, no O2 required. |
| Alcoholic fermentation | In plants & some microorganisms (yeast). 2 CO2 removed from 2 pyruvate -> 2 acetaldehyde, which accepts 4e- from NADH & becomes ethanol, which is released |
| Lactic acid fermentation | In animals & bacteria. No carbon is removed from pyruvate; 4e- are added to 2 pyruvate from 2 NADH -> 2 lactate. No intermediate step, unlike alcoholic fermentation |
| how may proteins & lipids be used in cellular respiration? | proteins broken down into amino acids may substitute key materials for cellular respiration, ex. pyruvate, acetyl CoA, citric acid cycle. Lipids -> glycerol, which can supply G3P in glycolysis, or fatty acids -> acetyl CoA |
| why do lipids hold more energy than carbs? | more C-H & C-C bonds sharing electrons more equally = e- further from either nucleus = more potential energy |
| describe beta-oxidation | for a 16C fatty acid chain: 28 e- are removed by splitting chain into 8 Acetyl CoA, which go to citric acid cycle producing 16CO2 & 64e-. e- caried by NADH & FADH2 to respiratory ETC. Overall yield of 108 ATP for 16C fatty acid. |
| how are amino acids used as an energy source? | amino acids can be converted into intermediaries to be included at dif. stages of the cycle by removal of amino group. amino acids -> deamination & ketoacids -> ammonia, amino group removed -> 2CO2 & 2 ATP -> urea |
| describe 3 sources of acetyl CoA & 2 fates of acetyl CoA | sources: glycolysis, beta-oxidation or deamination. Fates: citric acid cycle or ketone bodies (acetyl CoA + acetyl CoA) |
| contrast endotherms & ectotherms | endo: maintain internal constant temp = faster metabolism, more energy required, in mammals & birds. Ecto: internal temp defined by environment = slower/unpredictable metabolism, less energy-intensive, in reptiles & fish |
| how does surface area affect metabolism + elephant's ears | smaller animal = larger surface area:body volume ratio -> higher heat loss -> requires more energy to maintain body heat (higher metabolic rates). Elephant have large ears for thermoregulation - increased SA in ear -> larger heat loss |
Created by:
AntBanana
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