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BIOL2171 Sup
| Question | Answer |
|---|---|
| What are the two main functions of nutrients? | To provide energy and supply building blocks for growth, repair and new cells |
| Which nutrient is the body's primary immediate energy source? | Carbohydrates (glucose) |
| Which nutrient is the major long-term energy store? | Lipids (triglycerides) |
| What is the main role of proteins? | Building and maintaining body structures and acting as enzymes, transporters, receptors and antibodies |
| What is the function of nucleic acids? | DNA stores genetic information, while RNA helps express that information to make proteins |
| What is the monomer of proteins? | Amino acids |
| What is the monomer of carbohydrates? | Monosaccharides |
| What is the monomer of DNA and RNA? | Nucleotides |
| What are the components of a triglyceride? | One glycerol molecule and three fatty acids |
| Which functional group is found in all amino acids and acts as a base? | Amino group (–NH₂). |
| Which functional group is acidic and can donate H⁺? | Carboxyl group (–COOH). |
| Which functional group is found in ATP and DNA and is involved in energy transfer? | Phosphate group |
| Which functional group forms disulfide bonds in proteins? | Sulfhydryl group (-SH) |
| What is polymerisation? | The joining of small monomers to form large polymers |
| What type of reaction forms most biological polymers? | Dehydration (condensation) reactions |
| What molecule is released during a dehydration reaction? | Water (H2O) |
| What process breaks polymers into monomers? | Hydrolysis |
| What bond joins amino acids? | Peptide bond |
| What bond joins monosaccharides? | Glycosidic bond |
| What bond joins nucleotides? | Phosphodiester bond |
| What bond joins glycerol and fatty acids? | Ester bond |
| What is the overall purpose of glucose oxidation? | To extract energy from glucose and capture it as ATP and NADH |
| What are the three major stages of glucose metabolism? | Glycolysis, the TCA cycle, and the electron transport chain |
| Why is glucose oxidised in many small steps instead of one? | To capture energy efficiently in ATP and NADH instead of losing most of the energy to heat |
| What is free energy (ΔG)? | The energy available to do useful work in a reaction |
| What does a negative ΔG indicate? | The reaction is exergonic, releases energy, and is thermodynamically favourable |
| What does a positive ΔG indicate? | The reaction is endergonic and requires an input of energy |
| What does ΔG = 0 mean? | The reaction is at equilibrium, with no net change and no useful free energy available |
| Why are living cells maintained far from equilibrium? | So reactions can continue to release free energy and perform cellular work |
| What is activation energy? | The energy required to initiate a chemical reaction. |
| Does activation energy determine whether a reaction is favourable? | No, it determines the reaction rate, not whether the reaction is thermodynamically favourable |
| What effect do enzymes have on activation energy? | They lower activation energy speeding up reactions without changing ΔG or equilibrium. |
| What does ATP store? | Free energy in its phosphate bonds |
| What happens when ATP is hydrolysed? | ATP is converted to ADP + Pi, releasing energy for cellular work. |
| Why is ATP called the cell's energy currency? | Because it directly powers processes such as active transport, muscle contraction, and biosynthesis. |
| What does NADH store? | High-energy electrons |
| What is the oxidised form of NADH? | NAD⁺. |
| What is the primary role of NADH? | To carry electrons to the electron transport chain for ATP production |
| What is the main difference between ATP and NADH? | ATP stores free energy used directly for cellular work, whereas NADH stores electrons whose energy is later converted into ATP. |
| Where does carbohydrate digestion begin? | In the mouth with salivary amylase |
| Which organ secretes pancreatic amylase? | The pancreas |
| What is the function of pancreatic amylase? | To digest starch into maltose, maltotriose, and α-limit dextrins. |
| Where is carbohydrate digestion completed? | At the brush border of the small intestine |
| Which enzyme digests lactose? | Lactase |
| Which enzyme digests sucrose? | Sucrase |
| Which enzyme digests maltose? | Maltase |
| Which enzyme breaks α-1,6 branch points? | Isomaltase |
| Which transporter absorbs glucose and galactose? | SGLT1 |
| Which transporter absorbs fructose? | GLUT5 |
| Which transporter releases monosaccharides into the bloodstream? | GLUT2 |
| Why does oral rehydration solution work? | Glucose and sodium are co-transported by SGLT1, and water follows by osmosis |
| What causes lactose intolerance? | Deficiency of the brush border enzyme lactase |
| What causes glucose-galactose malabsorption? | Mutations in SGLT1 |
| Why is fructose absorption normal in glucose-galactose malabsorption? | Because glucose uses GLUT5, not SGLT1 |
| Why can't humans digest cellulose? | We lack enzymes that break β-1,4 glycosidic bonds. |
| What is an enzyme? | A biological catalyst that speeds up reactions by lowering activation energy |
| Do enzymes change ΔG or equilibrium? | No. They only lower activation energy and increase reaction rate |
| What is the active site? | The region where the substrate binds and catalysis occurs. |
| What is the transition state? | A high-energy intermediate that enzymes stabilise to speed up reaction rate |
| What is general acid catalysis? | The enzyme donates a proton (H⁺) to facilitate the reaction. |
| What is general base catalysis? | The enzyme accepts a proton, generating a more reactive species. |
| What is covalent catalysis? | The enzyme forms a temporary covalent bond with the substrate. |
| What is metal ion catalysis? | Metal ions assist catalysis by stabilising charged intermediates or participating in the reaction. |
| What is glycolysis? | The cytoplasmic pathway that converts one glucose into two pyruvate, producing ATP and NADH |
| Where does glycolysis occur? | In the cytoplasm |
| What are the two phases of glycolysis? | Energy investment and energy payoff |
| How many ATP are invested in glycolysis? | Two |
| How many ATP are produced in glycolysis? | Four |
| What is the net ATP yield in glycolysis? | Two ATP |
| How many NADH are produced in glycolysis? | Two |
| What enzyme catalyses the first step of glycolysis? | Hexokinase |
| Why is glucose phosphorylated? | To trap it inside the cell and prepare it for metabolism |
| Why can't glucose-6-phosphate leave the cell? | There are no glucose transporters that transport glucose-6-phosphate |
| What is the committed step of glycolysis? | Conversion of fructose-6-phosphate to fructose-1,6-bisphosphate by phosphofructokinase (PFK). |
| What activates PFK? | AMP and fructose-2,6-bisphosphate |
| What inhibits PFK? | ATP and citrate |
| What is substrate-level phosphorylation? | Direct transfer of a phosphate from a metabolic intermediate to ADP to form ATP. |
| How many substrate-level phosphorylation steps occur in glycolysis? | Two |
| Why is pyruvate converted to lactate? | To regenerate NAD⁺ so glycolysis can continue without oxygen. |
| Why is NAD⁺ regeneration essential? | NAD⁺ is required for the oxidation step of glycolysis; without it, the pathway stops. |
| What is Vmax? | The maximum reaction rate when all enzyme active sites are occupied |
| What does a low Km indicate? | High substrate affinity |
| Why don't allosteric enzymes follow Michaelis–Menten kinetics? | Because binding at allosteric sites changes enzyme conformation and substrate affinity. |
| What are the two conformational states of many allosteric enzymes? | T (tense, low-affinity) state and R (relaxed, high-affinity) state. |
Created by:
Samara Hayes