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Biochem 301 Exam 2 ACTUAL EXAM WITH QUESTIONS AND
100% CORRECT VERIFIED ANSWERS/ Biochem 301-Exam 2
LATEST 2025-2026 (BRAND NEW!!)
Intermediary Metabolism the entire set of cellular metabolic reactions What is Metabolism? A series of linked reactions that convert a specific reactant into a specific product What are the two types of metabolic pathways?
- catabolic
- anabolic Catabolic pathways
- combust carbon fuels to synthesize ATP
- degrade large molecules to produce small molecules and energy Anabolic pathways
- use ATP and reducing power to synthesize large biomolecules
- responsible for synthesis of all the components required for cell maintenance, growth, and reproduction
Amphibolic Pathway pathways that can function catabolically or anabolically True or False: Anabolic and Catabolic pathways may have some reactions in common True True or False: Although anabolic and catabolic pathways may have some reactions in common, the regulated, irreversible reactions are always distinct true What are the 3 stages generally of catabolism?
- Stage 1: Proteins, polysaccharides, and lipids are broken down into their component building blocks/monomers
- Stage 2: Building blocks are degraded into the common product (the acetyl groups of acetyl-CoA) (glycolysis)
- Stage 3: Converges to 3 principal end products: CO2, H2O, and NH3(Citric Acid Cycle + Oxidative Phosphorylation) What are the 2 criteria that must be met in order to construct a metabolic pathway?
- Individual reactions must be specific
- The pathway in total must be thermodynamically favorable
What is a metabolic map?
- indicates the reactions of intermediary metabolism and the enzymes that catalyze them
- comprised of over 500 different chemical intermediates (metabolites) and even more enzymes What kind of process is glycogenesis in terms of energy? energy-consuming What kind of process is oxidation in terms of energy? energy-releasing Which type of metabolism can have a one-step pathway? How so?
- catabolism
- uncontrolled combustion Which type of metabolism involves multistep pathways?
- both anabolism and catabolism Which type of metabolism is impossible to occur in a single step pathway? anabolism
True or false: glycogenesis and oxidation are reversible/have equilibrium arrows True! What do black dots on a metabolic map represent? intermediate what do lines on a metabolic map represent? enzymes On a metabolic map, what must a dot connected to a single line be?
- nutrient
- storage form
- end product
- excretory product On a metabolic map, what would a dot connected to two lines mean? probably an intermediate in one pathway and has only one fate in metabolism On a metabolic map, what would a dot connected to three lines mean?
What are the 2 models for metabolic pathways? Which is more traditional?
- Metabolite-centric (more common) (proteins are dots)
- Protein-centric (enzymes are dots) what type of enzyme is kinase? transferase what does kinase do in terms of regulation of metabolic pathway?
- phosphorylates cellular proteins when activated (OH - > P group with ATP->ADP)
- results in coordinated regulation of different pathways, whether it be through activation or inhibition are catabolic pathways exergonic or endergonic? exergonic (energy yielding) are anabolic pathways exergonic or endergonic? endergonic (energy requiring) what are the end products of catabolism? CO2 and H2O
True or false: many intermediates are shared between catabolism and anabolism, such as ATP true what are the energy-yielding nutrient reagents for catabolism?
- carbohydrates
- fats
- proteins What does NAD+ contain in its structure?
- nicotinamide ring
- adenine ring
- 2 sugar-phosphate groups what type of reactions are NAD+ and NADH used for? redox (electron carriers) do catabolic pathways converge or diverge converge
NADPH
Describe the NADP+ and NADPH cycle for anabolism and catabolism?
- Catabolism: NADP+ - > NADPH for oxidation
- Anabolism: NADPH - > NADP+ for reduction what are the energy-containing nutrients oxidized through catabolism?
- carbohydrates
- fats
- proteins what are the energy-depleted products of catabolism?
- CO
- H2O
- NH what are the precursor molecules to be reduced by anabolism?
- amino acids
- sugars
- fatty acids
- nitrogenous bases what are the cell macromolecule products of anabolism?
- proteins
- polysaccharides
- lipids
- nucleic acids What are the kinds of chemical energy outputted by catabolism?
- ATP
- NADH
- NADPH
- FADH what are the kinds of chemical energy outputted by anabolism?
- ADP + HPO4 - 2
- NAD+
- NADP+
- FAD what is difference between how phototrophs and heterotrophs obtain ATP?
why is hydrolysis of ATP exergonic? the triphosphate unit contains two phosphoanhydride bonds that are unstable Describe the phosphoryl-transfer potential of ATP?
- ATP has high phosphoryl-transfer potential intermediate between high phosphoryl-transfer potential compounds derived from molecules that require the addition of a phosphoryl group for cellular needs True or False: The activation energies for phosphoryl group transfer reactions are substantially larger than the free energy of hydrolysis of ATP True Describe the binding of the enzyme when ATP hydrolysis is coupled to a reaction? enzyme is binding the substrate AND ATP at the same time What are three examples of products of phosphoryl-transfer reactions that ATP has a central position in?
- creatine phosphate (kinase)
- PEP
- 1,3-BPG How does creatine phosphate work?
- muscle contains only enough ATP to power muscle contraction for less than a second
- creatine phosphate can regenerate ATP from ADP using creatine kinase, allowing a short burst of activity (ex. a sprint)
- once creatine phosphate stores are depleted, ATP must be generated by metabolic pathways What are the 3 regulatory controls that are especially prominent for metabolic processes?
- Amount of enzymes present
- Catalytic activity of enzymes
- Accessibility of substrates What is the order of compounds in Stage 1 of glycolysis?
- Glucose
- Glucose 6-phosphate
- Fructose 6-phosphate
- Fructose 1,6-bisphosphate 4.5. Dihydroyacetone phosphate (DHAP)
- Glyceraldehyde 3-phosphate (GAP) What is the order of enzymes in Stage 1 of glycolysis?
- Transferase
- Isomerase
- Transferase
- Isomerase
Briefly describe the first phase of glycolysis? converts glucose to two glyceraldehyde 3-phosphates Briefly describe the second phase of glycolysis? produces two molecules of pyruvate what are the 3 products of glycolysis?
- pyruvate
- ATP
- NADH What are the 3 fates of pyruvate from glycolysis?
- Anaerobic glycolysis to produce NAD+ and Lactate
- Aerobic Oxidation (Citric Acid Cycle + Oxidative Phosphorylation) to produce NAD+, ATP, CO2, and H2O
- Anaerobic Alcoholic Fermentation to produce NAD+, CO2, and EtOH how many molecules of pyruvate are produced by one molecule of glucose? 2 How is glycolysis a primitive pathway?
- operates even in the simplest and archaic cells
- DOES NOT require oxygen how many intermediate compounds in glycolysis? 9 how many enzymes in glycolysis? 10 where are the enzymes for glycolysis located in the cell? cytoplasm Balanced chemical equation for glycolysis? C6H12O6 + 2ADP + 2NAD+ + 2PI - > 2C3H4O3 + 2ATP + 2NADH + 2H+ + 2H2O True or False: Glycolysis only releases a small fraction of the total available energy of the glucose molecule, and the great change in free energy occurs when glucose is oxidized completely to CO2 and H2O True
What is significance of induced fit model for hexokinase?
- closure around glucose molecule plases ATP close to glucose and excludes water from active site True or False: Regulatory control can be imposed only on reactions at equilibrium False: can only be imposed on reactions not at equilibrium True or false: Phosphorylation keeps glucose in the cell True How does phosphorylation keep glucose in the cell?
- glucose is neutral and can usually diffuse across the cell membrane at very low rate
- phosphorylation puts negative charge on glucose (making glucose 6-phosphate), making it impermeable to it How is movement of glucose into cell favored during beginning of phase 1 of glycolysis? rapid conversion of glucose to glucose 6-phosphate by hexokinase keeps the intracellular concentration of glucose low isozymes enzymes that catalyze the same reaction, but are encoded by different genes
what is the alternative enzyme besides hexokinase that can convert glucose to glucose 6-phosphate? glucokinase Where is glucokinase found? liver What makes glucokinase different from hexokinase?
- highly specific for D-glucose
- higher Km for glucose (only important when liver glucose levels are high)
- not product-inhibited Which enzyme is primarily responsible for phosphorylating glucose when glucose levels are low? high?
- Low: Hexokinase
- High: glucokinase (inducible enzyme) what is amount of glucokinase in liver controlled by? insulin
