Bio 101 Quiz 2 Flashcards
What does the first law of thermodynamics state, and how does it relate to metabolism?
The first law states that energy is conserved. In metabolism, this means energy is transformed but not created or destroyed.
What does the second law of thermodynamics state, and how does it relate to chemical reactions?
The second law states that total entropy (disorder) increases in a system. Chemical reactions always increase the disorder of the universe.
What is the difference between endothermic and exothermic reactions?
Exothermic reactions release heat (ΔH < 0), and endothermic reactions absorb heat (ΔH > 0).
What is the difference between endergonic and exergonic reactions?
Exergonic reactions are spontaneous and release energy (ΔG < 0), and endergonic reactions require energy input (ΔG > 0).
What factors influence the rate of a chemical reaction?
Molecule movement and collision rate, which are affected by factors like temperature and concentration.
Why are oxidation and reduction reactions always coupled?
Because electrons released by oxidation must be accepted by another molecule through reduction.
Define activation energy.
Activation energy is the energy input required for all chemical reactions to occur.
What is the role of enzymes in chemical reactions?
Enzymes decrease the activation energy required for a reaction by bringing substrates into close proximity and destabilizing their bonds.
Briefly explain the induced fit model of enzyme-substrate interaction.
The enzyme’s protein structure changes upon substrate binding, increasing the likelihood of a chemical reaction.
What are cofactors, coenzymes, and prosthetic groups and how do they relate to enzyme function?
Cofactors are inorganic molecules that assist in enzyme function. Coenzymes are organic, non-protein molecules that assist in enzyme function. Prosthetic groups are non-protein molecules that are permanently bound to an enzyme.
What are some ways that enzymes can be inhibited?
Enzymes can be inhibited by molecules binding non-covalently or covalently.
How are metabolic pathways typically regulated?
Through feedback mechanisms.
What are the building blocks (elements and monomers) of carbohydrates?
Carbohydrates are composed of carbon, hydrogen, and oxygen, with a 2:1 ratio of hydrogen to oxygen; their monomer is a monosaccharide.
What type of chemical bond joins monosaccharides?
Glycosidic linkages, formed by dehydration reactions.
What distinguishes starch and glycogen from cellulose and chitin?
Starch and glycogen are made of α-glucose with 1-4 linkages for energy storage. Cellulose and chitin are made of β-glucose with 1-4 linkages for structural support.
Why can’t humans digest cellulose?
Humans lack the enzymes to break down β-1-4 glycosidic linkages.
What are some functions of carbohydrates besides energy storage?
Cell identity, modifying membrane proteins and lipids, and cellular structure such as cellulose in plant cell walls.
What are the inputs and outputs of glycolysis?
Inputs: Glucose and 2 ATP. Outputs: 2 Pyruvate, 2 net ATP, and 2 NADH.
Where does glycolysis take place in the cell?
Cytoplasm.
What are the committed steps in glycolysis?
Hexokinase and phosphofructokinase.
What are the inputs and outputs of pyruvate processing?
Inputs: Pyruvate, NAD+, CoA. Outputs: Acetyl CoA, NADH, CO2.
Where does pyruvate processing take place in the cell?
Mitochondrial matrix.
What are the inputs and outputs of the citric acid cycle?
Inputs: Acetyl-CoA and oxaloacetate. Outputs (per pyruvate): 3 NADH, 1 FADH2, CO2, 1 ATP.
Where does the citric acid cycle occur in the cell?
Mitochondrial matrix.
What are the inputs and outputs of oxidative phosphorylation?
Inputs: 10 NADH, 2 FADH2, oxygen. Outputs: NAD+, FAD (recycled), Water, 25 ATP.
Where does oxidative phosphorylation take place in the cell?
Inner mitochondrial membrane (cristae membranes).
What is the primary goal of fermentation in anaerobic respiration?
To regenerate NAD+.
