Enzymes
What are enzymes made of and what is their function?
Enzymes are made of proteins and they act as a chemical catalyst to speed up reactions without getting used up in the process.
Where does glycolysis take place in the cell?
Cytoplasm.
What is cellular respiration, where does it primarily take place, and what are the 3-4 general steps of the process?
(Double Jeopardy!!!)
Cell respiration: Process of cells producing ATP by oxidizing glucose that takes place inside the mitochondria
1. Glycolysis
2. Pyruvate oxidation
3. Citric acid cycle / Krebs cycle
4. Electron transport chain + chemiosmosis
Photosynthesis is a chemical process that requires CO2 as a reactant. How many membranes/layers does CO2 have to go through in order to reach the chloroplast in the plant cell?
3 total:
1. Plant cell membrane
2. Chloroplast outer membrane
3. Chloroplast inner membrane
What is the difference between anabolism and catabolism?
Anabolism: building molecules up - requires energy
Catabolism: breaking molecules down (catastrophe) - releases energy
Describe the steps that enzymes go through in order to turn a substrate into a product.
1. Substrate bonds to the active site in the enzyme.
2. Substrate binding causes a change in conformation (induced fit) to tighten the enzyme's hold on the substrate
3. Substrate gets converted into product by moving product into the transition state.
4. Product gets released from active site.
5. Enzyme returns to its original shape with the active site available for another substrate to come in.
What role does ATP and NADH/NAD+ play in glycolysis?
ATP gets hydrolyzed during glycolysis to donate phosphate groups
NAD+ acts as an electron carrier when modifying intermediates of glycolysis and produces NADH - it accepts electrons that were oxidized
What is the cellular respiration equation?
C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O + Energy/Heat
What are the 2 general stages of photosynthesis and where do they take place in a plant cell?
1. Light dependent reactions - thylakoids
2. Calvin cycle/Carbon Fixation - stroma of plant cell
What is fermentation and what is the main function of fermentation?
Glycolysis can lead to fermentation in the absence of O2.
Fermentation: process where pyruvate gets reduced by accepting hydrogen from NADH to make more NAD+
Regenerating NAD+ is important so that glycolysis can keep taking place in order to produce ATP
What are reversible inhibitors, and what are the 2 kinds of reversible inhibitors?
Reversible inhibitors: molecules that bind to enzymes non-covalently to prevent the enzyme from carrying out its function - they are not permanent
1. Competitive inhibitors: Binds to the active site and thus competes with the substrate for the active site
2. Non-competitive inhibitors: Binds to an area other than the active site (allosteric site) and causes a conformational change in the enzyme to prevent a substrate from bonding to the active site - does not compete
Glycolysis results in glucose being converted into what final product? What are the other final products produced in the process?
1 Glucose molecule (6-C) gets converted into 2 Pyruvate molecules (3-C), along with:
- 2 net ATP molecules produced
- 2 NADH molecules
What role does NADH and FADH2 play in cellular respiration? What is the final electron acceptor in the electron transport chain?
NADH and FADH2 act as electron carriers that bring electrons to the electron transport chain (ETC) to help make the H+ proton gradient.
Final electron acceptor in the ETC is oxygen.
What are reaction centers and which are found in Photosystem II and Photosystem I?
Reaction centers are a pair of chlorophyll pigments in the photosystems that pass electrons to electron carriers.
PSII: P680
PSI: P700
T/F: Glycolysis can only take place in environments with oxygen.
False - glycolysis doesn't need oxygen so it can take place with or without oxygen.
What is allosteric regulation and what are allosteric enzymes?
(Double Jeopardy!!!)
Allosteric regulation: regulation of an enzyme through the binding of a regulatory molecule to the enzyme, causing it to change in shape - it can turn the enzyme on or off
Allosteric enzyme: enzyme involved in allosteric regulation where it can switch btwn a high and low affinity state when a regulatory molecule bonds to it
What are the 3 general phases of glycolysis?
1. Energy investment phase: 2 ATP are used
2. Energy generation/liberation phase: 4 ATP are produced
3. Pyruvate formation
Why is it important to generate a proton (H+) gradient in the ETC?
Creating a proton gradient will cause H+ to diffuse down ATP synthase in order to provide the energy to phosphorylate ADP into ATP.
___ and _____, which are products of the light dependent reactions, get used as reactants for the Calvin Cycle / Carbon Fixation.
ATP and NADPH - these get oxidized in the cycle to reduce other intermediate carbon molecules
______ is the primary electron donor in the ETC during photosynthesis.
H2O
What is feedback inhibition?
When the final product of an enzyme pathway is used to negatively regulate an earlier step in the pathway in order to stop the pathway.
What are the 3 regulatory enzymes in glycolysis and their products?
1. Hexokinase - produces glucose-6-phosphate (G6P)
2. Phosphofructokinase-1 (PFK-1) - produces fructose-6-phosphate (F6P)
3. Pyruvate kinase - produces pyruvate
What are the products of pyruvate oxidation and the citric acid cycle?
Pyruvate oxidation: 2 pyruvate get converted into
- 2 Acetyl CoA
- 2 NADH are released
-2 CO2 are released
Citric acid cycle: For every 1 Acetyl CoA that enters the cycle,
- 2 CO2
- 3 NADH
- 1 FADH2
- 1 ATP
How many of the 6 glyceraldehyde-3-phosphate molecules actually leave the Calvin cycle to be used in other cellular processes?
Only 1 leaves the cycle, while the remaining 5 are used to regenerate RBP to keep the cycle going.
T/F: The Calvin Cycle produces glucose as a final end product.
False! Calvin cycle produces glyceraldehyde-3-phosphate which can then be used to make glucose (or fructose)