Lecture 6 Flashcards
1
Q
Fundamental Steps in Glycolysis:
A
- Glycolysis, occurring in the cytoplasm, involves the breakdown of glucose (6-carbons) into two molecules of pyruvate (3-carbons each).
- It is divided into two phases: Preparatory Phase (consumes 2 ATP) and Payoff Phase (produces 4 ATP and 2 NADH).
- Overall, glycolysis yields a net gain of 2 ATP molecules and 2 NADH molecules.
2
Q
Role of the Citric Acid Cycle (Krebs Cycle):
A
- Occurs in the mitochondrial matrix.
- Pyruvate from glycolysis is converted to Acetyl-CoA, which enters the cycle.
- Each cycle generates 1 ATP, 3 NADH, 1 FADH2, and 2 CO2 per Acetyl-CoA molecule.
3
Q
Fate of Electrons Produced by the Citric Acid Cycle:
A
- The electrons carried by NADH and FADH2 are transferred to the Electron Transport Chain (ETC), where they help drive ATP production.
4
Q
Basic Steps in the Electron Transport Chain (ETC):
A
- Occurs in the inner mitochondrial membrane.
- NADH and FADH2 pass electrons through a series of proteins, pumping protons into the intermembrane space, creating a proton gradient.
- ATP synthase uses this proton gradient to generate ATP via chemiosmosis.
5
Q
Different Ways ATP is Made:
A
- Substrate-level phosphorylation (e.g., during glycolysis and the Krebs cycle) directly produces ATP.
- Oxidative phosphorylation occurs in the ETC and is the primary way cells generate ATP, producing most of the ATP from one glucose molecule.
6
Q
Comparison of Anaerobic and Aerobic Respiration:
A
- Aerobic Respiration:
o Requires oxygen.
o Produces up to 36 ATP per glucose molecule.
o Complete breakdown of glucose through glycolysis, the Krebs cycle, and ETC. - Anaerobic Respiration:
o Occurs in the absence of oxygen.
o Relies on fermentation (e.g., lactic acid fermentation or alcohol fermentation) to regenerate NAD+.
o Produces only 2 ATP per glucose molecule, as it relies solely on glycolysis.
7
Q
The Three Steps Involved in the Energy Cycle of the Cell and the Organelles They Occur In:
A
- Glycolysis: Occurs in the cytoplasm of the cell.
- Krebs Cycle (Citric Acid Cycle): Takes place in the mitochondrial matrix.
- Electron Transport Chain (ETC): Located in the inner mitochondrial membrane.
8
Q
Description of Glycolysis and the Net ATP Molecules Generated:
A
- Glycolysis is the process of breaking down glucose (a 6-carbon molecule) into two pyruvate molecules (each with 3 carbons).
- It has two phases:
1. Preparatory Phase: ATP is consumed to convert glucose into intermediates.
2. Payoff Phase: ATP and NADH are produced. - Net ATP generated: 2 ATP per glucose molecule.
9
Q
Different Names of the Krebs Cycle, Description, and Net ATP Molecules Generated:
A
- The Krebs Cycle is also known as the Citric Acid Cycle or Tricarboxylic Acid (TCA) Cycle.
- Description: It involves the oxidation of Acetyl-CoA (derived from pyruvate) in a series of reactions that produce energy-rich molecules like NADH and FADH2, which are then used in the ETC.
- Net ATP generated: 1 ATP per cycle (per Acetyl-CoA), resulting in 2 ATP per glucose molecule.
10
Q
Description of the Electron Transport System (ETS) and Net ATP Molecules Generated:
A
- The Electron Transport Chain (ETC) involves transferring electrons from NADH and FADH2 through a series of proteins in the inner mitochondrial membrane, which generates a proton gradient used by ATP synthase to produce ATP.
- Net ATP generated: The ETC produces the majority of the ATP, contributing to a total of approximately 34 ATP molecules from one glucose molecule.
11
Q
The Fate of Pyruvate Molecules in Relation to the Energy Cycle:
A
- With Oxygen (Aerobic Respiration): Pyruvate is transported into the mitochondria, where it is oxidized to form Acetyl-CoA. Acetyl-CoA then enters the Krebs Cycle, leading to further ATP production through the ETC.
- Without Oxygen (Anaerobic Respiration): Pyruvate undergoes fermentation (e.g., lactic acid fermentation in muscles or alcohol fermentation in yeast) to regenerate NAD+, allowing glycolysis to continue and produce ATP without oxygen.
12
Q
- How many molecules of pyruvic acid formed in glycolysis does Krebs cycle use?
a. 2
b. 3
c. 1
d. 4
A
A
13
Q
- In which part of the cell does Krebs cycle take place?
a. Nucleus
b. Cell wall
c. mitochrondria
d. None of the above
A
C
14
Q
- When no oxygen is available, pyruvate is converted to
a. Lactic acid
b. muscle cells.
c. glucose.
d. oxygen.
A
A
15
Q
- Our cells mostly store energy in the form of
a. ATP
b. NAD
c. GTP
d. Glucose
A
A
