Week Six/Seven: Cellular Respiration

Question 1

Cellular Respiration

Answer 1

• The acquisition of chemical energy from organic fuel molecules.
• Consumes oxygen and produces CO2.
• Converts energy in organic molecules (food) to ATP.
• Change in G from complete combustion of glucose= -686kcal/mol.
• Highly exergonic; drives endergonic formation of many ATP molecules

Question 2

Redox Reactions or Oxidation reduction

Answer 2

Electrons are passed from one molecule to another
-Oxidation is the loss of an electron
-Reduction is the gain of an electron
^Both take place at the same time

Question 3

NAD = Electron Shuttle

Answer 3

*Nicotinamide adenine dinucleotide (NAD) can oxidize or reduce metabolites.
*NAD carries electrons between reactions during respiration.

Question 4

Substrate level phosphorylation

Answer 4

Enzymes transfer a phosphate group from an organic substrate to ADP to create ATP. Least efficient form of ATP production.

Question 5

Oxidative Phosphorylation

Answer 5

A type of ATP production that uses the energy harnessed from the redox reactions in an electron transport chain. Most efficient form of ATP production.

Question 6

3 stages of cellular respiration

Answer 6

1. Glycolysis
2. The Citric Acid Cycle (Kreb’s Cycle)
3. The Electron Transport Chain

Question 7

Glycolysis

Answer 7

Occurs in two phases: Energy investment and energy harvest. Takes place in the cytosol. Provides pyruvate for the citric acid cycle. The glycolytic production of pyruvate reduces the cytosol by increasing the ratio of NADH to NAD+

Question 8

The Citric Acid Cycle (Kreb’s Cycle)

Answer 8

Pyruvate molecule from glycolysis is taken into the mitochondria where it’s broken down into carbon dioxide. Generates high-energy electron carriers (NADH and FADH2) and GTP.

Question 9

The Electron Transport Chain/Oxidative phosphorylation

Answer 9

The harvested electrons are collected into the electron “shuttle” molecules of NADH & FADH2. The movement of electrons provides energy for the movement of hydrogen ions across the membrane.

Question 10

ATP Synthase produces ATP

Answer 10

This enzyme allows for the movement of the hydrogen ion pool back across the membrane. These hydrogen ions cause the enzyme to spin like a rotor. As the enzyme spins, ADP + P turns into ATP.

Question 11

How do cells make energy when oxygen is scarce?

Answer 11

• Fermentation
  -Fermentation Reactions Regenerate Electron Carriers
  -Occurs in the cytoplasm
  -Produces 2 ATP molecules
  -Anaerobic (non-oxygen-requiring) pathway for breaking down glucose.
  -Products: lactic acid, alcohol and very small amounts of ATP

Question 12

Storing excess calories/energy

Answer 12

Glycogen - short-term energy storage
Triglycerides - long-term energy storage

Question 13

NEAT

Answer 13

Daily activities, such as yard work, shopping, and walking a dog.

Question 14

What is NAD+ and NADH?

Answer 14

NAD+ is an oxidizing agent; it accepts electrons from other molecules and becomes reduced. This reaction forms NADH, which can then be used as a reducing agent to donate electrons.

Question 15

Chemical equation for cellular respiration

Answer 15

C 6 H 12 O 6 + 6 O 2 –> 6 CO 2 + 6 H 2 O + ATP

Question 16

How does an aerobic reaction differ from an anaerobic reaction?

Answer 16

Aerobic Respiration: Takes place in the presence of oxygen.
Anaerobic Respiration: Takes place in the absence of oxygen.

Question 17

How much ATP is generated in aerobic cellular respiration?

Answer 17

38 ATP Molecules

Question 18

What role do hydrogen ions play in the generation of ATP in aerobic cellular respiration?

Answer 18

In cellular respiration, hydrogen ions (protons) move down their concentration gradient through a membrane protein to produce ATP.