BIOL 1306: Cellular Respiration

What is cellular respiration?

A catabolic reaction that takes place in the mitochondria in which glucose is broken down into carbon dioxide and water

In cellular respiration, some of the energy is lost as ____________

heat

What kind of reaction is cellular respiration?

Redox

In cellular respiration, glucose is _____________ to carbon dioxide because it loses electrons

oxidized

In cellular respiration, oxygen is _____________ to water because it gains electrons

reduced

What is the purpose of glycolysis?

Breakdown glucose into pyruvate that will be used in the citric acid cycle

Where does glycolysis occur?

Cytosol

What is the first phase of glycolysis?

Energy investment- 2 ATP are invested into the reaction

What is the second phase of glycolysis?

Energy payoff- 2 NADH and 4 ATP are produced by susbtrate-level phosphorylation

What is the goal of pyruvate oxidation and the citric acid cycle?

Strip out electrons and generate carbon dioxide, NADH, and FADH

Where do pyruvate oxidation and the citric acid cycle occur in eukaryotes?

Matrix of mitochondria

Where do pyruvate oxidation and the citric acid cycle occur in prokaryotes?

Cytosol

What are the steps of pyruvate oxidation and the citric acid cycle?

1. 2 pyruvates from the cytosol are processed by pyruvate dehydrogenase before entering the citric acid cycle 

2. Carbonyl group is removed and given off as CO₂ 

3. Compound remaining is oxidized; NAD+ reduced to NADH 

4. Coenzyme A + two-carbon group = acetyl CoA 

5. 2 molecules of acetyl CoA enter citric acid cycle to complete oxidation/breakdown of glucose 

6. 2 full turns are needed to consume both acetyl CoA molecules; results in CO₂, 2 ATP, 6 NADH, 2 FADH₂

What is the role of oxidative phosphorylation?

Use electrons to do work/make ATP

Where does oxidative phosphorylation occur in eukaryotes?

Inner membrane of mitochondria

Where does oxidative phosphorylation occur in prokaryotes?

Plasma

What are the steps of oxidative phosphorylation?

1. NADH/FADH₂ deliver electrons to protein complexes of increasing electronegativity 

2. Electrons excite proteins to do work. O₂ at the bottom of the “hill” accepts 2 electrons and 2 H+; becomes reduced to H₂O 

3. Hydrogen enters channels in ATP synthase and binds to rotor structure. Spins and causes ADP to become phosphorylated

Reactants of glycolysis

Glucose

Products of glycolysis

2 pyruvates, 2 ATPs, 2 NADHs

Pyruvate oxidation reactants

2 pyruvates

Products of pyruvate oxidation

Acetyl Coenzyme A

Reactants of citric acid cycle

Acetyl CoA

Products of the citric acid cycle (after 2 turns)

CO₂, 2 ATP, 6 NADH, 2 FADH₂ 

Reactants of oxidative phosphorylation

Oxygen and 6 NADH/2 FADH₂ 

Products of oxidative phosphorylation

26-28 ATP

Phosphate group is directly transfered from a substrate molecule to ADP to form ATP

Substrate level phosphorylation

Where does substrate level phosphorylation occur?

Cytoplasm during glycolysis and in the mitochondria during the citric acid cycle

Where is the energy source derived from in susbtrate level phosphorylation?

Breaking of chemical bonds in in the substrate

Which process produces more ATP, susbtrate level phosphorylation or oxidative phosphorylation?

Oxidative phosphorylation

Oxidative phosphorylation uses external _________________ __________________

electron acceptors

What occurs in oxidative phosphorylation?

Electrons are transferred through a series of proteins for increasing electronegativity. This creates a proton gradient that drives ATP synthesis via ATP synthase.

Where does oxidative phosphorylation occur?

Inner mitochondrial membrane

What provides the energy needed to complete oxidative phosphorylation?

NADH and FADH₂ 

The electron donor is ______________ and the electron acceptor is _____________

oxidized; reduced

What kind of redox reaction is this? NAD+ to NADH

Reduction

NADH and FADH donate electrons to the electron transport chain. What happens to the NADH and FADH.

They are oxidized

How is the energy released from redox reactions used?

Make ATP via oxidative phosphorylation 

Hoe does the ETC power the final production of ATP by ATP synthase?

1. NADH/FADH2 constitute the ETC in the mitochondria. Electrons excite the proteins to do work. Oxygen accepts 2 electrons and 2 H+ to become reduced to H₂O 

2. Hydrogens passively diffuse from the intermembrane space to the mitochondrial matrix with the help of ATP synthase in the process of chemiosmosis 

3. Hydrogens enter the channels and bind to rotor structures. Spinning motion causes ADP to become phosphorylated. 26-28 ATP are produced. 

Glycolysis is regulated by negative feedback inhibition with the help of ___________________________

phosphofructokinase 

Phosphofructokinase is inhibited by…

High levels of ATP

What is the action of PFK when there are high levels of ATP?

PFK binds to the regulatory (allosteric site) and inhibits third enzyme

What is the action of PFK when ATP levels are low?

PFK binds to active site

Reaction rates are ________ when ATP and NADH are scarce

High

Obligate anaerobes

are poisoned by oxygen

Facultative anaerobes

Can make ATP by either aerobic/anaerobic conditions

Anaerobic fermentation ___________ ________ require oxygen

does not

How much ATP is produced by anaerobic fermentation?

2 per glucose molecule

What is the process of anaerobic fermentation?

Glycolysis followed by conversion of pyruvate into other compounds

Aerobic respiration

Occurs in mitochondria of eukaryotic cells or in the cytoplasm of prokaryotes

Characterized by a high ATP yield

Aerobic respiration

Anaerobic respiration

Glycolysis followed by fermentation 

What is the equation for cellular respiration?

C6 H12 O6 +6O2 →6CO2 +6H2O+ATP