09 Cellular respiration and fermentation

Question 1

Differentiate between aerobic and anaerobic respiration

Answer 1

Aerobic - oxygen is consumed as a reactant along with glucose/fat/other organic fuel
Anaerobic - when prokaryotes use substance other than O2 to harvest chemical energy

Question 2

Define cellular respiration

Answer 2

Both aerobic and non aerobic respiration but often refers to only aerobic in bio textbooks
It’s a catabolic exergonic reaction that gives off H2O, CO2, and energy (ATP + heat)

Question 3

Define redox reaction

Answer 3

the transfer of electrons from one reactant to another

Question 4

Define oxidation and reduction

Answer 4

Oxidation is the loss of electron charge/increasing + charge

Reduction is adding electrons/reducing + charge

Question 5

Define reducing agent and oxidizing agent. Which one becomes reduced, and which one becomes oxidized?

Answer 5

Reducing agent - X; electron donor; reduces the electron acceptor. This becomes oxidized

Oxidizing agent - Y; electron acceptor; this becomes reduced

Xe + Y –> X + Ye

Question 6

Give an example of an excellent fuel. Why are they so?

Answer 6

Organic mlcls that have an abundance of Hydrogen; because their electrons are a source of hilltop electrons that release their energy as they fall down an energy gradient

Question 7

What is NAD+ and NADH?

Answer 7

NAD+ is nicotinamide (nitrogenous base) adenine dinucleotide. Consists of 2 nucleotides joined together at their phospahte groups. It is an electron acceptor and oxidizing agent during repsiration

NADH: when 2 electrons and 1 proton from an organic mlcl in food is transferred to NAD+, it turns to NADH and the second H+ is released

Question 8

How does NAD+ trap electrons from glucose and other organic mlcls in food?

Answer 8

The dehydorgenase enzymes removes a pair of hydrogen atoms (2e- and 2H+) from the substrate (food particle), delivers 2e- and 1H+ to NAD+ and releases the final H+ to the surrounding solution.

Question 9

How do electrons that are extracted from glucose and stored as potential energy in NADH finally reach Oxygen?

Answer 9

Repsiration uses an eelctron transport chain to break the fall of electrons into smaller energy-releasing steps.
The ETC consists of proteins built into the inner mitochondrial membrane. ELectrons removed from C6H12O6 are shuttled tot the top high-energy end where O2 captures these elctrons and forms water. Each downhill carrier is more electronegative than its uhill neighbor and thus capable of oxidizing with Oxygen at the bottom

Question 10

List the four stages of cellular respiration and where they take place in prokaryotes and eukaryotes

Answer 10

Glyoclysis: brekaing glucose into 2 3-carbon compoundsof pyruvate/ Cytosol in both

Pyruvate oxidation: changing pyruvate to acetyl Coenzyme A/ P: cytosol E: mitochondrion

Citric acid cycle: breakdown of glucose to Carbon dioxide/ P: cytosol E: mitochondrion

Oxidative phosphorylation: electron transport chain and chemiosmosis to extract ATP/ P: plasma membrane e: inner membrane of mitochondrion

Question 11

Define substrate level phosphorylation

Answer 11

Alternative to oxidative phosphorylation in which an enzyme transfers P group from substrate mlcl to ADP

Question 12

Explain how glycolysis takes place. What are the reducing and oxidizing agents?

Answer 12

Energy investment phase: 2 ATP used to change glucose to ADP + P group

Energy payoff phase: substrate-level phosphorylation forms 4 ATPs / NAD+ is reduced to NADH by electrons released from glucose oxidation