Cell Respiration

Question 1

Cell respiration

Answer 1

Cells extract energy stored in food and transfer that energy to molecules of ATP

Question 2

Anaerobic respiration / Fermentation

Answer 2

● Cellular respiration without oxygen

● Consists of glcolysis puls alcohol or lactic acid fermentation

Question 3

Aerobic respiration

Answer 3

Cellular respiration requiring oxygen

Question 4

Glycolysis

Answer 4

● 2 ATP + 1 Glucose -> 2 Pyruvate + 4 ATP
● Net gain of 2 ATP
● Occurs in the cytoplasm and releases ATP without using oxygen

Question 5

Substrate level phosphorylation

Answer 5

● Produced ATP during glycolysis
● Direct enzymatic transfer of a phosphate to ADP, transfered by an enzyme kinase
● Only a small amount of ATP is released this way

Question 6

Phosphofructokinase (PFK)

Answer 6

● An allosteric enzyme that catalyzes the third step in glycolysis
● It inhibits glycolysis when the cell contains engough ATP and does not need to produce any more

Question 7

Alcoholic fermentation

Answer 7

● Certain cells convert pyruvate from glycolysis into ethyl alcohol and carbon dioxide in the absence of oxygen
● The process oxidize NADH back to NAD+
● Yeast

Question 8

Lactic acid fermentation

Answer 8

● Pyruvate is reduced to form lactic acid or lactate
● NADH gets oxidized back to NAD+
● Human skeletal muscles

Question 9

Formation of Acetyl Co A

Answer 9

● Takes place in the cytoplasm

● Each pyruvate becomes an Acetyle Co A (2 in total for every glucose)

Question 10

Ctric acid cycle / Krebs cycle

Answer 10

● Takes place in the matrix of mitochondria
● Requires pyruvate, the product of glycolysis
● Completes the oxidation of glucose to CO2
● Generates 1 ATP per turn by substrate-level phosphorylation, but most of the chemical energy is transferred to NAD+ and FAD
● By products (for each glucose) are 2 ATP, 4 CO2, 6 NADH, 2 FADH2

Question 11

Electron transport chain (ETC)

Answer 11

● Proton pump in the mitochondria
● Takes place in the inner membrane of the mitochondria
● Uses energy released from the exergonic flow of electrons to pump protons against a gradient from the matrix to the outer compartment
● This results in the establishment of a proton gradient inside the mitochondron
● ETC makes no ATP directly but sets the stage for ATP production during chemiosmosis

Question 12

Chemiosmosis

Answer 12

Uses potential energy stored in the form of a proton gradient (H+) to phosphorylate ADP and produce ATP

Question 13

Oxidative phosphorylation

Answer 13

● Phosphorylation of ADP into ATP by the oxidation of the carrier molecules NADh and FADH2
● Peter Mitchell named it chemiosmotic theory

Question 14

Reduction

Answer 14

Gain of electrons or hydrogen ions

Question 15

Oxidation

Answer 15

Loss of electrons or protons

Question 16

Redox reaction

Answer 16

An reaction in which one substance is reduced while the other is oxidized

Question 17

ATP

Answer 17

● Adenosine triphosphate
● Consists of adenosine (adenine and ribose) and three phosphates
● Unstable because the three phosphates in ATP are all negatively charged and repel one another
- When u move to a more stable molecule, ADP, it realeases energy

Question 18

Cristae membrane

Answer 18

Folded inner membrane of mitochondria

Question 19

Matrix

Answer 19

Inner compartment of the mitochondria

Question 20

NAD+ / FAD

Answer 20

● Required for normal cell respiration

● Coenzymes that carry protons or electrons from glycolysis and the citric acid cycle to the electron transport chain

Question 21

NADH

Answer 21

● Proton/electron carrier

● NAD+ + 2 e- + H+ = NADH

Question 22

Cytochromes

Answer 22

● Proteins structurally similar to hemoglobin

● Present in all aerobes and are used to trace evolutionary relationships

Question 23

Facutative anaerobes

Answer 23

● Can tolerate the pressure of oxygen

- They simply don’t use it

Question 24

Obligate anaerobes

Answer 24

Cannot live in an environment containing oxygen

Question 25

How is energy stored in the cell?

Answer 25

● Energy is temporarily stored in molecules of ATP ● Energy is instantly available for every cellular activity such as passing an electrical impulse, contracting a muscle, moving cilia, or manufacturing a protein

Question 26

What are the key points about ETC?

Answer 26

● Collection of moleulces embedded in the cristae membrane of the mitochondrion ● Thousands of copies of the ETC in every mitochondrion due to th extensive folding of the cristae membrane ● Carries electrons delivered by NAD and FAD from glycolysis and the Krebs cycle to oxygen, the final electron acceptor - Undergo redox reactions

Question 27

Which one dlivers its electrons to a higher enery level, NADH or FADH2 and what's the result of that?

Answer 27

● NADH ● NADH provides more energy for ATP synthesis than does FADH2 - Each NADH produces 3 ATp molecules, while each FADH2 produces 2 ATP molecules

Question 28

What are the key points about oxidative phosphorylation?

Answer 28

● Powered by the redox reactions of the ETC ● Protons are pumped from the matrix to the outer compartment by the ETC ● Proton gradient is created between the cristae membrane - THye can flow only down the gradient into the matrix through ATP synthase channels ● As protons flow through the ATP-synthase channels, they generate energy to phosphorylate ADP into ATP ● Oxygen is the final hydrogen acceptor, combining 1/2 O2 + 2 e- + 2 H+ = H2O - Water is a waste product of cell respiration and is excreted

Question 29

What are the two ways that ATP can be produced?

Answer 29

● Substrate level phosphorylation | ● oxidative phosphorylation

Question 30

How does substrate level phosphorylation produce ATP?

Answer 30

● When an enzyme, a knase, transfers a phosphate from a substrate directly to ADP ● Only a small amount of ATP is produced this way ● Energy is produced this way during glycolysis and the Krebs cycle

Question 31

How does oxidative phosphorylation produce ATP?

Answer 31

● Occurs during chemiosmosis ● 90% of all ATP is produced this way from cell respiration ● NAD and FAD lose protons to the ETC, which pumps them to the outer compartment of the mitochondrion, creating a proton gradient ● This proton gradient powers the phosphorylation of ADP into ATP

Question 32

What is the sequence that energy flow?

Answer 32

Glucose -> NAD / FAD -> ETC -> chemiosmosis -> ATP

Question 33

What is the requirement for fermentation to generate ATP?

Answer 33

● As long as there is an adequate supply of NAD+ to accept electrons during glycolysis ● Fermentation consists of glycolysis plus the reactions that regeenrate NAD+

Question 34

When do human skeletal muscles carry out lactic acid fermentation?

Answer 34

● When blood cannot supply adequate oxygen to muscles during strenuous exercise ● Lactic acid in the muscle causes fatigue and burning - They continue to build up until the blood can supply the muscles with adequate oxygen ● With normal oxygen levels, the muscle cells will revert to the more effficient aerobic respiration