C1.2 Cell Respiration

Question 1

Describe the structure of ATP.

Answer 1

A nucleotide composed of adenine, ribose and three phosphates

Question 2

Outline properties of ATP that make it suitable for the use as an energy currency within cells.

Answer 2

High energy bonds

Unstable bonds between phosphates and releases energy when broker

Question 3

Outline example cellular processes that require use of ATP.

Answer 3

Active transport across membranes

Anabolism

Movement of the whole cell

Movement of components within the cell

Question 4

Describe the ATP-ADP cycle, including the relative amount of energy and the roles of hydrolysis and phosphorylation.

Answer 4

The hydrolysis from ATP to ADP releases an inorganic phosphate used as activation energy for metabolic reactions

Energy is then required to go from ADP and P to ATP through condensation. Cellular respiration provides the energy

Question 5

State why heat is generated during the ATP-ADP cycle.

Answer 5

Due to inneficiencies in cellular respiration and metabolic reactions

Question 6

Define cellular respiration.

Answer 6

the controlled release of ATP energy from organic compounds within cells

Question 7

Distinguish between cellular respiration and gas exchange.

Answer 7

Gas exchange is the exchange of CO2 and oxygen in living cells and tissues whereas cellular respiration is the release of ATP energy from organic compounds within cells

Question 8

List common substrates of cellular respiration.

Answer 8

Glucose

Fatty Acids

Question 9

List reasons why cellular respiration must be continuously performed by all cells.

Answer 9

Sustaining metabolic and biochemical processes.
Maintenance of cellular homeostasis.
Fueling growth, repair, and reproduction.

Question 10

Compare and contrast anaerobic fermentation and aerobic respiration.

Answer 10

Aerobic and Anaerobic :
Occur in cells
Glucose as initial substrate
Enzymes to catalyse reaction pathways
Produces ATP

Aerobic
Oxygen is required
High yield (+36ATP)
CO2 and water are waste products
Most of the process occurs in mitochondria

Anaerobic
Oxygen isn’t used
Low yield (+2ATP)
Lactate
Occurs in cytoplasm (not mitochondria)

Question 11

List three approaches for determining the rate of cellular respiration.

Answer 11

Measuring volume gas produced by yeast

Measuring change in oxygen concentration using ocygen probes

Measuring the change in CO2 concentration using CO2 probes

Question 12

Outline oxidation and reduction reactions in terms of movement of hydrogen and electrons.

Answer 12

Oxidation results in removal of hydrogen and loss of electrons

Reduction results in addition of hydrogen and gain of electrons

Question 13

Define “electron carrier.”

Answer 13

a molecule or protein capable of accepting and donating electrons during metabolic reactions or electron transport processes

Question 14

State the name of the electron carrier molecule used in cellular respiration.

Answer 14

NAD

Question 15

Outline the formation of reduced NAD (=NADH + H+) during glycolysis.

Answer 15

NAD removes two electrons and hydrogen from substrates at various stages of respiration. When NAD gains electrons and hydrogen from a substrate it forms reduced NAD

Question 16

State the formula for the glycolysis reaction.

Answer 16

C6H12O6+6O2=6O2+6H2O

Question 17

State that glycolysis occurs in both anaerobic and aerobic respiration.

Answer 17

Glycolysis occurs in both anaerobic and aerobic respiration

Question 18

State the location of the glycolysis reaction in a cell.

Answer 18

Cytoplasm of the cell

Question 19

State that glycolysis is an example of a metabolic pathway catalyzed by enzymes.

Answer 19

Glycolisis is an example of a metabolic pathway

Question 20

Outline the glycolysis reaction, including phosphorylation of glucose, lysis, oxidation and ATP formation.

Answer 20

Phosphorylation of Glucose, two ATPs are hydrolysed bond to glucose formin Hexose Bisphosphate

Hexose Bisphosphate breaks apart into 2 triose phosphates

NAD is converted to reduced NAD as it takes electrons from the triose phosphates resulting in them being oxidized.

ADP+Pi turns to ATP as each carbon compound is converted to pyruvate

Glucose converts to pyruvate

• State the net yield of ATP and reduced NAD produced in glycolysis.

2 ATP and 2 reduced NAD

Question 20

State why NAD must be regenerated in anaerobic respiration.

Answer 20

Because glycolysis requires a constant supply of NAD

Question 21

State the condition in which humans would perform anaerobic respiration.

Answer 21

When oxygen isn’t present in human cell

Question 21

Compare anaerobic respiration in yeasts and humans.

Answer 21

Yeast produces ethanol and CO2

Humans produce lactic acid

Question 22

Outline the process of regenerating NAD and production of lactate in humans during anaerobic respiration.

Answer 22

Pyruvate is converted to lactate by oxidizing reduced NAD to NAD

Question 23

Outline the process of regenerating NAD and production of ethanol in yeast during anaerobic respiration.

Answer 23

Pyruvate is converted to ethanol and carbon through oxidizing reduced NAD to NAD

Question 24

Outline how anaerobic respiration in yeast is used in brewing and baking.

Answer 24

CO2 produced by yeast during anaerobic respiration causes the dough to rise Yeast produces ethanol in the brewing process

Question 25

Summarize the reactants and products of the link reaction.

Answer 25

Reactants : NAD, Pyruvate, Co enzyme A, Acetyl Product : Reduced NAD, Acetyl Coenzyme A

Question 26

State that the link reaction occurs in the matrix of the mitochondrion.

Answer 26

The link reaction occurs in the matrix of the mitochondrion

Question 27

Outline the link reaction with references to decarboxylation, oxidation and binding of CoA.

Answer 27

Decarboxylation of pyruvate : loss of CO2 to produce a 2 carbon acetyl group Reduction of NAD : Pyruvate is oxidized as it loses electrons and hydrogen. NAD is reduced as it gains electrons and hydrogens Formation of acetyl coenzyme A : acetyl group combines with coenzyme A to form acetyl coenzyme A.

Question 28

State that the Krebs cycle occurs in the matrix of the mitochondrion.

Answer 28

Krebs cycle occurs in the matrix of the mitoochondrion

Question 29

Outline the events of the Krebs cycle, referencing the formation of citrate from oxaloacetate, decarboxylation of citrate to reform oxaloacetate, formatting of CO2, formation of ATP and the oxidation reactions that form reduced NAD (=NAD + H+) and reduced FAD (=FADH2).

Answer 29

Oxaloacetate (4 carbon) combines with acetyl coA to form citrate (6C), Citrate loses CO2 twice to form a 4 carbon compound. Citrate is converted back to oxaloacetate through three intermediate compunds losing electrons and hydrogens to NAD to from reduced NAD, one carbon compound is oxidised and lsoes electrons and hydrogne to the elcetron carrier FAD producing reduced FAD Each Kreb cycle provides enough energy to convert ADP and a phosphate to ATP through condensation reaction.

Question 30

State that the reduced NAD and reduced FAD produced in the Krebs cycle carry electrons to the mitochondrial electron transport chain.

Answer 30

Reduced NAD and FAD produced in the krebs cycle carry electrons to mitochondrial electron transport chain

Question 31

List the net products of one turn of the Krebs cycle.

Answer 31

NAD and FAD to Reduced NAD and FAD + 1 ATP

Question 32

State that at the mitochondrial electron transport chain, reduced NAD (=NAD + H+) and reduced FAD (=FADH2) are oxidized with the transfer electrons to electron carrier proteins.

Answer 32

Reduced NAD and FAD are oxidized thanks to the mitochondrial electron chain transporting electrons to electron carrier proteins

Question 33

List the reactions that generated the reduced NAD (=NAD + H+) and reduced FAD (=FADH2) used in the electron transport chain.

Answer 33

Isocitrate to α-ketoglutarate (NADPH) α-ketoglutarate to succinyl-CoA(NADPH)

Question 34

Describe how the movement of electrons through the electron transport chain is used to generate a proton gradient in the intermembrane space.

Answer 34

Movement of electrons provides energy for active transport of protons from the mitochondrial matrix into the intermembrane space

Question 35

Define chemiosmosis.

Answer 35

The generation of ATP using kinetic energy as protons move trhough ATP synthase

Question 36

Describe the structure ATP synthase.

Answer 36

A proton channel

Question 37

Outline the formation of ATP by ATP synthesis, with reference to movement of protons and phosphorylation of ADP.

Answer 37

Protons pass trough ATP synthase from the high concentration in the intermembrane space to the low concentration in the matrix through facilitated diffusion. These protons provide energy to convert ADP and phosphate to ATP

Question 38

Compare the total amount of ATP made from anaerobic and aerobic respiration.

Answer 38

Anaerobic 1 ATP Aerobic 36 ATP

Question 39

State that the formation of water in the matrix at the end of the electron transport chain helps to maintain the proton gradient between the intermembrane space and the matrix.

Answer 39

Formation of water in the matrix at the end of the electron transport chain helps maintain the proton gradient between the intermembrane spacce and the matrix

Question 40

State that oxygen is the final electron acceptor in the electron transport chain.

Answer 40

Oxygen is the final electron acceptor in the electron transport chain

Question 41

Explain why aerobic respiration will stop if oxygen is not present.

Answer 41

Because it requires oxygen as the final electron receptor

Question 42

Compare the use of carbohydrates and lipids as respiratory substrates in aerobic and anaerobic respiration.

Answer 42

Lipids and carbohydrates can be respired (fatty acids not all lipids) can produce acetly coenzyme A Carbohydrates glycolisis and anaerobic respiration only occur with carbohydrates

Question 43

Explain the greater energy yield of lipids compared to carbohydrates when used as respiratory substrates.

Answer 43

Lipids have a higher yield as the have less oxygen nand more oxidizable hydrogen and carboe

Question 44

Outline the process by which lipids can be a substrate for respiration.

Answer 44

Lipolysis :break down into glycerol and fatty acids Beta-oxidation : fatty acids break down into acetyl CoA through a series of oxidation reactions where each round generates NADH and FADH2