Respiration

Question 1

Outline aerobic respiration

Answer 1

Requires oxygen and produces carbon dioxide, water and much ATP

Question 2

Outline anaerobic respiration

Answer 2

Takes place in the absence of oxygen, and produces lactate (animals), or ethanol and CO2 (plants and fungi). Only a little ATP.

Question 3

4 stages of respiration?

Answer 3

Glycolysis, link reaction, krebs cycle, oxidative phosphorylation

Question 4

What does glycolysis produce?

Answer 4

Two 3C pyruvate molecules

Question 5

Where does glycolysis occur?

Answer 5

Cytoplasm

Question 6

Outline the process of glycolysis.

Answer 6

1. Phosphoylation occurs (2 ATP hydrolysed into 2 ADP + Pi).
2. Each molecule pf phosphorylated glucose is split into 2x 3C molecules (triose phosphate).
3. This triose phosphate is oxidised, forming two molecules of pyruvate. The hydrogen (lost from oxidation) is transferred to NAD to form NADH.
4. 4ATP are produced (net gain of 2).

Question 7

What are the energy yields from glycolysis?

Answer 7

2 ATP
2NADH
2 pyruvate

Question 8

How can glycolysis provide evidence for evolution?

Answer 8

Because it’s a universal feature of every organism

Question 9

Why can glycolysis take place in the cytoplasm and not an organelle?

Answer 9

Because the enzymes for the glycolytic pathway are found in the cytoplasm.

Question 10

Where does the link reaction occur?

Answer 10

Mitochondria

Question 11

What is produced in the link reaction?

Answer 11

Acetyl CoA

Question 12

How do the pyruvate molecules produced in glycolysis get from the cytoplasm to mitochondria?

Answer 12

Active transport

Question 13

Outline the process of the link reaction

Answer 13

1. The pyruvate molecules are actively transported to matrix of mitochondria.
2. The pyruvate is oxidised into acetate. In this, the 3C pyruvate molecule loses a CO2 molecule and 2 hydrogens (which are used to form NADH).
   3 The 2C acetate combines with CoA to produce acetyl CoA.

Question 14

What is the word equation of the link reaction?

Answer 14

Pyruvate + NAD + CoA —> Acetyl CoA + NADH + CO2

Question 15

The link reaction and krebs cycle occur twice for every glucose molecule. Why?

Answer 15

Because 2 pyruvate molecules are made for every glucose molecule entering glycolysis.

Question 16

What is produced from the krebs cycle?

Answer 16

she ATP and a large quantity of NADH and FADH

Question 17

Where does the krebs cycle occur?

Answer 17

Matrix of mitochondria.

Question 18

What type of reactions occur in the krebs cycle?

Answer 18

A series of oxidation-reduction reactions.

Question 19

Outline the process of the krebs cycle

Answer 19

1. Acetyl CoA (from LR) combines with a 4C molecule to produce a 6C compound.
2. In a series of oxidation-reduction reactions. the 6C compound loses 2 molecules of CO2 and hydrogen to give to a 4C molecule, and 1 ATP produced due to substrate level phosphorylation.
3. The 4C molecule can now combine with a new molecule of acetyl CoA to begin the cycle again.

Question 20

How many carbons does acetyl CoA have?

Answer 20

2C

Question 21

For each molecule of pyruvate, the krebs cycle produces…

Answer 21

• 1 ATP
• 3x CO2
• reduced coenzymes e.g. NAD and FAD

Question 22

How is the CO2 produced as a waste product in respiration removed?

Answer 22

During gaseous exchange

Question 23

Where does oxidative phosphorylation occur?

Answer 23

Mitochondria (within the cristal (folded inner membrane), the enzymes and other proteins involved in OP are found)

Question 24

What’s the difference between mitochondria in metabolically active cells?

Answer 24

• larger quantities

- more densely packed christie

Question 25

Outline the process of oxidative phosphorylation

Answer 25

1. NADH and FADH donate the hydrogen atoms they’re carrying to the first molecule in the electron transfer chain/
2. The electrons pass along a chain of electron transfer molecules in a series of oxidation-reduction reactions .
   As electrons flow down this chain, the energy they release causes the active transport of protons across the inner mitochondrial space into the inter-membranal space.
3. Protons accumulate in the inner membrane space. Then, they diffuse back into the matrix through ATP synthase channels imbedded in the inner-mitochondrial membrane.
4. At the end of the chain, electrons and protons combine with oxygen to form water. (Oxygen is there terminal acceptor of electrons).

Question 26

Why are the electrons carried by NAD and FAD not transferred in one explosive step in OP, but instead are passed along a series of electron transfer carrier molecules?

Answer 26

Because the transfer of electrons down an energy gradient allows their energy to be released gradually, therefore more usefully (e.g. not as heat).

Question 27

Name two alternative respiratory substrates

Answer 27

Lipids and proteins

Question 28

Outline the respiration of protein as an alternative respiratory substrate

Answer 28

It is first hydrolysed into its constituent AAs. These have their amino group removed (deamination) before entering the respiratory pathway at different point depending on the amount of carbon they contain.

Question 29

Outline the respiration of lipids as an alternative respiratory substrate

Answer 29

Lipids are first hydrolysed into glycerol and fatty acids.
The glycerol is then phosphorylated and converted into triode phosphate which enters the glycolysis pathway and subsequently the Krebs cycle.
The fatty acid component is broken down into 2C fragments which are converted to acetyl CoA (then enters Krebs cycle)

Question 30

How many times does decarboxylation happen during one turn of the Krebs cycle?

Answer 30

Twice

Question 31

What do electrons lose as they move along the electron transport chain in oxidative phosphorylation?

Answer 31

Energy

Question 32

What is the total amount of ATP that can be produced from one glucose molecule?

Answer 32

32