respiration

Question 1

what is the purpose of respiration?

Answer 1

to provide energy (in the form of ATP) to living cells

Question 2

what are the products of respiration?

Answer 2

• CO2
• water
• energy (ATP)

Question 3

what are the two things in the respiration equation that produce the products?

Answer 3

• glucose

- oxygen

Question 4

what is the respiration equation?

Answer 4

C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

Question 5

what are the stages of aerobic respiration?

Answer 5

1. glycolysis
2. link reaction
3. Krebs cycle
4. oxidative phosphorylation

Question 6

where does glycolysis occur?

Answer 6

the cell cytoplasm (not in mitochondria)

Question 7

what is the function of the mitochondria?

Answer 7

aerobic respiration

Question 8

briefly describe what glycolysis is:

Answer 8

the splitting of 6C glucose into two 3C pyruvate molecules

Question 9

what is the initial stage of aerobic and anaerobic respiration?

Answer 9

glycolysis

Question 10

describe the process of glycolysis:

Answer 10

• Glucose is phosphorylated using a phosphate ion from ATP
• This produces glucose-6-phosphate
• Another phosphate is added from ATP to form hexose bisphosphate
• This then splits into two 3C molecules of triose phosphate
• Triose phosphate is oxidised which forms 2 pyruvate molecules
• NAD picks up the hydrogen forming 2 NADH
• 4 ATP are produced (but 2 have already been used)

Question 11

what is the NET yield of glycolysis?

Answer 11

• 2 ATP
• 2 NADH
• 2 pyruvate

Question 12

what is the anaerobic respiration in plants and yeast?

Answer 12

alcoholic fermentation

Question 13

what is the process of alcoholic fermentation?

Answer 13

• takes place in plants in yeast
• pyruvate is decarboxylated to from ethanal
• ethanal is oxidised to from ethanol

Question 14

what is the form of anaerobic respiration in animals and some bacteria?

Answer 14

lactate fermentation

Question 15

what is the process of lactate fermentation?

Answer 15

• occurs in animals and some bacteria

- pyruvate is oxidised into lactate

Question 16

where does the link reaction occur?

Answer 16

in the matrix of the mitochondria

Question 17

describe the process of the link reaction:

Answer 17

• pyruvate is oxidised and decarboxylated to form acetate (2C) and a reduced NAD
• acetate is combined with coenzyme A to from acetyl coenzyme A (2C)

Question 18

what is the NET yield of the link reaction?

Answer 18

• 2 acetyl coA
• 2 CO2
• 2 reduced NAD

Question 19

what is the name of the cycle involved in respiration?

Answer 19

Krebs cycle

Question 20

Describe the process of the Krebs cycle:

Answer 20

1. Acetyl coA from link reaction combines with 4C oxaloacetate to form 6C citrate
2. Decarboxylation and dehydrogenation occurs and 6C citrate is converted into a 5C molecule
3. Decarboxylation and dehydrogenation occur, producing two molecules of reduced NAD and one molecule of reduced FAD
4. ATP is produced by substrate-level phosphorylation from an intermediate compound to ADP
5. The 5C compound is now converted into 4C oxaloacetate

Question 21

how many times does the link reaction occur per glucose molecule?

Answer 21

two

Question 22

what is oxaloacetate?

Answer 22

a 4C compound that combines with acetyl coenzyme A in the Krebs cycle to form citrate

Question 23

what occurs during oxidative phosphorylation?

Answer 23

• energy carried by electrons, from reduced coenzymes, is used to produce ATP

Question 24

where does oxidative phosphorylation take place?

Answer 24

the cristae

Question 25

Describe the process of oxidative phosphorylation:

Answer 25

1. Hydrogen atoms are released from NADH and FADH (they are oxidised) and the H atoms then split into protons (H+) and electrons (e-) 2. The electrons move down electron transport chain (lose energy at each carrier) 3. This energy is used to pump protons from the mitochondrial matric into the intermembrane space 4. The concentration of protons is now higher in the intermembrane space than in the matrix - electrochemical gradient 5. Protons therefore move down their concentration gradient back into the matrix via ATP synthase which synthesise ATP from ADP and Pi 6. In the matrix at the end of the transport chain, protons, electrons and oxygen (from the blood) combine to form water Oxygen is said to be the final acceptor of electrons

Question 26

How many ATP can be made from one glucose molecule?

Answer 26

32

Question 27

How can lipids be used as an alternative respiratory substrate?

Answer 27

- Lipids are hydrolysed into glycerol and fatty acids - Glycerol is then phosphorylated and converted into triose phosphate which enters the glycolysis pathway and then Krebs cycle - Fatty acids are hydrolysed into 2C fragments which are converted into acetyl coenzyme A which joins the Krebs cycle - The oxidation of lipids produced hydrogen atoms which are used to produce ATP during OP

Question 28

How can proteins be used as an alternative respiratory substrate?

Answer 28

- Proteins are first hydrolysed into amino acids - Then they are deaminated - Then they enter the respiratory pathway at different points depending on their number of carbons - 3C are converted to pyruvate, and 4C or 5C are converted to intermediates in the Krebs cycle

Question 29

What is chemiosmosis?

Answer 29

The process of ATP production driven by the movement of H+ ions across a membrane - due to electrons moving down an electron transport chain