M5 C18: respiration

Question 1

why do we need respiration?

Answer 1

need energy for metabolic reactions such as protein synthesis, maintaining temperature

Question 2

what is the respiration equation?

Answer 2

C6H1206 + 6 O2 → 6 CO2 + 6 H20 + 2870kJ

Question 3

what is the function of mitochondrion?

Answer 3

synthesize ATP

Question 4

how many membranes do mitochondria have?

Answer 4

2

Question 5

what is the outer membrane of the mitochondria?

Answer 5

Smooth
Permeable to several small molecules

Question 6

what is the inner membrane of the mitochondria?

Answer 6

Folded (cristae)
Less permeable
The site of the electron transport chain (used in oxidative phosphorylation)
Location of ATP synthase enzymes (used in oxidative phosphorylation)

Question 7

what are some key features about the intermembrane space?

Answer 7

Has a low pH due to the high concentration of protons
The concentration gradient across the inner membrane is formed during oxidative phosphorylation and is essential for ATP synthesis

Question 8

what are some features of the matrix?

Answer 8

Is an aqueous solution within the inner membranes of the mitochondrion
Contains ribosomes, enzymes and circular mitochondrial DNA necessary for mitochondria to function

Question 9

what are the 4 stages of aerobic respiration?

Answer 9

glycolysis
link reaction
Krebs cycle
Oxidative phosphorylation

Question 10

what is the result of glycolysis?

Answer 10

2 Pyruvate (3C) molecules
Net gain 2 ATP
2 reduced NAD

Question 11

what happens in phosphorylation in glycolysis?

Answer 11

glucose (6C) is phosphorylated by 2 ATP to form hexose bisphosphate (6C) this then splits into 2 triose phosphate molecules (3C)

Question 12

what happens in oxidation in glycolysis?

Answer 12

hydrogen is removed from each molecule of triose phosphate and transferred to coenzyme NAD to form 2 reduced NAD
4H + 2NAD → 2NADH + 2H+

Question 13

what happens in dephosphorylation in glycolysis?

Answer 13

phosphates from triose bisphosphate and from cell cytoplasm are transferred from the intermediate substrate molecules to form 4 ATP through substrate-linked phosphorylation
4Pi + 4ADP → 4ATP

Question 14

what happens after pyruvate is produced?

Answer 14

When oxygen is available pyruvate will enter the mitochondrial matrix and aerobic respiration will continue

Question 15

what happens after dephosphorylation in glycolysis?

Answer 15

pyruvate is produced (3C) which is used in the next stage of respiration

Question 16

how does the pyruvate move across the membrane?

Answer 16

active transport

Question 17

what happens in the link reaction?

Answer 17

-pyruvate moves into matrix
-Pyruvate is oxidised by enzymes to produce acetate, CH3CO(O)- and carbon dioxide, requiring the reduction of NAD to NADH
- Combination with coenzyme A to form acetyl coenzyme A (acetyl CoA)

Question 18

what are the products of link reaction?

Answer 18

acetyl CoA + carbon dioxide + reduced NAD

Question 19

where does the krebs cycle take place?

Answer 19

in the matrix

Question 20

what happens to acetyl CoA at the start of the krebs cycle?

Answer 20

-carbon (4C) oxaloacetate accepts the 2C acetyl fragment from acetyl CoA to form the 6 carbon (6C) citrate
Coenzyme A is released in this reaction

Question 21

what happens after citrate is made in the krebs cycle?

Answer 21

Decarboxylation of citrate
Releasing CO2 as waste gas making it now a 5C compound
Oxidation (dehydrogenation) of citrate
Releasing H atoms that reduce NAD

Question 22

what happens to the 5C compound in the krebs cycle?

Answer 22

it is decarboxylised meaning it is now a 4C compound
dehydrogenated- reduicng NAD to NADH
adp then becomes atp due to the addition of a phopshate
FAD and NAD are then reduced and the compound is now oxaloactate (4C)

Question 23

what happens to FAD and NAD in oxidative phosphorylation?

Answer 23

reduced NAD and FAD deliver their hydrogen atoms to the electron transport chain causing them to be reoxidised

Question 24

what happens after NAD and FAD are deoxidised?

Answer 24

the hydrogen atoms split to become protons and electrons.
h+ ions go into the matrix through proteins
e- are accepted by the first electron carrier protein in the chain

Question 25

how do the proteins in the membrane accept the electron?

Answer 25

iron at centre of carrier becomes reduced, the elcetron is then donated to the next protein in the chain and so on

Question 26

what does the energy released from the electrons going down the electron transport chain do?

Answer 26

used to pump the h+ ions from the matrix to the intermembrane space

Question 27

what happens after the h+ ions are in the intermembrane space?

Answer 27

proton gradient forms across the membrane

Question 28

what happens due to the proton gradient?

Answer 28

H+ ions diffuse through the channels and form a comformational change in the atp synthase enzyme. this catalyses ADP to ATP.

Question 29

what happens to the electrons in the electron transport chain?

Answer 29

oxygen combines with the electrons that have come off the last protein and also combine with the protons forming water

Question 30

why is oxygen needed for respiration?

Answer 30

electron cant be received by final electron receptor so NAD wont be oxidized to be recycled

Question 31

what are the 2 pathways of anaerobic respiration?

Answer 31

lactate pathway ethanol fermentation pathway

Question 32

what happens in the lactate pathway?

Answer 32

the pyruvate accepts hydrogen atom from the reduced NAD becoming lactate. this then can become oxidized and recycled in glycolysis.

Question 33

what enzyme catalyses the pyruvate molecules accepting the h+ atoms from NAD?

Answer 33

lactate dehydrogenase

Question 34

what happens in the ethanol fermentation pathway?

Answer 34

the pyruvate loses a carbon to release CO2 and become ethanal. this then gains hydrogen atoms from reduced NAD, which is then reoxidsed to be used again

Question 35

how do you calculate respiratory quotient?

Answer 35

volume of CO2 out divided by volume of O2 in

Question 36

what is the respiratory quotient of glucose in anerobic respiration?

Answer 36

1 or over

Question 37

what is the respiratory quotient of carbohydrates in aerobic respiration?

Answer 37

1

Question 38

what is the respiratory quotient of proteins and lipids in aerobic respiration?

Answer 38

proteins- 0.9 lipids - 0.7

Question 39

how does a respirometer work?

Answer 39

used to measure the rate of oxygen consumption during aerobic respiration consists of a chamber containing the organism or tissue, a manometer to measure pressure changes, and an absorber of carbon dioxide1. measuring changes in gas volumes allows us work out rate of respiration

Question 40

what is different between a simple and complex respirometer?

Answer 40

complex has 2 tubes 1 being a control