respiration (key notes)

Question 1

max ATP produced in aerobic respiration is 32, but usually only 30 is produced. Why?

Answer 1

• energy lost as heat
• some ATP used in active transport of pyruvate into mitochondria
• Protons may leak through membranes and not travel through ATP synthase enzyme

Question 2

similarities between structure of NAD and ATP

Answer 2

• both have ribose sugar
• both have adenine base
• both have phosphate group

Question 3

differences between structure of NAD and ATP

Answer 3

• NAD has one phosphate, ATP has 3
• NAD has 2 nitrogenous bases, ATP only has one
• NAD is di-nucleotide, ATP is nucleotide

Question 4

symbol equation for anaerobic respiration in yeast

Answer 4

glucose -> ethanol + carbon dioxide

Question 5

symbol equation for anaerobic respiration in humans

Answer 5

glucose -> lactic acid

Question 6

After glycolysis has occurred, there is no more NAD left to be reduced… explain how we reoxidise NADH with oxygen again?

Answer 6

activate the lactate fermentation pathway in animals and ethanol fermentation pathway in fungi.

Question 7

how does lactate fermentation work so that NAD can be reused in glycolysis again?

Answer 7

pyruvate binds with NADH which becomes oxidised (loses H ion). This is transferred to pyruvate which becomes lactate catalysed by lactate dehydrogenase enzyme. The products are lactate and NAD.

Question 8

how does ethanol fermentation work so that NAD can be reused in glycolysis again?

Answer 8

stage 1: pyruvate broken down using pyruvate decarboxylase into ethanal and carbon dioxide.

stage 2: ethanal binds with NADH and is catalysed by ethanol dehydrogenase to form ethanol and NAD.

Question 9

why do we continue to breath heavily after exercise?

Answer 9

this provides extra oxygen to liver cells to enable them to metabolise lactate.

Question 10

why might athletes experience fatigue?

Answer 10

reduction in pH caused by presence of lactate - this will reduce enzyme activity in muscles

Question 11

why do brewers place their yeast in aerobic conditions first?

Answer 11

to allow them to respire to grow and produce really fast.

Question 12

what is the hydrogen acceptor in lactate fermentation

Answer 12

pyruvate

Question 13

what is the hydrogen acceptor in ethanol fermentation

Answer 13

ethanal

Question 14

which fermentation pathway produces CO2?

Answer 14

ethanol fermentation

Question 15

enzyme used in lactate fermentation

Answer 15

lactate dehydrogenase

Question 16

enzyme used in ethanol fermentation

Answer 16

pyruvate decarboxylase and ethanol dehydrogenase

Question 17

where does oxidative phosphorylation occur?

Answer 17

inner membrane

Question 18

what are the products of link reaction?

Answer 18

2 x CO2
2 x acetyl coA
2x NADH

Question 19

what is oxidative phosphorylation

Answer 19

formation of ATP in presence of oxygen

Question 20

what do coenzymes in inner membrane do?

Answer 20

pumps H ions into inner membrane and uses energy released to cause proton-electrochemical gradient

Question 21

how is water made at the end of an electron transport chain?

Answer 21

• electrons are passed from the last electron carrier in the chain and donated to oxygen which acts as final electron accepter.
• H ions also join so oxygen is reduced to water.

Question 22

state the equation for the making of water in ETC

Answer 22

2h+ + 4e- + O2 —–> 2H20

Question 23

why do lipids have higher energy content than that of carbs and proteins?

Answer 23

they have higher proportion of h atoms compared with C and O. These H ions are used in oxidative phosphorylation of so they produce lots of ATP.

Question 24

why are lipids useful in glycolysis?

Answer 24

when lipids are broken down into fatty acids these are concerted into TP which is used in glycolysis to make pyruvate.