Respiration 5.7

Question 1

what is the need for cellular respiration

Answer 1

occurs in living cells, releases energy and makes ATP

for active processes like endo/exocytosis, movement of flagella/cilia and DNA replication

Question 2

what are anabolic reactions

Answer 2

when a large mol is synthesised from smaller ones

Question 3

what are catabolic reactions

Answer 3

hydrolysis of large mol into smaller ones

Question 4

describe the structure of the mitochondria

Answer 4

matrix fluid

outer membrane

inner membrane

intermembrane space

Question 5

describe the fluid matrix

Answer 5

where link reaction and Krebs cycle takes place

contains enzymes and coenzymes FAD and NAD

mitochondrial DNA (codes for enzymes and proteins) and ribosomes

Question 6

describe the outer membrane

Answer 6

contain channel and carrier proteins

controls movement in and out

Question 7

describe the inner membrane

Answer 7

folds to form cristae the site of the ETC

Question 8

describe the intermembrane space

Answer 8

where oxidative phosphorylation occurs

close in contact with the matrix so reduced NAD and FAD can easily deliver H2 to the ETC

Question 9

what is the first stage of respiration

Answer 9

glycolysis

Question 10

what is the second stage of aerobic respiration

Answer 10

link reaction

Question 11

what is the third stage of aerobic respiration

Answer 11

Krebs cycle

Question 12

what is substrate level phosphorylation

Answer 12

when a phosphate group is directly transferred from one mol. to another

Question 13

what is the fourth stage of aerobic respiration

Answer 13

oxidative phosphorylation

Question 14

why is oxidative phosphorylation useful

Answer 14

energy carried by e- from reduced coenzymes are used to create ATP

Question 15

define the chemiosmotic theory

Answer 15

process of ATP production caused by the movement of H+ along membrane due to e- moving down ETC

Question 16

importance of decarboxylation

Answer 16

releases CO2 waste product

produces energy to e- carriers to make ATP

connects link reaction to Krebs cycle

Question 17

importance of dehydrogenation

Answer 17

transfers e- to carriers like NAD and FAD, reducing them

reduced NAD and FAD transport e- to ETC and energy used to make ATP
occurs throughout respiration

w/o this no high energy e- carriers so ETC doesn’t function and no ATP made

Question 18

importance of NAD

Answer 18

e- carrier accepts H+ and becomes reduced

glycolysis: NAD –> NADH

Krebs cycle: NADH from dehydrogenation

ETC: NADH donates e- and produces ATP

Question 19

importance of FAD

Answer 19

e- like NAD

Krebs cycle: FAD —> FADH2

ETC: FADH2 donates e- at a lower lvl than NADH and prod ATP

Question 20

importance of coenzyme A

Answer 20

carriers and transfers acetyl group

Link reaction: combines w/ acetyl group from pyruvate decarboxylation to form acetyl coA

Krebs cycle: acetyl coA transfers acetyl group into oxaloacetate to form citate

Question 21

importance of substrate level phosphorylation

Answer 21

immediate source of energy

in the absence of O2 ETC cant function and can rely entirely on subs-lvl-phosp in glycolysis for ATP

this is important in low O2 environments or during intense exercise

Question 22

what happens if O2 is absent

Answer 22

O2 cant act as final e- acceptor

H+ and e- cant make H2O

conc. of H+ in matrix inc

conc. of H+ reduces in inner mitochondrial membrane

oxi-phosp comes to an end

reduced NAD and FAD unable to unload H+ and cant be reoxidised

Krebs and Link reaction stop

Question 23

how is reduced NAD reoxidised for fungi and plants

Answer 23

ethanol fermentation pathway

Question 24

describe what happens in the ethanol fermentation pathway

Answer 24

every mol of pyruvate from glycolysis is decarboxylated and converted to ethanal using pyruvate decarboxylase

ethanal accepts H2 atoms from reduced NAD and forms ethanol using enzyme ethanol dehydrogenase

NAD reoxidised and can now accept more H2 atoms from TP so glycolysis can continue

Question 25

how is reduced NAD reoxidised in mammals

Answer 25

lactate fermentation pathway

Question 26

describe the lactate fermentation pathway

Answer 26

pyruvate from glycolysis accepts H2 from reduced NAD catalysed by enzyme lactate dehydrogenase pyruvate reduced into lactate NADH reoxidised so can accept more H2 atoms from TP in glycolysis and can continue to make more ATP needed for muscle contraction in a short period

Question 27

where is lactate produced and where does it go

Answer 27

muscle tissue carried in the blood to liver

Question 28

when more O2 is available what can lactate do?

Answer 28

converted to pyruvate which can enter the Krebs cycle by Link reaction recycled to glucose and glycogen

Question 29

what happens if lactate was not removed from muscle tissues

Answer 29

pH lowers inhibits actions of many enzymes in glycolysis and muscle contraction

Question 30

describe the ATP yield from respiration

Answer 30

ethanol and lactate dont prod ATP only allow glycolysis to continue so net gain of 2 ATP can still be made

Question 31

compare the ATP yield in anaerobic and aerobic respiration

Answer 31

in anaerobic: glucose only partly broken down so many mol can undergo glycolysis so yield of ATP made per min is very large however yield of ATP in anaerobic respiration is smaller than aerobic

Question 32

what are respiratory substrates

Answer 32

organic mol. that can be broken down to release energy to make ATP

Question 33

describe carbs as a respiratory substrate

Answer 33

glucose as main substrate disaccharides digested into monosaccharides monosaccharides into glucose by isomerase enzymes

Question 34

what type of carbohydrate do RBC and brain cells use

Answer 34

glucose

Question 35

what type of carb do animals and some bacteria use

Answer 35

glycogen hydrolysed into glucose for respiration

Question 36

what carbs do plants use

Answer 36

starch hydrolysed into glucose for respiration

Question 37

describe lipids as a substrate

Answer 37

for muscles triglycerides hydrolysed to FA and glycerol by lipase glycerol converted to pyruvate before oxidative decarboxylation to prod an acetyl group picked up by coenzyme A from acetyl coA

Question 38

compare carbs and lipids

Answer 38

greater proportion of C-H bonds in FA compared to carbs so prod. more ATP than an equal mass of carbs lipids store 2x more energy than carbs

Question 39

what is B-oxidation

Answer 39

when the FA-coA complex transported to matrix and broken to acetyl coenzyme A

Question 40

describe proteins as respiratory substrate

Answer 40

excess AA deaminated in liver from urea and keto acid keto acid enters respiratory pathway as pyruvate, acetyl coA or krebs cycle acid like oxaloacetic acid

Question 41

how does the energy value for each substrate different

Answer 41

differs depending on the availibilty of protons fro chemiosmosis the more hydrogen atoms a respiratory substrate has the more ATP it can make

Question 42

what is the mean energy value for carbs, lipids and proteins

Answer 42

15.8kJg-1 39.4 17.0

Question 43

what is the respiratory quotient

Answer 43

RQ= CO2 prod/O2 consumed no units bcs its a ratio

Question 44

what is the RQ value used for

Answer 44

to deduce the substrate being used for respiration

Question 45

compare the RQ value in aerobic and anaerobic conditions

Answer 45

in aerobic (normal) conditions, RQ is 0.8 to 1 if RQ is more than 1, anaerobic respiration is happening bcs more CO2 is prod than O2 consumed

Question 46

what happens when glucose lvls are insufficient

Answer 46

proteins used and broken down into AA then undergoes deamination forming keto acids

Question 47

net gain of ATP in each cycle and why the total value is theoretical

Answer 47

- glycolysis - 2 ATP - same for Krebs - oxidative phosphorylation - 34 ATP - total should be 34 but because of leaky membranes its actually 32