Respiration 5.7 Flashcards
what is the need for cellular respiration
occurs in living cells, releases energy and makes ATP
for active processes like endo/exocytosis, movement of flagella/cilia and DNA replication
what are anabolic reactions
when a large mol is synthesised from smaller ones
what are catabolic reactions
hydrolysis of large mol into smaller ones
describe the structure of the mitochondria
matrix fluid
outer membrane
inner membrane
intermembrane space
describe the fluid matrix
where link reaction and Krebs cycle takes place
contains enzymes and coenzymes FAD and NAD
mitochondrial DNA (codes for enzymes and proteins) and ribosomes
describe the outer membrane
contain channel and carrier proteins
controls movement in and out
describe the inner membrane
folds to form cristae the site of the ETC
describe the intermembrane space
where oxidative phosphorylation occurs
close in contact with the matrix so reduced NAD and FAD can easily deliver H2 to the ETC
what is the first stage of respiration
glycolysis
what is the second stage of aerobic respiration
link reaction
what is the third stage of aerobic respiration
Krebs cycle
what is substrate level phosphorylation
when a phosphate group is directly transferred from one mol. to another
what is the fourth stage of aerobic respiration
oxidative phosphorylation
why is oxidative phosphorylation useful
energy carried by e- from reduced coenzymes are used to create ATP
define the chemiosmotic theory
process of ATP production caused by the movement of H+ along membrane due to e- moving down ETC
importance of decarboxylation
releases CO2 waste product
produces energy to e- carriers to make ATP
connects link reaction to Krebs cycle
importance of dehydrogenation
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
importance of NAD
e- carrier accepts H+ and becomes reduced
glycolysis: NAD –> NADH
Krebs cycle: NADH from dehydrogenation
ETC: NADH donates e- and produces ATP
importance of FAD
e- like NAD
Krebs cycle: FAD —> FADH2
ETC: FADH2 donates e- at a lower lvl than NADH and prod ATP
importance of coenzyme A
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
importance of substrate level phosphorylation
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
what happens if O2 is absent
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
how is reduced NAD reoxidised for fungi and plants
ethanol fermentation pathway
describe what happens in the ethanol fermentation pathway
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
how is reduced NAD reoxidised in mammals
lactate fermentation pathway
describe the lactate fermentation pathway
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
where is lactate produced and where does it go
muscle tissue carried in the blood to liver
when more O2 is available what can lactate do?
converted to pyruvate which can enter the Krebs cycle by Link reaction
recycled to glucose and glycogen
what happens if lactate was not removed from muscle tissues
pH lowers
inhibits actions of many enzymes in glycolysis and muscle contraction
describe the ATP yield from respiration
ethanol and lactate dont prod ATP
only allow glycolysis to continue so net gain of 2 ATP can still be made
compare the ATP yield in anaerobic and aerobic respiration
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
what are respiratory substrates
organic mol. that can be broken down to release energy to make ATP
describe carbs as a respiratory substrate
glucose as main substrate
disaccharides digested into monosaccharides
monosaccharides into glucose by isomerase enzymes
what type of carbohydrate do RBC and brain cells use
glucose
what type of carb do animals and some bacteria use
glycogen hydrolysed into glucose for respiration
what carbs do plants use
starch hydrolysed into glucose for respiration
describe lipids as a substrate
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
compare carbs and lipids
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
what is B-oxidation
when the FA-coA complex transported to matrix and broken to acetyl coenzyme A
describe proteins as respiratory substrate
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
how does the energy value for each substrate different
differs depending on the availibilty of protons fro chemiosmosis
the more hydrogen atoms a respiratory substrate has the more ATP it can make
what is the mean energy value for carbs, lipids and proteins
15.8kJg-1
39.4
17.0
what is the respiratory quotient
RQ= CO2 prod/O2 consumed
no units bcs its a ratio
what is the RQ value used for
to deduce the substrate being used for respiration
compare the RQ value in aerobic and anaerobic conditions
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
what happens when glucose lvls are insufficient
proteins used and broken down into AA then undergoes deamination forming keto acids
net gain of ATP in each cycle and why the total value is theoretical
- glycolysis - 2 ATP
- same for Krebs
- oxidative phosphorylation - 34 ATP
- total should be 34 but because of leaky membranes its actually 32
