respiration Flashcards
definition of respiration
breakdown of glucose molecules to produce ATP
what produces glucose
photosynthesis produces TP, which is converted to starch/sucrose, then glucose
what produces oxygen in plants
photolysis of water
what 3 processes make ATP
photophosphorylation
substrate-level phosphorylation
oxidative phosphorylation
fate of CO2 produced in respiration in plants
fixed into RuBP
fate of H2O produced in respiration in plants
evaporates out of the stomata
why does photophosphorylation produce ATP
cyclic or non-cyclic
produces ATP to convert GP to TP, and TP to RuBP in th Calvin cycle
when does substrate-level phosphorylation occur?
in Krebs cycle and glycolysis
purpose of ATP produced by substrate-level phosphorylation
allow movement of respiratory intermediates around cell
where does oxidative phosphorylation occur
final electron acceptor?
how is ATP produced
in mitochondria
oxygen
large of numbers of ATP produced due to chemiosmosis
uses of ATP in a plant
H+ pumps in companion cells (active loading of sucrose)
GP to TP and TP to RuBP
active transport of mineral ions into root hairs
pumping of ions into/out of guard cells
Na+/K+ pump
DNA replication, protein synthesis, mitosis
photosynthesis purpose
conversion of light energy to chemical energy in organic molecules
respiration purpose
releasing energy in form of ATP (for protein synthesis, cell division and DNA replication)
photosynthesis reactants and origins
CO2 (from Krebs cycle)
H2O (from photolysis or pushed up from soil/roots)
respiration reactants and origins
glucose (nutrition or photosynthesis)
O2 (final e- acceptor, from photosynthesis/ventilation)
photosynthesis products and fates
glucose (synthesised as TP, 1/6 leave cycle to be converted to sugars)
O2 (diffuse out of stomata)
respiration products and fates
CO2 (used in Calvin cycle)
H2O(transpired)
photosynthesis type of reaction
endothermic
respiration type of reaction
exothermic
photosynthesis use of coenzymes
NADP carries H atoms to convert GP to TP
respiration use of coenzymes
NAD and FAD carry H atoms to the electron transport chain
coenzyme A carries an acetyl group from the link reaction to the Krebs cycle
bonds connecting phosphate groups in an ATP molecule
phosphoanhydride
bond between phosphate and ribose in an ATP molecule
phosphoester
bond between ribose and adenine in ATP molecule
covalent
chemiosmosis definition
movement of protons (H+) down an electrochemical gradient through ATP synthase
compare process of chemiosmosis in photosynthesis and respiration
high energy electrons come from photolysis of water in p/s, and reduced NAD/FAD in resp
electron transport chain in thylakoid membrane vs inner mitochondrial membrane
cyclic/non-cyclic photophosphorylation produces ATP vs oxidative phosphorylation produces ATP
PS1/NADP vs oxygen as final electron acceptor
parts of a mitochondrion
outer membrane
inner membrane
inter membrane space
mitochondrial matrix
ribosomes (70s)
circular DNA
where does a high H+ concentration form in the mitochondria
inter membrane space
LOW in mitochondrial matrix
what is the inner membrane folded into?
why
cristae
increased surface area for ATP synthase
4 stages of aerobic respiration
glycolysis
link reaction
krebs cycle
oxidatie phosphorylation
where does glycolysis take place
in cytoplasm
stages of glycolysis
glucose phosphorylated to hexose bisphosphate
split by lysis into 2 triose phosphate molecules
phosphorylated, donates its 2 phosphate groups to ADP molecules (forms 2 ATP molecules)
TP is oxidised/dehydrogenated, which reduces NAD
2 pyruvate molecules produced
purpose of phosphorylation of glucose in glycolysis
makes glucose more reactive
prevents glucose from leaving the cell
ATP produced in glycolysis?
per glucose molecule, 4x ATP produced, but 2x ATP are used to phosphorylate glucose
NET GAIN OF 2 ATP/ glucose
define substrate level phosphorylation
removal of a phosphate group form a phosphorylated substrate (e.g. TP)
the phosphate group is directly added to ADP to produce ATP
where does the link reaction take place?
mitochondrial matrix
how do pyruvate and reduced NAD from glycolysis reach the link reaction in the matrix?
mitochondrial shunt mechanism:
AT (using ATP) of pyruvate and reduced NAD from cytoplasm into the mitochondrial matrix
stages of link reaction
pyruvate is decarboxylated to produce CO2, and dehydrogenated/oxidated to reduce NAD
acetate (acetyl group) is produced
coenzyme A (CoA) added to produce Acetyl CoA (2C)
role of coenzyme A
carries acetyl group to Krebs cycle
ATP produced in link reaction?
none
glycolysis reactants per glucose molecule
glucose
2 NAD
2 ATP
glycolysis products per glucose molecule
2 pyruvate
2 NADH
4 ATP
link reaction reactants per glucose molecule
2 pyruvate
2 NAD
2 Coenzyme A
link reaction products per glucose moleucle
2 CO2
2 Acetyl CoA
2 NADH
where does the Krebs cycle take place?
mitochondrial matrix
input to Krebs cycle?
acetyl CoA from link reaction loses CoA (recycled to link reaction)
acetyl group enters krebs cycle
stages of Krebs cycle?
DENA
DENA
A
FA
NA
intermediates in krebs cycle
oxaloacetate (4C)
combined w acetyl group to produce citrate (6C)
Krebs cycle DENA
decarboxylation and reduction of NAD
Krebs cycle A
production of ATP (substrate level phosphorylation)
Krebs cycle FA
reduction of FAD
Krebs cycle NA
reduction of NAD
how many turns of Krebs cycle per glucose molecule?
2
products of krebs cycle per glucose molecule
6 reduced NAD
2 reduced FAD
2 ATP
4 CO2
products of krebs cycle per turn
3 reduced NAD
1 reduced FAD
1 ATP
2 CO2
what happens to the CO2 produced by the link reaction in plant species
used as a reactant in the light-independent stage of p/s (Calvin cycle), using RuBisCO
suggest why oxaloacetate is present in cells at very low concentrations
high turnover rate: 2C acetate is added to form 6C citrate
constantly recycled and reformed so little needed
where does oxidative phosphorylation take place?
on the folded inner membrane (Cristal)
ATP yield of oxidative phosphorylation per glucose molecule?
32 ATP
stages of oxidative phosphorylation?
reduced NAD dehydrogenated at complex 1 and H atoms are split into H+ and e-: e- move into electron transport chain
reduced FAD “ “
as e- lose energy,H+ are actively pumped across the inner mitochondrial membrane, into the intermembrane space
high H+ concentration in inter membrane space
H+ flow by chemiosmosis and proton motive force through ATP synthase
ADP +Pi -> ATP
O2 acts as final e- acceptor
2H+ + 2e- +1/2 O2 -> H2O
theoretical yield of ATP per molecule of glucose
36
when do eukaryotic cells respire anaerobically?
when there is insufficient oxygen to act as the final electron acceptor
so only glycolysis occurs
why does only glycolysis continue when oxygen is absent?
H+ moving through ATP synthase by chemiosmosis cannot be accepted by oxygen
H+ conc increases in the mitochondrial matrix
no proton gradient, no chemiosmosis so oxidative phosphorylation stops
buildup of reduced NAD and reduced FAD as they cannot be oxidised
Krebs and Link reaction stop bc no NAD/FAD to accept H atoms
mechanisms of anaerobic respiration in plants/fungi
ethanol fermentation
mechanisms of anaerobic respiration in animals
lactate fermentation
describe ethanol fermentation
pyruvate is decarboxylated (CO2 produced) using pyruvate decarboxylase to produce ethanal
ethanal reduced to ethanol by reduced NAD using ethanal dehydrogenase
this allows NAD to return to glycolysis and accept H atoms in the conversion of TP to pyruvate
describe lactate fermentation
pyruvate reduced to lactate by reduced NAD using lactate dehydrogenase
(reduced NAD donates H atoms to pyruvate)
NAD can return to glycolysis so cell can keep producing the net 2xATP/glucose
is ATP produced by anaerobic respiration?
no significant ATP is produced in either of these reactions
however, glycolysis is able to continue for a short time, producing a net of 2x ATP per glucose molecule
examples of respiratory substrates besides glucose
amino acids
triglycerides (glycerol and fatty acids)
lactate
which stage of respiration do amino acids enter as respiratory substrate?
determined by the number of C atoms; but either Link or Krebs
which stage of respiration do fatty acids enter as respiratory substrate?
Krebs cycle
which stage of respiration does glycerol enter as respiratory substrate?
link reaction
which stage of respiration does lactate enter as respiratory substrate?
Link reaction
which molecules are amino acids used to form when used as respiratory substrates?
pyruvate
acetate
Krebs cycle intermediate
which molecule is glycerol used to form when used as respiratory substrates?
pyruvate
which molecule are fatty acids used to form when used as respiratory substrates?
acetyl groups
which molecule is lactate used to form when used as respiratory substrates?
pyruvate
which cells can only use glucose as a respiratory substrate?
human brain cells
red blood cells
what is the respiratory quotient
the ratio of CO2 produced by a respiring organism to oxygen consumed in a given time
RQ equation
CO2 produced / O2 absorbed
what is the RQ if anaerobic respiration is being used
infinity
what is the RQ if a mixture of aerobic and anaerobic respiration are being used?
a value greater than 1 (e.g. 4)
what is the RQ if purely aerobic respiration is being used?
1 or less
energy per g of carbohydrates, triglycerides and proteins
carbs 16 kJ
triglycerides 39 kJ
proteins 17 kJ
how to infer which respiratory molecule is formed from a particular amino acid
based on the number of carbon atoms
e.g. asparagine has 4C so oxaloacetate (4C)
parts of a respirometer
2 test tubes
manometer containing coloured fluid
gauze: one holds maggots, the other holds glass beads of same mass of maggots (built in control)
syringe to reset apparatus
screw clip so airtight
sodalime/KOH/NaOH solution absorbs CO2 in the tube from decarboxylation reactions
why do u allow the maggots to equilibrate at the temperature for 2 minutes
allows rate of respiration to stabilise bc may be panicked at first
why do you leave screw clip open at first
allows oxygen into the apparatus
why are woodlice worse for a respirometer than maggots
they are sedentary so respire less
why do you measure the distance moved by the dye each minute for 5 minutes
built-in 5 repeats
explain why coloured dye moves towards the maggots in respirometer
O2 absorbed by maggots
CO2 absorbed by sodalime
decreased pressure in tube
explain how to make respirometer results more repeatable
more repeats at each temperature
identify anomalies and calculate mean
students unpaired t test to see significance of difference between means at different temperatures
explain how to measure rate of respiration at diff temperatures more accurately
more intermediate values (esp around optimum)
suggest why plants and fungal organisms should be used to investigate the effect of temperature on rate of respiration above 40C
ethical reasons
not right to cause harm to animals
why does a low acid concentration mean no ATP is present in mitochondria
less of a H+ gradient between matrix and IM space so less movement of H+ by chemiosmosis, and less proton motive force
therefore less ATP made
why does absence of oxygen mean no ATP present in mitochondria
no final e- acceptor to accept H+ and e- so no H2O produced
unit for colorimetry
grams/ mol dm-3
why can you not use different sized maggots in respirometer
how to fix
one large maggot may respire less than 2 smaller ones. therefore when measuring 2g of maggots, remove any large or small ones to standardise the size
why must respirometer be airtight
how to do
if gas leaves apparatus, pressure decreases so underestimate of rate of respiration therefore pressure is not ONLY affected by oxygen uptake in respiration
use vaseline to seal joints
discuss how respirometer can be used to calculate RQ of germinating peas
equilibrate peas for 5 minutes
germinating peas in left tube and glass beads in right tube (control)
sodalime in each tube to absorb CO2
measure distance moved by fluid in certain time and use formula pi r2 d to calculate volume of O2
repeat experiment without NaOH and calculate volume of (CO2 + O2) and subtract vol of O2 to find vol of CO2
repeats
same volume of sodalime
same mass of peas/beads
same temperature
what requires the largest amount of energy to oxidise it completely
polysaccharides
is oxidation complete in aerobic and anaerobic respiration?
only complete in aerobic
does anaerobic respiration animals produce CO2
no
outline the roles of named coenzymes in aerobic respiration
NAD/FAD transport H+ and e-. dehydrogenation. transport to cristae for oxidative phosphorylation
NAD accepts H in glycolysis, Link Reaction and Krebs cycle
Coenzyme A is bound to an acetyl group to form acteyl-coA. carries this from link reaction to Krebs cycle. reacts with oxaloacetate to produce citrate
compare photophosphorylation and oxidative phosphorylation
OP: inner mitochondrial membrane, oxygen is final electron acceptor, reduced NAD/FAD donates electrons
PP: thylakoid membrane, NADP is final electron acceptor, water is electron donor (from photolysis in photosystem)
BOTH: have electron transport chains, produce ATP (but more in OP), both use ATP synthase and H+ chemiosmosis/proton motive force
