Warde Respiration Flashcards
what does respiration produce?
ATP
what is the structure of atp?
adenine base
ribose
3 phosphate groups
how is atp useful in biological processes?
releases energy in small manageable amounts
one step hydrolysis so immediate energy compound
can phosphorylate substances to make them more reactive
can be reformed
small & soluble so easily transported around cell
cannot pass out of cell
by what 2 processes is atp formed?
- substrate-level phosphorylation
phosphate group is transferred by an enzyme from substrate onto ADP molecule - chemiosmosis
involves the diffusion of protons down electrochemical gradient across ppm
this releases energy needed by ATP synthase to combine ADP + Pi
only in aerobic respiration
what does chemiosmosis require to work?
specialised membrane containing specific proteins:
- electron transport chain including e- carriers/proton pump proteins
- ATP synthase
source of excited/high energy e-s to be passed along etc
final e- acceptor to enable redox reactions in etc to happen
source of protons (from NADH)
what is glycolysis?
the first stage anaerobic and aerobic respiration that occurs in the cytoplasm & is an anaerobic process
what stages does glycolysis involve?
phosphorylation of glucose to glucose phosphate (6C) using ATP
splitting of phosphorylated glucose into triose phosphate (3C)
oxidation of triose phosphate to pyruvate (3C) with a net gain of ATP & reduced NAD
what happens in glycolysis in anaerobic respiration?
if respiration is only anaerobic, pyruvate is converted to ethanol or lactate
reduced NAD is oxidised
oxidised NAD can be used in further glycolysis, producing ATP
what happens after glycolysis in aerobic respiration?
if respiration is aerobic, pyruvate from glycolysis enters the mitochondrial matrix by active transport
then link reaction
what stages does the link reaction involve?
- pyruvate from glycolysis enters the mitochondrial matrix by active transport
- pyruvate is oxidised to acetate, producing reduced NAD
- acetate combines with coenzyme A to produce acetylcoenzyme A
- no atp produced
happens twice so products are 2x
overview of Krebs cycle
in a series of oxidation-reduction reactions, the Krebs cycle generates reduced coenzymes and ATP by substrate-level phosphorylation, and carbon dioxide is lost
what stages does the Krebs cycle involve?
series of oxidation-reduction reactions in the matrix
1. 2C acetylcoenzyme A from link reaction combines with 4C molecule to produce 6C molecule
2. 6C molecule loses CO2 & hydrogen to form a 4C molecule & single ATP molecule by substrate-level phosphorylation
3. 4C molecule combines with new acetylecoenzyme A to repeat cycle
4. NAD & FAD are reduced in the Krebs cycle too
cycle happens twice bc 2 pyruvate molecules so 2 acetylecoenzyme A molecules
define oxidative phosphorylation
the mechanism by which some of the energy in e-s in H atoms carried by reduced NAD & reduced FAD is conserved in the formation of ATP
describe the process of oxidative phosphorylation
- H atoms are released from reduced NAD & reduced FAD as they are oxidised to NAD & FAD. H atoms split into H+ & e-
- e-s move along the electron transport chain made up of e- carrier proteins in a series of oxidation-reduction reactions, releasing energy at each carrier
- this energy is used by e- carrier proteins to pump protons from mitochondrial matric into intermembrane space
- conc. of protons in intermembrane space is greater than in matrix, forming electrochemical gradient
- protons diffuse down electrochemical gradient through ATP synthase embedded in the inner mitochondrial membrane. this synthesises ATP from ADP & Pi
- the diffusion of H+ ions across membrane is called chemiosmosis
- at the end of the etc, the e-s & protons combine with an O2 molecule to form H2O. the O2 molecule is the final electron acceptor
what are other respiratory substrates?
lipids
amino acids
which enters the Krebs cycle
application: what is the effect of cyanide on the processes of respiration?
prevents transfer of e-s from e- carrier to O2 molecule
–> prevents movement of e-s down etc
–> prevents pumping of protons
–> no electrochemical gradient & no diffusion of H+ through ATPsynthase
–> no ATP produced by oxidative phosphorylation
–> no aerobic respiration
so death of cells that rely on aerobic respiration e.g. cardiac muscles & neurones
application: what is the effect of uncoupling proteins on the processes of respiration?
protein channel inserted into inner mitochondrial membrane
gives alternative routes for H+ to diffuse from intermembrane space into matrix not through ATP synthase
this releases heat energy
(common in mitochondria in adipose fat in newborns)
application: what is the effect of DNP on the processes of respiration?
gives alternative routes for H+ to diffuse from intermembrane space into matrix not through ATP synthase
this releases heat energy
what happens in respiration when oxygen is removed?
etc does not function bc no final electron acceptor
reduced NAD & reduced FAD accumulate bc they cannot release their H atoms at atc to become oxidised
Krebs cycle stops because less NAD or FAD available to transport H
link reaction stops bc no 4C molecule is regenerated so acetylcoenzyme A cannot enter Krebs cycle
only glycolysis can continue, producing 2 ATP molecules
describe lactate fermentation in anaerobic respiration
commonly happens in skeletal muscles during exercise when O2 demand exceeds O2 supply
pyruvate is reduced to lactate (lactic acid)
reduced NAD is oxidised
oxidised NAD can be used in further glycolysis, producing ATP
what is the problem with lactate & how is it removed?
lactate is acidic & toxic as it can denature enzymes & proteins involved in muscle contraction
lactate is transported to liver where it is oxidised to pyruvate & respired aerobically or converted back into glucose & stored as glycogen
describe ethanol fermentation in anaerobic respiration
pyruvate is decarboxylated (CO2 lost) & reduced to ethanol
reduced NAD is oxidised
oxidised NAD can be used in further glycolysis, producing ATP
what is the use of ethanol fermentation?
ethanol used in brewing
CO2 used to make bread rise
describe a method to investigate the effect of temperature on the rate of respiration of yeast
- put known conc. & col. of glucose into test tube & add yeast & buffer solution
- put known vol. of the yeast & glucose solution to three different test tubes. place the test tubes in the 35°C water bath. leave them in there for 10 minutes so the solution temp. equilibrates
- add methylene blue indicator, using the pipette, to each test tube and start the stopwatch. shake the test tube for 10 seconds then place it back in the water bath.
- record the time taken for the methylene blue to turn colourless in each test tube
- repeat the experiment using temperatures 20°C, 30°C, 40°C, 50°C, 60°C and 70°C. 20°C (room temperature water bath) could be used as a control experiment
- find the mean time at each temperature to calculate the average rate of respiration using the formula rate = 1/mean time
- plot a graph of temperature (x-axis) against rate of respiration (y-axis)
anaerobic yeast
respirometer
