5.1 Flashcards
cellular respiration
define cellular respiration
process by which energy from food molecules is transferred to ATP
what is the respiratory substrate
the substance that is broken down in respiration (usually glucose)
define aerobic respiration
the form of cellular respiration that takes place in the presence of oxygen
how does ATP release energy
the third phosphate bond is broken by a hydrolysis reaction and a Pi and ADP are left
outline the stages of aerobic respiration
glucose
glycolysis
link reaction
krebs cycle
electron transfer chain
what is the symbol equation for aerobic respiration
C6H12O6 + 6O2 -> 6CO2 + 6H2O + ATP
what happens in glycolysis
splitting of the respiratory substrate begins and the molecules are prepared for the second stage
why is the link reaction needed
move the products of glycolysis into the kreb cycle and electron transport chain
explain the structure of a mitochondria
double membrane
inner membrane forms many folds called cristae
what does the cristae contain that is associated with ATP synthesis
stalked particles
how are redox reactions involved in respiration
a series of redox reactions take place and release a small amount of energy which is used to drive the synthesis of ATP
what is soda lime/potassium hydroxide needed for in the respiration practical
absorbs CO2 produced so that any changes in volume will be due to the uptake of oxygen by organisms
how does a respirometer work
as organisms use O2 pressure reduces pulling the liquid towards the tube containing the organisms
where does glycolysis occur
cytoplasm
state the differences in anaerobic & aerobic respiration
aerobic:
occurs in mitochondria
complete oxidation
waste products - H2O, CO2
anaerobic:
occurs in cytoplasm
incomplete oxidation
waste products - lactic acid/ethanol, CO2
why do your muscles tire and eventually stop during anaerobic respiration
movement of lactate &hydrogen ions into blood lowers the blood pH which reduces nervous simulation so eventually stops muscle contraction
why do you continue to breath heavily after exercise
levels of lactate in the blood remain high therefor it must be oxidized back to pyruvate as it is toxic
what is the main waste products of anaerobic respiration in yeast
ethanol & CO2
what is the kreb cycle
series of biochemical steps that lead to the complete oxidation of glucose resulting in carbon dioxide, water and ATP
what are decarboxylase & dehydrogenase
decarboxylase - enzyme that removes CO2
dehydrogenase - enzyme that removes hydrogen (carries out oxidation)
summarise the kerb cycle
acetyl coenzyme A + 4C compound (oxaloacetate) -> citrate
decarboxylation produces CO2 and dehydrogenation reduces NAD
intermediate 5C compound is formed
decarboxylation produces CO2 and dehydrogenation reduces NAD and phosphorylation converts ADP to ATP
FAD is reduced
NAD is reduced
4C compound (oxaloacetate) is produced
summarise glycolysis
glucose forms glucose 1,6 diphosphate through the conversion of ATP -> ADP this then forms fructose 6 phosphate which forms fructose 1,6 diphosphate through the conversion of ATP -> ADP this then splits into 2 G3P molecules which continue on to form pyruvate through the conversion of 2ADP -> 2ATP and NAD+ -> NADH + H+
summarise the link reaction
pyruvate (3C) from glycolysis
decarboxylation produces CO2
NAD is reduced (pyruvate is oxidised)
joins with Coenzyme A to form acetylCoA
define oxidative phosphorylation
the oxygen dependent process in the electron transport chain where ADP is phosphorylated
summarise the electron transport chain
NADH and FADH donates their electrons to proteins in the etc and release H+ ions
electrons release energy as they pass along the chain of proteins in the etc
this energy pumps H+ ions from the matrix to the intermembrane space
the H+ ions then diffuse back across the membrane via ATPsynthase which generates the energy for chemiosmosis that synthesizes ATP
the electrons leave the etc pass along to the terminal electron acceptor (oxygen) and form water
what are cytochromes
protein pigments with an iron group which are reduced by electrons from reduced FAD to form a molecule of ATP
what is cytochrome oxidase
an enzyme in the etc which receives electrons from the cytochromes therefor is reduced and produces a molecule of ATP
what is the role of NAD and FAD in the etc
act as a hydrogen acceptor
where does the link reaction and kreb cycle occur
matrix of the mitochondria
where does the electron transport chain occur
inner membrane
where is ATP synthase found
stalked particles
summarise chemiosmosis in the etc
hydrogen ions are actively transported from the matrix to the intermembrane space using energy provided by electrons moving along the etc
this creates a higher concentration of hydrogen ions in the intermembrane space making a concentration, pH and electrochemical gradient across the membrane so hydrogen ions diffuse back to the matrix through ATP synthase which drives the synthesis of ATP
why is it thought that respiration evolved in very early stage in development of organisms
the process is the same in almost all living organisms suggesting that it evolved at a very early stage in the development of organisms on earth
overall how many molecules of ATP are produced in respiration
36 (38 created 2 used)
although this fluctuates and is expected to be on average 31
where does anaerobic respiration take place
cytoplasm
summarise alcoholic fermentation
2 pyruvate molecules undergo decarboxylation which produces 2CO2 and ethanal
2NADH molecules undergo oxidation to produce 2NAD+ molecules
ethanal is reduced by alcohol dehydrogenase and 2 ethanol are formed
summarise lactate fermentation
2 pyruvate molecules are reduced to 2 lactate molecules by lactate dehydrogenase
2NADH molecules undergo oxidation to produce 2NAD+ molecules
why must anaerobic respiration be carried out when there is little to no oxygen present
there is no terminal electron acceptor for the etc
the electron transport chain stops functioning
no more ATP can be produced from oxidative phosphorylation
reduced NAD and FAD aren’t oxidized by an electron carrier
no oxidized NAD and FAD available for the Kreb cycle
Kreb cycle stops
what cells use alcoholic fermentation
yeast and other fungal microorganisms
what cells use lactate fermentation
bacteria and mammalian muscle cells
what are the steps in anaerobic respiration
glycolysis
alcoholic/lactate fermentation
what acts as the hydrogen acceptor in alcoholic fermentation
ethanal
what occurs to ethanol after alcoholic fermentation
it is a waste product as it cannot be further metabolized
what acts as the hydrogen acceptor in lactate fermentation
pyruvate
why is lactate fermentation important in mammals
because the lactate fermentation pathway re-oxidises the reduced NAD so that it can be re used in glycolysis
why must lactate be removed
it is acidic so if it is not removed from the muscle tissue it can lower the pH which inhibits the actions of important enzymes
how is lactate removed
it is transported to the liver and converted back to pyruvate when more oxygen is available
give similarities and differences between anaerobic and aerobic respiration
similarities:
glycolysis
production of ATP
requires glucose
produces CO2
Anaerobic:
cytoplasm
no oxygen
produces lactic acid
involves alcoholic/lactate
fermentation
eukaryotic & prokaryotic cells
Aerobic:
mitochondria
requires oxygen
more ATP is produced
involves Kreb cycle & etc
only eukaryotic cells
