5.7 respiration Flashcards by Sophie Hank

need for cellular respiration

to drive biological processes and metabolic pathways
for active transport
endocytosis and exocytosis
synthesis of large molecules
DNA replication
cell division
movement etc

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anabolic reactions

large molecules are synthesised

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catabolic reactions

hydrolysis of large molecules to smaller ones

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heterotrophs

consumers and decomposers
obtain energy and molecules from other organisms

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autotrophs

trap and use energy to make own molecules

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role of ATP

hydrolysed to release energy

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structure of a mitochondrion and why its suited

matrix - link reaction and krebs cycle takes place, contains enzymes, NAD/FAD, mitochondrial DNA and ribosomes
outer membrane - contains proteins to allow the passage of molecules into the mitochondria
inner membrane - folds to form cristae which gives a large surface area, electron carriers and ATP synthase enzymes embedded in them
ATP synthase - large and protude from I.M to matrix, protons can pass through
intermembrane space - involved in oxidative phosphorylation and has a short space to allow reduced NAD/FAD to deliver hydrogens to TC
ETC - has cofactors and coenzymes to allow chemiosmosis

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name the stages of respiration

glycolysis
link reaction
krebs cycle
oxidative phosphorylation

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describe the process of glycolysis

glucose is phosphorylated into hexose bisphosphate
uses hydrolysis of ATP twice
hexose bisphosphate (6C) splits into two triose phosphates (3C)
oxidation of the 2 triose phosphates to 2 pyruvates catalysed by the reduction of NAD and synthesis of 2ATP

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products of glycolysis

pyruvate
net gain of 2 ATP
2 molecules of reduced NAD

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describe the process of the link reaction

pyruvate is decarboxylated (carboxyl groupis removed) - C02 produced
dehydrogenation occurs and produces an acetyl group - NAD gets reduced
acetyl group combines with coenzyme A to become acetyl coenzyme A (acetyl CoA)

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where does the link reaction and kreb cycle occur

mitochondrial matrix

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describe the process of (1) the krebs cycle

acetyl group (2C) is released from acetyl CoA
combines with oxaloacetate (4C)
to form citrate
citrate is decarboxylated and dehydrogenated CO2 and reduced NAD is produced
5c compound is decarboxylated/dehydrogenated to produce C02 and reduced NAD
ATP synthesis occurs = 1 ATP
dehydrogenated and produced reduced FAD
dehydrogenated again to regenerate a molecule of oxaloacetate

3x NAD is reduced
1x FAD is reduced
1x ATP synthesis
2x CO2 produced

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describe what happens in oxidative phosphorylation

reduced NAD and Fad are reoxidised when they deliver the hydrogen atoms to the ETC
hydrogens split into protons and electrons
protons go into matrix and the electrons are passed along the electron carriers by donating electrons to the next
this releases energy which is used to pump protons across the membrane into the intermembrane space
creates a proton gradient so can now diffuse back into matrix through proton channels associated with ATP synthase enzymes
flow of protons causes change in ATP synthase shape which allows synthesis of ATP (chemiosmosis)
oxygen in the matix accepts electrons from the ETC and and protons (H) forms water

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where does oxidative phosphorylation occur

in matrix/ on the cristae

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net gain of ATP during each stage
-glycolysis
-link
-krebs
-o.p
- overall

2
0
2
28
32

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how much reduced NAD and FAD produced in each stage of respiration for 1 glucose molecule

NADH
glycolysis - 2
LR - 2
Krebs - 6
FADH
Glycolysis - 0
LR - 0
Krebs - 2

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how much C02 is produced during each stage of respiration

glycolysis - 0
LR - 2
Krebs - 4

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when does anaerobic respiration occur

when no oxygen is present

what happens if oxygen is absent

oxygen cannot act as the final electron acceptor at the end of oxidative phosphorylation
protons diffusing through ATP synthase cannot combine with e- and oxygen = no water
conc. of protons in the matrix increases = reduces proton gradient across membrane
oxidative phosphorylation ceases
reduced FAD and NAD cannot be reoxidised and unload hydrogen atoms
kreb cycle stops

what is used in anaerobic respiration

pyruvate

describe anaerobic respiration in mammals

glycolysis produces pyruvate
pyruvate accepts 2 hydrogens from the reduced NAD (made in glycolysis)
pyruvate is reduced to lactate
reduced NAD is reoxidised

describe anaerobic respiration in yeast

pyruvate is decarboxylated (loses C02) and is converted to ethanal
ethanal accepts 2 hydrogen atoms from reduced NAD and becomes reduced to ethonol
the reduced NAD is reoxidised

what happens to lactate in mammals

carried away in the blood
when oxygen is available then it can be converted to pyruvate or recycled to glucose and glycogen

what would happen if lactate remains in the blood

pH would be lowered and it would inhibit the action of many enzymes

name respiratory substrates

carbohydrates lipids protein

what is a respiratory substrate

Molecule broken down / hydrolysed to release energy in respiration

how are carbohydrates used in repsiration

animals can store glycogen plants store starch disaccharides can be digested to mono. and into glucose for respiration

how are lipids used in respiration

triglycerides are hydrolysed by lipase to glycerol and fatty acids can be converted into TP

how are fatty acids used with the beta oxidation pathway

fatty acids can be combined with CoA transported into matrix broken down into acetyl groups beta oxidation pathway generates reduced NAD and FAD acetyl groups are released and enter krebs cycle

how are proteins used as a respiratory substrate

excess amino acids are deaminated the keto group enters the respiratory pathway

explain which respiratory substrate produces the highest mean energy value and why

lipids greater availability of of protons for chemiosmosis as lots of hydrogen more ATP can be produced

what is the respiratory quotient

ratio of C02 produced and 02 consumed C02 produced/02 consumed

what does the RQ value indicate

greater then 1 = anaerobic respiration taking place as more C02 produced then oxygen consumed

describe what happens to respiration in the absence of oxygen

oxygen cannot act as the final acceptor at the end of oxidative phosphorylation so protons diffusing through channels associated with ATP synthase are not able to combine with e- and o2 to form water so conc. of protons increase in the matrix reduces proton gradient = o.p stops reduced NAD and FAD can't unload hydrogen atoms and cannot be reoxidised Krebs cycle stops - and the link reaction

what is the difference between lactate and ethanol fermentation

lactate = mammals ethanol = yeast/ plants

word equation for both types of anaerobic respiration

glucose -> lactic acid glucose -> C02 + ethanol

where does anaerobic respiration take place

cytoplasm of cells

describe anaerobic respiration in yeast/ plants

pyruvate is decarboxylated and produces ethanal ethanal accepts hydrogen atoms from reduced NAD and is reduced to ethanol (as NAD is reoxidised it can accept more hydrogen atoms from TP so glycolysis can continue)

describe anaerobic respiration in mammals

pyruvate accepts hydrogen atoms from reduced NAD and is reduced to lactate (reduced NAD is reoxidised and can accept more hydrogen atoms from glycolysis so it can continue to produce ATP to sustain muscle contraction for short periods.)

what happens to lactate once its produced

when more oxygen is prodcued it can convert lactate to pyruvate (enters kreb cycle) recycled to glucose and glycogen

why does lactate need to be removed from muscle tissues

the pH will be lowered = inhibit action of enzymes involved in glycolysis and muscle contraction

ATP yield from anaerobic respiration

net gain of 2 ATP as the pathways allow glycolysis to continue rather then producing any itself glucose only partly broken down = yield is about 1/15 of whats produced in aerobic

describe what a respirometer is and how it works

apparatus used to measure the rate of respiration of living organisms C02 is produced + oxygen absorbs from tube with organisms = volume stays the same soda lime placed in tube = absorbs C02 produced = volume changes is down to volume of oxygen absorbed by organisms so pressure in tube reduced and liquid in capillary tube/ manometer moves measure length of liquid moved and radius = volume of oxygen absorbed

how can you measure the effect of temperature on respiration

using a respirometer taking readings at different temperatures

why is yeast a faculative anaerobe

can respire aerobically and anaerobically

how can you measure respiration rates in yeast

using a haemocytometer to count the number of cells produced