c1.3 - respiration Flashcards

1
Q

respiration

A

set of metabolic reactions that take place in organisms + break down respiratory substances
e.g: glucose into smaller inorganic molecules, like water + CO2
linked to synthesis of ATP

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2
Q

why respiration described as catabolic process

A

complex molecules (respiratory substrates) broken down into smaller, simpler molecules

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3
Q

why organisms need to respire

A

produces chemical energy in ATP for variety of processes
e.g: active transport, metabolic reactions, muscle contraction
releases heat energy for thermoregulation

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4
Q

aerobic respiration

A

takes place in presence of O2 + produced CO2, water + ATP
C6H12O6 + 6O2 -> 6CO2 + 6H2O

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5
Q

four main stages of aerobic respiration + where they occur

A

glycolysis - cytosol
link reaction - mitochondrial matrix
krebs cycle - mitochondrial matrix
electron transport chain - inner mitochondrial matrix

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6
Q

stages of glycolysis

A
  1. glucose (hexose sugar) phophorylated to hexose bisphosphate by 2x ATP
  2. hexose bisphosphate splits into 2x triose phosphate (TP)
  3. 2 molecules of TP oxidised to 2x pyruvate
    net gain of 2x reduced NAD (NADH) + 2x ATP per glucose
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7
Q

equation to summarise glycolysis

A

glucose + 2NAD + 2ADP + 2Pi -> 2 pyruvate + 2NADH + heat

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8
Q

how does pyruvate from glycolysis enter mitochondria

A

active transport

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9
Q

link reaction

A
  1. oxidative decarboxylation + dehydrogenation of pyruvate to form acetate
    net gain of CO2 + 2x reduced NAD
  2. acetate combines w/ coenzyme A (CoA) to form acetyl coenzyme A
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10
Q

equation to summarise link reaction

A

pyruvate + NAD + CoA -> acetyl CoA + reduced NAD + CO2

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11
Q

krebs cycle

A

series of oxidation-reduction reaction in matrix of mitochondria in which acetyl CoA is oxidised generating reduced NAD, reduced FAD, ATP + CO2

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12
Q

function of krebs cycle

A

means of releasing energy from carbon bonds to provide ATP, reduced NAD + reduced FAD (with release of CO2)

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13
Q

how many NAD + FAD does complete oxidation of 1 glucose molecule yield

A

10 reduced NAD
2 reduced FAD

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14
Q

electron transport chain

A

series of electron carrier proteins that transfer electrons in a chain of oxidation-reduction reaction, releasing energy

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15
Q

what happens in ETC

A

electrons released from reduced NAD + FAD undergo successive redox reactions
energy released is coupled to maintaining proton gradient or is released as heat
oxygen acts as final electron acceptor

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16
Q

role of reduced NAD + FAD in ETC

A

source of electrons + protons

17
Q

how chemiosmosis produces ATP during aerobic respiration

A

protons flow down conc gradient from intermembrane space into mitochondrial matrix via ATP synthase
ATP synthase phophorylates ADP to form ATP as protons flow through it

18
Q

role of O2 in ETC

A

final electron acceptor
O2 + 4H+ + 4e- -> 2H2O

19
Q

how many ATP produced per oxidised NAD in aerobic respiration

20
Q

how many ATP produced per oxidised FAD in aerobic respiration

21
Q

anaerobic respiration

A

takes place in absence of oxygen
less ATP formed than aerobic

22
Q

product of anaerobic respiration in animals

A

lactic acid

23
Q

anaerobic respiration in animals

A

only glycolysis continues
reduced NAD (product of glycolysis) transfers H to pyruvate, forming lactic acid + regeneration NAD
catalysed by enzyme lactate dehydrogenase

24
Q

products of anaerobic respiration in plants + microorganisms

A

ethanol + CO2

25
anaerobic respiration in plants + microorganisms
only glycolysis continues pyruvate decarboxylated to form ethanal ethanal accepts H for reduced NAD making ethanol NAD regenerated for glycolysis
26
yield of ATP in aerobic v anaerobic respiration
aerobic - 30 to 32 ATP anaerobic - 2 ATP
27
why is max yield of ATP in aerobic respiration never reached
ATP lost due to leaky membranes energy required to move pyruvate + ADP into mitochondrial matrix
28
2 types of molecules that can be used as alternative respiratory substrates
(amino acids from) proteins (glycerol + fatty acids from) lipids
29
how lipids used in respiration
hydrolysed to glycerol + fatty acids glycerol converted to a 3C sugar + enter glycolysis fatty acids broken down into 2C acetate fragments which enter krebs cycle as acetyl CoA
30
how proteins used in respiration
hydrolysed to amino acids amino acid deaminated in liver forming keto acids + ammonia keto acids enter glycolysis + krebs cycle