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Bio Yr 13: Energy Transfers In + Between Organisms > Respiration > Flashcards

Respiration Flashcards

1
Q

What is the function of mitochondria?

A
  • site of aerobic respiration in eukaryotic cells
  • synthesises ATP during oxidative phosphorylation
    • relies on membrane proteins: make up electron transport chain + ATP synthase enzyme
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2
Q

What is the structure of mitochondria?

A
  • 2 phospholipid membranes
    • outer: smooth + permeable to some small molecules
    • inner: folded cristae, less permeable + site of electron transport chain + ATP synthase (used in oxidative phosphorylation)
  • intermembrane space = low pH bc of high conc. of protons
    • conc gradient across inner membrane formed during oxidative phosphorylation = needed for ATP synthesis
  • matrix = (aq) solution within inner membrane
    • contains ribosomes, enzymes + circular mitochondrial DNA
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3
Q

What is the relationship between the structure + function of mitochondria?

A
  • large SA of inner membrane due to cristae: enables membrane to hold many electron transport chain proteins + ATP synthase enzymes
  • more active cells may have larger mitochondria w longer + more tightly packed cristae = larger SA so synthesises more ATP
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4
Q

What does work in a living organism require?

A
  • energy
  • usable carbon compounds
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5
Q

What are the diff. types of essential work within organisms?

A
  • transporting substances across membranes: active transport in cell membranes + exocytosis
  • anabolic reactions: synthesising DNA from nucleotides + protein from AAs
  • movement: movement of chromosomes via spindles + muscle contraction
  • maintaining body T°C: in mammals + birds only
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6
Q

What is the primary source of energy for most organisms?

A
  • the sun
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7
Q

How do reactions of photosynthesis store energy in organic molecules?

A
  • light energy transformed into chemical potential energy to synthesis carbs.
  • used to synthesis ATP or are combined + modified to form usable organic molecules: essential for all metabolic processes in plant
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8
Q

What does respiration involve?

A
  • releasing energy from breakdown of organic molecules
  • the transfer of chemical potential energy from nutrient molecules into usable energy used for work in an organism
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9
Q

What is the equation for respiration?

A
  • glucose + oxygen —-> carbon dioxide + water + energy
  • C6H12O6 + 6O2 —-> 6CO2 + 6H2O +2870kJ
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10
Q

What are autotrophs + heterotrophs?

A
  • autotrophs: organisms able to synthesis their own usable carbon compounds from CO2 in atmo. through photosynthesis
  • heterotrophs: require pre-made supply of usable carbon compounds from food
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11
Q

What is aerobic respiration?

A
  • process of breaking down a respiratory substrate ( mainly glucose) in order to produce ATP using oxygen
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12
Q

What are the 4 stages of aerobic respiration + where does each stage occur?

A
  • glycolysis: cell cytoplasm
  • link reaction: matrix of mitochondria
  • Krebs cycle: matrix of mitochondria
  • oxidative phosphorylation: inner membrane of mitochondria
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13
Q

What is glycolysis?

A
  • phosphorylation + splitting of glucose in 1st stage of respiration
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14
Q

Describe the stages of glycolysis.

A
  • phosphorylation: glucose made more reactive by adding 2 Pi molecules, from hydrolysis of 2 ATP molecules to ADP, to form glucose phosphate (6C)
  • which is split into 2 triose phosphate molecules (3C)
  • oxidation: H+ is removed from each molecule + transferred to NAD (coenzyme) to form 2 reduced NAD/NADH
  • enzyme controlled reactions convert each oxidised triose phosphate into pyruvate (3C) which regenerates 2 ATP molecules from ADP
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15
Q

What products are formed from glycolysis?

A
  • 2 ATP (net gain)
  • 2 reduced NAD
  • 2 pyruvate (3C)
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16
Q

How does pyruvate + reduced NAD/NADH enter matrix of the mitochondria from cytoplasm?

A
  • moves across double membrane of mitochondria via active transport
  • requires a transport protein + small amount of ATP
17
Q

What does the link reaction do?

A
  • links glycolysis to the Krebs cycle
18
Q

Describe the stages of the link reaction.

A
  • pyruvate (made in glycolysis) is oxidised (loses an electron [H+]) by enzymes to acetate + CO2 in which NAD picks up the H+ to form reduced NAD
  • acetate combines w coenzyme A to produce acetyl coenzyme A (acetyl CoA)
19
Q

What is a coenzyme?

A
  • biological molecule that binds to an enzymes active site to help enzymes catalyse reactions
  • not an enzyme
20
Q

What products are formed from the link reaction?

A
  • 1 glucose molecule produces 2 pyruvate molecules which each produce:
    • 1 acetyl coenzyme A
    • 1 CO2
    • 1 reduced NAD
21
Q

What is the Krebs cycle?

A
  • 2nd stage of respiration consisting of a series of enzyme-controlled reactions
22
Q

Describe the stages of the Krebs cycle.

A
  • acetyl coenzyme A (produced from link reaction) reacts w a 4-carbon molecule, releasing coenzyme A (can be reused in link reaction), + forming a 6-carbon molecule
  • a series of redox reactions causes the 6C molecule to regenerate into a 4C molecule by losing 2 CO2 molecules [decarboxylation] + H+ (used to reduce coenzymes NAD [3] + FAD [1])
  • 1 ATP molecule is also formed due to substrate-linked phosphorylation
23
Q

What products are formed from the Krebs cycle?

A
  • 1 glucose molecule produces 2 acetyl CoA which each produce:
    • 3 reduced NAD
    • 1 reduced FAD
    • 1 ATP
    • 2 CO2
24
Q

What are the 2 coenzymes involved in aerobic respiration?

A
  • NAD
  • FAD
25
Q

What is the role of the coenzymes NAD + FAD in aerobic respiration?

A
  • to transfer H atoms (H+ + e-) from diff stages of respiration to electron transport chain, on cristae, where coenzymes lose H atoms (oxidised)
26
Q

How many reduced NAD + FAD are produced, during glycolysis - Krebs cycle, from 1 glucose molecule?

A
  • NADH = 10
  • FADH = 2
27
Q

What is the current model for oxidative phosphorylation?

A
  • chemiosmotic theory
28
Q

Describe the stages of oxidative phosphorylation.

A
  • NADH + FADH, produced from glycolysis to Krebs cycle, releases H+ + e- (oxidised)
  • energy, produced from e- passed along ETC, allows H+ ions to move from matrix into intermembrane space, creating a conc. gradient
  • H+ move down conc gradient, by facilitated diffusion, through ATP synthase back into matrix
  • produces energy for phosphorylation of ADP into ATP by ATP synthesis
  • O2 combines w e- at end of ETC, + H+ passed through ATP synthase, to produce water
29
Q

What products are formed from oxidative phosphorylation?

A
  • 1 glucose molecule produces:
  • 30-32 ATP
  • 6 H2O
30
Q

Why is oxygen so important for aerobic respiration?

A
  • O2 acts as the final e- acceptor
  • w/o O2 the ETC can’t continue bc e- have nowhere to go
  • so reduced coenzymes, NADH + FADH2 can’t be oxidised to regenerate NAD + FAD, so can’t transport more H2 from link reaction + Krebs cycle
31
Q

What is anaerobic respiration + where does it occur?

A
  • respiration in the absence of O2
  • occurs in cytoplasm
32
Q

How is energy released during anaerobic respiration?

A
  • pyruvate, produced in glycolysis, is reduced to form ethanol + CO2 in plants, or lactate in animals, by gaining the H+ from NADH
  • this oxidises NAD, so it can be reused in glycolysis, so small amounts of ATP is still produced
33
Q

How is ethanol produced by anaerobic respiration?

A
  • pyruvate, produced from glycolysis, loses a CO2 molecule (decarboxylated) to form ethanal
  • which is reduced (gains a H+ from NADH) to ethanol by alcohol dehydrogenase
34
Q

How is lactate produced by anaerobic respiration?

A
  • pyruvate, produced from glycolysis, is reduced (gains a H+ from NADH) to lactate by lactate dehydrogenase
  • it can then be oxidised back to pyruvate (to be used in Krebs cycle) or converted into glycogen for storage in liver

Bio Yr 13: Energy Transfers In + Between Organisms (4 decks)

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