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Biology > Respiration > Flashcards

Respiration Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is respiration?

A

The process by which organic molecules are oxidised in a series of stages to synthesise ATP from ADP and Pi

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2
Q

The mitochondria in muscles contain many cristae. Explain the advantage of this (2)

A

Larger surface area for electron carrier system/oxidative phosphorylation
Provides more ATP/energy for muscle contraction

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3
Q

What are the 4 stages in aerobic respiration? (4)

A

Glycolysis
Link reaction
Krebs cycle
Oxidative phosphorylation (electron transport chain)

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4
Q

Where does glycolysis occur?

A

Cytoplasm of the cell

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5
Q

Where, in the mitochondria, does the link and Krebs reaction occur?

A

Matrix of mitochondria

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6
Q

Where, in the mitochondria, does oxidative phosphorylation occur?

A

Mitochondrial membranes

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7
Q

During respiration, what are the two ways in which ATP can be generated? (2)

A

Substrate-level phosphorylation
Oxidative phosphorylation

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8
Q

Where does substrate level phosphorylation occur? (1)

A

In glycolysis and Krebs cycle - ATP can be generated directly through energy released via respiration reactions

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9
Q

Where does oxidative phosphorylation occur?

A

At the electron transport chain

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10
Q

Describe glycolysis (6)

A

Glucose is activated by phosphorylation.
This requires the hydrolysis of 2 molecules of ATP to 2 x ADP to provide the 2 phosphates
Glucose phosphate (phosphorylated glucose ‘unstable’) then splits into 2 x triose phosphate
Triose phosphate is then oxidised to pyruvate.
This step involves the loss of H (via dehydrogenase enzyme) which reduces the Hydrogen carrier molecule NAD to NADH
ATP is also produced via substrate level phosphorylation

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11
Q

What does glycolysis of glucose yields? (3)

A

2 molecules of pyruvate
2 NET ATP directly by substrate level phosphorylation
2 reduced NAD

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12
Q

Why does glycolysis occur in the cytoplasm? (2)

A

Glycolysis enzymes are only found in the cytoplasm
Glucose too large to enter matrix of mitochondria

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13
Q

Describe the link reaction (5)

A

Pyruvate is actively transported into the mitochondrial matrix
Pyruvate is oxidised to acetate and the hydrogen removed is used to reduce the hydrogen carrier ‘NAD’ to form reduced
A molecule of CO2 is lost in this reaction (decarboxylation)
Acetate combines with a molecule of coenzyme A to form acetyl coenzyme A
No ATP produced directly in the link reaction

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14
Q

What are the products of link reaction? (3)

A

Reduced NAD
2 molecules of acetyl coenzyme A
CO2

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15
Q

Describe the Krebs cycle (5)

A

Acetyl coenzyme A combines with 4C molecule to form 6C compound
6C compound loses CO2 and hydrogen to convert to a 4C compound and 1xATP (via substrate-level phosphorylation)
FAD reduced
NAD reduced

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16
Q

What are the products of Krebs cycle? (3)

A

2 x CO2 produced
Some ATP produced directly by substrate level phosphorylation
3 x reduced NAD and 1 x FAD produced to be used in oxidative phosphorylation

17
Q

How many times the Krebs cycle take place per molecule of glucose? (1)

A

2 times

18
Q

Describe how oxidation takes place in glycolysis and in the Krebs cycle

A

Removal of hydrogen/dehydrogenation
By enzymes/dehydrogenases
H accepted by NAD/reduced NAD formed
In Krebs cycle, FAD used as well

19
Q

Describe oxidative phosphorylation (9)

A

Reduced H carriers (reduced NAD and reduced FAD) are oxidised losing hydrogen
Electrons from H pass down a series of electron carrier proteins within the mitochondrial membranes in a series of redox reactions
As the electrons pass along the electron transport chain they lose energy, some of which is used to pump the H+ (proton) through the inner mitochondrial membrane into intermembrane space
Some of the energy is also lost as heat
The H+ diffuse down a proton gradient across the inner membrane into the matrix via ATP synthase enzymes and as they diffuse through the enzymes, enough energy is provided to form ATP
The electrons and H+ recombine with oxygen gas to form water
Oxygen is the final/terminal electron acceptor
Without oxygen removing H+ and electrons, there would be a ‘back up’ of electrons along the ETC and the process of cellular respiration will come to a halt

20
Q

Water is a waste product of aerobic respiration. Describe how water is formed at the end of aerobic respiration. (2)

A

Oxygen is the terminal/final electron acceptor
Combines with electrons and protons (to form water)

21
Q

Describe the roles of the coenzymes and carrier proteins in the synthesis of ATP (3)

A

NAD/FAD reduced / hydrogen attached to NAD/FAD;
H+ ions/electrons transferred from coenzyme to coenzyme/carrier to carrier (ETC on cristae of inner membrane)
Energy released (from electrons) through series of redox reactions;
Energy released used to pump H+/ protons into intermembrane space forming an electro-chemical gradient (of protons);
H+/ protons flow back through ATP synthase to produce ATP from ADP and phosphate

22
Q

Describe how ATP is made in mitochondria. (6)

A

Substrate level phosphorylation / ATP produced in Krebs cycle
Krebs cycle/link reaction produces reduced coenzyme/reduced NAD/reduced FAD
Electrons released from reduced /coenzymes/ NAD/FAD
(Electrons) pass along carriers/through electron transport chain/through series of redox reactions
Energy released
ADP/ADP + Pi
Protons move into intermembrane space;
ATP synthase

23
Q

Describe the events of oxidative phosphorylation

A

NAD/FAD reduced / hydrogen attached to NAD/FAD;
H+ ions/electrons transferred from coenzyme to coenzyme/carrier to carrier (ETC on cristae of inner membrane)
Energy released (from electrons) through series of redox reactions;
Energy released used to pump H+/ protons into intermembrane space forming an electro-chemical gradient (of protons);
H+/ protons flow back through ATP synthase to produce ATP from ADP and phosphate.

24
Q

What are alternative respiratory substrates? (2)

A

Lipids and proteins

25
Q

How do lipids act as alternative respiratory substrates? (3)

A

Glycerol is phosphorylated and converted to triose phosphate which enters glycolysis and Krebs cycle
Fatty acids are broken down into 2C fragments and converted into acetyl co A
Oxidation of fatty acids yields many hydrogen atoms to reduce NAD/FAD to be used in oxidative phosphorylation of ATP

26
Q

How do proteins act as alternative respiratory substrates? (3)

A

Amino groups are removed (deamination)
Enter the respiratory pathway at different stages on the number of carbon atoms they contain
- 3C into pyruvate
- 4C and 5C into Krebs cycle intermediates

27
Q

Explain how the amount of ATP is increased by reactions occurring inside a mitochondrion.

A

oxidation of/removal of electrons and H+
from pyruvate
acetyl CoA / 6 carbon compound; (credit oxidative decarboxylation)
substrate level production of ATP / ATP produced in Krebs cycle
production of reduced NAD / FAD (allow they take up hydrogen)
in matrix of mitochondria
electrons fed into electron transport chain / used in oxidative phosphorlation
(Electrons) pass along carriers/through electron transport chain/through series of redox reactions
Energy is released
Protons move into intermembrane space
ADP/ADP + Pi
ATP synthase

28
Q

How many ATP molecules are produced in aerobic respiration (1)

A

Net 38 molecules of ATP per molecule of glucose

29
Q

How many ATP molecules are produced in anaerobic respiration? (1)

A

2 molecules of ATP per molecule of glucose

30
Q

What needs to be measured in a respirometer? (3)

A

The distance the ink/bubble moves
Over a fixed time period
Volume/diameter/cross-sectional area of tube

31
Q

Give two reasons why the respirometer was left for 10 minutes when it was first placed in the water bath (3)

A

Equilibrium reached
Allow for expansion/pressure change in apparatus
Allow respiration rate of seeds to stabilise

32
Q

Describe how anaerobic respiration occurs in animals (3)

A

Pyruvate is reduced to form lactate
Using H from the oxidation of NADH to produce NAD
So NAD regenerated and glycolysis can continue

33
Q

Describe how anaerobic respiration occurs in plants and microorganisms (3)

A

Pyruvate is reduced to form ethanol and carbon dioxide
Using H from the oxidation of NADH to produce NAD
So NAD regenerated and glycolysis can continue

34
Q

Describe the advantage of the electron transport chain (2)

A

Energy is released gradually
Less energy lost as heat

35
Q

Disadvantage of producing ethanol during anaerobic respiration (1)

A

Ethanol dissolves cell membranes

36
Q

Disadvantage of producing lactate during anaerobic respiration (2)

A

Acidic so decreases pH
Causes muscle fatigue

Biology (33 decks)

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