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Cellular Respiration Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is ATP?

A

-Phosphorylated nucleotide
-Univeral energy currency
-Short term energy molecule
-Large so cannot diffuse across memb
-Can be hydrolysed by ATP synthase to release energy to form ADP + Pi + energy

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2
Q

Why is ATP needed by all living organisms?

A

(supply energy to drive metabolic reaction & other processes inside cells)

Muscle contraction
Anabolic reactions eg protein synthesis
Homeostasis
Active transport
Bulk transport eg. endocytosis, exocytosis
Bioluminescence
Cytokenesis
Chemical activation e.g. activation DNA nucleotides

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3
Q

Properties of ATP

A

-small and water soluble
-bond between adjacent phosphates is easily broken
-easily hydrolysed & reformed

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4
Q

Why is ATP called universal energy currency?

A

universal : found in all prokaryotes and eukaryotes

currency:
Terminal phosphate hydrolyses to release energy
So ATP links energy-releasing reactions to energy-consuming reactions

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5
Q

Coenzymes
How do they differ from co-factor

A

-Cofactors aid function of enzymes and can include organic or inorganic molecules
-Coenzymes sub-group
-Small, non-protein organic molecules which bind temporarily to AS

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6
Q

Coenzymes role in Redox reactions

A

Carry chemical groups between molecules to link reactions

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7
Q

What type of reaction are coenzymes usually involved in in respiration

A

oxidation

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8
Q

What happens to H atoms carried by coenzyme

A

-H splits into proton and e-
-Proton passes inner membrane of mitochondria
-Accumulates in inter membrane space to be used in oxidative phosphorylation to produce ATP

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9
Q

Where does reoxidation of coenzymes take place and why is this necessary

A

Cristae to combine more H atoms from the first 3 stages of respiration

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10
Q

NAD
(Coenzyme)

A

structure: adenine, ribose, Pi, Pi, ribose, nicotinamide

NAD is hydrogen carrier

Nicotinamide part accepts pair of hydrogen atoms.
NAD <-> red NAD (reversible)
Becomes oxidised when it donates 2H atoms

NAD+ + 2H+ 2e- -> red.NAD + H+

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11
Q

FAD
(coenzyme)

A

-similar to NAD
-acts as a hydrogen carrier
-Becomes red FAD when it accepts pair of H atoms
-Oxidised FAD when it donates pair of H atoms

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12
Q

CoA

A

-Adenosine triphosphate (ATP), cysteine, pantothenic acid
-carries 2C fragments (acetyl groups) from LR to KC

CoA + acetyl group <-> acetylCoA (aCoA)

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13
Q

Explain why living organisms do not contain much NAD or CoA at any one time

A

-They are both constantly recycled
-There is no net production or no net breakdown

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14
Q

Structure and Adaptation of mitochondrion

A

-Mitochondrial envelope. inter membrane space enables H+ to accumulate to generate proton motive force to form ATP production via chemiosmosis

-Cristae- large SA, site for oxidative phosphorylation

-Inner membrane impermeable to H+, outer permeable

-Matrix contains enzymes, lipid droplets, DNA plasmids

-Possess 70s ribosomes

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15
Q

Overview aerobic & anaerobic

A

Glycolysis common for both. Then:

Aerobic: LR, KC, OP
Anaerobic: LA pathway or fermentation

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16
Q

Location of glycolysis
why?

A

Cytosol
Requires specific enzymes only found there

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17
Q

Glycolysis function

A

Split glucose (hexose, 6C) into 2 triodes (3C) (pyruvate)

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18
Q

Source of glycolysis in plants

A

Amylose: unbranched polysaccharide, soluble. 1-4 alpha glycosidic

Amylopectin: branched polysaccharide, insoluble, 1-4 & 1-6 alpha glycosidic

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19
Q

Source of glycolysis in animals

A

Glycogen found in liver cells ad muscle cells
Many branches, many terminal end glc molecules, quickly hydrolysed to form glc

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20
Q

Glycolysis input

A

Glucose
2 ATP
2 NAD
Enzymes

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21
Q

Glycolysis output

A

2 Pyruvate
2 red NAD
4 ATP

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22
Q

Glycolysis in terms of net ATP

A

2 in, 4 out
Net gain of 2 ATP (gross of 4)
Substrate level phosphorylation occurs

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23
Q

give each stage of the conversion from a. glucose to pyruvate

A

Glucose (6C)
(ATP → ADP)
Glucose Phosphate
Fructose Phosphate
(ATP → ADP)
Fructose biphosphate
2 glyceraldehyde 3-phosphate (3C)
(2 Pi) (2 red. NAD→NAD)
2 glycerate 1,3-biphosphate
(2 ADP→ATP)
2 glycerate 3-phosphate
( 2 ADP→ATP)
2 pyruvate

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24
Q

what is phosphorylation? what is its use in glycolysis?

A

-Addition of a phosphate group from molecule
-Supplied from ATP
-Adds negative charge to glc. Repelled by hydrophobic core of ppl bilayer of csm, so cannot diffuse out)

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25
Q

Substrate Level Phosphorylation

A
  • accounts for 10% of ATP in aerobic respiration
    -Involves direct additional of phosphate group to ADP to produce ATP
    -Does not involve ETC
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26
Q

Where does the Link Reaction occur
why?

A

Mitochondrial matrix
CoA and other enzymes are only found here

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27
Q

How does pyruvate reach mitochondrial matrix?

A

moves across the mitochondrial envelope through specialised intrinsic protein through A.T.

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28
Q

What 3 types of reactions are involved in the LR

A

Oxidation: e- removed from pyruvate (H gained by CoA)

Reduction: NAD gains protons (and e-)

Decarboxylation: Co2 removed from pyruvate

This is all called: oxidative decarboxylation

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29
Q

Mechanism of LR

A

______________⬈ CO2
Pyruvate + CoA -> aCoA
______________⬊2e- & 2H+
NAD -> red. NAD

Occurs TWICE per glc

A C is removed from pyruvate, forming CO2, to turn it into a 2C acetate. During the conversion into acetate, H is also removed and is picked up by NAD to form red. NAD. Acetate is combined with CoA to form aCoA.

30
Q

Procucts of LR (per 1 glc)

A

2CO2
2aCoA
2red NAD

31
Q

How can fats be converted into a CoA molecule

A

Hydrolysis of fatty acids hydrocarbon tail can release 2C fragments
Each 2C fragment can make 1 CoA
Process: B-oxidation

32
Q

Where does K cycle take place

A

Mitochondrial matrix

33
Q

What is K cycle controlled/ limited by?

A

Since it is a series of enzyme controlled reactions, limited by:

[S], [E], [I], Temp, pH

34
Q

Krebs Cycle

A

aCoA (2C) combines with 4C
⇩ out CoA
Citrate (6C)
⇩. out CO2
⇩. NAD-> red NAD
5C
⇩ out CO2
⇩ NAD-> red NAD
⇩ADP+P= ATP
4C
⇩ FAD-> red FAD
4C
⇩ NAD -> red NAD
oxaloacetate

35
Q

Products of KC

A

Per cycle
1 ATP
2 CO2
3 red NAD
1 red FAD

Per glc
2 ATP
2 CO2
6 red NAD
2 red FAD

36
Q

Recap of ATP, redNAD, redFAD
per glc

A

ATP: 2 net Glycolysis, 2 Krebs

red NAD: 2 Glycolysis, 2LR, 6 Krebs

red FAD: 2 Krebs

37
Q

Main points K cycle

A

-oxaloacetate is regenerated for KC to continue
-Most important products (NAD & FAD)- reduced hydrogen carriers
-Substrate level phosphorylation occurs- direct production of ATP
- No O2 been used yet (But KC can only continue in presence of O2 as oxidised NAD & FAD required)

38
Q

What is the purpose of red NAD and red FAD

A

Co enzymes that act as hydrogen carriers to ETC
Allows ATP production via oxidative phosphorylation

39
Q

Oxidative phosphorylation

A

-Accounts for 90% of ATP production of aerobic respiration
-Is the combined effect and outcome of both the electron transport chain and chemiosmosis

40
Q

Where does oxidative phosphorylation take place

A

Cristae of mitochondria

41
Q

What molecules are involved in the ETC

A

red NAD
red FAD
e- carriers
Oxygen

42
Q

ETC: what are e- carriers?

A

Specialised carrier globular proteins
accept/donate e-
Have quaternary structure (prosthetic group)

43
Q

ETC

A

-Consists of series of redox reactions using specialised proteins

-Dehydrogenase enzyme interacts with reduced H carrier
-H atoms released from co-enzyme and split into H+ and e-
-E- flow down ETC
-Energy released as e- flow from one carrier to another
-Energy used to pump proton into inter membrane space
-Generates proton gradient
-At the end, oxygen acts as final e- acceptor to form H2O (in absence of O, ETC stops)

NB: only red NAD from Krebs enters at first carrier

44
Q

Chemiosmosis def

A

movement of ions across partially permeable membrane, down their electrochemical gradient

45
Q

Chemiosmosis outline

A

-proton pumping leads to accumulation in inter membrane space
-Creates proton motive force
-Protons flow down electrochemical gradient through ATP synthase (stalked particles) into matrix
-This flow of protons releases energy
-Energy used to ADP + Pi-> ATP
-Protons react with O to form h2o- maintains proton gradient

46
Q

Products of Chemiosmosis (ATP)

A

red NAD from Krebs: 3 (2.5)
red FAD from Krebs: 2 (1.5)
red NAD from glycolysis: 2 (1.5)
red NAD from LR: 2 (1.5)

47
Q

ATP
- glycolysis
- link reaction
- krebs cycle
- oxidative phosphorylation

as substrate-level phosphorylation?

A

Used Produced. Gain
2. 4 2
0 0 0
0 2. 2
0 0 0

48
Q

ATP direct
(from chemiosmosis)
- 2 red. NAD from glycolysis
- 2 red. NAD from link reaction
- 6 red. NAD from Krebs cycle
- 2 red. FAD from Krebs cycle?

A

Used Produced. Gain
0 4 3
0 4 3
0 18 15
0 4 3

49
Q

Theoretical yield & ATP production

A

1 glc molecule has potential to produce 36 ATP

Rarely achieved as ATP used to:
-Move pyruvate to matrix
-pump protons into inter membrane space
-shuttle H from red NAD produced in glycolysis to matrix

Also, some protons leak across mitochondrial membrane reducing the proton motive force, so less ATP made

50
Q

Role of oxygen

A

-Acts as final e- acceptor
-accepts protons to form water
-Enables ETC to continue
-Which in turn allows chemiosmosis to take place
-Increased ATP production

51
Q

Where can anaerobic respiration take place?
Whta is its principle?

A

only in skeletal muscles
enables glycolysis to continue to ensure 2 ATP is made per glc

52
Q

Lactate fermentation

A

-H atoms removed from red. NAD
-Join with pyruvate to make lactate
-so red. NAD deoxidised back to NAD
-Can then be re-used in glycolysis
-Enables low rate of substrate level phosphorylation

53
Q

Role of pyruvate in lactate fermentation

A

Pyruvate acts as an alternative hydrogen acceptor

54
Q

Fate of lactate

A
  • Build up causes inhibition of glycolysis, cramp & fatigue
    -Lactate transported to liver in plasma
    -lactate is oxidised back to pyruvate by lactate dehydrogenase (when O is available again) so reversible
    -1/5 respired anaerobically
    -4/5 converted to glucose and stored as glycogen
55
Q

Alcoholic fermentation

A

-Pyruvate is decarboxylated to form ethanal & CO2 by pyruvate decarboxylate
-Ethanal acts as H acceptor and removes H from red. NAD
-Forms ethanol and is catalysed by Ethanol dehydrogenase
-Oxidises red NAD back to NAD so it can be used in glycolysis

56
Q

why is yeast considered a ‘facultive anaerobe’?

A

it can survive in both anaerobic and aerobic conditions (although growth is faster in aerobic)

57
Q

What type of aerobic respiration in yeast?

A

alcoholic fermentation

58
Q

why is alcoholic fermentation considered wasteful for the yeast?

A

As the chemical potential energy is trapped in ethanOl so wasteful

59
Q

What is a respiratory substrate

A

an organic molecule that can be broken down in respiration to produce ATP

60
Q

why do different respiratory substrates produce different amounts of ATP?

A

have different amounts of hydrogen

∴ different number of H+ that can be pumped into the IMS

∴ different proton motive forces generated

∴ different numbers of ATP molecules can be produced

61
Q

name two cells that only use glucose as a respiratory substrate

A

Mature RBC
Human brain cells

62
Q

how are carbohydrates converted and used as respiratory substrates?

A

-Glycogen/ amylose/ amylopectin can be hydrolysed to glc

63
Q

how are proteins converted and used as respiratory substrates?

A

-Excess amino acids deaminated
-remainder of molecule converted to glycogen or lipids for energy storage
-during starvation, proteins can be hydrolysed to release amino acids

64
Q

how are lipids converted and used as respiratory substrate?

A

-triglycerides can be hydrolysed into 3 fatty acids and 1 glycerol
-glycerol is converted to glc
-Hydrocarbon fatty acid tail hydrolysed during B oxidation to release 2C fragments (acetyl)
-each acetyl can join with CoA to form aCoA to join Krebs

65
Q

Define Respiratory Quotient

A

The ratio of the volume of CO2 produced by a respiring organism to that of oxygen consumed by an organism, tissue cell IN A GIVEN PERIOD OF TIME

66
Q

RQ formula

A

volume CO2 released/ volume O2 taken up

67
Q

what does the RQ indicate?

A

the type of respiratory substrate being used

68
Q

what is the RQ value for anaerobic conditions?

A

infinite

69
Q

RQ value for subrates aerobically

A

carbohydrates 1
proteins 0.8-0.9
lipids 0.7

70
Q

EQ Outline the stage of aerobic respiration that occurs in the cytoplasm

A

-Glycolysis
-Phosphorylation of glucose
-Splitting of fructose biphosphate into two triose phosphate (3C)
-Each 3C Oxidised to form pyruvate
-net 2 atp production & 2 red. NAD formed

Biology (18 decks)

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