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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 the energy in food molecules is made available for an organism to do biological work - make ATP

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2
Q

What is ATP?

A
  • Form of chemical energy that is used to fuel endergonic biological activities
  • Universal energy source
  • Covalent bond between last phosphate is unstable, so is removed during an exergonic hydrolysis reaction
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3
Q

What is energy needed for?

A
  • Active transport
  • Endocytosis/exocytosis
  • Cell division
  • DNA replication
  • Synthesis of large molecules
  • Movement (e.g. cilia)
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4
Q

Structure of ATP

A
  • 3 phosphate groups held together by covalent bonds
  • Ribose sugar
  • Adenine nitrogenous base
  • Phosphorylated nucleotide
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5
Q

Steps of glycolysis (simple)

A
  • 6C glucose
  • 6C glucose diphosphate
  • 2x 3C triose phosphate (glyceraldehyde 3-phosphate)
  • 2x 3C pyruvate
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6
Q

Glycolysis (detailed)

A

•6C glucose:
-Phosphorylation reaction
-2ATP->2ADP
•6C glucose-diphosphate:
-More polar (less chance to diffuse out of the cell)
-More unstable (less activation energy needed for enzymes)
-Splits…
•x2 3C TP (glyceraldehyde 3-phosphate):
-Dehydrogenation reaction (exergonic) removes 2H (from each) which reduce NAD (carrier)
-Energy released from dehydrogenation is used to synthesise 2 ATP molecules (from each) by substrate-level phosphorylation
•x2 3C pyruvate

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7
Q

How much ATP is used in glycolysis?

A

2 ATP

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8
Q

How many ATP molecules are gained during glycolysis?

A

4 ATP

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9
Q

What is the net gain of ATP from glycolysis?

A

2 ATP

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10
Q

How many NAD carriers are reduced during glycolysis?

A

2 NADred

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11
Q

Where does glycolysis occur?

A

Cytoplasm

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12
Q

Does glycolysis require oxygen?

A

No

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13
Q

What is NAD?

A

A coenzyme that acts as a hydrogen carrier

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14
Q

What is a dehydrogenation reaction?

A
  • Involves removal of pairs of hydrogen atoms from a molecule
  • Catalysed by a dehydrogenase enzyme
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15
Q

What is substrate-level phosphorylation?

A

Synthesis of ATP using energy released from the breakdown of a high-energy substrate molecule

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16
Q

What is phosphorylation?

A

The addition of a phosphate group (Pi)

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17
Q

Why is NAD regarded as a coenzyme?

A

It assists dehydrogenases

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18
Q

Link reaction (simple)

A
  • x2 pyruvate (3C)

* Acetyl-CoA (2C)

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19
Q

Link reaction detailed

A
  • Pyruvate enters mitochondrial matrix by active transport
  • Oxidative decarboxylation
  • Dehydrogenation reduces NAD
  • Forms acetate
  • Acetate combines with coenzyme-A to form acetyl coenzyme-A
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20
Q

Where does the link reaction occur?

A

Mitochondrial matrix - pyruvate is transported by protein

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21
Q

Where does the Krebs cycle occur?

A

Mitochondrial matrix

-Requires O2

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22
Q

What is the Krebs cycle?

A
  • Involves a series of decarboxylation and dehydrogenation reaction
  • CO2, ATP, NADred, FADred
  • 2 cycles per glucose molecule
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23
Q

How can the Krebs cycle be continuous?

A
  • Carriers are regenerated

* If more acetyl-CoA is available, the cycle can start again

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24
Q

Krebs cycle process (simple)

A 
•4C + 2C (acetyl-CoA)
-CoA is removed
•6C
-dehydrogenation removes 2H (NADred)
-decarboxylation 
•5C
-decarboxylation of CO2
-substrate-level phosphorylation of ATP
-dehydrogenation removes 2H (NADred)
•4C
-dehydrogenation removes 2H (FADred)
•4C
-dehydrogenation removes 2H (NADred)
•4C (oxaloacetate)
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25
Q

How much NADred is produced from the Krebs cycle per one glucose molecule?

A

6 NADred

These go on to form 18 ATPs

26
Q

How much FADred is produced from the Krebs cycle per one glucose molecule?

A

2 FADred

These go on to form 4 ATPs

27
Q

How much ATP is directly made from the Krebs cycle per one glucose molecule?

A

2 ATPs

28
Q

How much CO2 is produced from the Krebs cycle per one glucose molecule?

A

4 CO2

29
Q

What is the main purpose of the Krebs cycle?

A
  • To feed electrons into the next stage of aerobic respiration
  • Electrons come from reduced NAD and FAD molecules which carry hydrogen atoms
30
Q

What are cytochromes?

A
  • Iron-containing pigmented molecules
  • Embedded in inner membranes of mitochondria where they form an ETS
  • Each redox reaction in the ETS releases energy which can be used to synthesise ATP
31
Q

What is oxidative phosphorylation?

A

Oxygen dependent synthesis of ATP within mitochondria using energy released from redox reactions

32
Q

What is chemiosmosis?

A
  • Energy from electrons during redox reactions is used to pump H+ protons from the matrix into the inter-membrane space
  • H+ accumulate so that steep conc & electrochemical gradient are established across the inner membrane
  • H+ diffuse back into matrix via stalked particles which consists of a chemiosmotic channel protein attached to ATPsynthase
  • Flow of protons through ATPsythase provides energy to produce ATP from ADP and Pi
33
Q

Why are stalked particles required for chemiosmosis?

A
  • Inner membrane is impermeable to protons

* Has ATPsynthase which produces ATP

34
Q

How much ATP is made from one NADred entering the chain?

A

3 ATP molecules

-3 proton pumps involved

35
Q

How much ATP is made from one FADred entering the chain?

A

2 ATP molecules

-2 proton pumps involved

36
Q

What is the terminal electron acceptor?

A

•Oxygen

-combines protons (H+) and electrons (e-) and is reduced to H2O

37
Q

Why is oxygen important in aerobic respiration?

A

•It is the terminal electron acceptor in the ETC
-accepts H+ and e- and is reduced to H20
•Drives the ECT
•Allows NAD and FAD to return to the Krebs cycle

38
Q

How can cyanide affect aerobic respiration?

A

•Respiratory inhibitor
•Non-competitive inhibitor of cytochrome oxidase
-an enzyme associated with the final proton pump in the ETC
•When cyanide attaches to the enzyme, the ETC cannot function and oxidative phosphorylation cannot occur
-ATP is not produced

39
Q

Where does each stage of respiration take place?

A
  • Glycolysis - cytoplasm
  • Link reaction - mitochondrial matrix
  • Krebs cycle - mitochondrial matrix
  • ETC - inner mitochondrial membrane/cristae
40
Q

What is produced at each stage of respiration?

A
  • Glycolysis - pyruvate, ATP, NADH2
  • Link reaction - Acetyl Co-A, NADH2, CO2
  • Krebs cycle - CO2, ATP, NADH2, FADH2
  • ETC - NAD, FAD, ATP, H2O
41
Q

Where is ATP produced and how much?

A 
•Glycolysis
-2 ATP
•Krebs cycle
-2 ATP
•ETC 
-34 ATP
42
Q

Where in the cell does anaerobic respiration occur?

A

In the cytoplasm

43
Q

How does anaerobic respiration occur?

A

•NADred and FADred are not oxidised
-become limiting factors
-dehydrogenation reactions of Krebs cycle and Link reaction cannot occur
•Glycolysis continues as the pyruvate enters a different pathway and is reduced
-oxidising NADred to NAD

44
Q

What is the pyruvate converted into in animals?

A

Lactate (3C)

45
Q

What is the pyruvate converted into in plants and fungi?

A

Ethanol (2C)

46
Q

Respiratory quotient (RQ)

A

RQ =
Volume of CO2 produced/
Volume of O2 taken in

47
Q

What is the RQ of glucose?

A

1.0

48
Q

What is the RQ of a fatty acid?

A

0.7

49
Q

What is the RQ of protein?

A

0.9

50
Q

What is the RQ of anaerobic respiration?

A

> 1

51
Q

Compare the breakdown of glucose in aerobic and anaerobic respiration

A

•Aerobic respiration
-complete breakdown to CO2 and H2O
•Anaerobic respiration
-incomplete breakdown of glucose

52
Q

Compare ATP production of aerobic and anaerobic respiration

A

•Aerobic respiration
-38 ATP
•Anaerobic respiration
-2 ATP

53
Q

Compare efficiency of aerobic and anaerobic respiration

A 
•Aerobic respiration 
-40% efficient 
•Anaerobic respiration
-2% efficient 
-energy remains locked up in lactate/ethanol
54
Q

Why do lipids release lots of energy? (Alternative respiratory substrates)

A

•Longer fatty acids have more H

  • more NAD reduced
  • more ATP
55
Q

How can lipids be used in respiration? (Alternative respiratory substrates)

A

•Glycerol is converted into 3C
-enters Glycolysis
•Long-chain fatty acid molecules are split into 2C acetate fragments
-enter Krebs cycle as acetyl CoA

56
Q

How can proteins be used in respiration? (Alternative respiratory substrates)

A

•High protein diet
-excess amino acids are metabolised in the liver
•If a person is starving, tissue protein is hydrolysed into amino acids
•Amino acids are deaminated, forming ammonia and a keto-acid
-keto-acids enter glycolysis and Krebs cycle

57
Q

Explain the advantages of collecting results from the whole class

A
  • A statistical test can be used to increase confidence

* Increase reproducibility

58
Q

Where is the most acidic region of the mitochondria and why?

A
  • Intermembrane space

* H+ ions

59
Q

Function of DNA in respiration

A

Allows coding for polypeptides

60
Q

Function of ribosomes in respiration

A

Protein synthesis to produce ATP

61
Q

Suggest a suitable tissue to examine mitochondrial function and explain why

A
  • Muscle tissue
  • Abundance of mitochondria
  • Easy to extract
62
Q

Why does aerobic respiration yield fewer molecules of ATP than the theoretical maximum?

A
  • Some is used to actively transport pyruvate into the mitochondria for Link Reaction
  • Some used to actively transport H+ from reduced NAD formed in glycolysis, into the mitochondria
  • Not all NADH2 is used to feed the ETC
  • Not all H+ is used to generate ATP through ATP synthase

Biology🧬 (24 decks)

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