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BIOLOGY 110 > Chapter 5 - cellular respiration > Flashcards

Chapter 5 - cellular respiration Flashcards

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1
Q

what does the cellular respiration do?

A
  1. Breaks down carbohydrates, lipids, and proteins
  2. Converts energy that is liberated into ATP
  3. Allows the cell to do work
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2
Q

What is cellular respiration?

A

Collection of metabolic reactions within cells that breaks down food molecules (catabolic reactions) to produce ATP

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3
Q

What is ATP?

A

ATP is the form of chemical energy required for thousands of biosynthetic reactions (anabolic reactions) taking place within the cell
- produced in glycolysis
- Result from substrate-level phosphorylation

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4
Q

Where is energy coming from?

A
  • The Sun: Ultimate source of energy for most organisms
  • Photosynthesis: Captures energy of sunlight; Converts it to chemical energy of complex organic molecules
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5
Q

What happens in cellular respiration?

A

Photosynthesis uses light energy to convert carbon dioxide and water into energy-rich organic molecules,
such as glucose, which, in turn, are oxidized by cellular respiration.

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6
Q

What are the two fuel molecules

A

gasoline and glucose

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7
Q

What is a Oxidation-Reduction (Redox)
Reaction?

A

Chemical reactions in which electrons are transferred from one atom or molecule to another
1. Loss of Electrons = Oxidation
2. Gain of Electrons = Reduction

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8
Q

Explain oxidation

A
  • The partial or full loss of electrons from a substance
  • The substance from which the electrons are lost (the e- donor) is oxidized
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9
Q

Explain reduction

A
  • The partial or full gain of electrons to a substance
  • The substance that gains the electrons (the e- acceptor) is reduced
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10
Q

what is a redox reaction

A

Redox reactions are coupled reactions: The oxidation reaction and the reduction reaction occur simultaneously

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11
Q

cellular respiration is ….

A

controlled combustion

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12
Q

what is NAD+

A

NAD+ is the oxidized form of an electron carrier. Two electrons and a proton are added to produce the
reduced form, NADH

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13
Q

equation for cellular respiration

A

Glucose+ Oxygen = Carbon dioxide + Water + energy

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14
Q

steps of cellular respiration

A
  1. Glycolysis (cytosol)
  2. Pyruvate oxidation and the citric acid cycle (mitochondria)
  3. Oxidative phosphorylation
    (mitochondria)
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15
Q

The parts of a mitochondria

A
  • Most reactions of cellular respiration take place in
    mitochondria.
    1. inner mitochondrial membrane: electron transfer; ATP synthesis by ATP synthases
    2. Matrix: pyruvate oxidation and the citric cycle
    3. intermembrane compartment: is between inner and outer membrane
    4. outer mitochondrial membrane
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16
Q

Reactions of glycolysis

A
  • Glycolysis is a universal and ancient metabolic process
  • Glycolysis occurs in cytosol of all cells, and involves a series of soluble enzymes
  • First ATP consuming reaction
  • Second ATP consuming reaction
  • Cleavage of 6 carbon sugar to two 3-carbon molecules - Pyruvate (2 molecules)
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17
Q

Summarize glycolysis

A
  • Glycolysis does not require O2
  • Series of 10 chemical reactions, each catalyzed by a different enzyme, and that can be grouped into an ”energy investment” phase, and an “energy payoff” phase”
  • Converts glucose (6 carbons) into two molecules of pyruvate (3 carbons each)
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18
Q

what is the substrate level phosphorylation?

A
  • Substrate-level phosphorylation
    * Enzyme-catalyzed reaction
    * Transfers phosphate group from substrate to ADP - - A phosphate group is transferred from a high-energy donor directly to ADP, forming ATP
  • Substrate-level phosphorylation produces only a small amount of the ATP generated in cellular respiration
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19
Q

Most of the ATP produced during
cellular respiration is generated
during ……

A

oxidative phosphorylation

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20
Q

Where does pyruvate oxidation take place?

A

mitochondria

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21
Q

What type of group is pyruvate oxidized to?

A

acetyl group

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22
Q

_____________ is produced when pyruvate is oxidized with an acetyl

A

CO2

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23
Q

what happens during pyruvate oxidation?

A
  • Electrons removed are accepted by (or used to reduce) NAD+ to form NADH
  • Acetyl group linked to Co-Enzyme A (CoA)
  • Pyruvate oxidation converts pyruvate to acetyl-CoA. This process is aerobic.
  • Pyruvate oxidation occurs within the mitochondrial matrix
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24
Q

What is the product of each pyruvate molecule?

A
  • 1 acetyl group
  • 1 NADH
  • 1 CO2
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25
Q

what is an acetyl group attached to?

A

coenzyme A

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26
Q

Pyruvate oxidation links _______________________

A

glycolysis and the citric acid cycle

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27
Q

At the End of Pyruvate Oxidation

A

1 pyruvate molecule yields:
* 1 acetyl-CoA
* 1 CO2
* 1 NADH

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28
Q

During glycolysis, glucose produced

A

2 pyruvate molecules

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29
Q

What takes place in the citric acid?

A
  • Acetyl groups completely oxidized to CO2
  • Electrons removed in a series of oxidations
    • Accepted by NAD+ or FAD (which get reduced to NADH and FADH2)
  • Some ATP made by substrate-level phosphorylation
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30
Q

Each acetyl group that enters the cycle and gets oxidized produces what?

A
  • 2 CO2
  • 1 ATP
  • 3 NADH
  • 1 FADH
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31
Q

other names of the citric acid are ….

A

tricarboxylic acid cycle or Krebs cycle

32
Q

summarize the citric acid

A

The eight reactions of the citric acid cycle (tricarboxylic
acid cycle or Krebs cycle) oxidize acetyl groups
completely to CO2, generate 3 NADH and 1 FADH2, and
synthesize 1 ATP by substrate-level phosphorylation

33
Q

At the end of the cycle two molecules of acetyl - CoA yield_______________

A
  • 2 ATP
  • 6 NADH
  • 2 FADH2
34
Q

What is the electron transfer system ?

A

The electron transport chain converts the potential energy in NADH and FADH2 into a proton-motive
force, which is used to drive ATP synthesis

35
Q

Explain the stages of electron transfer

A

Stages 1 - 2:
Glucose is oxidized through a series of chemical reactions, releasing energy in the form of ATP and reduced electron carriers.
Stage 3:
Electron carriers donate electrons to the electron transport chain, leading to the synthesis of ATP.
- oxidative phosphorylation, the reduced electron carriers generated in stages 1-2 donate electrons to the
electron transport chain and a large amount of ATP is
produced

36
Q

Electrons pass from NADH ____________

A

FADH2 to O2

37
Q

Electron Transport Chain includes:

A
  • 4 protein complexes
  • 2 smaller shuttle carriers

*Electrons move spontaneously along the
electron transport chain

38
Q

what are 3 major protein complexes of the Respiratory Electron Transport Chain?

A

I, III, and IV
* Pump H+ from Matrix to IMS
* Contain prosthetic groups that
cycle between reduced and
oxidized states

39
Q

What happens to the electrons in the respiratory electron transport chain ?

A
  • the electrons are depleted of energy
  • they are Delivered to oxygen as final
    electron acceptor
40
Q

The complete oxidation of glucose
during stages 1-2 of cellular respiration
results in the production of _____________

A

the reduced electron carriers, NADH and FADH2

41
Q

The electron transport chain consists of four complexes (I to IV) in the____________________

A

inner mitochondrial membrane

42
Q

the steps of the electron transport:

A
  1. Electrons donated by NADH and FADH2 are transported along the series of ETC complexes
  2. Complexes I and II harvest electrons from NADH and FADH2
  3. Coenzyme Q (or Ubiquinone) is reduced to CoQH2 and transfers electrons from complexes I and II to complex III.
  4. Cytochrome c moves to complex IV where oxygen is reduced to form water
  5. Within each protein complex of the ETC, electrons are passed from electron donors to electron acceptors
  6. When oxygen accepts electrons at the end of the ETC, it is reduced to form water
43
Q

Explain Proton transport and ATP synthesis:

A
  • The transport of electrons in complexes I, III, and IV is coupled with the transport of protons across the inner membrane, from the mitochondrial matrix to the intermembrane space
  • ATP synthase uses the electrochemical proton gradient to drive the
    synthesis of ATP
  • Due to the proton pumping of the ETC, protons have a high concentration in the intermembrane space and a low concentration in the mitochondrial matrix. The proton concentration gradient contains high potential energy
44
Q

ATP synthase catalyzes ATP synthesis
using energy from _______________

A

H+ gradient across the membrane

45
Q

What is chemiosmosis?

A

ATP synthase catalyzes ATP synthesis using energy from the H+ gradient across the membrane

46
Q

What is ATP synthase?

A
  • Molecular motor
  • Embedded in inner mitochondrial membrane with electron transfer system
47
Q

What does ATP synthase do?

A

ATP synthase converts the energy of the proton gradient into the energy of ATP

48
Q

Electron transport and chemiosmotic generation of ATP are separate and distinct processes. TRUE OR FALSE

A

TRUE

49
Q

Where can energies be extracted from?

A

Besides simple sugars, energy can be extracted from fats, proteins, and carbohydrates that enter the respiratory chain at different points

50
Q

Explain respiratory intermediates.

A
  • Intermediates of glycolysis and the citric acid cycle are routinely diverted and used as starting substrates to synthesize amino acids, fats, and the pyrimidine and purine bases needed for nucleic acid synthesis
51
Q

What do respiratory intermediates supply?

A

carbon backbones for hormones, growth factors, prosthetic
groups, and cofactors essential to cell function

52
Q

What is meant by carbon backbones?

A

carbon skeleton; carbon atoms make up the backbone of many important molecules in your body, including proteins, DNA, RNA, sugars, and fats (macromolecules)

53
Q

In anaerobic respiration, what is not the terminal electron acceptor?

A

Oxygen

54
Q

What results in fermentation?

A

low oxygen levels

55
Q

What is fermentation?

A

pathway of respiration that oxidizes fuel molecules in the absence of oxygen

56
Q

what are two types of fermentations that are anaerobic?

A
  • lactate fermentation
  • alcohol fermentation
57
Q

What happens when oxygen is present in aerobic respiration ?

A

pyruvate is converted to acetyl-CoA, which then enters the citric acid cycle,
followed by the ETC

58
Q

In what type of respiration is oxygen not present? and what happens?

A

in anaerobic respiration oxygen is not present. When oxygen is not
present, pyruvate is metabolized along a number of different
pathways

59
Q

What is produced in fermentation and where is it used?

A

NAD+ produced in fermentation is used in glycolysis

60
Q

The breakdown of glucose by fermentation yields what?

A

only 2 molecules of ATP, since lactic acid and ethanol are not fully oxidized and still contain a large amount of chemical energy in their bonds.

61
Q

what does lactic fermentation occur in?

A

animals and bacteria

62
Q

What happens in lactic fermentation?

A

Electrons from NADH are transferred to pyruvate to produce lactic acid and NAD+

63
Q

What does alcoholic fermentation occur in?

A

plants and fungi

64
Q

What happens in alcoholic fermentation?

A

Electrons from NADH are transferred to pyruvate to produce ethanol and NAD+

65
Q

What do anaerobic respiration lack?

A

mitochondria, many bacteria and archaea have respiratory electron transport chains, located on internal membrane systems

66
Q

what are some common electron acceptors?

A

Sulfate, nitrate, and ferric ion

67
Q

what are Strict anaerobes?

A

Cannot grow in presence of oxygen

68
Q

What do Strict aerobes require?

A

Require oxygen

69
Q

what are Facultative aerobes?

A

they can grow in presence of oxygen and can grow using fermentative pathways

70
Q

Reactive oxygen species (ROS)…..

A
  • Include superoxide and hydrogen peroxide
  • Strong oxidizing agents
71
Q

what does reduction of oxygen to water result in?

A

results in the formation of the intermediate ROS, which are potentially harmful

72
Q

what are some defence mechanisms against reactive oxygen species?

A
  • Antioxidant defence system
    • Enzymes
      * Superoxide dismutase and catalase
  • Non enzymes
    - Antioxidants: vitamin C and vitamin E
73
Q

what is phosphofructokinase?

A

PFK is an allosteric enzyme

74
Q

In eukaryotes ( plants), what is oxygen?

A

it is a terminal electron acceptor

75
Q

doneee

A

wooooo

BIOLOGY 110 (3 decks)

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