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Cell biology pt 2 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

metabolism

A

all the chemical reactions that occur within the human body

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2
Q

what do metabolic pathways involve?

A

the building up and breaking down of molecules

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3
Q

what do anabolic pathways require?

A

energy

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4
Q

what are anabolic pathways?

A

biosynthetic (building up) processes

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5
Q

catabolic pathways release…?

A

energy

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6
Q

what do catabolic pathways involve?

A

the breakdowns of molecules e.g the breakdown of glucose in glycolysis

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7
Q

are the steps of metabolic pathways reversible?

A

metabolic pathways have both reversible and in-reversible steps

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8
Q

what is activation energy?

A

the energy needed to break chemical bonds in the reactant chemicals is called activation energy

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9
Q

how does activation energy work?

A

the bonds break when the molecules of the reactant have been absorbed enough energy to make them unstable (this is called the transition state) and the reaction can occur

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10
Q

what is the rate of chemical reaction indicated by?

A

the quantity of chemical change that occurs per unit time

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11
Q

what is an enzyme?

A

an enzyme is a biological catalyst which lowers the activation energy required by the reactants to form the transition state and speeds up the rate of reaction. it also is made of proteins

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12
Q

what factors affect enzyme activation?

A

temperature
pH
substrate concentration
enzyme concentration

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13
Q

what affect do inhibitors have on the rate of enzyme controlled reactions?

A

they may slow them down or bring them to a halt

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14
Q

what is an active site?

A

an enzyme contains an active site which is a specific shape (due to the structure and bonding of the amino acids in the polypeptide chain) it is also where a substrate molecule binds and undergoes a chemical reaction

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15
Q

why do enzyme’s only act on one substrate?

A

an enzyme only acts on one substrate because the enzyme is specific to its substrate and the molecules of the substrate are complementary to the enzymes active site for which they show on affinity (chemical attraction)

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16
Q

what happens to the products after enzyme reaction?

A

the products have low affinity for the active site and are released leaving the enzymes free to repeat this process with new molecules of the substrates

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17
Q

is the active site of an enzyme a rigid structure?

A

the active site of an enzyme is not a rigid structure it is instead flexible and dynamic

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18
Q

what happens when a molecule of a substrate enters the active site of an enzyme?

A

the shape of the enzyme molecule and the active site change slightly making the active site fit very closely round the substrate molecule, this is called induced fit

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19
Q

what happens if there is more than one substrate involved in a reaction?

A

the shape of the site determines the orientation if the reactions. this ensures that they are held together in such a way that the reaction can take place

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20
Q

what are metabolic pathways controlled by?

A

the presence and absence of an enzyme

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21
Q

what is a competitive inhibitor?

A

it is a substance which has a similar molecular structure to the substrate and competes with the substrate for the active site on the enzyme, it blocks the active site preventing the substrate from binding so the rate of reaction decreases

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22
Q

how are competitive inhibitors reversed?

A

by increasing the substrate concentration

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23
Q

qualities of a non-competitive inhibitor?

A
  • does not have similar molecular structure
  • does not combine directly with the active site
  • attaches to a non-active (allosteric) site and changes the shape of the enzyme molecule
    • indirectly altering the shape of the active site so the substrate cannot bind and rate of reaction decreases
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24
Q

when does feedback inhibition happen?

A

it occurs when the end product in the metabolic pathway reaches a critical concentration

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25
Q

what does feedback inhibition prevent?

A

a waste of resources by preventing further synthesis of the end product

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26
Q

what happens when the concentration of the end product decreases in feedback inhibition?

A

less of the earlier enzyme is affected and the pathway resumes this pathway is kept finely tuned control called negative feedback

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27
Q

what is cellular respiration?

A

cellular respiration is a series of metabolic pathways that releases energy from food and generates a high energy compound called adenosine triphosphate (ATP)

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28
Q

what is ATP composed of?

A

ATP is composed of adenosine and three inorganic phosphate (Pi) groups

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29
Q

when and how is energy released from ATP?

A

energy is released from ATP when the bond attached to the terminal phosphate is broken by enzyme action

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30
Q

what forms when ATP releases energy?

A

ATP releases energy and breaks down to form Adenosine diphosphate (ADP) and inorganic phosphate (Pi)

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31
Q

what is the reaction known as phosphorylation?

A

ADP + Pi –> ATP

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32
Q

why is ATP important?

A

it acts as the link between catabolic energy releasing reactions (e.g. respiration) and anabolic energy-consuming reactions (e.g protein synthesis)

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33
Q

what is there a rapid turnover of in a cell?

A

ATP

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34
Q

do humans have a vast store of ATP?

A

ATP is continuously used up so it is being continuously produced so there is no need for humans to have a vast store of ATP

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35
Q

what is phosphorylation?

A

an enzyme controlled process by which a phosphate group is added to a molecule

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36
Q

when does phosphorylation happen?

A

it occurs when the phosphate and energy are transferred from the ATP to the molecules of a reactant in the metabolic pathway, making them more reactive

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37
Q

steps of cellular respiration

A

step one - glycolysis

step two - citric acid cycle

step three - electron transport chain

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38
Q

where does glycolysis occur?

A

in the cytoplasm of a cell

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39
Q

where does the citric acid cycle happen?

A

in the central matrix of the mitochondria

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40
Q

where does the electron transport chain happen?

A

occurs in the inner membrane of mitochondria

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41
Q

what is glycolysis?

A

the breakdown of glucose to pyruvate under the control of enzymes in the cytoplasm

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42
Q

steps of glycolysis

A
  1. energy investment phase
    - 2 ATP are required for the phosphorylation of glucose
    and intermediates
  2. energy payoff phase
    • ATP are produced during the breakdown of the final
      intermediate into pyruvate
  3. net gain of 2 ATP per molecule of glucose
  4. dehydrogenase enzymes remove
    hydrogen ions and electrons and pass them to the coenzyme NAD forming NADH
43
Q

is oxygen required for glycosis?

A

no

44
Q

steps of the formation of citrate

CAC

A

*this stage only happens in aerobic conditions (aerobic respiration)

stage 1 - pyruvate is broken down to an acetyl group that combines with coenzyme A which then carries acetyl to the citric acid cycle

stage 2. Acetyl Coenzyme A + `Oxaloacetate —> citrate
acetyl with coenzyme A forms with Oxaloacetate to become citrate.

stage 3 - CAC involves many enzyme controlled steps which results in ;

  • release of CO2
  • generation of a small amount of ATP
  • Dehydrogenase enzymes remove H+ ions and electrons and pass them to NAD to make NADH
  • regeneration of oxaloacetate
45
Q

Electron transport chain

A
  1. the hydrogen ions and electrons from NADH are passed to the electron transport chain
  2. the electron transport chains is a series of carrier proteins attached to the inner membrane of the mitochondria which allows ATP synthesis
  3. electrons are passed along the electron transport chain releasing energy
  4. this energy is used to pump hydrogen ions across the inner mitochondrial membrane
  5. these ions then pass back through the membrane protein ATP synthase synthesising ATP
  6. oxygen combines with hydrogen ions and electrons to form water
46
Q

dehydrogenase enzymes function

A

they remove hydrogen ions and electrons and pass them to the coenzyme NAD forming NADH

47
Q

net gain

A

overall gain of ATP during gycolysis

48
Q

matrix

A

central cavity of a mitochondrion in which the CAC occurs

49
Q

NAD

A

coenzyme which carries hydrogen and electrons from glycolysis and the CAC to the electron transport chain

50
Q

why does fermentation occur?

A

because the cells lack oxygen

51
Q

what stage of respiration happens in fermentation

A

glycolysis

52
Q

how does glycolysis in fermentation work

A

glucose —> pyruvate —-> lactate

53
Q

what does the conversion during glycolysis in fermentation involve?

A

involves the transfer of hydrogen from NADH to produce lactate

54
Q

what happens during vigorous exercise?

A

the muscle cells do not receive sufficient oxygen to support the electron transport chain. under these conditions pyruvate is converted into lactate

55
Q

where does lactate gather and what does this cause?

A

lactate gathers in muscle cells and causes fatigue and an oxygen debt builds up

56
Q

what does it mean if NAD is regenerated?

A

that ATP production through glycolysis can continue

57
Q

how does the oxygen debt in fermentation get repaid?

A

when exercise comes to a halt and energy mode from Aerobic respiration is used to convert lactate back to pyruvic acid and glucose in the liver

58
Q

myoglobin

A

is an oxygen strong protein present in muscle cells and has a stronger affinity to oxygen than haemoglobin

59
Q

what are body movements brought about by?

A

the action of skeletal muscle fibres

60
Q

what do skeletal muscles contain?

A

a genetically determined mixture of slow-twitch fibres.

61
Q

why is there always a fixed quantity of ATP?

A

because of how ATP is manufactured the same time it is used up therefore there isnt any need for a living organism to possess a vast store of ATP.

62
Q

what are skeletal muscles connected to the skeleton by?

A

skeletal muscles are connected to the skeleton by tendons and contracts to cause movement during exercise.

63
Q

what are the two types of skeletal muscles?

A

slow twitch and fast twitch

64
Q

what are qualities of skeletal muscles?

A

they contract relatively slowly but can sustain contractions for longer. they are used for endurance activities such as long distance running.

65
Q

what do slow twitch muscles rely on?

A

slow twitch muscles rely on aerobic respiration to generate ATP and have many mitochondria, a good supply with a dense capillary network and a high concentration.of the oxygen strong protein called myoglobin.

66
Q

why do slow twitch muscle fibres take up more oxygen and sustain activity for longer?

A

by using stored fats as a main energy source

67
Q

qualities of fast twitch muscle fibres?

A

they contract relatively quickly over short periods and are useful for activities such as sprinting. they contract more quickly and powerfully but fatigue very quickly, sustaining only short bursts of activity before muscle contraction becomes painful.

68
Q

why does muscle contraction become painful after short bursts of activity?

A

due to lactate build up

69
Q

what is the storage fuel for fast twitch fibres?

A

the major storage fuel of fast twitch muscle fibres of glycogen

70
Q

How do fast twitch muscle fibres generate ATP?

A

through glycolysis only

71
Q

What do fast twitch muscle fibres have fewer of than slow twitch muscle fibres?

A

mitochondria, blood vessels and myoglobin

72
Q

what is the substance which builds up in muscle cells as they become fatigued?

A

lactate

73
Q

when does oxygen debt build up?

A

builds up during fermentation in muscle cells

74
Q

what is lactate produced by?

A

fermentation of pyruvate in mammalian muscle cells

75
Q

what is affinity?

A

attraction between the activate site of an enzyme and its substrate

76
Q

what is the definition of glycolysis?

A

the breakdown of pyruvate in the cytoplasm

77
Q

what is ATP?

A

ATP is a substrate that is involved in the transfer of chemical energy in cells.

78
Q

what is ATP built up from?

A

ATP is regenerated from ADP and inorganic phosphate using the energy released from cellular respiration.

79
Q

what is respiration?

A

respiration is a catabolic pathway which converts the chemical energy stored in glucose into chemical energy stored in ATP

80
Q

what is ATP used for?

A

ATP is used to transfer the chemical energy from cellular respiration to anabolic synthesis pathways and other cellular processes where energy is required. For example, DNA replication.

81
Q

how is the energy in ATP released?

A

it is released when ATP is broken down into ADP

82
Q

where does aerobic respiration start and end?

A

aerobic respiration starts in the cytoplasm and ends in the mitochondria

83
Q

what is glucose converted into?

A

pyruvate (2 ATP are made)

84
Q

what is pyruvate broken down into?

A

carbon dioxide and water using oxygen

85
Q

what is ATP required in?

A

any cell process that requires energy. the majority of anabolic reactions needs ATP

86
Q

what happens when ATP releases energy?

A

makes ADP and Pi

87
Q

phosphorylation

A

the addition of phosphate to the molecule

88
Q

what happens when ADP is phosphorylated?

A

ATP is formed

89
Q

what is dephosphorylation?

A

removal of phosphate group from a molecule

90
Q

what is the role of ATP during the energy investment phase?

A

to phosphorylate glucose and its intermediates

91
Q

what do you gain from investing 2 ATP?

A

you get 4 back meaning that you gain 2 ATP

92
Q

where does CAC happen?

A

the matrix of the mitochondria

93
Q

what is CAC controlled by?

A

enzymes

94
Q

what is CoA?

A

coenzyme A

95
Q

what happens to acetyl when it enters the CAC?

A

it combines with oxaloacetate to form citrate

96
Q

during CAC why is CO2 lost?

A

because of loss of carbons is lost in the form of CO2

97
Q

where does the electron transport chain happen?

A

inner membrane of the mitochondria

98
Q

what is the final acceptor of hydrogen?

A

oxygen

99
Q

how much ATP is made from CAC?

A

a small amount

100
Q

how much ATP is made from ETC?

A

a large amount

101
Q

what are the raw materials used in CAC?

A

pyruvate/acetyl

102
Q

what are the raw materials used in glycolysis

A

glucose

103
Q

what are the raw materials used in ETC?

A

hydrogen ions, electrons and oxygen.

human biology (6 decks)

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