gen bio 1 exam 3 Flashcards

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1
Q

cellular metabolism

A

The chemical reactions that occur in cells, including those
that use and release energy

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2
Q

metabolic pathways

A

ordered series of chemical reactions that build or break
down a molecule

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3
Q

ways cells respond to the environment:

A

*Building and breaking down macromolecules
* Transporting proteins across cell membranes
* Packaging materials into vesicles,
* Dividing, mutating, dying, etc.

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4
Q

catabolism reaction

A

starts from a larger molecule and breaks down to a smaller one and releases energy

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5
Q

anabolism reaction

A

starts from a smaller molecule and combines with energy to create a larger molecule

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6
Q

1st law of thermodynamics

A

Energy is conserved. Energy cannot be created nor destroyed, but only transferred and transformed.

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7
Q

kinetic energy

A

energy in motion
Ex: thermal energy, electricity, electromagnetic radiation (e.g. light/photons), sound waves

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8
Q

potential energy

A

stored energy
Ex. gravity or chemical bonds

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9
Q

what happens to energy when a chemical bond is broken

A

may be converted into light, heat, new chemical bonds
By breaking a bond, potential energy can be converted to kinetic energy such as light and
thermal energy (heat)

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10
Q

total energy in a molecule is measured in…

A

Enthalpy (H)

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11
Q

ΔH =

A

potential energy of product – potential energy of reactant

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12
Q

A chemical reaction that has reactants of high potential energy and low kinetic energy can result in products with…

A

low potential energy and high kinetic energy. This produces a –ΔH

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13
Q

exothermic reactions have a…

A

–ΔH; usually produces heat

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14
Q

A chemical reaction that has reactants of low potential energy and high kinetic energy can result in products with…

A

high potential energy and low kinetic energy. This produces a +ΔH

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15
Q

endothermic reactions have a…

A

+ΔH

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16
Q

high entropy means..

A

high disorder

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17
Q

Entropy, S =

A

amount of disorder

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18
Q

ΔS =

A

Entropy of product – Entropy of reactant

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19
Q

high entropy reactants and low entropy products result in a…

A

–ΔS

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20
Q

Gibbs free energy describes…

A

determines whether a chemical reaction is spontaneous or non-spontaneous and whether energy is stored or released

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21
Q

ΔG =

A

ΔH - TΔS

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22
Q

the symbols in the gibbs free energy equation:

A

ΔH = Potential energy of product – Potential energy of reactant
ΔS = Entropy of product – Entropy of reactant
T = Temperature
Conversion: T in Kelvin = Celsius +273

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23
Q

more energy is unavailable to do work when a reaction occurs at higher temperature because….

A

an increase in temperature increases entropy

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24
Q

a spontaneous reaction (exergonic), has a..

A

-ΔG and releases energy

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25
Q

a non-spontaneous reaction (endergonic), has a…

A

+ΔG, requires an input of energy to proceed; stores energy

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26
Q

a +ΔH means +ΔG and vice versa

A

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27
Q

Chemical energy can drive non-spontaneous
reactions via:

A
  1. Harnessing energy by breaking
    (cleavage) of chemical bonds (ATP to
    ADP or AMP)
  2. Electron transfer (via redox reactions)
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28
Q

ATP stores a large amount of potential energy
in the form of…

A

phosphanyhydride bonds

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29
Q

when ATP is hydrolyzed…

A

energy is released

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30
Q

ATP hydrolysis (breaking a phosphoanhydride
bond)…

A

releases free energy (-ΔG), an exergonic
reaction

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31
Q

Exergonic reactions can provide energy for
endergonic reactions like cellular
respiration

A

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32
Q

Redox reactions transfer energy via…

A

electrons

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33
Q

redox reaction

A

chemical reaction involving the loss or
gain of one of more electrons

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34
Q

oxidation

A

loss of electrons; when product has less electrons than reactant

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35
Q

reduction

A

gain of electrons; when product has more electrons than reactant

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36
Q

catalyst

A

a substance that increases the rate of a reaction
without being consumed

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37
Q

enzyme

A

a catalyst that speeds up the rate of a biochemical
reaction
* most are proteins

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38
Q

substrate

A

Substance the enzyme acts upon

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39
Q

When a substrate binds to the
active site of an enzyme, the
enzyme slightly changes its
shape to better accommodate
the substrate → creates a
more precise fit → facilitates
the chemical reaction

A

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40
Q

conformational change

A

a change in the shape of a molecule such as a protein

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41
Q

Enzymes lower the activation energies of chemical
reactions → Amount of enzymes and enzyme activity
determine which biochemical reactions will proceed

A

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42
Q

Enzyme levels and activity are tightly regulated in cells in order to…

A

maintain homeostasis and organismal health

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43
Q

3 mechanisms for enzyme regulation:

A
  1. molecular regulation
  2. Compartmentalization
  3. Feedback inhibition
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44
Q

Molecular regulation of enzymes

A

Mechanism that regulates enzyme activity through the action of inhibitors or activators

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45
Q

enzyme inhibitors

A

molecules or substances that reduce the activity of an
enzyme
- Leads to reduction in amount of products
- Substrates may accumulate

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46
Q

3 Mechanisms for enzyme inhibition:

A
  1. Competitive inhibition
  2. Non-competitive inhibition
  3. Allosteric inhibition
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47
Q

competitive inhibition

A

A molecule or substance competes with the substrate for binding to an active site (substrate unable to bind to enzyme)→ decreased enzyme activity
* A competitive inhibitor usually resembles the structure or shape of a substrate

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48
Q

non-competitive inhibition

A

An inhibitor binds to the enzyme in a location other than the active
site (allosteric site) → decreased enzyme activity

49
Q

allosteric site

A

a location in an enzyme other than the active site that allows for
regulation of enzyme activity

50
Q

non-competitive inhibitors prevent the substrate from binding to the active site via

A

a number of mechanisms including
1. conformational change in the active
site (allosteric inhibition)
2. crowding

51
Q

enzyme activators

A

molecules or substances that increase the activity of
an enzyme
- Leads to an increase in the amount of
products

52
Q

allosteric activators

A

bind to locations on an enzyme away from the active site →
conformational change → increased binding of substrate to active site

53
Q

Many enzymes require helpers such as … for optimal conformation and function (activity)

A

coenzymes and cofactors

54
Q

cofactors

A

inorganic ions

55
Q

coenzymes

A

organic molecules comprised of carbon and hydrogen

56
Q

Compartmentalization

A

regulates enzyme activity (certain biochemical reactions only occur within specific areas in the cell → more efficient biochemical reactions)

57
Q

feedback inhibition

A

Mechanism by which the reaction’s end product inhibits or controls the enzyme’s function that helped make it

58
Q

feedback inhibition prevents…

A

overproduction of product or depletion of a substrate

59
Q

cellular respiration

A

A pathway for the production of ATP involving the transfer of
electrons from compounds with high potential energy through
an electron transport chain involving electron carriers and
ultimately to a final electron acceptor

60
Q

Sites of cellular respiration in prokaryotes:

A

cytoplasm, inner cell membrane

61
Q

Sites of cellular respiration in eukaryotes:

A

cytoplasm, mitochondria

62
Q

aerobic respiration

A

cellular respiration pathway that requires oxygen

63
Q

anaerobic respiration

A

cellular respiration pathway that does not require oxygen

64
Q

Aerobic and anaerobic respiration both use glycolysis as the first major step to produce ATP

A

65
Q

Under what conditions cellular respiration will proceed to all 4 steps

A

aerobic conditions

66
Q

4 steps of cellular respiration

A
  1. glycolysis
  2. transition reaction
  3. Kreb’s cycle
  4. electron transport chain
67
Q

what does glycolysis do

A

break down glucose with ATP

68
Q

transition reaction

A

pyruvate converted to acetyl CoA releasing CO2

69
Q

where does the krebs cycle happen

A

the matrix

70
Q

what does the krebs cycle do

A

oxidize acetyl CoA to CO2. releases ATP and coenzymes (NADH, FADH2)

71
Q

where does the electron transport chain happen

A

inner membrane

72
Q

what does the electron transport chain do

A

uses high energy electrons from NADH and FADH2 to create a proton gradient that powers ATP synthesis

73
Q

photoautotroph

A

converts energy in light to build carbohydrates

74
Q

chemoautotroph

A

can use inorganic energy to produce carbohydrates and energy

75
Q

photosynthesis

A

use of light to manufacture carbohydrates

76
Q

photosynthesis chemical reaction

A

6CO2 + 6H2O -> C6H12O6 + 6O2

77
Q

2 components of photosynthesis

A
  1. light capturing reactions
  2. calvin cycle (dark reaction)
78
Q

light producing reactions

A

triggered by light, produces O2 from H2O; produces ATP and NADPH

79
Q

Calvin cycle (dark reaction)

A

uses products from light capturing reactions (ATP and NADH); produces sugars from CO2

80
Q

where does photosynthesis occur

A

chloroplast

81
Q

the thylakoid membrane contains …

A

pigments (e.g. chlorophyll)

82
Q

clorophyll

A

most abundant pigment in thylakoid membrane

83
Q

granum

A

stack of thylakoids

84
Q

stroma

A

fluid between thylakoid and inner membrane of chloroplast

85
Q

how does chlorophyll absorb light energy

A

excited electrons of oxygen atoms

86
Q

light

A

a type of electromagnetic radiation; behaves both as a particle (photon) and wave

87
Q

how is electromagnetic radiation measured

A

in wavelength

88
Q

violet has the shortest wavelength and the highest photon energy

A
89
Q

chlorophylls absorb…

A

violet to blue to red. transmits green

90
Q

carotenoids absorb…

A

blue and green. transmit yellow, orange, or red

91
Q

blue photons excite electrons to a higher energy state

A
92
Q

red photons excite electrons to a high energy state

A
93
Q

the 4 things that can happen when ana electron gets excited:

A
  1. fluorescence
  2. heat
  3. resonance energy transfer
  4. redox
94
Q

how do electrons fluoresce and/or give off heat

A

they drop back to low energy state

95
Q

how do electrons resonance energy transfer

A

energy in electron is transferred to a nearby pigment to the reaction center

96
Q

how do electrons undergo a redox reaction

A

electron is transferred to a new compound (electron acceptor) from the reaction center

97
Q

photosystem

A

functional unit of photosynthesis; located within the thylakoids; site where light dependent reactions take place

98
Q

components of a photosystem

A

antenna complex
reaction center

99
Q

antenna complex

A

chlorophyll molecules the harvest light and are organized in an array of proteins

100
Q

reaction center PSII (P680)

A

contains specialized chlorophyll pigments that can donate high energy electrons to an electron acceptor; located in the thylakoid membrane

101
Q

plastoquinone

A

electron carrier in photosystem II, carries electrons to cytostome complex and H+ to the thylakoid lumen

102
Q

cytochrome complex

A

bridge from photosystem II to photosystem I

103
Q

photosystem II overall process

A

feeds excited electrons to an electron transport chain (cytochrome complex) which is used to produces ATP via an electrochemical gradient

104
Q

events in PS II

A

energy in light is used to oxidize water to produce oxygen, hydrogen ions, and

105
Q

pheophytin

A

transfers electrons to PQ

106
Q

reaction center in PS I (P700)

A
107
Q

overall process in PS I

A

energy from light is used to excite the electrons and move them to an electron transport chain to reduce NAD+ to NADPH

108
Q

ferredoxin

A

electron acceptor in photosystem I

109
Q

why is the linkage of photosystems important

A
  • captures light more efficiently
  • protects from excessive ROS production when there is too much light
  • regulate the amount of electrons transported
  • PSI serves as a backup if PSII is damaged by UV light
110
Q

what light does PSII absorb better

A

blue

111
Q

what light does PSI absorb better

A

red

112
Q

3 phases of the calvin cycle

A
  1. fixation
  2. reduction
  3. regeneration
113
Q

carbon fixation

A

process by which inorganic carbon is converted to organic compounds by living organisms

114
Q

reduction phase in the calvin cycle

A
115
Q

regeneration phase in Calvin cycle

A

One phosphate in ATP is transferred to G3P -> regenerates RuBP -> cycle repeats

116
Q

how does CO2 enter plant cells

A

stoma

117
Q

C3 plants

A
  • use the calvin cycle
  • temperate climates
  • disadvantage in hot climates
  • stoma open
118
Q

C4 pathway

A
  • tropical environments
  • can fix CO2 when CO2 is low
119
Q

CAM pathway

A
  • close their stoma during the day and take upCO2 at night, when air temperature is lower
  • prevents excessive water loss