Chapters 8-10 Flashcards
(180 cards)
1
Q
what kind of organism converts energy to light
A
bioluminescence
2
Q
what is the totality of an organism’s chemical reactions
A
metabolism
3
Q
what kind of property is metabolism
A
emergent property, as it arises from interactions between molecules within the cell
4
Q
what does a metabolic pathway begin and end with
A
begins with a specific molecule and ends with a product
5
Q
describe a catabolic pathway and give an example
A
releases energy by breaking down complex molecules into simpler compounds, cellular respiration breaks down glucose in the presence of oxygen
6
Q
describe an anabolic pathway and give an example
A
consume energy to build complex molecules from simpler ones, the synthesis of proteins from amino acids
7
Q
this is the study of how organisms manage their energy resources
A
bioenergetics
8
Q
this is the capacity to cause change
A
energy
9
Q
this is energy associated with motion
A
kinetic energy
10
Q
this is energy associated with random movement of atoms or molecules
A
heat (thermal energy)
11
Q
this is energy that matter possesses because of its location or structure
A
potential energy
12
Q
this is energy available for release in a chemical reaction
A
chemical energy
13
Q
this is the study of energy transformations
A
thermodynamics
14
Q
this type of system is isolated from its surroundings
A
closed
15
Q
this type of system can transfer energy and matter from its surroundings
A
open
16
Q
what type of system are organisms
A
open
17
Q
what is the first law of thermodynamics
A
energy can be transformed, but it cannot be created or destroyed
18
Q
what happens during every energy transfer or transformation
A
some energy is unusable, and is often lost as heat
19
Q
what is the second law of thermodynamics
A
every energy transfer or transformation increases the entropy of the universe
20
Q
this type of process occurs without an input of energy
A
spontaneous
21
Q
for a process to occur without energy input, it must _________
A
increase the entropy of the universe
22
Q
how does energy enter and exit an ecosystem
A
enters as light exits as heat
23
Q
this is energy that can do work when temperature and pressure are uniform
A
free energy
24
Q
the symbol for the change in free energy
A
delta G
25
when delta G is negative, the process is ______
spontaneous
26
spontaneous processes are harnesses to _______
preform work
27
free energy is a measure of a system's _____
instability, its tendency to change to a more stable state
28
during a spontaneous change what increases and what decreases
free energy decreases and stability increases
29
this is the state of maximum stability
equilibrium
30
when can a spontaneous process preform work
when it is moving towards equilibrium
31
this type of reaction proceeds with a net release of free energy and is spontaneous
exergonic reactions
32
this type of reaction absorbs free energy from its surroundings and is nonspontaneous
endergonic
33
reactions in a closed system eventually reach _____
equilibrium
34
cells are a _____ system
open, constant flow of material
35
this is a defining feature of life regarding metabolism
metabolism never reaches equilibrium
36
what are the three main types of work a cell does
chemical, transport, and mechanical
37
which kind of work pushes endergonic reactions
chemical
38
this kind of work pumps substances across membrane against spontaneous process
transport
39
this kind of work beats cilia and triggers muscle contractions
mechanical
40
this is the use of an exergonic process to drive an endergonic one
energy coupling
41
describe the structure of ATP
a sugar (ribose), a nitrogenous base (adenine), and three phosphate groups
42
what process breaks the bonds between the phosphate groups of ATP's tails
hydrolysis
43
when is energy released from ATP
when the terminal phosphate bond is broken, and the chemical change to a state of lower free energy
44
what powers the three types of cellular work
the hydrolysis of ATP
45
how does ATP drive endergonic reactions
phosphorylation, the transferring of a phosphate group to some other molecule, such as a reactant, the recipient molecule is phosphorylated
46
how is ATP renewed
energy from catabolic reactions allows ADP to be phosphorylated
47
what is the initial energy needed to start a chemical reaction
free energy of activation or activation energy
48
what supplies activation energy
heat from the surroundings
49
how do enzymes catalyze a reaction
by lowering the activation energy barrier, can only quicken reactions that would eventually happen anyway
50
what is the reactant that an enzyme works on
substrate
51
what is it called when an enzyme is bonded to its substrate
enzyme-substrate complex
52
this is the region of the enzyme where the substrate binds
the active site
53
this brings chemical groups of the active site into positions that enhance their ability to catalyze the reaction
induced fit
54
how does the enzyme lower activation energy
orienting substances correctly, straining substrate bonds, providing a favorable microenvironment, covalently bonding to the substrate
55
what are nonprotein enzyme helpers
cofactors (metal, vitamins)
56
an organic cofactor
coenzyme
57
how do competitive inhibitors work
they bind to the active site of an enzyme, competing with the substrate
58
how do noncompetitive inhibitors work
they bind to another part of an enzyme, causing the enzyme to change shape and making the active site less effective
59
examples of inhibitors
toxins, poisons, pesticides, antibiotics
60
how does a cell regulate its metabolic pathways
switching on or off the genes that encode specific enzymes or by regulating the activity of enzymes
61
this is when a regulatory molecule binds to a protein at one site and affects the protein's function at another site
allosteric regulation
62
what are most allosterically regulated enzymes made from
polypeptide subunits
63
this is a form of allosteric regulation that can amplify enzyme activity by binding a substrate to one active site stabilizes favorable conformational changes at all other subunits
cooperativity
64
in this process, the end product of a metabolic pathway shuts down the pathway, preventing a cell from wasting chemical resources by synthesizing more product than is needed
feedback inhibition
65
what is another function of some enzymes
some act as structural components of membranes
66
is the breakdown of organic molecules exergonic or endergonic
exergonic
67
this is a partial degradation of sugars that occurs without O2
fermentation
68
this consumes organic molecules and O2 and yields ATP
fermentation
69
though cellular respiration includes aerobic and anaerobic respiration, it often only refers to _______
aerobic, as the cycle cannot be completed without O2
70
what is the equation for cellular respiration
C6H12O6 + 6O2 = 6CO2 + 6H2O + ENERGY
71
How is energy obtained to synthesize ATP
the transfer of electrons during chemical reactions releases the energy stored in organic molecules
72
what are chemical reactions that transfer electrons between reactants
oxidation-reduction reactions or redox reactions
73
this is when a substance loses an electron
oxidation
74
this is when a substance gains an electron
reduction
75
what is reduced in reduction
the amount of positive charge
76
what is the electron donor called
the reducing agent
77
what is the electron receptor called
the oxidizing agent
78
How do redox reactions work in covalent bonds
they alter the electron sharing, often include O or Fl
79
what is oxidized and reduced in cellular respiration
glucose is oxidized and O2 is reduced
80
during cellular respiration, electrons are first transferred to this coenzyme
NAD+
81
this is the reduced form of NAD+
NADH
82
this represents stored energy that is tapped to synthesize ATP
NADH
83
NADH passes electrons to the ________
electron transport chain
84
How does the electron transport chain pass electrons
in a series of steps, O2 pulls electrons down the chain in an energy yielding tumble that is used to regenerate ATP
85
what are the three stages of cellular respiration
glycolysis, citric acid cycle, and oxidative phophorylation
86
this step of cellular respiration breaks glucose into two molecules of pyruvate
glycolysis
87
this step of cellular respiration completes the breakdown of glucose
citric acid cycle
88
this step of cellular respiration accounts for most (90%) of the ATP synthesis
oxidative phosphorylation
89
this process produces smaller amounts of ATP during glycolysis and the citric acid cycle
substrate-level phosphorylation
90
where does glycolysis occur
in the cytoplasm
91
what are the two phases of glycolysis and what do they do
energy investment phase puts in a small amount of energy so that the energy pay off phase can make a lot of ATP as long as O2 is available
92
in the presence of O2, pyruvate enters the ______
mitochondria
93
pyruvate must be converted to this before the citric acid cycle can begin
acetyl CoA
94
where does the citric acid cycle take place
the mitochondrial matrix
95
what is generated during 1 cycle of the citric acid cycle
1 ATP, 3 NADH, 1 FADH2
96
how many steps in the citric acid cycle
8
97
how does the acetyl group of acetyl CoA join the cycle
by combining with oxaloacetate, forming citrate
98
what do steps 2-8 accomplish in the citric acid cycle
they decompose the citrate back to oxaloacetate, making the process a cycle
99
this is produced by the citric acid cycle and relays electrons extracted from food to the electron transport chain
NADH, FADH2
100
where is the electron transport chain
the cristae of the mitochondrion
101
most of the chain's components are ______
proteins that exist in multiprotein complexes (cytochromes each with an iron atom)
102
electrons drop in _________ as they go down the chain and are finally passed to _____ to form ______
free energy, O2, H2O
103
what is the function of the electron transport chain
to break the large free energy drop from food to O2 into smaller steps that release energy in managable amounts
104
what is caused by electron transfer in the chain
causes proteins to pump H+ from the mitochondrial matrix to the intermembrane space
105
what is permitted as a result of the created pH gradient
H+ move back across the membrane through channels in ATP synthase, ATP synthase uses this exergonic flow of H+ to drive the phosphorylation of ATP
106
this is the use of energy is a H+ gradient to drive cellular work
chemiosmosis
107
the H+ gradient is referred to as this and emphasizes the capacity to do work
proton-motive force
108
describe the sequence most energy flows in in cellular respiration
glucose, NADH, electron transport chain, proton-motive force, ATP
109
what percentage of energy from a glucose molecule is transferred to ATP
about 40%, 30-32 ATP
110
how is ATP produced in anaerobic conditions
glycolysis is coupled with fermentation or anaerobic respiration
111
how does anaerobic respiration work
uses the electron transport chain with an electron acceptor other than O2, such as sulfate
112
how does fermentation work
uses phosphorylation instead of an electron chain to generate ATP, consists of glycolysis plus reactions that regenerate NAD+, which can be reused by glycolysis
113
two common types of fermentation
alcahol fermentation and lactic acid fermentation
114
describe alcahol fermentation
pyruvate is converted to ethanol in two steps, with the first releasing CO2, done by yeast and used in baking
115
describe lactic acid fermentation
pyruvate is reduced to NADH, forming lactate as an end product, with no release of CO2. used to make cheese and yogurt when done by bacteria, used by muscle cells when O2 is low
116
what is the final electron acceptor in fermentation
an organic molecule (such as pyruvate or acetaldehyde)
117
how much ATP is produced in fermentation
2 ATP per glucose molecule
118
these can survive using either fermentation or cellular respiration
facultative anaerobes
118
these carry out fermentation or anaerobic respiration and cannot survive in the presence of O2
obligate anaerobes
119
what form must proteins take to be used in cellular respiration
amino acids
120
what form do fats take in cellular respiration
glycerol in glycolysis and fatty acids used to generate acetyl CoA in beta oxidation
121
how do fats and carbs compare in terms of ATP
an oxidized gram of fat produces more than twice as much ATP than an oxidized gram of carbohydrate
122
describe feedback inhibition
when ATP concentration drops, respiration speeds up, when ATP accumulates respiration slows down
123
these sustain themselves without eating anything derived from other organisms
autotrophs
124
these are organisms that use the energy of sunlight to make organic molecules from H2O and CO2
photoautotrophs
125
these obtain their organic material from other organisms
heterotrophs
126
CO2 enters the cells and O2 exits through the ______
microscopic pores called stomata
127
chloroplasts are found mainly in cells of the _______
mesophyll, the interior tissue of the leaf
128
how many chloroplasts does the typical meosphyll cell have
30-40
129
the chlorophyll is in membranes of ______
thylakoids (connected sacks in the chloroplasts)
130
thylakoids may be stacked in columns called ____
grana
131
a dense fluid within chloroplasts
stroma
132
the equation for photosynthesis
6CO2 + 12H2O + LIGHT = C6H12O6 + 6H2O
133
chloroplasts split H2O into ______ and ______, incorporating the ______ of hydrogen into ________
hydrogen and oxygen, electrons, sugar molecules
134
photosynthesis is a redox reaction in which _____ is oxidized and _____ is reduced
H2O, CO2
135
photosynthesis consists of what two parts
the light reactions and Calvin cycle
136
where do light reactions happen
in the thylakoids
137
what do light reactions do
split H2O, release O2, reduce NADP+ to NADPH, generate ATP from ADP by photophosphorylation
138
where does the calvin cycle happen
in the stroma
139
what does the calvin cycle do
forms sugar from CO2 using ATP and NADHP
140
this starts the calvin cycle, incorporating CO2 into organic molecules
carbon fixation
141
thylakoids transform light energy into ______
chemical energy of ATP and NADPH
142
what kind of energy is light
electromagnetic
143
the descrete particles that make up light
photons
144
this measures a pigment's ability to absorb various wavelengths
spectrophotometer
145
how does a spectrophotometer work
it sends light through pigments and measures the fraction of light transmitted at each wavelength
146
this is a graph plotting a pigment's light absorption versus wavelength
absorption spectrum
147
what colors work best for photosynthesis according to the absorption spectrum of chlorophyll a
violet-blue and red
148
this profiles the relative effectiveness of different wavelengths of radiation in driving a process
action spectrum
149
this is the main photosynthetic material
chlorophyll a
150
these accessory pigments absorb excessive light that would damage chlorophyll
carotenoids
151
what happens when a pigment absorbs light
it goes from a ground state to an excited state, which is unstable, when they fall back down to the ground level, photons are given off and an afterglow called fluorescence will give off light and heat
152
this consists of a reaction-center complex surrounded by light harvesting complexes
photosystem
153
these are pigment molecules bound to proteins that funnel the energy of photons to the reaction center
light-harvesting complexes
154
this is in the reaction center and accepts an excited electron from chlorophyll a
primary electron acceptor
155
describe the first step of light reactions
solar-powered transfer of an electron from a chlorophyll a molecules to the primary electron acceptor
156
describe photosystem II
functions first and is best at absorbing a wavelength of 680 nm
157
describe photosystem I
functions second, is best a absorbing a wavelength of 700 nm
158
describe linear electron flow
the primary pathway, involves both photosystems and produces ATP and NADPH using light energy
159
what are the steps to linear electric flow
a photon hits a pigments and its energy is passed among pigment molecules until it excited P680, an excited electron is then transferred to the primary electron acceptor, H2O is split by enzymes, and electrons are transferred to P680+, O2 is released as a byproduct, each electron falls down an electron transport chain from PS II to PS I, the energy released drives a proton gradient across the thylakoid membrane, diffusion of H+ drives ATP synthesis, transferred light energy excited P700 which loses an electron acceptor, P700+ accepts an electron passed down the chain, each electron falls down the chain to protein ferredoxin, electrons then transferred to NADP+, electrons of NADPH are available for the reaction of the calvin cycle
160
describe cyclic electron flow
uses only photosystem I and produces ATP, but not NADPH, generate surplus ATP, satisfying the higher demand in the calvin cycle
161
which type of electron flow is thought to have evolved first
cyclic
162
cyclic electron flow may protect cells from _______
light induced damage
163
describe proton movement in chloroplasts
protons are pumped into the thylakoid space and drive ATP synthesis as they diffuse back into the stroma
164
where are ATP and NADPH produced in photosynthesis
on the side facing the stroma, where the calvin cycle takes place
165
how are the calvin and citric acid cycles similar
they regenerate the starting material after molecules enter and leave the cell
166
how does the calvin cycle build sugars
from smaller molecules by using ATP and the reducing power of electrons carried by NADPH
167
how does carbon enter and leave the calvin cycle
enters as CO2 and leaves as a sugar names glyceraldehyde-3-phosphate (G3P)
168
what must occur for the net synthesis of 1 G3P
the calvin cycle must take place 3 times, fixing 3 molecules of CO2
169
what are the three phases of the calvin cycle
carbon fixation, reduction, regeneration of the CO2 acceptor (RuBP)
170
what do plants do when they are dehydrated?
close stomata, which conserves H2O, but limits photosynthesis, reduces access to CO2 and causes O2 to build up, begins to favor photorespiration
171
in most plants the initial fixation of CO2, via rubisco forms what
a three-carbon compound
172
in photorespiration rubisco adds _____instead of CO2 in the calvin cycle
O2
173
photorespiration consumes ____ and ____ and releases _____ without producing _____ or _____
O2, organic fuel, CO2, ATP, sugar
174
what are the benefits of photorespiration
limits damaging products of light reaction that build up in the absence of the calvin cycle
175
C4 plants minimize the cost of photorespiration by incorporating _____ into four-carbon compounds in __________, which requires the enzyme _____
CO2, mesophyll cells, PEP carboxylase
176
PEP carboxylase has a higher affinity for _____ than rubisco does; it can fix CO2 even when CO2 concentrations are _____
CO2, low
177
these four-carbon compounds are exported to _________, where they release _____ that is then used in the calvin cycle
bundle-sheath cells, CO2
178
some plants, including succulents use ________ to fix carbon
crassulacean acid metabolism (CAM)
179
how do CAM plants work
they open their stomata at night, incorporating CO2 into organic acids, the stomata close during the day, and CO2 is released from organic acids and used in the Calvin cycle
