Lectures 4 & 5 Flashcards
(253 cards)
1
Q
what are the two fundamental tasks all cells need to accomplish?
A
synthesize new parts
harvest energy to power reactions
2
Q
what new parts do cells need to synthesize?
A
cell walls, membranes, ribosomes, nucleic acids
3
Q
what is the sum of chemical reactions in a cell?
A
metabolism
4
Q
what are some implications of microbial metabolism?
A
biofuels
food and beverage production
important in laboratory
important models for study
unique pathways are potential drug targets
5
Q
what are the two parts of metabolism?
A
catabolism
anabolism (or biosynthesis)
6
Q
what is catabolism?
A
process that degrade compounds to release energy
7
Q
what do cells make in catabolism?
A
ATP
8
Q
what does ATP do in anabolism?
A
drive reactions
9
Q
what do cells do during anabolism?
A
assemble units of macromolecules
10
Q
what is energy?
A
the capacity to do work
11
Q
what are the two types of energy?
A
potential and kinetic
12
Q
describe potential energy
A
stored energy (chemical bonds, rock on hill, water behind dam)
13
Q
describe kinetic energy
A
energy of motion (moving water)
14
Q
which organisms harvest energy in sunlight?
A
photosynthetic organisms
15
Q
photosynthetic organisms covert kinetic energy of _______ to potential energy of ____________
A
photons
chemical bonds
16
Q
what do chemoorganotrophs obtain energy from?
A
organic compounds
17
Q
photosynthetic organisms power synthesis of organic compounds from ______________
A
CO2
18
Q
what do chemoorganotrophs depend on?
A
activities of photosynthetic organisms or chemolithoautotrophs
19
Q
when is energy released?
A
when a chemical bond is broken
20
Q
_________ ________ is energy available to do work
A
free energy
21
Q
what is an exergonic reaction?
A
reactants have more free energy than products
22
Q
what is an endergonic reaction?
A
products have more free energy than reactants
23
Q
energy is released in an (exergonic/endergonic) reaction
A
exergonic
24
Q
an (exergonic/endergonic) reaction requires input of energy
A
endergonic
25
how do the number of steps in a reaction change the free energy?
change in free energy for a given reaction is the same regardless of number of steps involved
26
what powers endergonic reactions?
energy released from exergonic reactiosn
27
what is a metabolic pathway?
series of chemical reactions that converts starting compound to an end product
28
what are the shapes of metabolic pathways?
they may be linear, branched, cylindrical
29
what would happen without enzymes?
energy-yielding reactions would occur too slowly
30
what is the role of enzymes?
they are biological catalysts
- speed up conversion of substrate into product by lowering activation energy
31
specific ________ required for each step of a metabolic pathway
enzyme
32
what is the energy currency of a cell?
adenosine triphosphate (ATP)
33
what is ATP composed of?
ribose
adenine
three phosphate groups
34
how do cells produce ATP?
they use energy to add a phosphate to adenosine diphosphate (ADP)
35
removing a phosphate from ATP results in....
energy being released
ADP
36
streptococci acquires all their energy from....
substrate-level phosphorylation
37
what is substrate level phosphorylation?
energy generated in exergonic reactions
38
what is oxidative phosphorylation?
energy generated by proton motive force
39
what are the two processes chemoorganotrophs use to make ATP?
substrate level phosphorylation
oxidative phosphorylation
40
what are the two processes chemoorganotrophs use to generate ATP?
substrate level phosphorylation
oxidative phosphorylation
41
what process do photosynthentic organisms use to generate ATP?
photophosphorylation
42
what is photophosphorylation?
sunlight used to create proton motive force
43
an energy source has a _________ affinity for electrons
low
44
a _________________ has a high affinity for electrons
terminal electron acceptor
45
energy is released when electrons move from ___________ to _______________
an energy source to a terminal electron acceptor
46
when the difference in _______________ is greater, more energy is released
electronegativity
47
what is electronegativity?
affinity for electrons
48
what do prokaryotes use as energy sources?
organic and inorganic compounds
49
what do prokaryotes use as terminal electron acceptors?
O2 and other molecules
50
a substance that loses electrons is ____________
oxidized
51
a substance that gains electrons is _________
reduced
52
what is transferred in a redox reaction?
electron-proton pair, or a hydrogen atom
53
what is dehydrogenation?
oxidation
54
what is hydrogenation?
reduction
55
the reducing agent undergoes.....
oxidation
56
the oxidizing agent undergoes....
reduction
57
when cells initially remove electrons from an energy source, where do they go?
electron carrier
58
electron carriers can also be considered....
hydrogen carriers
59
what are some examples of electron carriers?
NAD+/NADH
NADP+/NADPH
FAD/FADH2
60
reduced electron carriers represent.....
reducing power
61
where can reduced electron carriers easily transfer electrons to?
chemicals with higher affinity for electrons
62
what effect do reduced electron carriers have on their recipient molecule?
reduced electron carriers raise energy level of recipient molecule
63
what effect do reduced electron carriers ultimately have?
ultimately drives synthesis of ATP or biosynthesis
64
what 3 things are generated by central metabolic pathways?
oxidizing glucose molecules to generate
1.ATP
2. reducing power
3. precursor metabolizes
65
when are the electrons carried by NADPH used?
in biosynthesis
66
what processes transfer the electrons carried by NADH and FADH2 to the terminal electron receptor?
cellular respiration or fermentation
67
what are the two key processes of catabolism?
oxidizing glucose molecules and transferring the electrons carried by NADH and FADH2
68
what do central metabolic pathways do?
oxidize glucose to CO2
69
describe why central metabolic pathways are termed "amphibolic"
the process is catabolic, but precursor metabolites and reducing power can be diverted for use in biosynthesis
70
what happens during glycolysis?
glucose (6C) is split into two pyruvate molecules
71
what does glycolysis generate?
small amount of ATP, reducing power, and 6 precursor metabolites
72
what is the primary role of the pentose phosphate pathway?
production of precursor metabolites and NADPH
73
the tricarboxylic acid (TCA) cycle is also called?
the citric acid cycle or the Krebs cycle
74
what occurs right before the TCA cycle?
a single reaction called the transition step
75
what happens during the transition step?
pyruvate is oxidized and this releases CO2
76
what does the tricarboxylic acid (TCA) cycle generate?
lot of reducing power, precursor metabolites, and ATP
77
where are electrons transferred with cellular respiration?
from glucose
to electron transport chain (ETC)
to terminal electron acceptor
78
what does the electron transport chain generate?
proton motive force
79
how does cellular respiration make ATP?
through oxidative phosphorylation
80
during aerobic respiration, what is the terminal electron acceptor?
O2
81
what is considered a modified version of the TCA cycle?
Anaerobic respiration
82
what does fermentation do?
recycles electron carriers in a cell that cannot respire so that it can continue to make ATP
83
how does fermentation receive H from NADH?
it uses a pyruvate or a derivative as a terminal electron acceptor
84
what does fermentation regenerate?
NAD+ so that glycolysis can continue
85
what does glycolysis provide?
a small amount of ATP
86
what are the three pathways of the central metabolic pathways?
glycolysis, pentose phosphate pathway, and tricarboxylic acid (TCA) cycle
87
which processes use an electron transport chain?
a) aerobic respiration
b) fermentation
c) anaerobic respiration
a) aerobic respiration
c) anaerobic respiration
88
what is the terminal electron receptor in fermentation?
an organic molecule (pyruvate or a derivative)
89
how much ATP is generated by substrate-level phosphorylation in aerobic respiration ?
2 in glycolysis
2 in TCA cycle
______________
4 total
90
how much ATP is generated by oxidative phosphorylation in aerobic respiration?
34
91
how much total ATP is generated by aerobic respiration?
38
92
how much ATP is generated by anaerobic respiration?
number varies, but less than aerobic respiration and more than fermentation
93
how much ATP is generated by substrate-level phosphorylation in fermentation?
2 in glycolysis
94
how much ATP is generated by oxidative phosphorylation in fermentation?
0
95
how much total ATP is generated by fermentation?
2
96
what are enzymes?
biological catalysts; they increase the rate of a reaction
97
what binds substrates on an enzyme?
active site (weakly)
98
what does the enzyme-substrate complex do?
destabilizes existing bond or allows new ones to form
99
what are enzymes used for?
to break large molecules into smaller ones or to build large molecules from its subunites
100
what prevents reversibility of enzyme-catalyzed reactions?
free energy of some reactions
101
what are some examples of cofactors?
magnesium, zinc, copper, other trace elements
102
what do cofactors do?
assist different enzymes
103
what are coenzymes?
organic cofactors
104
what are some examples of coenzymes?
FAD
NAD+
NADP+
105
what are coenzymes derived from?
vitamins
106
what vitamin is coenzyme A derived from?
panthothenic acid (vitamin B5)
107
what vitamin is flavin adenine dinucleotide (FAD) derived from?
riboflavin (vitamin B2)
108
what influences enzyme activity?
temperature, pH, salt concentration
109
what are optimal conditions for enzymes?
low salt and neutral pH
110
what vitamin is nicotinamide adenine dinucleotide (NAD+) derived from?
niacin (vitamin B3)
111
what vitamin is pyridoxal phosphate derived from?
pyridoxine (vitamin B6)
112
what vitamin is tetrahydrofolate derived from?
folate/folic acid (vitamin B9)
113
what vitamin is thiamin pyrophosphate derived from?
thiamine (vitamine B1)
114
what substance is transferred by coenzyme A?
acyl groups
115
what substance is transferred by flavin adenine dinucleotide (FAD)?
hydrogen atoms (2 electrons and 1 proton)
116
what substance is transferred by nicotinamide adenine dinucleotide (NAD+)?
hydride ions (2 electrons 1 proton)
117
what substance is transferred by pyridoxal phosphate?
amino groups
118
what substance is transferred by tetrahydrofolate?
1-carbon molecules
119
what substance is transferred by thiamin pyrophosphate?
aldehydes
120
what does coenzyme A do?
carries the acetyl group that enters the TCA cycle
121
what does flavin adenine dinucleotide (FAD) do?
carrier of reducing power
122
what does nicotinamide adenine dinucleotide (NAD+) do?
carrier of reducing power
123
what does pyridoxal phosphate do?
transfers amino groups in amino acid synthesis
124
what does tetrahydrofolate do?
it is a 1-carbon donor in nucleotide synthesis
125
what does thiamin pyrophosphate do?
helps remove CO2 from pyruvate in transition step
126
____________ increase doubles speed of enzymatic reaction up to maximum.
10 degrees Celsius
127
when do proteins denature?
higher temperatures
128
what is allosteric regulation?
enzyme activity controlled by regulatory molecules binding to allosteric site
129
what happens when a regulatory molecule binds to the allosteric site?
it distorts the enzyme shape, prevents or enhances binding of substrate to active site
130
what is usually the end product of a metabolic pathway?
regulatory molecule
131
what does a regulatory molecule allow?
feedback inhibition
132
what occurs during competitive inhibition?
inhibitor binds to active site
133
the chemical structor of ____________ is usually similar to substrate
inhibitor
134
what does enzyme inhibition depend on?
it is concentration dependent; the inhibitor blocks substrate
135
provide an example of enzyme inhibition
sulfa drugs that block folate synthesis
136
what occurs during non-competitive inhibition?
inhibitor binds to a site other than the active site, for example allosteric inhibitors
137
what is an example of a reversible non-competitive inhibitor?
an allosteric inhibitor
regulatory molecules
138
what is an example of a non-reversible non-competitive inhibitor?
mercury oxidizes the s-h groups of amino acid, cysteine, which converts to cystine. cystine cannot form the disulfide bond (S-S). the enzyme changes shape, and is therefore nonfunctional.
139
what do central metabolic pathways generate?
ATP
reducing power: NADH, FADH2, NADPH
precursor metabolites
140
different glucose molecules can be completely oxidized to _______, generating maximum ATP
CO2
141
different glucose molecules can be siphoned off as ____________ for use in biosynthesis
precursor metabolites
142
what does glycolysis generate?
2 ATP by substrate-level phosphorylation
2 NADH + 2H+
six different precursor metabolites
143
what does the pentose phosphate cycle generate?
NADPH + H+
two different precursor metabolite
144
whaat does the transition step generate?
2 NADH + 2 H+
one precursor metabolite
145
why is the transition step repeated twice?
to oxidize two molecules of pyruvate to acetyl-CoA
146
what does the TCA cycle generate?
2 CO2
2 ATP by substrate level phosphorylation (may involve conversion of GTP)
6 NADH + 6 H+
2 FADH2
two different precursor metabolites
147
why is the TCA cycle repeated twice?
to incorporate two acetyl groups
148
glycolysis converts 1 glucose to ________________
2 pyruvate molecules
149
during the investment phase of glycolysis, 2 _______ are consumed, ________ phosphate groups are added, and glucose split to 2 _________________.
ATP
two
3-carbon molecules
150
during the pay-off phase of glycolysis, __________________ are converted to pyruvate
3-carbon molecules
151
the pay-off phase of glycolysis generates....
4 ATP
2 NADH + H+
152
the pentose phosphate pathway breaks down _______________
glucose
153
the pentose phosphate pathway is important in __________________ for precursor metabolites
biosynthesis
154
what precursor metabolites are produced in the pentose phosphate pathway?
ribose 5-phosphate
erythrose 4-phosphate
155
the pentose phosphate pathway produces reducing power in the form of?
NADPH
156
what product of the pentose phosphate pathway enters glycolysis?
glyceraldehyde-3-phosphate
157
during the transition step, CO2 is removed from ___________.
pyruvate
158
during the transition step, electrons transfer to NAD+, reducing it to _____________________.
NADH + H+
159
during the transition step, 2-carbon acetyl group are joined to coenzyme A form ________________
acetyl CoA
160
the transition step links previous pathways to _____________-
TCA cycle
161
what does the TCA cycle complete?
the oxidation of glucose
162
oxidative phosphorylation uses ____________, ________________, and __________________ to synthesize ATP.
reducing power (NADH, FADH2)
transition step
TCA cycle
163
during cellular respiration, electron transport chain uses ___________________ to generate proton motive force
reducing power of NADH, FADH2
164
during cellular respiration, __________________ uses energy of proton motive force to generate ATP
ATP synthase
165
what are the two processes of oxidative phosphorylation?
- generating a proton motive force
- synthesizing ATP
166
who proposed the association between the electron transport chain and ATP synthesis (and when)?
Peter Mitchell (in 1961)
167
when/ what did Peter Mitchell receive a Nobel prize for?
chemiosmotic theory in 1978
168
the electron transport chain is a series of _____________________
membrane-embedded electron carriers
169
what does the electron transport chain accept electrons from?
NADH, FADH2
170
when is energy released during the electron transport chain?
as electrons are passed from one carrier to the next
171
during the electron transport chain, energy pumps _____________ across membrane
protons
172
where does the electron transport chain occur in prokaryotes?
cytoplasmic membrane
173
where does the electron transport chain occur in eukaryotes?
inner mitochondrial membrane
174
the electron transport chain creates....
an electrochemical gradient called proton motive force
175
electron transport chain carriers are grouped into large protein complexes that function as ____________________
proton pumps
176
describe quinones
lipid-soluble, can move freely in membrane
177
what is the function of quinones?
can transfer electrons between complexes
178
describe cytochromes
contain heme, molecule with iron at center
several types
179
what is the function of cytochromes?
can be used to distinguish bacteria
180
describe flavoproteins, and provide an example
proteins to which a flavin is attached
FAD
181
what are FAD and other flavins synthesized from?
riboflavin
182
what is accepted by proton pump carriers?
some only accept hydrogen atoms (proton-electron pairs)
some only accept electrons
183
___________ in membrane shuttles protons to outside of membrane
spatial arrangement
184
when hydrogen carrier accepts electron from electron carrier it __________________________
picks up proton from inside cell (or mitochondrial matrix)
185
when hydrogen carrier passes electrons to electron carrier, ________________________________________
protons released to outside of cell (or inter membrane space of mitochondria)
186
____________ is movement of protons across membrane
net effect
187
what establishes a concentration gradient?
protons moving across the membrane
188
the concentration gradient could not be established if.....
energy were not released during electron transfer
189
electron transport chain of prokaryotes is tremendously __________________
varied
190
single prokaryotic species can have _________________ in their electron transport chains
several alternate carriers
191
aerobic respiration in E. coli can use 2 different ____________-
NADH dehydrogenases
192
what is equivalent to complex I of mitochondria in prokaryotes?
the NADH dehydrogenase proton pump
193
what is equivalent to complex II of mitochondria?
succinate dehydrogenase
194
aerobic respiration in e.coli lacks equivalents of....
complex III or cytochrome c
195
in aerobic respiration of E. coli, quinones shuttle electrons directly to ____________________________.
functional equivalent of complex IV.
196
does aerobic or anaerobic respiration of e.coli harvest more energy?
aerobic respiration
197
anaerobic respiration of e.coli has _________________ of terminal electron acceptors that aerobic.
lower electron affinities
198
anaerobic respiration in E. coli can synthesize _________________________ that uses nitrate as terminal electron acceptor
terminal oxidoreductase
199
what does terminal oxidoreductase produce?
nitrite
200
with terminal oxidoreductase, E. coli converts to......
less toxic ammonia
201
a group of obligate anaerobes called the sulfate reducers use sulfate as ___________________________
terminal electron acceptor
202
what do sulfate-reducers produce as and end product?
hydrogen sulfide
203
other bacteria can reduce nitrate even further, into.....
nitrous oxide (N2O) or nitrogen gas (N2)
204
what is the ATP yield of aerobic respiration in prokaryotes: substrate-level phosphorylation?
2 ATP (from glycolysis; net gain)
2 ATP (from the TCA cycle)
__________________________________
4 ATP (total)
205
what is the total ATP gain from aerobic respiration in prokaryotes?
38
206
when is fermentation used?
when respiration is not an option
207
what is E.coli characterized as?
facultative anaerobe
208
which ATP-generating pathways does e.coli use?
aerobic respiration, anaerobic respiration, and fermentation (ALL of them)
209
streptococcus pneumoniae lacks ____________________
electron transport chain
210
what is the only option for streptococcus pneumoniae to produce energy?
fermentation
211
ATP generating reactions are only those of ________________
glycolysis
212
additional steps of fermentation oxidize NADH as a means to regenerate ________
NAD+
212
additional steps of fermentation oxidize NADH as a means to regenerate ________
NAD+
213
how are fermentation end products helpful?
helpful in identification, commercially useful
214
name some examples of fermentation end products
lactic acid
ethanol
butyric acid
propionic acid
mixed acid
2.3-butanediol
215
how do microbes use other compounds (besides glucose) as energy sources?
1) secrete enzymes
2) transport subunits into cell
3) degrade further to appropriate precursor metabolites
216
what are polysaccharides and disaccharides broken down by?
amylases, cellulases, disacharrides
217
while glucose enters glycolysis directly, other monosacharrides are converted to ___________________________
precursor metabolites
218
what are lipides broken down by?
lipases
219
what is glycerol converted into to enter glycolysis?
dihydroxyacetone phosphate
220
what are fatty acids degraded by to enter the TCA cycle?
B-oxidation
221
what are proteins broken down by?
proteases
222
what happens to the amino group of proteins to be catabolized?
they are deaminated
223
what are the carbon skeletons of proteins converted into?
precursor metabolites
224
prokaryotes are unique in their ability to use ____________________ as energy sources
reduced inorganic compounds
225
what is produced by anaerobic respiration when inorganic molecules (like sulfate and nitrate) serve as terminal electron acceptors?
hydrogen sulfide and ammonia
226
hydrogen sulfide and ammonia are used as energy sources for....
sulfur bacteria and nitrifying bacteria
227
what is the source of energy for hydrogen bacteria?
H2
228
what is the source of energy for sulfur bacteria?
H2S (hydrogen sulfide)
229
what is the source of energy for iron bacteria?
reduced iron (Fe2+)
230
what is the source of energy for nitrifying bacteria?
NH3 (ammonia) or HNO2
231
common genera of hydrogen bacteria
Hydrogenomonas
232
common genera of sulfur bacteria
Acidithiobacillus, Thiobacillus, Beggiatoa, Thiothrix
233
common genera of iron bacteria
Sphaerotilus, Gallionella
234
common genera of nitrifying bacteria
Nitrosomonas, Nitrobacter
235
this organism can also use simple organic compounds for energy
hydrogen bacteria
236
some members of this group can live at a pH of less than 1
sulfur bacteria
237
iron oxide present in the sheaths of this bacteria
iron bacteria
238
this bacteria is important in the nitrogen cycle
nitrifying bacteria
239
fastidious bacteria require many _________________
growth factors
240
prokaryotes synthesize subunits using precursor molecules formed in the ________________________
central metabolic pathways
241
if enzymes are lacking during the biosynthesis processes, then....
end product must be supplied by an external source
242
what does lipid synthesis require?
fatty acids and glycerol
243
what are fatty acids?
2-carbon units added to acetyl group from acetyl-CoA
usually 14, 16, or 18 carbon atoms
244
what is glycerol synthesized from?
dihydroxyacetone phosphate generated during glycolysis
245
what is commonly used via glutamate synthesis?
ammonium
246
____________ can generate other amino acids
transamination
247
during amino acid synthesis, the synthesis of glutamate provides mechanism for incorporation of ____________ into organic material
nitrogen
248
during nucleotide synthesis, DNA and RNA are initially synthesized as:
ribonucleotides
249
atoms added to ribose 5-phosphate to form ring
purines
250
ring made, then attached to ribose 5-phosphate
pyrimidines
251
Amino acids are __________ of enzymes that directs branch to its own synthesis
feedback inhibitors
252
what is the result of the aromatic amino acid branching pathway?
the cell does not make amino acids that are already present
