Lecture 4 and 5 Microbial Metabolism Flashcards
(177 cards)
1
Q
What is metabolism?
A
Sum of chemical reactions in a cell
2
Q
What are the two parts of metabolism?
A
Catabolism, anabolism/biosynthesis
3
Q
What is catabolism
A
Processes that degrade compounds to release energy
- cells capture to make ATP
4
Q
What is anabolism?
A
Assemble subunits of macromolecules
uses ATP to drive reactions
5
Q
What is energy?
A
Capacity to do work
6
Q
What is potential energy?
(chemical bonds, rock on a hill, water behind a dam)
A
Stored energy
7
Q
What is kinetic energy?
A
Energy of motion
8
Q
Photosynthetic organisms harvest energy in sunlight
- power synthesis of organic compounds from ______
- converts kinetic energy of _____ to potential energy of ____
A
CO2
photons, chemical bonds
9
Q
_______ obtain energy from organic compounds
A
Chemoorganotrophs
10
Q
Chemoorganotrophs depend on activities of ______
A
Chemolithoautotrophs
11
Q
What is free energy?
A
Energy available to do work
- released when a chemical bond is broken
12
Q
What is exergonic reactions
A
When reactants have more free energy than products
13
Q
Is energy released in exergonic reactions?
A
yes
14
Q
Endergonic reactions
A
Products have more free energy than reactants
15
Q
In an endergonic reaction, the reaction requires what?
A
An input of energy
16
Q
Change in free energy is the ______ regardless of number of steps involved
A
Same
17
Q
Cells use multiple steps when _________ compounds
A
degrading
18
Q
Energy released from _____ reactions power ______ reactions
A
Exergonic, endergonic
19
Q
Metabolic pathway
A
Series of reactions that converts starting compounds to a product
20
Q
Metabolic pathways may be….
A
Linear, branched, cyclical
21
Q
What is the role of biological catalysts
A
Speeds up conversion of substrate into a product by LOWERING activation energy
22
Q
What is ATP long form
A
Adenosine triphosphate
23
Q
What is ATP
A
Energy currency of a cell
24
Q
What is ATP composed of?
A
Ribose, adenine, three phosphate groups
25
Cells use energy to produce ATP by adding Pi to what?
Adenosine disphosphate (ADP)
26
How is energy released in a metabolic pathway?
removing Pi from ATP to yield ADP
27
What is substrate level phosphorylation?
energy generated in exergonic reactions
28
What process do some bacteria, especially steptococci, get their energy from?
Substrate-level phosphorylation
29
What is oxidative phosphorylation
Energy generated by proton motive force
30
What type of organisms use substrate level phosphorylation and oxidative phosphorylation
Chemoogranotrophs
31
What is photophosphorylation?
Sunlight used to create proton motive force
32
What type of organisms use photophosphorylation?
Photosynthetic organisms
33
What is an electron that has a low affinity for electrons called
energy source
34
What is a molecule that has a high affinity for electrons called
Terminal electron acceptor
35
How is energy release in terms of affinity?
electrons move from a molecule that has a low affinity to a molecule that has a high affinity
AKA energy source to terminal electron acceptors
36
More energy is released when the difference in ______ is greater
Electronegativity
37
Electronegativity is the same as ______
Affinity for electrons
38
Prokaryotes use diverse energy sources and ______
terminal electron acceptors
39
In prokaryotes, what compounds are used as energy soruce?
inorganic compounds
40
In prokaryotes, what compounds are used as terminal electron acceptors?
O2 and other moecuels
41
Electrons are removed through what process?
Redox reactions
42
Substances that loses electrons is ______
Oxidized
43
Substances that gains electrons is ______
Reduced
44
______ is transferred in a redox reaction
Electron proton pair or hydrogen atoms
45
What is dehydrogenation?
oxidation
46
What is hydrogenation?
Reduction
47
Electrons are initially transferred to what?
electron carriers
48
What are common electron carriers?
NAD/NADH, NADP/NADPH, FAD/FADH2
49
Reduced electron carriers represent what power?
Reducing
50
What is the role of reduced electron carriers?
Easily transfer electrons to chemicals with HIGHER affinity for electrons/electronegativity
Raise energy level of recipient molecules
drive synthesis of ATP or biosynthesis
51
What occurs in central metabolic pathways?
Oxidized glucose molecules generate ATP, reducing power (NADH, FADH2 and NADPH) and precursor metabolites
52
Transferring the electrons carried by NADH and FADH2 to the terminal electron acceptor which is done by either ________ or ________
cellular respiration or fermentation
53
What do central metabolic pathways do?
Oxidize glucose to CO2
54
The catabolic, but precursor metabolites and reducing power can be also used in biosynthesis
- this means it is called ________ because of dual role
Amphibolic
55
What does glycolysis do?
Splits glucose to two pyruvate molecules
56
What does glycolysis generate?
ATP, reducing power, precursors
57
What is the role of pentose phosphate patway?
production precursor metabolites, NADH
58
What does tricarboxylic acid (TCA) cycle do?
Oxidizes pyruvate, release CO2
59
What does TCA cycle generate?
Reducing power, precursor metabolites, ATP
60
What process transfers electrons from glucose to ETC to terminal electron acceptor?
Cellular respiration
61
What does electron transport chain generate?
proton motive forces
62
In aerobic respiration, what is the terminal electron acceptor?
O2
63
In anaerobic respiration, what is the terminal electron acceptor?
Molecule other than O2
64
Anaerobic respiration is a modified version of what?
TCA cycles
65
What does fermentation do?
recycles electron carriers in a cell that cannot respire so that it can continue to make ATP
66
What is the terminal electron acceptor in fermentation process?
Pyruvate or derivate
- receives H from NADH
67
Fermentation regenerates NAD so that
glycolysis can continue
68
What does glycolysis provide
small amount of ATP
69
What are enzymes and what do they do?
biological catalysts, increase the rate of a reaction
70
enzymes are highly specific ________
enzymes are not changed by a reaction so a single molecules can be used ________
substrates
again and again
71
________ on surface of enzymes binds substrates weakly
active site
72
What does the enzyme fitting in an active sit result in?
enzyme substrate complex that destabilizes existing bond or allows new ones to form
73
What does the enzyme substrate complex do to the activation energy?
lowers in
74
enzyme- catalyzed reactions are ________
reversible
- but free energy of some reactions prevents reversibility
75
What assists different enzymes?
cofactors
76
What are common cofactors?
magnesium, zinc, copper
77
What are coenzymes
Organic cofactors
78
What are examples of coenzymes
electron carriers FAD, NAD, NADP
-derived from enzymes
79
What are environmental factors that influence enzyme activity
Temp, pH, salt concentration
80
What happens to proteins at high temperatures?
They denature
81
What is the optimum condition for most enzymes?
Low salt, neutral pH
82
What does 10 degrees celsius increase do to the speed of enzyme reaction?
Doubles speed
83
What is allosteric regulation?
enzyme activity controlled by regulatory molecules binding to allosteric site
84
What does allosteric regulation do the the enzyme shape and binding of substrate to active site?
Distorts enzyme shape
Prevents or enhances binding of substrate
85
What is the regulatory molecule in a metabolic pathway?
The end product that allows feedback inhibition
86
What is competitive inhibition?
When the inhibitor binds to the active site
87
The chemical structure of inhibitor is similar to what?
Substrate
88
What happens in non-competitive inhibition?
inhibitor binds to a site other than the active site
89
In which non competitive inhibitor is the action reversible?
Allosteric inhibitors
Some are not reversible
90
Mercery oxidizes the S-H groups of amino acid cysteine and converts to ______
Cystine
- cystine cannot form important S-S bond, so enzyme changes shape and becomes nonfunctional
91
What do the central metabolic pathways generate?
ATP, reducing power NADH, NADPH, precursor metabolites
92
Glucose molecules can be completely oxidized to CO2 which does what?
Generates maximum ATP
93
Glucose molecules can bo siphoned off as ________ for use in biosynthesis
How much ATP does it produce?
Precursor metabolite
It won't produce maximum ATP
94
What does glycolysis generate?
2 ATP by substrate level phosphorylation
2 NADH
2 H
6 different precursor metabolites
95
What does the pentose Phosphate Cycle generate?
NADPH
H
2 different precursor metabolites
96
What does the transition step repeated twice do?
oxidizes two molecules of pyruvate to acetyl -CoA
97
What does the transition step generate?
2 NADH
2H
1 precursor metabolite
98
What does the TCA cycle, repeated twice do?
incorporates two acetyl groups
99
What does the TCA cycle generate?
2 ATP by substrate level phosphorylation
6 NADH
6 H
2 FADH2
2 different precursor metabolites
100
Glycolysis converts what to what?
1 glucose to 2 pyruvates
net yield: 2 ATP, NADH
101
What happens in the investment phase of glycolysis?
2 ATP consumed
2 phosphate groups added
Glucose split to two 3-carbon molecules
102
What happens in the pay-off phase of glycolysis?
3-carbon molecules converted to pyruvate
generates 4 ATP, 2 NAD
103
What does the pentose phosphate pathway do?
Breaks down glucose?
104
What is pentose phosphate pathway important for?
biosynthesis for precursor metabolites
105
What are the precursor metabolites in pentose phosphate pathway?
Ribose 5-phosphate
erythrose 4-phosphate
106
What does pentose phosphate pathway generate variable amounts of?
NADPH
107
What is the product of pentose phosphate pathway
Glyceraldehyde-3-phosphate can enter glycolysis
108
What happens in the transition step ?
CO2 is removed from pyruvate
Electrons transfer to NAD ruding it to NADH and H
109
What happens with the 2-carbon acetyl group in the transition step?
joins coenzyme A to form Acetyl- CoA
- links previous pathways to TCA cycles
110
What does TCA cycle stand for?
Tricarboxylic Acid cycle
111
What does the TCA cycle do?
Completes oxidation of glucose
112
What does TCA cycle produce?
2 CO2
2 ATP
6 NADH
2FADH2
Precursor metabolites
113
What does oxidative phosphorylation do?
Uses reducing power (NADH, FADH2) generated by glycolysis, transition step, TCA cycle to syntehsize ATP
114
What are the two processes in oxidative phosphorylation?
1. Electron transport chain uses reducing power of NADh, FADH2 to generate proton motive force
2. ATP synthase uses energy of proton motive force to generate ATP
115
Who developed the oxidative phosphorylation process?
Peter Mitchell in 1961
116
Peter Mitchell received a Nobel Prize in 1978 for what?
Chemiosmotic theory
117
What is the electron transport chain?
series of membrane-embedded electrons carrier
118
What does the ETC accept electrons from?
NADH, FADH2
119
In ETC, energy released as ______ are passed from one carrier to the next
electrons
120
in ETC, energy pumps _______ across membrane
Protons
121
What is the membrane that protons are pumped across in prokaryotes?
Cytoplasmic membrane
122
What is the membrane that protons are pumped across in prokaryotes?
Inner mitochondrial membrane
123
ETC creates an electrochemical gradient called
Proton motive force
124
What are quinones
what do they do
Lipid-soluble; move freely in membrane
can transfer electrons between complexes
125
What do cytochromes contain?
Heme, molecule with iron atom
several types, can be used to distinguish bacteria
126
What are flavorpteins
Proteins to which a flavin is attached
FAD, other flavins synthesized from RIBOFLAVIN
127
Mechanism of proton pumps
- some carriers accept only _______
- some carriers accept only _______
Hydrogen atoms (proton-electron pairds)
electrons
128
In proton pumps, _______ arrangement in membrane shuttles protons outside of membrane
Spatial
129
In a proton pump, when hydrogen carriers ACCEPTS electron from electron carrier, it does what?
picks up proton from inside cell
130
In a proton pump, when hydrogen carrier PASSES electrons to electron carrier, it does whata?
protons are released to outside of cell
131
What is the net effect in a proton pump?
movement of protons across membrane
132
What is the ETC like of prokaryotes/
Variation, single species can have several alternate carriers
133
in aerobic respiration in E. coli can use 2 different _______
NADH dehydrogenases
134
In aerobic respiration of E. coli, _______ is equivalent to complex I of mitochondria
Proton pump
135
In aerobic respiration of E. coli, _______ is equivalent to complex II of mitochondria
Succinate dehydrogenase
136
In aerobic respiration of E.Coli, ther is a lack of equivalents for In aerobic respiration of E. coli, _______ is equivalent to complex I of mitochondria
Complex III or cytochrome c
137
In aerobic respiration in E.Coli, _______ shuttle electrons directly to functional equivalent of complex IV
Quinones
138
which harvests less energy, anaerobic respiration or aerobic respiration in E.Coli?
Anaerobic
139
Anaerobic respiration in E. Coli can synthesize terminal _______ that uses NITRATE as terminal electron acceptor
oxidoreductase
140
What does terminal oxidoreductase produce?
nitrite
141
E.coli converts nitrite to what?
less toxic ammonia
142
Selfate reducers use what as terminal electron acceptors?
SO24, sulfate
143
What do sulfate reducers produce as end product?
Hydrogen sulfide
144
what is the ATP yield of aerobic respiration in prokaryotes for substrate level phosphorylation?
2 ATP (from glycolysis; net gain)
2 ATP from TCA cycle
4 ATP TOTAL
145
What is the ATP yield of aerobic respiration in prokaryotes for oxidative phosphorylation?
6 ATP from reducing power gained in glycolysis
6 ATP from reducing power gained in transition step
22 ATP from reducing power gained in TCA cycle
34 ATP total
146
What is the total ATP gain in aerobic respiration for prokaryotes?
38 ATP
147
When is fermentation used?
When respiration is not an option/ when the cell doesn't have an ETC
148
What type of of bacteria is E. Coli?
Facultative anaerobe
149
What does streptoccus pneumoniae lack?
ETC
150
What must strep. pneumoniae use for respiration?
fermentation
151
ATP generating reactions are only those of _______
Glycolysis
152
microbes other than glucose can secrete _______, transport subunits into a cell, degrade into _______
Enzymes, precursor metabolites
153
_______ and _______ are broken down by amylases, cellulases, disaccharides
Polysaccharides and disaccharides
154
for polysaccharides and disaccharides, _______ enters glycolysis directly, other _______ convert to precursor metabolites
glucose, monosaccharides
155
for lipids broken down my lipases, _______ converts to _______ and enters glycolysis
Glycerol, dihydroxyacetone phosphate
156
for lipids, fatty acids are degraded by _______ to enter _______ phase
B-oxidation, TCA cycle
157
Proteins are broken down by
Proteases
158
For proteins, amino group is _______
_______ convert to precursor metabolites
Deaminated
carbon skeletons
159
What are chemolithotrophs?
Prokaryotes who can use reduced inorganic compounds as energy sources
160
Hydrogen sulfide and ammonia are produced by _______ respiration when _______ molecules serve as terminal electron acceptors
Anaerobic respiration, inorganic
161
Hydrogen sulfide and ammonia are used as energy sources for _______ and _______
Sulfur bacteria and nitrifying bacteria
162
hydrogen bacteria can also use _______ compounds for energy
simple organic
163
Sulfur bacteria can live at a pH of _______
less than 1
164
iron bacteria have _______ in their sheaths
Iron oxide
165
Nitrifying bacteria are important in the _______ cycle
Nitrogen
166
prokaryotes similar in biosynthesis processes synthesize subunits using precursor metabolites formed in _______ pathways
central metabolic pathways
167
If enzymes are lacking, end product must be supplies
- _______ bacteria require many growth factors
Fastidious
168
Lipid synthesis requires _______ and _______
Fatty acids and glycerol
169
What are fatty acids made of?
2 carbon units added to acetyl group from acetyl-CoA
- usually 14, 16, 18 carbons
170
What is glycerol synthesized from?
Dihydroxyacetone phosphate generated during glycolysis
171
Synthesis of _______ provides mechanism for incorporation of nitrogen into organic material
Glutamate
172
what is commonly used via glutamate synthesis?
Ammonium
173
_______ can generate other amino acids in amino acid synthesis
Transamination
174
Aromatic amino acids: branching pathway
- precursors form _______ compound that enters branching pathway
- amino acids are _______ inhibitors of enzymes that directs branch to its own synthesis
- Amino acids also inhibit formation of _______
- Result is _______
7-carbon
feedback
original 7-carbon
cell does not make amino acids that are already present
175
in nucleotide synthesis, DNA, RNA are initially synthesized as _______
Ribonucleotides
176
What are purines?
Atoms added to ribose 5-phosphate to form ring
177
What are pyrimidines?
Ring made than attached to ribose 5-phosphate
