Metabolism Chapter Flashcards
(166 cards)
1
Q
Metabolism
A
Chemical reactions that organisms use to break down substances to release energy and reactions that use the released energy to build new substances.
2
Q
Anabolic metabolism
A
Build new substances using energy and molecules
3
Q
Catabolic metabolism
A
Breaks down substances to release energy
4
Q
Other definition of metabolism
A
All of the anabolic and catabolic chemical reactions in a cell
5
Q
What must something contain to be considered organic?
A
Carbon and hydrogen
6
Q
What are the phases of cellular respiration?
A
Glycolysis
Krebs cycle
Electron transport chain
7
Q
What is ATP?
A
Adenosine Tri-phosphate
8
Q
How to catabolic reactions recharge ADP to ATP?
A
They use energy extracted from nutrients.
9
Q
What kind of phosphorylation are glycolysis and the Krebs cycle?
A
Substrate level phosphorylation
10
Q
What kind of phosphorylation is the electron transport chain?
A
Oxidative phosphorylation
11
Q
Amphibolic pathways
A
Used for both breaking down and building substances
12
Q
What are the functions of enzymes?
A
Catalyst for chemical reactions
Lower the energy of activation
13
Q
What are enzymes?
A
Protein catalysts that help chemical reactions occur under cellular conditions.
14
Q
What is a catalyst?
A
Something that is only needed in small amounts to make a reaction happen faster, or increases the reaction rate.
15
Q
Are catalysts consumed or permanently changed by a reaction?
A
No
16
Q
Do enzymes facilitate chemically impossible reaction?
A
No, they help chemical reactions occur under physiological conditions within a time frame conductive to life.
17
Q
Chemical reactions involve what?
A
The making or breaking of chemical bonds.
18
Q
What is collision theory?
A
Atoms and molecules are constantly moving and often hit one another. The energy transferred during these collisions can disturb the electron structures of atoms and molecules enough to make or break chemical bonds.
19
Q
Where to substrates bind on the enzyme?
A
Specifically to the active sites.
20
Q
What is the lock-and-key model
A
Stayed that an enzyme is like a lock that can only be opened by a specific key: the substrate. The keyhole is the active site.
21
Q
What is the enzyme’s active site?
A
The site where the substrate and enzyme interact to generate a chemical reaction.
22
Q
T or F: the lock-and-key model is outdated.
A
True
23
Q
What is the model we now use to describe how substrates and enzymes interact in the active site?
A
Induced fit model.
24
Q
Describe the induced fit model
A
Enzymes and substrates are somewhat flexible, both can change shape slightly upon interacting. This allows enzymes to slightly mold and position the substrate in a way that will encourage reaction.
25
What is an enzyme-substrate complex?
When an enzyme and a substrate come together. Here the activation energy required to start a chemical reaction and proper positioning of the reactants are achieved so the chemical reaction can occur. Also stabilizes the transition state of the reaction.
26
What is a transition state?
A brief yet critical point when reactants are chemically becoming products, but the reaction is not yet completed.
27
Stabilizing a transition state does what?
Facilitates chemical reactions.
28
How do enzymes lower activation energy?
By the combined effects of efficiently branding reactants together and stabilizing transition states.
29
General mechanism of enzyme-substrate interaction steps
1. Enzyme is available with empty active site
2. Substrate bonds to active site, forming an enzyme-substrate complex
3. Substrate is converted to products after going through a transitional state
4. Products are released and enzyme is again available
30
What are cofactors?
Additional components that some enzymes need to function.
31
What is an enzyme without it's necessary cofactor called?
An apoenzyme. It is inactive.
32
What is an apoenzyme
An enzyme that is without it's necessary cofactor and is thus inactive.
33
What is a holoenzyme?
The functional form of th enzyme that includes the enzyme and any necessary cofactors.
34
What are examples of inorganic cofactors that may help catalyze a reaction by forming a bridge between the enzyme and a substrate?
Iron, zinc, magnesium, and claim ions.
35
Organic cofactors are typically called
Coenzymes.
36
Coenzymes:
Nonprotein factors anchored to the enzyme they assist. Often vitamins or are made from vitamins.
37
What are common electron-carrier coenzymes?
NAD+, NADP+, FMN, and FAD
38
What are electron-carrier enzymes?
Coenzymes that collect electrons from one reaction and shuttle them to other reactions in the cell.
39
What is phosphorylation?
The addition of a phosphate onto an ADP molecule through catabolic reactions.
40
What is responsible for releasing energy to fuel anabolic reactions?
Phosphate
41
What is another name for anabolic reactions?
Biosynthetic reactions
42
What do anabolic reactions use to build molecules?
Energy
43
What happens if a cell loses its ability to make ATP?
It will die.
44
How is ATP made?
By catabolic reactions. Provides energy for anabolic reactions.
45
Cells break down nutrients to get:
ATP
46
Where do organic molecules such as proteins, lipids, and carbohydrates store energy?
In their bonds.
47
What is ATP made up of?
Adenine, ribose, and three phosphate groups.
48
What happens when the last phosphor group from ATP is removed dephosphorylation?
Energy and adenosine diphosphate are released (ADP)
49
Adenosine diphosphate contains how many phosphate groups?
Two
50
How can a cell get more ATP?
By adding a phosphate group to ADP via phosphorylation
51
What is the ATP-ADP Cycle?
The adding and removing of the terminal phosphate group.
52
Where does the energy to recharge ADP back to ATP come from?
Catabolic reactions.
53
What can the energy released when ATP becomes ADP do?
Fuel anabolic reactions
54
What happens in an oxidation reaction?
An atom or molecule loses electrons.
55
What happens in a reduction reaction?
An atom or molecule gains electrons.
56
How are oxidation-reduction reactions coupled?
When an atom or molecule loses an electron (is oxidized) another entity absorbs that electron and is reduced.
57
What are oxidation-reduction reactions referred to?
Redox reactions.
58
What are redox reactions?
Oxidation-reduction reactions.
59
What is a common oxidizing agent in biochemical reactions? What is a common reducing agent?
Oxygen is oxidizing and hydrogen is reducing.
60
How do cells harvest energy from nutrients?
By oxidizing them: stripping electrons from them.
61
Molecules that contain abundant hydrocarbon bonds are
Highly reduced.
62
Examples of highly reduced molecules that cells can extract energy from using redox reactions:
Sugars and fats.
63
Why do proteins make less ATP than carbohydrates and fats?
Because they are less reduced.
64
Enzyme names usually end in what suffix?
-ase
65
What are the six different classes that enzymes fall into?
```
Oxidoreductase
Transferase
Hydrolase
Lyase
Isomerase
Ligase
```
66
What are the classes enzymes fall under based on?
The reactions they catalyze
67
Why is CoA (coenzyme A) important?
In far metabolism and in the Krebs cycle.
68
NAD+ and FAD are found in ___ pathways and NADP+ is often involved in ____ pathways.
Catabolic, anabolic
69
What makes ribozymes different from protein enzymes?
They are made I'd RNA and have more limited range of substrates.
70
Ribozymes have only been shown to act on
Other RNA molecules.
71
T or F: man made ribozymes have also been developed to carry out a variety of research applications.
True
72
Do man-made ribozymes hold promise as drug therapies, especially in genetic disorders and as antiviral therapies?
Yes
73
What are some factors that can affect enzyme activity?
Cofactors, temperature, pH, how much substrate is present, the phosphorylation state, and the presence of inhibitors.
74
Lowering temperature does what to enzyme activity in most cases?
Lowers it, which causes cells to grow slower.
75
Why does keeping dos at cold temperatures usually slow food spoilage?
Because lower temperatures slow enzyme activity.
76
What is the optimal temperature of an enzyme?
The temperature where a given enzyme's activity is highest
77
What happens if the temperature is too much above the optimal temperature for the enzyme?
Enzyme activity can be significantly reduced.
78
What does denatured mean?
They lose their three-dimensional structure and become nonfunctional.
79
Exposing cells to high temps can cause enzymes and other proteins to become:
Denatured.
80
Denaturation can be
Reversible or irreversible.
81
For most pathogenic bacteria and human cells temperature about _____ can lead to denaturation
41 C or 105.8 F
82
What else can cause enzymes to denature other than temperature?
Contact with strong acids, bases, salts, detergents, alcohol, radiation, and heavy metals such as ions of lead, arsenic, or Mercury.
83
A pH above or below optimal pH will
Alter enzyme structure, leading to reduced reaction rate.
84
Why do changes in pH alter an enzyme's structure?
Because H+ (acid) and OH (base) affect the hydrogen and ionic bonds that support the three-dimensional structure of a protein.
85
Most pathogens prefer what kind of pH?
Nuetral
86
What is an example of a bacteria that can live in pH extremes?
Helicobacter pylori. Can thrive in low level pH environment of the stomach and cause stomach ulcers.
87
How do cells regulate enzyme activity?
By controlling how much of an enzyme is physically present and by adjusting how active a given enzyme is via phosphorylation, inhibitors, and allosteric regulatory factors.
88
What does the rate of product formation depend on?
How many active sites are available (enzyme concentration) and how much substrate is present.
89
What is the enzyme concentration?
How many active sites are available.
90
What is a saturation point and when does it occur?
It is when every enzyme active site is occupied by a substrate and occurs when the amount of substrate increases while the amount of enzyme remains unchanged.
91
An enzyme's function is closely linked to
It's structure. Even small structural changes can affect function.
92
How can cells change the structure of certain enzymes?
By adding or removing phosphate groups. They use specialized enzymes called kinases and phosphatases to accomplish this type of regulation.
93
How do kinases add phosphates to targets
By using phosphorylation reactions
94
How do phosphatases remove phosphate groups from their targets?
By using dephosphorylation reactions.
95
What does E. Cool use phosphorylation to regulate?
The production of lipopolysaccharide in an infected person, causing septic shock
96
A key enzyme in making cholesterol in humans, HMG-CoA, is inactivated by _____ and activated by ____
Phosphorylation, dephosphorylation
97
Examples of how modern medicine has employed enzyme inhibitors to improve human health:
- Penicillin-based antibiotics inhibit an enzyme's that helps bacteria produce their cells walls
- the statin drug Lipitor inhibits a human liver enzyme that makes cholesterol.
98
Competitive inhibitors do what?
Slow reactions by competing with a substrate for the target enzyme's active site.
99
In competitive inhibition the affected enzyme
Cannot carry out the reaction until the competitive inhibitor leaves the active site and the substrate can enter.
100
How can competitive inhibition be overcome?
If the concentration of substrate is greater than the concentration of the inhibitor.
101
Example of a competitive inhibitor:
Sulfanilamide.
102
What do noncompetitive inhibitors do?
Decrease enzyme activity by binding to the enzyme at a site other than the active site.
103
What is the difference between competitive inhibitors and noncompetitive inhibitors?
Noncompetitive inhibitors do not compete with a substrate for the enzyme's active site.
104
What happens if the noncompetitive inhibitor and the substrate simultaneously bind to the enzyme?
The enzymes activity is reduced, since the inhibitor distorts the enzyme's normal structure.
105
What is an example of a noncompetitive inhibitor?
Lead, which can build up to a point that it impacts enough host enzymes to cause lead poisoning.
106
Allosteric regulation
Occurs when an allosteric inhibitor or an allosteric activator binds to a place on the enzyme called the allosteric site. Do not compete with the enzyme's substrate.
107
What are three general mechanisms for recharging ADP to ATP?
Substrate-level phosphorylation
Oxidative phosphorylation
Photophosphorylation
108
Substrate-level phosphorylation
Occurs when an enzyme transfers a phosphoryl from a donor substrate directly to ADP to Mae ATP. Sometimes the group donors are called high energy intermediates.
109
Oxidative phosphorylation
Involved a collection of redox reactions that strip electrons from a food source, and eventually hand off those electrons to an electron transport chain to fuel phosphorylation or ADP to ATP.
110
What are electron transport chains sometimes called?
Respiratory chains.
111
Photophosphorylation
Relies on the redox reactions of an electron transport chain. Uses light energy to activate electrons. Only in photosynthetic cells.
112
Cellular respiration
A collection of reactions that extract energy from foods using redox reactions and then transfer that energy into the bonds of ATP.
113
Substrate-level phosphorylation
Occurs when an enzyme transfers a phosphoryl from a donor substrate directly to ADP to Mae ATP. Sometimes the group donors are called high energy intermediates.
114
Oxidative phosphorylation
Involved a collection of redox reactions that strip electrons from a food source, and eventually hand off those electrons to an electron transport chain to fuel phosphorylation or ADP to ATP.
115
What are electron transport chains sometimes called?
Respiratory chains.
116
Photophosphorylation
Relies on the redox reactions of an electron transport chain. Uses light energy to activate electrons. Only in photosynthetic cells.
117
Cellular respiration
A collection
118
Carbohydrate catabolism is
The breakdown of carbohydrates to release energy, is central to a cell's survival.
119
Cells primarily extract energy from carbohydrates through what?
Cellular respiration and fermentation.
120
What are the pathways that cellular respiration occurs through?
- Glycolysis
- intermediate step
- Krebs cycle
- electron transport chain
121
Up to 60% of the total energy available in the original nutrients is lost as what in cellular respiration?
Heat, the rest makes its way into ATP.
122
What is the final electron acceptor in aerobic respiration?
Oxygen
123
What is the final electron acceptor in anaerobic respiration?
An inorganic substance such as nitrate or sulfate
124
Carbohydrate catabolism is
The breakdown of carbohydrates to release energy, is central to a cell's survival.
125
Cells primarily extract energy from carbohydrates through what?
Cellular respiration and fermentation.
126
What are the pathways that cellular respiration occurs through?
- Glycolysis
- intermediate step
- Krebs cycle
- electron transport chain
127
Up to 60% of the total energy available in the original nutrients is lost as what in cellular respiration?
Heat, the rest makes its way into ATP.
128
Glycolysis
Glucose is split in half to create 2 pyruvic acid, using 2 ATP. 2 NADH are made and collect electrons. 4 ATP molecules are made. Profit is 2 ATP molecules. 2 pyruvic acid molecules are made and can be oxidated to make more ATP.
129
Glycolysis steps investment stage
1. ATP is invested to phosphorylate glucose
2. The molecule is rearranged to make fructose 6-phosphate
3. Second ATP is invested to make fructose 1, 6-biphosphate
4. Sugar is split into 2 3-carbon molecules.
5. DHAP is chemically rearranged to make glyceraldehyde 3-phosphate
130
Payoff stage of glycolysis
6. Phosphorylation and redox reaction
7. ATP is made by substrate-level phosphorylation
8. There is a chemical rearrangement
9. Water is removed, causing the phosphate bond to become high energy
10. Substrate level phosphorylation produces ATP.
131
What is the net gain of ATP molecules in glycolysis?
Two molecules of ATP for each molecule of glucose.
132
Intermediate step
2 pyruvic acid molecules lose carbon molecules in the form of carbon dioxide. Pyruvic acid is oxidated and NAD+ is reduced to NADH. Leaves us with 2 molecules of Co-A which goes into Krebs cycle.
133
Where does the intermediate step occur in the cells?
In the cytoplasm of prokaryotic cells and the mitochondrial matrix in eukaryotic cells.
134
What happens during the Krebs cycle?
Acetyl Co-A is broken down by decarboxilation reactions, reactions that remove carbon as CO2, and redox reactions, which makes more NADH and FADH2.
135
How often does the Krebs cycle run?
It runs twice for each glucose that originally entered respiration.
136
What is the profit of Krebs cycle?
2 ATP
6 NADH
2 FADH
137
Where does the Krebs cycle occur in the cell?
In the cytoplasm of prokaryotic cells and the matrix of the mitochondria in eukaryotic cells.
138
What happens in the electron transport chain?
Electrons are taken by NADH and FADH2. They drive production or 34 ATP and water. Electrons are passed from electron carriers to electron carriers using redox reactions. Passed to final acceptor.
139
What is the max amount of ATP that can be made in aerobic reaction?
34 ATP
140
Where does the electron transport chain take place in cells?
In the inner membrane of mitochondria in eukaryotic cells and in the plasma membrane in prokaryotic cells.
141
How does oxidative phosphorylation recharge ADP to ATP?
Using chemiosmosis
142
Why are anaerobic organisms sometimes not able to grow in the presence of oxygen?
Because they are not as well equipped as aerobic bacteria are to deal with toxic oxygen intermediates such as oxygen radicals.
143
What is the difference between anaerobic respiration and fermentation?
Fermentation does not use a respiratory chain, while respiration does. Fermentation occurs in the cytoplasm of a cell while respiratory chains are associated with a membrane
144
What is the maximum amount of ATP aerobic respiration can make?
38 ATP. Anaerobic makes less.
145
What is the proton motive force?
The accumulation of protons on one side of the membrane.
146
What is the proton motive force's role in chemiosmosis?
They accumulated protons are funneled through ATP synthase to make ATP.
147
What are other catabolic pathways for oxidizing nutrients?
Pentode phosphate pathway
| Entner-doudoroff pathway
148
Is fermentation as efficient as aerobic or anaerobic respiration?
No
149
What is the main goal of fermentation?
To sustain ATP production by glycolysis when respiratory chains are no available.
150
What are the different types of fermentation?
Homolactic
Heterolactic
Alcohol
Mixed acid and butanediol
151
All cells depend on what reactions to make ATP?
Redox
152
What is the final electron acceptor in fermentation?
An organic molecule that is usually a metabolic intermediate made by the cell.
153
What is the final electron acceptors in photosynthesis
Coenzymes and photosynthetic pigments.
154
Exoenzymes
The enzyme's secreted during extracellular catabolism by bacteria into their local environment.
155
What pathway are fatty acids fed into?
Krebs cycle
156
How are fatty acids broken down?
Two carbons at a time, into acetyl-Co-A molecules, then fed into Krebs cycle. This is called beta-oxidation
157
Beta-oxidation
The catabolic process by which fatty acid molecules are broken down to generate acetyl-Co-A
158
Where does glycolysis take place in the cell?
Cytoplasm
159
What is the fate of pyruvic acid in an organism that uses aerobic respiration?
It is converts into acetyl Co-A
160
Where in cellular respiration is carbon dioxide released?
Krebs cycle
161
Endergonic
Chemical reaction that requires the absorption of energy.
162
Exergonic
Reaction that loses energy during the process of the reaction.
163
What is a decarboxilation reaction?
When carbon dioxide is removed.
164
Endoenzyme
An enzyme that functions within the cell in which it was produced.
165
Constitutive enzymes
Produced by the cell under all physiological conditions. Not controlled by induction or repression. Produced in constant amounts.
166
Inducible enzyme
Expressed only under conditions in which is is clear of adaptive value. Is used for the breaking down of things in the cell.
