Ch 5 Microbial Metabolism Flashcards
1
Q
Conjugated proteins
A
Enzyme components that include apoenzyme and cofactor/coenzyme
2
Q
What is fermentation
A
Any metabolic process that releases energy from a sugar other organic molecule. It does not require oxygen or an Elektron transport system and uses an organic molecule as a final electron acceptor.
3
Q
Catabolism
A
The breakdown of complex organic compounds into simpler ones
4
Q
Metabolism
A
Refers to the sum of all chemical reactions within a living organism. Includes 2 classes: release of energy and requiring energy
5
Q
Catabolism in living cells is an enzyme regulated chemical reaction that _____________ energy
A
Releases
6
Q
What are 3 characteristics of catabolic reactions
A
- Enzyme regulated chemical reaction that releases energy
- Generally hydrolytic reactions: use water to break chemical bonds
- Exergonic: produce more energy than they consume
7
Q
Example of catabolic reaction
A
Cells break down sugars into CO2 and H20
8
Q
Anabolism
A
The building of complex organic molecules from simpler ones
9
Q
Characteristics of an anabolic reaction
A
- Enzyme regulated energy requiring reaction
- Involved in dehydration synthesis reaction: reactions that release water
- Endergonic–> consume more energy than they produce
10
Q
Another word for catabolic reaction
A
Degradative reaction
11
Q
Another word for anabolic reaction
A
Biosynthetic reaction
12
Q
Example of anabolic reaction
A
Formation of:
- protein from aa,
- nucleic acid from nucleotides,
- polysaccharides from simple sugars
13
Q
How do catabolic reactions help anabolic reactions
A
They provide the building blocks for anabolic reactions. They furnish the energy needed to drive anabolic reactions–>ATP.
14
Q
What is ATP
A
Stored energy derived from catabolic reactions. They use it later to drive anabolic reactions and perform other cellular work
15
Q
When is ADP formed
A
Formed when terminal phosphate group split from ATP and energy is released to drive anabolic reactions.
16
Q
Metabolic pathway
A
A sequence of chemical reactions
17
Q
What determines a metabolic pathway
A
Its enzymes which are determined by the cells genetic make up
18
Q
Collision theory
A
The principle that chemical reactions occur because energy is gained as particles collide (atoms, ions, molecules)
19
Q
What effect does the energy transfer of colliding particles have on electron structure and chemical bonds
A
It can disrupt electron structure enough to break chemical bonds and build new bonds
20
Q
What factors determine if a chemical reaction will occur
A
- Velocity of colliding particles
- Their energy
- Specific chemical configurations
21
Q
How does velocity of particles effect chemical reaction
A
The higher the velocity the higher the probability of reaction
22
Q
How does energy effect a chemical reaction
A
Each chemical reaction requires a specific level of energy
23
Q
How does configuration affect a chemical reaction
A
Particles need to be properly oriented toward each other to react
24
Q
What is activation energy
A
The collision required for a chemical reaction to take place. The amount of energy needed to disrupt the stable electronic configuration of any specific molecule so the electrons can be rearranged.
25
What is reaction rate
The speed at which a reactant is converted to a product.
26
What is reaction rate dependent on
The frequency of collisions containing sufficient energy to bring about a reaction depend on the number of reactant molecules at or above the activation energy level
27
What things increase a reaction rate
Temperature, pressure, enzymes
28
In living things, why are enzymes a crucial function
They can speed up biochemical reactions at temperatures compatible with normal functioning of cell. Their reactions are also reversible.
29
Catobolites
Catabolism intermediates
30
What is a catalyst
Substance that can speed up a chemical reaction without being altered themselves
31
Biological catalyst
Specific for a chemical reaction not used up in that reaction
32
In a living substance, enzymes serve as
Biological catalysts that act on specific substance(s)/enzymes substance
33
Example of biological catalyst of sucrose and teleological reasoning
* Sucrase is an enzyme and biological catalyst. •Sucrose is a substrate of sucrase.
* Sucrase catalyzes the hydrolysis of sucrose.
* The end products are glucose and fructose
34
Active site
Region that interacts with specific substance
35
How do enzyme accelerate chemical reactions
The 3D molecule has an active site, it orients substrate into position that increases probability of reaction
36
Enzyme substrate complex
Temporary binding of enzyme and reactants that enables collisions to be more effective and lowers activation energy of reaction
37
What allows for enzyme specificity
Made possible by structure and 3D shape with specific surface configurations
38
What makes enzyme efficient
At optimal conditions they
1. catalyze at rates of 10^8-10^10 times or higher 2. can have a turnover of 1-10,000 or as high as 500,000 per sec ok nd
39
What is meant by enzyme turnover number
The max substrate to product an enzyme converts per second
40
Are enzymes in cell always active
No, can be inactive. Its determined by cellular environment.
41
What are the 6 classes of enzymes
1. Oxidoreductase
2. Transferase
3. Hydrolase
4. Lyase
5. Isomerase
6. Ligase
42
Oxidoreductase
Oxidation-reduction in which oxygen and hydrogen are gained or lost
43
Tranferase
Transfer of functional groups such as amini group, acetyl group, phosphate group
44
Hydrolase
Hydrolysis-->addition of water
45
Lyase
Removal of groups of atoms without hydrolysis
46
Isomerase
Rearrangement of atoms within a molecule
47
Ligase
Joining of 2 molecules, using energy usually derived from the breakdown of ATP
48
What is an enzyme made of
Some made mostly of proteins and others made up of a portion of protein and a non protein component
49
Apoenzyme
Protein portion if the enzyme and is inactive without cofactor/conenzyme
50
Cofactor
Non protein component of the enzyme made up of ions of a specific metal ion such as iron, zinc, magnesium, or calcium
51
Conenzyme
Is a non protein component of the enzyme made up of an organic molecule
52
Holoenzyme
Apoenzyme+cofactor. It is an active enzyme. If the cofactor is removed it will not function.
53
How do coenzymes assist enzymes
Coenzymes act as electron carriers:
1. Accept atoms removed from substrate
2. Donate atoms required by substrate.
54
Where do coenzymes come from
```
Derived from vitamins:
Vit B 1,2,6,12
Niacin
Pantothenic acid
Biotin
Folic acid
Vit E and K
```
55
2 most important coenzymes
1. NAD+ : nicotinamide adenine dinucleotide
| 2. NADP+: nicotinadine adenine dinucleotide phosphate
56
NAD and NADP both (3)
Derived from B vitamin
Function as electron carriers
Important in cellular metabolism
57
What kind of reactions are NAD mostly involved in
Catabolic reactions
58
NADP are primarily involved in __________ reactions
Anabolic
59
Common coenzymes
Flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), CoA (coenzyme A)
60
What major role does FAD in Cellular respiration
Act as electron carriers
61
What role does CoA play
In the synthesis and breakdown of fats and Krebs cycle
62
What do cofactor consist of
They are metal ions like iron, copper, magnesium, zinc,calcium, and cobalt
63
How do cofactors help catalyze a reaction
By forming a bridge between enzyme and substrate
64
What is an allosteric site
AKA regulatory site. A different site of attachment for non-competitive inhibitor. Substrate cannot attach here.
65
What is the mechanism of enzymatic action
1. Substate comes in contact with active site
2. Forms enzyme substrate complex
3. Substrate molecule is transformed
4. Produts of reaction are released from enzyme
5. Unchanged enzyme is free to react with other substrates
66
What factors influence enzyme activity
Temperature
pH
Substrate concentration
Inhibitors
67
Mechaniism of enzymatic action is based on...
Collision theory; proximity and orientation
68
Endoenzyme
Active inside cell
69
Exoenzyme
Active outside cell; secreted out
70
Constitutive enzyme
Expressed at constant levels in cell at all times
71
Inducible enzymes
Made/expressed only when needed
72
Example of gram negative exoenzyme
Lipid A layer of phospholipid outer cell layer has a toxin that can be released into the surrounding environment if activated
73
Enzymes lower___________ ___________of chemical reaction
Activation energy
74
How is substrate molecule transformed into products
After enzyme-substrate complex is formed the following can occur:
1. Rearrangement of existing atoms
2. Breakdown of substrate molecule or combination with another substrate molecule
75
What things allow for an enzyme to have specificity of a particular substrate
1. 3d shape of active site is like a lick and key fit
2. Active site and substrat and substrate flexible
3. Substrate smaller than enzyme
4. Few aa make up active site
76
What are the 2 primary cellular controls in enzymatic activity
1. Enzyme synthesis -->how much
| 2. Enzyme activity --> how active
77
How does temperature influence enzyme activity
Rate of most chemical reactions increase as temperature increases. At lower temperatures molecules move slower and may not have enough energy to cause chemical reaction
78
What is the optimal temperature for disease producing bacteria in human body
35°C to 40°C
79
What happens to enzymes above 40°C
Enzymes denature: loss of 3D structure and breaking hydrogen bonds and non covalent bonds, also changes arrangement of aa on active site and loses ability to catalyze.
80
What can cause denaturing of enzymes
Concentrated acids, based, heavy metal ions (lead, arsenic, mercury), alcohol, uv radiation
81
What happens to enzymes at ir below optimal range
Reactions decrease, can cause alteration of struct6and denaturing of proteins
82
What happens to chemical reactions at substrate concentrations above max rate
This happens when all the active sites on enzyme are saturated. Increasing substrate above this has no farther effect
83
What happens to enzyme when there is a lack of substrate
Become inactive
84
What are enzyme inhibitors used for
Control growth of bacteria by controlling their enzymes .
85
What are enzyme inhibitors
They are analogous to substrate and compete for activation site of enzyme or bind at allosteric site. When they combine with enzyme they either decease reaction rate or prevent their normal function. This can cause the cell to stop working and can cause cell death.
86
Examples of enzyme inhibitors
Poisons--> cyanide, arsenic, mercury
| Antibiotics--> Sulfa. Ampicillin
87
What are the 2 classes of enzyme inhibitors
1. Competitive inhibitors
| 2. Non competitive inhibitors
88
Competitive inhibitors
1. Compete for and Fill the active site of enzyme
2. Does not undergo reaction
3. Some bind irreversibly to aa at active site
4. Others bind reversibly: occupy and leave
5. Certain chemicals can bind or tie up metal ion activators and prevent enzymatic reaction
89
What happens to active site once allosteric site is occupied
It becomes altered, enzyme changes shape, active site changes, and it becomes inactive for substrate
90
How does Sulfa inhibit bacterial enzyme
It selectively toxic on bacteria. It attaches to active site and prevents substrate PABA from binding with enzyme. PABA is required for folic acid synthesis. Without this bacteria cannot grown and will dies.
91
Non competitive inhibitors
1. Do not compete with substrate for active site
2. interact with allosteric site
3. Active site becomes non functional
4. Enzyme activity decreases
5. Can be reversible or irreversible
6. Can sometimes activate enzyme instead of inhibiting
92
What is end product inhibition
It is a biochemical control. Also know as feedback inhibition. It stops a cell from making more of a substance than it needs/ prevents wasting of chemicals
93
What is the allosteric inhibitors role
The final product of anabolic pathway is used to inhibit the activity of one of the enzymes earlier in the metabolic pathway, usually the first enzyme. The prevents the fist enzymatic reaction and the entire pathway is shut down.
94
How long does feedback inhibition last
It is maintained until supply is depleted.
95
What are ribozymes
A unique type of RNA. Just like protein enzymes they function as catalysts , have active sites, and are not used up in chemical reaction
96
What restrictions do ribozymes have
Their interaction with substrates are restricted. They act specifically on strands of RNA by removing sections and splicing together remaining pieces
97
How is energy produced
Nutrient molecules have energy associated with electrons that form bonds between atoms. Catabolic pathways concentrate energy into bonds of ATP, making them readily available for anabolic reactions
98
How are ATPs high energy bonds useful for anabolic reactions
They are unstable and can be easily released for quick and easy use in anabolic reactions, and they are not large molecules.
99
Oxidation-reduction
The removal of electrons from an atom or molecule coupled with simultaneous gain of one or more electrons of another atom or molecule
100
In biological systems, electrons are often associated with ________ _________.
Hydrogen atoms
101
Biological oxidation are often
Dehydrogenations
102
Hydrogenation is made up of
1 electron and 1 proton
103
Dehydrogenation reaction
Loss of hydrogen atoms
104
Which has more energy NADH or NAD+
NADH. It has energy that can be used to generate ATP in later reaction
105
How is ATP generated
By phosphorylation of ADP
106
Cells use biological redox reactions in catabolism to
Extract energy from nutrient molecules. These energy sources are degrade from highly reduced compounds to highly oxidized compounds
107
What type of compounds are highly reducible
Compounds that have many hydrogen atoms like glucose
108
Where is energy trapped after it is released from redox reaction
Within cell by formation of ATP
109
What is phosphorylation
The addition of a phosphate to a chemical compound
110
What is substrate level phosphorylation
The generation of ATP from the direct transfer of a high energy phosphate from a phosphorylated compound to ADP
111
Oxidative Phosphorylation
Electrons are transferred from organic compounds to one group of electron carriers, usually NAD and FAD
112
What happens after oxidation phosphorylation takes place
Electrons are passed through a series of different electron carriers to molecules to molecules of 02 or other oxidized inorganic or organic molecules
113
Where does oxidative phosphorylation take place
In plasma of prokaryotes or inner mitochondrial membrane of eukaryotes
114
What is the sequence of electron carriers called that takes place during oxidative phosphorylation
Electron transport chain
115
What is chemiosmosis
A process that transfers electrons from one carrier to the next , releasing energy, some of which is used to make ATP
116
Photophosphorylation
Occurs only in photosynthetic cells. They have a light trapping pigment called chlorophyll that give up electrons. Light energy is converted to chemical energy of ATP and NADH, ETC involved.
117
Metabolic pathway
A sequence of enzymatically catalyzed chemical reactions occurring in a cell
118
What is carbohydrate catabolism
The oxidation of carbohydrates; breakdown of carbohydrate molecules to produce energy
119
What is the primary source of cellular energy
Carbohydrates
120
What substance is the most common energy source by cells
Glucose
121
What are the 2 general processes of the metabolism of glucose
Cellular respiration and fermentation
122
What are the 3 principle stages of Respiration
1. Glycolysis
2. Krebs cycle
3. Electron Transpor Chain
123
What is glycolysis
The oxidation of glucose to pyruvic acid with the production of some ATP and energy containing NADH
124
What is the Krebs Cycle
Oxidation of acetyl CoA to C02 with production of some ATP, energy containing NADH, and another reduced electron carrier-->FADH2
125
What is electron transfer chain
The process of which involves the oxidation of NADH and FADH2 and the transfer of their electrons to generate ATP.
126
Wherebdies the most generation of ATP occur in cellular respiration
ETC
127
Is oxygen required for glycolysis
No
128
What are the 2 basic stages of glycolysis
1. Preparatory stage
| 2. Energy conserving stage
129
Glycolysis also known as
Embeden- Meyerhof pathway
130
How many pathways are in6in glycolysis
10
131
What is the preparatory stage of glycolysis
Glucose is split to form (2) glucose-3 phosphate,(2) ATP are used in this process
132
What happens during the energy conserving stage of glycolysis
(2) glucose-3 phosphate is oxidized to (2) pyruvic acid, and 2 net ATP, 2 NADH are produced
133
What happens if glycolysis takes place in an anaerobic environment
NADH unload onto pyruvate and create lactic acid
134
What are alternatives to glycolysis
Bacteria can use another pathway to oxidize glucose:
1. Penrose phosphate pathway
2. Entner-Doudoroff Pathway
135
Pentose phosphate pathway
Uses pentose instead of hexose and NADPH, Operates with glycolysis, provides means for breakdown of 5 penthouse sugar and glucose
136
What bacteria use pentose phosphate pathway
Bacillus subtilis, E. coli
137
Entner Doudoroff pathway
Produces 2 NADPH and 1 ATP
| Does not involve glycolysis
138
What bacteria use ED Pathway
Normally found in gram negative bacteria such as Rhizonium, Pseudomonas, Agrobacterium
139
What are the key features of pentose phosphate pathway
Produces important intermediate pentose used in nucleic acids, glucose from C02 in photosynthesis, and certain aa
140
Cellular Respiration
An ATP generating process in which molecules are oxidized, liberating electrons for an electron transport chain
141
What is commonly the final electron acceptor in cellular respiration
An organic molecule
142
How is ATP generated in cellular respiration
By oxidative phosphorylation
143
What are the 2 types of cellular respiration
Aerobic and anaerobic
144
What is the FEA for aerobic respiration
02
145
What is the FEA for anaerobic respiration
Can be either an inorganic molecule other than 02 or an organic molecule (rarely)
146
Aerobic respiration
Involves the Krebs cycle, in which a series of biochemical reactions take place and a large amount of potential chemical energy stored in acetyl CoA is released step by step
