1 pp. 115-138; 144-148 Microbial Metabolism 5-a. 2 Chapter 5 Overview Metabolism Enzymes Common...
-
Upload
emory-owens -
Category
Documents
-
view
217 -
download
1
Transcript of 1 pp. 115-138; 144-148 Microbial Metabolism 5-a. 2 Chapter 5 Overview Metabolism Enzymes Common...
1
pp. 115-138; 144-148
Microbial MetabolismMicrobial Metabolism5-a5-a
2
Chapter 5 OverviewChapter 5 Overview
• Metabolism
• Enzymes
• Common energy pathways used by microbes
– Fermentation– Aerobic respiration– Anaerobic respiration
• Metabolic diversity among organisms
• Release energy– Catabolism – Breakdown of
molecules• Sugar CO2 + H20
– Provides ‘building blocks’ for anabolism
– Provides energy for anabolism
• ATP ADP + energy
• Requires energy– Anabolism – Synthesis of
molecules• Amino acids protein
– Provides molecules for catabolism
– Provides ATP for catabolism
• ADP + energy ATP
3
Metabolism Metabolism Energy-Balancing Process
Molecule breakdown coupled with molecules synthesized
4
Enzymes Enzymes …Enable Energy-Balancing Process
• Are a catalyst = speed up reaction• Increase the reaction rate • Lower the energy of activation • Are not altered in the reaction• Are highly specific • Each acts on a specific substance, the substrate• Each catalyzes only one reaction
5
EnzymesEnzymes
• Provide a structure, a framework
– To allow collisions to occur
– And the chemical reaction to occur
AB A + BAB A + BSubstrate Products
6Fig. 5.2
Energy Requirements - Chemical ReactionEnergy Requirements - Chemical Reaction
The reaction is: AB A + B
7
Mechanism of Enzymatic Action:Mechanism of Enzymatic Action:
When an enzyme and substrate combine:– The substrate is transformed, to products– And the enzyme is recovered, unaltered
Turnover number ~ 1-10,000 molecules per second
Fig. 5.4a
8
• Names usually end in –ase
Naming enzymes:Naming enzymes:
Enzyme classification:Enzyme classification:• Based on the type of chemical reaction they
catalyze – Example: oxidoreductases (ox-redox rxns)
• Within each class, named for the specific reaction– If remove hydrogen, called dehydrogenases
9
Enzyme classification (6 classes):Enzyme classification (6 classes):
10
• Some enzymes consist only of protein
• Most consist of both a protein and a non-protein component– The protein called an apoenzyme– The non-protein part called a cofactor
• Cofactors are– Ions of iron, zinc, magnesium, calcium etc*
– If a cofactor is an organic molecule, it is called a:• Coenzyme
Enzyme ComponentsEnzyme Components
* p. 119
11
• Apoenzymes are inactive by themselves– They must be activated by cofactors
• Apoenzymes + cofactors form a– Holoenzyme
Fig. 5.3
+
12
Enzyme & CofactorsEnzyme & Cofactors
NAD+NADP+FMN, FADCoenzyme A
Nicotinamide adenine dinucleotideNicotinamide adenine dinucleotide phosphateFlavin mononucleotide, Flavin adenine dinucleotideImportant in the Krebs cycle
13
Enzymes are characterized by specificity – Specificity is a function of their active sites
(see ‘groove’) – Enzyme + substrate = slight shape change
* Animation: Enzyme–Substrate Interactions. The Microbiology Place.
Fig. 5.4b
• Chemotrophs– Oxidation-reduction reactions of organic or
inorganic compounds for energy
• Phototrophs – Use light as primary source of energy
• Autotrophs – Use CO2 for principal carbon source
• Heterotrophs– Use organic carbon source
14
Organisms - Metabolic DiversityOrganisms - Metabolic Diversity
• Photoautotrophs– Energy = light; carbon = CO2
• Photoheterotrophs– Energy = light; carbon = organic source
• Chemoautotrophs– Energy = organic or inorganic compounds;
carbon = CO2
• Chemoheterotrophs* – Energy = organic or inorganic compounds;
carbon = organic source 15
Combine Energy & Carbon
16Fig. 5.27
Nutritional Classification of Organisms
17
1. All of the following are enzymes except:
a. Threonine deamainaseb. Acetylc. Peroxidased. Urease
Q’sQ’s
2. Enzymes work most effectively at their optimal temperature and pH.
a. True b. False
18
1. Beggiatoa bacteria use carbon dioxide for their carbon source and hydrogen sulfide as an energy source. This organism is a:
a. Photoheterotroph
b. Chemoheterotroph
c. Photoautotroph
d. Chemoautotroph
Q’sQ’s
Hint: Fig. 5.27
19
Q’sQ’sIn the figure shown, what is the small organic molecule called that is needed to activate the apoenzyme?
A. Holoenzyme B. Enzyme C. Coenzyme D. Substrate E. Reactant
20
Q’sQ’s1. A dehydrogenase is an example of a/an
_____________?
2. Nitrobacter bacteria use CO2 for their carbon source and nitrate ions as an energy source. This organism is a:
A. Chemoautotroph
B. Chemoheterotroph
C. Photoheterotroph
D. Photoautotroph Hint: Fig. 5.27
21
Q’sQ’s1. A coenzyme assists an enzyme by
accepting or donating matter. What does NAD+ transfer?
A. CoA
B. Electrons
C. Acetyl groups
D. ATP
Hint: Table 5.2
22
Q’sQ’s1. Organisms that use carbon dioxide as a
carbon source and energy sources such as ammonia or hydrogen sulfide are called:
A. Photoautotrophs
B. Photoheterotrophs
C. Chemoheterotrophs
D. Chemoautotrophs
Hint: Fig. 5.27
23
Q’sQ’s
OrganismCarbon Source
Energy Source
Photoautotroph
Photoheterotroph
Chemoautotroph
Chemoheterotroph
Fill in the blanks: