ch 5 - microbial metabolism sp 2017 - napa valley college · microbial metabolism chapter 5 bio 220...

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2/7/2017 1 Microbial metabolism Chapter 5 BIO 220 Metabolism Sum of all the chemical reactions occurring in an organism Metabolism = Catabolism + Anabolism Fig. 5.1 Collision Theory In order for chemical reactions to take place, atoms/ions/molecules must collide with each other The energy transferred during these collisions allows for the formation or the break down of chemical bonds Enzymes Enzymes increase reaction rate by increasing the probability that the starting molecules will interact in an orientation that promotes product formation They lower the Energy of Activation of the reaction (decrease the randomness of substrate interactions)

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Page 1: Ch 5 - Microbial metabolism Sp 2017 - Napa Valley College · Microbial metabolism Chapter 5 BIO 220 Metabolism • Sum of all the chemical reactions occurring in an organism • Metabolism

2/7/2017

1

Microbial metabolism

Chapter 5

BIO 220

Metabolism

• Sum of all the chemical reactions occurring in

an organism

• Metabolism = Catabolism + Anabolism

Fig. 5.1

Collision Theory

• In order for chemical reactions to take place,

atoms/ions/molecules must collide with each

other

• The energy transferred during these collisions

allows for the formation or the break down of

chemical bonds

Enzymes

• Enzymes increase reaction rate by increasing

the probability that the starting molecules will

interact in an orientation that promotes

product formation

• They lower the Energy of Activation of the

reaction (decrease the randomness of

substrate interactions)

Page 2: Ch 5 - Microbial metabolism Sp 2017 - Napa Valley College · Microbial metabolism Chapter 5 BIO 220 Metabolism • Sum of all the chemical reactions occurring in an organism • Metabolism

2/7/2017

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Activation energy

Fig. 5.2

Enzyme action

Fig. 5.3

Enzyme Characteristics

1. Biological catalysts

– Can process substrates very efficiently

– Turnover number

2. Induced fit vs. lock and key

3. Usually proteins

4. Substrate smaller than enzyme

5. Specificity (affinity)

6. Naming

– End in -ase

– Based on type of chemical reactions they catalyze

For oxidation-reduction rxns remember “OIL RIG”

Page 3: Ch 5 - Microbial metabolism Sp 2017 - Napa Valley College · Microbial metabolism Chapter 5 BIO 220 Metabolism • Sum of all the chemical reactions occurring in an organism • Metabolism

2/7/2017

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Enzyme components

• Some enzymes require additional factors in

order to function

• Holoenzymes are composed of an apoenzyme

(protein) and a cofactor (nonprotein)

Fig. 5.4

Enzyme components

Types of cofactors

• Metal ions

– Zn2+ , Fe2+ , Cu2+ , Mg2+ , Ca2+

• Coenzymes (organic)

– Often derived from vitamins

– Attachment to protein is non-covalent (not

permanent)

Examples of coenzymes

• Nicotinamide adenine dinucleotide (NAD+)

• Nicotinamide adenine dinucleotide

phosphate (NADP+)

• Flavin mononucleotide (FMN)

• Flavin adenine dinucleotide (FAD)

• Coenzyme A

Page 4: Ch 5 - Microbial metabolism Sp 2017 - Napa Valley College · Microbial metabolism Chapter 5 BIO 220 Metabolism • Sum of all the chemical reactions occurring in an organism • Metabolism

2/7/2017

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Factors that affect enzyme activity &

reaction rate

1. Temperature

2. pH

3. Substrate concentration

4. Inhibitors

Temperature

Figs. 5.5a and 5.6

pH

Figs. 5.5b and 5.6

Substrate concentration

Fig. 5.5c

Page 5: Ch 5 - Microbial metabolism Sp 2017 - Napa Valley College · Microbial metabolism Chapter 5 BIO 220 Metabolism • Sum of all the chemical reactions occurring in an organism • Metabolism

2/7/2017

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Inhibitors

• May be competitive or noncompetitive

Fig. 5.7

Competitive inhibition

Inhibitors

• May be competitive or noncompetitive

Fig. 5.7

Feedback inhibition

Fig. 5.8

Page 6: Ch 5 - Microbial metabolism Sp 2017 - Napa Valley College · Microbial metabolism Chapter 5 BIO 220 Metabolism • Sum of all the chemical reactions occurring in an organism • Metabolism

2/7/2017

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Energy production

• Oxidation – reduction

– Used to extract energy from nutrient molecules

– OIL RIG

• Mechanisms of ATP generation

Oxidation-reduction

• Oxidation and reduction reactions are coupled

(redox reactions)

• Most biological oxidation reactions involve the

loss of hydrogen ions (dehydrogenation rxns)

Figs. 5.9, 5.10

ATP generation

• Nutrient molecules are catabolized using a

series of oxidation-reduction reactions, then

the energy contained within the bonds of the

nutrients can be trapped within the bonds of

ATP, which can then serve as an energy source

for energy-requiring reactions

ATP generation

• Substrate – level phosphorylation

• Oxidative phosphorylation

• Photophosphorylation

Page 7: Ch 5 - Microbial metabolism Sp 2017 - Napa Valley College · Microbial metabolism Chapter 5 BIO 220 Metabolism • Sum of all the chemical reactions occurring in an organism • Metabolism

2/7/2017

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Carbohydrate catabolism

• Glucose is the most common carbohydrate

used as an energy source

• Microbes can use cellular respiration,

anaerobic metabolism, or fermentation to

produce energy from glucose

Fig. 5.11

(Cellular) Respiration

• An ATP-generating process in which molecules

are oxidized and the final electron acceptor

comes from outside the cell and is (almost

always) inorganic

• Aerobes use oxygen as the final electron

acceptor

• Anaerobes do not use oxygen, rather some

other inorganic molecule as the final acceptor

Cellular respiration

• Glycolysis

• Transition reaction

• Krebs cycle

• Electron transport chain (system)

Page 8: Ch 5 - Microbial metabolism Sp 2017 - Napa Valley College · Microbial metabolism Chapter 5 BIO 220 Metabolism • Sum of all the chemical reactions occurring in an organism • Metabolism

2/7/2017

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Glycolysis

Fig. 5.12

Alternatives to glycolysis

• Pentose phosphate pathway

– Used to catabolize pentose sugars

– 1 ATP and 2 NADPH are produced

– Bacillus subtilis, Escherichia coli, Enterococcus

faecalis

• Entner-Doudoroff pathway

– Produces 1 ATP and 2 NADPH

– Some gram negative bacteria (Pseudomonas,

Rhizobium) utilize

Transition reaction and Krebs cycle

Fig. 5.13

Electron transport chain (system)

Fig. 5.14

Page 9: Ch 5 - Microbial metabolism Sp 2017 - Napa Valley College · Microbial metabolism Chapter 5 BIO 220 Metabolism • Sum of all the chemical reactions occurring in an organism • Metabolism

2/7/2017

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Electron transport chain

Carrier molecules include

• Flavoproteins

– Contain coenzymes derived from riboflavin

– Flavin mononucleotide (FMN)

• Cytochromes

– Protein with iron-containing group

– Cytochrome b/c1, cytochrome c, cytochrome a/a3

• Ubiquinones (coenzyme Q)

Electron transport chain (system)

Fig. 5.16

Chemiosmosis

Fig. 5.15

Page 10: Ch 5 - Microbial metabolism Sp 2017 - Napa Valley College · Microbial metabolism Chapter 5 BIO 220 Metabolism • Sum of all the chemical reactions occurring in an organism • Metabolism

2/7/2017

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Fig. 5.17

Aerobic respiration (summary)

Anaerobic respiration

• The final electron acceptor is NOT oxygen

• Pseudomonas and Bacillus use nitrate ions

• Desulfovibrio uses sulfate

• Other organisms use carbonate

• Aerobic respiration is a much more efficient

ATP producer than anaerobic respiration!

Fig. 5.11

Page 11: Ch 5 - Microbial metabolism Sp 2017 - Napa Valley College · Microbial metabolism Chapter 5 BIO 220 Metabolism • Sum of all the chemical reactions occurring in an organism • Metabolism

2/7/2017

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Fermentation

• Releases energy from sugars or other organic

molecules

• Does not require oxygen

• Does not use the Krebs cycle or an electron

transport system

• Uses organic molecules as final electron

acceptors

• Does not produce buckets of ATP

Fig. 5.18

Types of

fermentation

Fig. 5.19

Page 12: Ch 5 - Microbial metabolism Sp 2017 - Napa Valley College · Microbial metabolism Chapter 5 BIO 220 Metabolism • Sum of all the chemical reactions occurring in an organism • Metabolism

2/7/2017

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Catabolism of nutrients

Fig. 5.21