Microbiology Chapter 9

Front 1

All biological energy is derived from ___/___ reactions

Back 1

oxidation/reduction.
Electrons released during oxidation of chemical energy sources must be accepted by an electron acceptor. Micros. vary in terms of the acceptors they use.

Front 2

Exogenous electron acceptors

Back 2

?

Front 3

Aerobic respiration

Back 3

Enery source degraded using oxygen as terminal (exogenous) electron acceptor. Yield large amount of energy, primarily by e transport activity.

Front 4

Anaerobic respiration

Back 4

Eneryg source oxidized and degraded using molecules other than oxygen as terminal (exogenous) electron acceptors, e.g, nitrate or sulfate.
Can yield large amt of E

Front 5

Fermentation

Back 5

Energy source oxidized and degraded using an organic compound as the electron acceptor. Occur under anaerobic conditions.

Front 6

Overview of aerobic catabolism

Back 6

large molecules (polymers)->small molecules (monomers)
inital oxidation and degradation to pyruvate
oxidation and degredation of pyruvate by the tricarboxylic acid cycle (TCA cycle)

Front 7

Three stages of catabolism

Back 7

Fig. 9.3
Many different energy sources are funneled into common degradative pathways. Macromolecules. Degradation to pyruvate. TCA.

Front 8

What is an amphibolic pathway?

Back 8

Function both as catabolic and anabolic pathways.

Front 9

Three common routes for the breakdown of glucose to pyruvate

Back 9

(1)Embden-Meyerhof pathway (glycolysis)
(2) Pentose phosphate pathway (hexose monophosphate shunt)
(3) Entner-Doudoroff pathway

Front 10

Glycolysis

Back 10

Fig. 9.5
Addition of phosphates "primes the pump"
Oxidation step-generates NADH
High-energy molecules used to synthesize ATP by substrate-level phosphorylation

Front 11

Why would an organism have both the pentose phosphate and the Embden-Meyerhof pathways?

Back 11

?

Front 12

Pentose phosphate pathway

Back 12

Fig. 9.6
Oxidation steps. Produce NADPH, which is needed for biosynthesis. Produce ribulose-5-P, precursors for nucleic acids. Produce sugars needed for biosynthesis.

Front 13

Entner-Doudoroff Pathway

Back 13

Reactions of pentose phosphate pathway
Reactions of glycolytic pathway
Yield per glucose molecule: 1 ATP, 1 NADPH, 1 NADH

Front 14

Tricarboxylica acid cycle

Back 14

Also called citric acid cycle and Kreb's cycle.

Front 15

Amphibolic

Back 15

provides carbon skeletons for biosynthesis

Front 16

Kreb's cycle

Back 16

oxidation steps-form NADH & FADH2.
Substrate-level phosphorylation

Front 17

What is an electron transport system?

Back 17

Series of electron carriers that operate together to transfer electrons from NADH and FADH2 to a terminal electron acceptor.

Front 18

Electron transport chain

Back 18

As electrons transferred, energy is released. Some released energy used to make ATP by oxidative phosphorylation.

Front 19

How do the electron transport systems of procaryotes differ from those of eucaryotes?

Back 19

Located in cell membrane. Some resemble mitochondrial ETC, but many are diff; diff e- carriers, may be branched, may be shorter.

Front 20

Upper branch

Back 20

Stationary phase and low aeration

Front 21

Lower branch

Back 21

Log phase and high aeration

Front 22

What is oxidation phosphorylation?

Back 22

Chemiosmotic hypothesis is the most widely accepted explanation of oxidative phosphorylation. Postulates that energy released during e- transport used to establish a proton gradient and charge difference across membrane. Called proton motive force (PMF).

Front 23

The proton motive force drives ATP synthesis

Back 23

movement of protons back across membrane (down gradient) drives formation of ATP.

Front 24

ATP synthase (synthetase)

Back 24

enzyme that uses proton movement down gradient to catalyze ATP synthesis

Front 25

Chemiosmoss (same in pro as mito)

Back 25

Movement of protons establishes PMF. ATP synthase uses proton flow down gradient to make ATP.

Front 26

Anaerobic respiration

Back 26

Uses inorganic electron acceptors other than O2. Generally yields less enery becuase E0 of electron acceptor is less positive than E0 of O2.

Front 27

Dissimilatory nitrate reduction

Back 27

Use of nitrate as terminal electron acceptor. Denitrification.

Front 28

Denitfification

Back 28

Reduction of nitrate to nitrogen gas. In soil, causes loss of soil fertility.

Front 29

Assimilatory nitrate reduction

Back 29

Use to nitrate as nitrogen source

Front 30

ETC of Paracoccus denitrificans
Aerobic or anaerobic?

Back 30

Aerobic

Front 31

ETC of P.denitrificans
Aerobic or anaerobic?

Back 31

Anaerobic

Front 32

Fermentations

Back 32

Oxidation of NADH produced by glycolysis. Pyruvate or derivative used as endogenous electron acceptor. ATP formed by substrate-level phosphorylation.

Front 33

Some common microbial fermentations

Back 33

Homolactic fermenters
Alcoholic fermentation

Front 34

Methyl red test

Back 34

Detect pH change in media caused by mixed acid fermentation

Front 35

Strickland reaction

Back 35

Oxidation of one amino acid with use of second amino acid as electron acceptor

Front 36

What is a Strickland reaction?

Back 36

?

Front 37

Catabolism of carbohydrates and intracellular reserves

Back 37

Many diff carbs can serve as energy source. Carbs can be supplied externally or internally

Front 38

Carbohydrate catabolism

Back 38

Monosaccharides
-converted to other sugars that enter glycolytic pathway
Disaccharides & polysaccharides
-cleaved by hydrolases or phosphorylases

Front 39

Give some examples of compounds used as stored energy

Back 39

-glycogen and starch; cleaved by phosphorylases. gluocse-1-P enters glycolytic pathway
-PHB and other poly-alkanoates; acetyl-CoA enters TCA cycle

Front 40

What is chemolithotrophy?

Back 40

Oxidation of inorganic molecules. Carried out by chemolithotrophs. Electrons released from energy source. ATP sythesized by oxidative phosphorylation

Front 41

Chemolithotrophs are usually aerobic or anaerobic?

Back 41

Aerobic

Front 42

Describe the electron transport system of ammonia-oxidizing bacteria

Back 42

?

Front 43

What is meant by reverse electron flow?

Back 43

?

Front 44

Metabolic flexibility of chemolithotrophs

Back 44

Many switch from chemolithotropic metabolism to chemoorganotrophic metabolism
Many switch from autotrophic metabolism (via Calvin Cycle) to heterotrophic metabolism

Front 45

Autotrophic growth by chemolithotrophs

Back 45

Calvin cycle requires NADH as electron source for fixing CO2. Many energy sources used by chemolithotrophs have E0 more positive than NAD/NADH. Use reverse electron flow to generate NADH.

Front 46

Distinguish between the light and dark reactions of photosynthesis

Back 46

light reactions; in which light E is trapped and converted to chemical energy

dark reactions; in which the energy produced in the light reactions is used to reduce CO2 and synthesize cell constituents

Front 47

Photosynthesis

Back 47

Energy from light trapped and converted to chemical energy

Front 48

Oxygenic Photosynthesis

Back 48

Eucaryotes and cyanobacteria

Front 49

Anoxygenic photosythesis

Back 49

All other bacteria

Front 50

Chlorophylls

Back 50

Major light-absorbing pigments

Front 51

Accessory pigments

Back 51

Transfer light energy to cholorphylls. e.gm carotenoids & phycobiliproteins

Front 52

Antennas

Back 52

Highly organized arrays of chlorophylls and accessory pigments

Front 53

Photosystems

Back 53

Antenna and its associated reaction center chlorophyll

Front 54

Green plate photosynthesis
Procaryotes

Back 54

Cyclic electron flow; ATP + NADHPH made (cyclic phosphosphorylation)

Plants & cyanobacteria noncyclic electron flow- ATP made (noncyclic phosphorylation)

Front 55

How does anoxygenic photosynthesis differ from plant photosynthesis?

Back 55

H2O not used as an electron source; therefore O2 is not produced. Only one photosystem involved. ???

Front 56

Describe the difference between photoosynthesis in the nonsulfur purple bacteria and the green sulfur bacteria

Back 56

?

Front 57

Succinate fumarate

Back 57

Electron source for generation of NADH by reverse electron flow

Front 58

Reverse electron flow

Back 58

ATP or PMF used to drive "upward" (reverse) flow of electrons

Front 59

Green sulfur bacteria

Back 59

Uses hydrogen sulfide as the electron donor