Microbiology: Chapter 10

Front 1

What is the primary cycle of Carbon assimilation used by autotrophic bacteria?

Back 1

The Calvin-Benson Cycle

Front 2

What is the role of NADPH in CO2 fixation?

Back 2

NADPH acts as an electron donor

Front 3

The generation of glyceraldehyde-3-phosphate from 3-phophoglycerate uses parts of what other pathway?

Back 3

It is essentially a reversal of a portion of the glycolytic pathway (EMP) (except it uses NADP+ rather than NAD+)

Front 4

The conversion of glyceraldehyde-3-phosphate to ribulose-5-phosphate uses parts of what other pathway?

Back 4

Reverse PPP

Front 5

What is the cost in ATP and NADPH to fix one CO2?

Back 5

Cost: 3 ATP and 2 NADPH

Front 6

What is gluconeogenesis and when would a cell engage in it?

Back 6

Gluconeogenesis is the synthesis of of new glucose (from noncarbohydrate precursors). A cell would engage in it when it requires more glucose (i.e. a heterotroph)

Front 7

Does gluconeogenesis require ATP and does it produce coenzymes?

Back 7

Yes, it requires 2 ATP. No, it does not produce coenzymes.

Front 8

Can you recognize the addition units for polysaccharide biosynthesis?

Back 8

ADP- or UDP-glucose, UDP-galactose, adn UDP-glucuronic acid.

Front 9

In assimilatory nitrate reduction, N is reduced to what level before it is incorporated into organic constituents in the cell in "primary amination" rxns?

Back 9

N is reduced to an ammonium ion (NH4+) to be incorporated into organic constiuents.

Front 10

What is the role of transaminases?

Back 10

Transaminases catalyze the formation of several amino acids using the same AA as an amino group donor (they transfer the alpha-amino group to other carbon skeletons)

Front 11

What enzyme complex is responsible for N fixation?

Back 11

Nitrogenase (complex of MoFe protein and 1 or 2 Fe proteins)

Front 12

What kinds of organisms can fix N?

Back 12

Only prokaryotes have nitrogenase and can fix N (1. free-living bacteria, 2. symbiotic bacteria, and 3. cyanobacteria)

Front 13

What is the role of the heterocyst and how does it insure the functionality of Nitrogenase?

Back 13

The heterocyst protects nitrogenase from toxic O2. It has thick cell walls and employs cyclic (anoxygenic) photophosphorilation.

Front 14

What is Leghemoglobin? Is it bacterial (Rhizobium) or plant (legume) in origin?

Back 14

Leghemoglobin is a compound molecule that converts N2 to NH4+. It is part bacterial (from Rhizobium) and part plant (from legume) in origin.

Front 15

Which metabolites of the central metabolic pathways are the substrates for AA biosynthesis (5 'Families' of AAs)?

Back 15

(1)alpha-ketoglutarate, (2)Oxaloacetate, (3) Pyruvate, (4) 3-Phosphoglycerate, and (5) Erythrose-4-phosphate

Front 16

Why are anaplerotic reactions required?

Back 16

Anaplerotic reactions are required to replenish components of cyclical pathways (both catabolic and anabolic) (Pg. 210)

Front 17

What is the Glyoxylate Cycle and when is it used?

Back 17

The Glyoxylate Cycle is a modified TCA cycle in which the decarboxylation reactions are bypassed by the enzymes isocitrate lyase and malate synthatse; it is used to convert (2)acetyl-CoA to succinate and other matabolites (oxaloacetate). It is used in orgs using acetate as sole C source.

Front 18

How does the pentapeptide formation on UDP-NAM differ from polypeptide formation in translation?

Back 18

Pentapeptide formation on UDP-NAM is a strictly enzyme driven process, it does not occur on a ribosome or involve RNA

Front 19

What is unique about the terminal two amino acids (UDP-NAM pentapeptide)?

Back 19

They are 2 alanine residues: D-alanyl-D-alanine, in the form of a dipeptide

Front 20

What is bactoprenol?

Back 20

Bactoprenol is a 55-carbon alcohol tht attaches to NAM by a pyrophosphate group and moves peptidoglycan components through the hydrophobic membrane

Front 21

What happens after the NAG is added to the bactoprenol-NAM-pentapeptide?

Back 21

After NAG is added to the bactoprenol-NAM-pentapeptide the complex is translocated to the exterior of the membrane

Front 22

What provides the energy for the glycosidic bond formed with the addition of the repeat unit to the peptidoglycan?

Back 22

-PO4 bond is energy is used to add onto glycosidic backbone

Front 23

What provides the energy for the peptide bond formed in the cross-linkage of adjacent glycosidic backbones in the PG?

Back 23

The D-ananyl-D-alanine bond is cleaved and provides the energy for cross-linkage of adjacent glycosidic backbones.

Front 24

What becomes of the bactoprenol after it donates a repeat unit?

Back 24

The bactoprenol returns to the cytoplasm to do its job again after it donates a repeat unit.

Front 25

Describe the centripetal growth of cell walls for Streptococci.

Back 25

In Streptococci centripetal cell wall growth, there is usually only 1 to a few zones of growth; the cell wall lengthens along an equitorial band and a notch is formed; this notch pinches together (septation) and forms 2 daughter cells.

Front 26

How does cell wall growth of Streptococci differ from growth of Gram-negative bacilli?

Back 26

In cell wall growth for Gram-negative bacilli, many growth sites are scattered along the cylindrical portion of the rod (diffuse growth); the rod must lengthen then divide (by septation as with Step.)

Front 27

What are autolysins?

Back 27

Autolysins are enzymes that partially digest peptidoglycan in growing bacteria so that the peptidoglycan can be enlarged.