bacterial growth, metabolism and respiration L9

Question 1

CATABOLISM

Answer 1

large molecules broken down into smaller molecules

proteins, glycerol fatty acids, polysaccharides, all are broken down, and go through a oxidation to pyruvate intermediate

Question 2

2 ways to produce

Answer 2

substrate-level phosphorylation - from glycolysis, KREBs

oxidative phosphorylation - from the ETC

Question 3

NAD+ —> NADH

Answer 3

reduction, gaining proton is reduction

Question 4

NADH —> NAD+

Answer 4

oxidation, losing proton

Question 5

bacterial respiration

Answer 5

series coupled oxidation and reduction reactions, using proton gradient

ETC transfer electrons down the chain, increasing H+ concentration out of cell

atp synthase, coverts kinetic energy by flow of protons down electrochemical gradient to produce ATP

Question 6

aerobic respiration

Answer 6

final electron acceptor = oxygen

oxygen is required

pathways = Glycolysis —> Krebs (TCA) —> ETC

up to 38 ATP produced

NAD+ regenerated in ETC

end products = co2 + h2o

high efficiency

Question 7

e.coli example as variant

Answer 7

has cytochrome b03 oxidase instead of cytochrome c

Question 8

anaerobic respiration

Answer 8

final electron acceptor = inorganic molecules, NO3-, SO42-, CO32-

oxygen not required but process isnt inhibited when o2 is around

pathways = glycolysis —> Krebs —> ETC

less ATP produced, depends on final electron acceptor

NAD+ regenerated at ETC

end products = CO2 + reduced compounds

moderate efficiency

Question 9

why is ATP yield less in anaerobic?

Answer 9

because only parts of Krebs cycle works in anaerobic conditions so less substrate level phosphorylation and less redox potential of final electron acceptor compared to O2

Question 10

compounds in anaerobic respiration

Answer 10

Reductase enzyme is used instead of cytochrome C

nO3- REDUCED to NO2-

so42- —> h2s

co32- —> ch4

Question 11

fermentation

Answer 11

no final electron acceptor, uses internal organic molecule instead of

no oxygen required, strictly anaerobic

glycolysis pathway only

2 ATP produced per glucose

NAD+ regenerated by pyruvate oxidation

end products = organic acids, alcohols, gases

low efficiency

Question 12

lactic fermentation

Answer 12

lactic acid produced

streptococcus, bacillus

Question 13

mix acid fermentation

Answer 13

produced ethanol, lactic, succinct, CO2 H2

e.coli, salmonella

Question 14

butyrate fermentation

Answer 14

butyric acid co2 and h2

clostridium

Question 15

ethanol fermentation

Answer 15

ethanol and co2 produced

yeast

Question 16

obligate aerobes

Answer 16

oxygen is required, aerobic respiration

Question 17

facultative aerobes

Answer 17

oxygen not required but grows better with it

undergoes aerobic anaerobic respiration and fermentation

Question 18

microaerophillic

Answer 18

requires oxygen at really lower levels

undergoes aerobic respiration

Question 19

aerotolerant anaerobes

Answer 19

oxygen not required and growth is no better when oxygen is there

undergoes fermentation or anaerobic respiration

Question 20

obligate anaerobes

Answer 20

oxygen is lethal
prefer fermentation but can do anaerobic respiration

Question 21

mycobacterium tuberculosis

Answer 21

this is an acid -fast rod
non motile
strictly pathogenic
facultative aerobe
and can be dormant

Question 22

metabolic flexibility of M.tuberculosis

Answer 22

survives in latent phase (dormant) in granulomas which have low oxygen and low nutrients

does this by switching to use fatty acids and cholesterol as carbon source (inside its self)

uses glyoxylate shunt to conserve carbon as bypass decarboxylation steps in KREBS

adapts ETC by cytochrome bd oxidase (better as higher o2 affinity), can use nitrate respiration and can survive via fermentation

Question 23

fermentation —> dental disease

Answer 23

lactic acid bacteria ferments sugars which produce lactic acid on teeth

this dissolves calcium phosphate

Question 24

binary fission

Answer 24

increase number of cells not size

budding, conidiospores and fragmentation are other methods

Question 25

binary fission process

Answer 25

1. elongation of cell wall, membrane and volume and chromosome duplication starts 2. septum wall grows inward and chromosomes pulled to opposite poles 3. septum is formed and cell membrane separated cell chambers

Question 26

Fts proteins

Answer 26

filamentous temperature sensitive these proteins interact to form the division, a cell division tool that forms the septal ring and helps define the cell division plane of where the two cells will divide

Question 27

dna replication and binary fission process

Answer 27

starts at origin oriC which is ignited by DnaA and then migrates to poles FtsZ protein forms Z-ring in middle of cell and contracts to form septum cell splits

Question 28

Min proteins

Answer 28

minCDE are cytoskelatal coiled in poles, form bipolar gradient to help localise ring in the centre MinC + MinD = inhibits FtsZ formation into Z-ring MinE moves MinCD from mid cell this allows Z-ring to form at mid cell and not a poles

Question 29

endospore formation

Answer 29

this is a survival mechanism triggered by harsh conditions endospores are resting stages that are highly resistant to heat, drying out etc protects bacterial genome until environment is better conditions

Question 30

endospore structure

Answer 30

core - DNA, ribosome, proteins inner membrane - lipids and proteins germ cell wall - peptidoglycan cortex = modified thick peptidoglycan, keratin, to reverse osmosis to dehydrate outermembrane coat = protein layers for UV and chemical protection exosporium in some species - glycoproteins

Question 31

what does dipicolinic acid do in endospores

Answer 31

forms a complex with ca2+, to bind water to make spore drier and more compact

Question 32

endospore formation

Answer 32

mother cell secreted protein coat - calcium dipicolinate to protect spore and then lyses to release spore asymmetric division of mother cell and forespore spore germinates when conditions are favourable