Bacterial Aerobic Respiration L13

Question 1

what is the terminal electron acceptor

Answer 1

in aerobic respiration oxygen is used as terminal electron acceptor in electron transport chain

Question 2

what are the pathways in aerobic respiration

Answer 2

glycolysis
Krebs cycle/citric acid cycle (CAC)/tricarboxylic acid cycle(TCA)
oxidative phosphorylation via electron transport chain

Question 3

what is the net result of aerobic respiration

Answer 3

all C atoms in glucose are converted to carbon dioxide

38 ATP molecules from one molecule of glucose

Question 4

where does glycolysis and TCA cycle occur in bacteria

Answer 4

in bacteria glycolysis and the TCA cycle occur in the cytoplasm

Question 5

what happens to the electrons after glycolysis and TCA cycle

Answer 5

electrons are picked up from intermediates of glycolysis and TCA cycle by NAD /FAD

Question 6

what produces NADH

Answer 6

conversion of pyruvic acid to acetyl CoA

Question 7

what does NADH and FADH2 do

Answer 7

NADH or FADH2 take the electrons to the electron transport chain

Question 8

what creates the most ATP

Answer 8

Most ATP is generated by the chemi-osmotic potential generated as part of electron transport = oxidative phosphorylation

Question 9

what reactions in glycolysis use ATP

Answer 9

glucose in cell and prepared we start to consume ATP – preparatory reactions use ATP

Question 10

what happens in stage 2 glycolysis

Answer 10

+2 ATP
+1 NADH
-1 Pi

Question 11

what is the structure of glucose at the start of the reaction

Answer 11

glucose –> glucose-6-phosphate

Question 12

what is formed at the end of glycolysis

Answer 12

pyruvate 3 carbon atoms

Question 13

what is produced in the TCA cycle

Answer 13

3 carbon dioxide
4 NADH
FADH
GTP

Question 14

what happens in the TCA cycle

Answer 14

pyruvate enters lose COA = acetyl Coa
Lose c if lose a CO2
Join cycle with a4 c
Lose two more carbon round cycle

Question 15

how does the electron transport system allow energy conservation

Answer 15

production of the proton motive force which is used to synthesise ATP

Question 16

what is oxidative phosphorylation

Answer 16

electrons ——————->O2
ADP–>ATP
electron flow - proton motive force

Question 17

what is a classic experiment to show bacteria can grow under a range of different atmospheric conditions

Answer 17

Bacteria are inoculated at low cell density (not visible) into soft agar
Poured into test tubes and incubated to allow growth
agar becomes opaque = growth
Cells evenly distributed in the tube wont move around as embedded in agar

Question 18

what happens if oxygen is the terminal electron acceptor - patterns of growth in test tube

Answer 18

growth at top where oxygen is

Question 19

what happens if bacteria grows all through the tube

Answer 19

doesn’t require oxygen for growth

Question 20

what do patterns reveal - growth of bacteria in test tubes

Answer 20

ability of bacteria to adapt to different levels of oxygen present in their environment

Question 21

how does the bacterial electron transport chain differ to mitochondria

Answer 21

Bacterial electron transport chains are usually shorter than those in mitochondria

Question 22

how do the bacterial electron transport chains vary

Answer 22

contain different cytochromes

also contain branches allowing alternative routes of electron flow

Question 23

what are the cytochromes

Answer 23

CytO

CytD

Question 24

what is CytO

Answer 24

better at pumping out hydrogen levels, but limited as not as good at finding oxygen
high aeration, fast growth

Question 25

what is CytD

Answer 25

better at scavenging oxygen when low | low aeration, stationary phase growth

Question 26

what is NADH

Answer 26

electron donor

Question 27

what is ubiquinone

Answer 27

(Q) connects NADH dehydrogenase to branches I and II

Question 28

what happens in electron transport

Answer 28

Electrons pumped out – energise, membrane Electron go from cytochrome B to O On other side B B D Different options of which cytochromes will form complexes Change depending on the conditions

Question 29

why does the system change between CtyO and CytD

Answer 29

``` System I (Cyt D) is better at scavenging oxygen when concentrations are low but is less efficient at pumping out H+ ions System II (Cyt O) is better at pumping out H+ ions but requires higher oxygen concentrations to function Different systems used to optimise energy production depending on the external environment ```

Question 30

what is ArcB

Answer 30

transcription regulator

Question 31

what does the transcription regulator do

Answer 31

senses the levels of O2 and switches from low affinity to high affinity cytochromes will pickup phosphate and autophosphorylate in response to lower [O2 ] Transfers phosphate to cytoplasmic ArcA which can regulate gene expression

Question 32

cytochrome O

Answer 32

cyoABCDE

Question 33

cytochrome D

Answer 33

cydAB

Question 34

where is ArcB

Answer 34

in the membrane

Question 35

what happens in regulation of gene expression by redox-sensitive Arc

Answer 35

1. High [O2] ArcB predominates – cyo O made from cyoABCDE 2. [O2] drops, ArcB-P formed; 3. ArcA-P down regulates cyoABCDE 4. ArcA-P induces cydAB

Question 36

what is the response of further growth patterns

Answer 36

responses are bacteria making different cytochromes

Question 37

what is a way we can classify bacteria according to growth pattern

Answer 37

bacteria can grow under different atmospheric conditions

Question 38

what is a strict aerobe

Answer 38

cant grow without oxygen | growth at top of test tube only

Question 39

example of a strict aerobe

Answer 39

pseudomonas spp.

Question 40

what is a facultative anaerobe

Answer 40

grows fastest with oxygen but can grow without | growth most at top of test tube and spreads down

Question 41

what is an example of a facultative anaerobe

Answer 41

Enterobacteriaceae (e.g. Escherichia coli); | has to live in the environment and in the GI tract

Question 42

what is a microaerophile

Answer 42

requires lower oxygen than atmospheric growth | growth only under the 'agar' at top of the test tube

Question 43

example of a microaerophile

Answer 43

campylobacter | Intestinal pathogen capable of surviving in the environment

Question 44

what is aerotolerant anaerobe

Answer 44

grows best anaerobically but tolerates oxygen evolved before oxygen around growth throughout test tube

Question 45

examples of aerotolerant anaerobe

Answer 45

Lactobacillus & Streptococcus | used in fermentations (cheese & yoghurt)

Question 46

what is a strict anaerobe

Answer 46

requires O2 to be absent | growth only at the bottom of the test tube

Question 47

examples of strict anaerobe

Answer 47

Clostridium spp. in soil C. tetani in deep wounds C. perfringens causing GI infections Methanogens in GI tract

Question 48

what is a canophile

Answer 48

grows best with raised carbon dioxide levels | microaerophiles and aerotolerant anaerobes