Metabolism and Nutrition

Question 1

what do bacteria need to grow

Answer 1

suitable conditions: temp, pH, oxygen, salinity, pressure
carbon and an energy source
nutrients, vitamins

Question 2

bacteria can grow over a range of conditions

Answer 2

neutrophiles: pH 5.5-8.5
halophiles: 30% salinity
barophiles: 10 atm pressure
acidophiles: pH 1-5.5

Question 3

most bacteria are

Answer 3

chemoheterotrophs

Question 4

where do bacteria get their carbon from

Answer 4

photoautotrophs

Question 5

what is the most abundant monosaccharide on earth

Answer 5

glucose

Question 6

bacteria need what to grow

Answer 6

carbohydrate
phospholipid
amino acids

Question 7

binary fission

Answer 7

colonies start as a single bacterium and grow to a visible size

Question 8

what temp is bacteria grown at

Answer 8

room temp or incubator set to 37C

Question 9

selective medium

Answer 9

encourages growth of some species but not others

Question 10

example of selective media

Answer 10

inhibitory Mold Agar (IMA)… contains antibiotics to restrict growth of bacteria but not fungi

Question 11

differential medium

Answer 11

everything grows but there is a colour change to tell what is what

Question 12

selective and differential medium together

Answer 12

MacConky Agar…
selective: contains bile salts, disrupts peptidoglycan (Gram-_
differential: contains lactose and pH indicator, lactose fermentation produces pink

Question 13

example of differential medium

Answer 13

hemolysis on sheep blood agar
sugar fermentation… neutral=red, acidic=yellow

Question 14

metabolism

Answer 14

the sum of all chemical reactions in a cell

Question 15

catabolism

Answer 15

large molecules broken down into smaller ones, releases energy… exergonic-energy producing

Question 16

anabolism

Answer 16

small molecules are assembled into larger ones, using energy… endergonic-energy requiring

Question 17

enzymes

Answer 17

biological catalysts
lowers activation energy
catalyst is not depleted itself
end in “ase”

Question 18

induced fit

Answer 18

the enzyme shape changes to best fit the transition state of the reaction

Question 19

how do enzymes work

Answer 19

1. substrate enters active site of enzyme
2. enzyme/substrate complex forms
3. substrate is converted to products
4. products leave the active site of the enzyme
   -highly specific for substrates
   -reactants are the substrates of the enzyme

Question 20

enzymes are often ______

Answer 20

holoenzymes
1. aponenzyme becomes active by binding of coenzyme or cofactor to enzyme
2. holoenzyme is formed when associated cofactor or coenzyme binds to the enzyme’s active site

Question 21

______ are common cofactors

Answer 21

vitamins

Question 22

enzyme inhibition

Answer 22

competitive inhibitor: blocks the active site
allosteric inhibitor: changes the confirmation of the active site, no longer recognizes substrate
feedback inhibition: end product alters the beginning product

Question 23

six classes of enzyme

Answer 23

redox
single replacement
double replacement/acid-base
decomposition
isomerisation
synthesis

Question 24

how does energy move around the cell

Answer 24

electrochemical energy: ion gradients across membranes, rotate flagella, solute transport, ATP synthesis
chemical energy: carried in high energy molecules, drive biosynthetic reactions, phosphate bonds of ATP, reduced electron carriers, move electrons

Question 25

adenosine triphosphate (ATP)

Answer 25

energy currency of the cell
negative charges repel each other, bonds inherently unstable
generated during catabolism, and expended during anabolism
-adenine, ribose, adenine + ribose = adenosine, mono-, Di, Triphosphate

Question 26

electron carriers - oxidation-reduction (Redox) reactions

Answer 26

transfer energy between molecules in the form of electrons, occurs in pairs
reduction- gaining on electron
oxidation- losing an electron
both accept two electrons and two protons

Question 27

key functions of central metabolism

Answer 27

1. generate ATP
2. generate reducing power- drives electron transport chain, provide electrons for reduction reactions in biosynthetic pathways
3. precursor metabolites for other pathways

Question 28

catabolism of glucose- glycolysis

Answer 28

Embden-Meyerhoff-Parnas (EMP) pathway glycolytic pathway
does not require oxygen
produces ATP by substrate level phosphorylation
produces NADH and pyruvate
precursor metabolites

Question 29

transition reaction between glycolysis and Krebs cycle

Answer 29

1. a carboxyl group is removed from pyruvate, releasing carbon dioxide
2. NAD+ is reduced to NADH
3. acetyl group transferred to coenzyme A, resulting in acetyl CoA

Question 30

Krebs cycle

Answer 30

acetyl transferred from acetyl-CoA to oxaloacetate to form citrate
reduces CoA
produces: NADH, NADPH, FADH2, ATP, and CO2, precursors to 10 amino acid, oxaloacetate

Question 31

what does the electron transport chain generate

Answer 31

proton motive force

Question 32

how is the proton motive force generated

Answer 32

from the H+ ions that exit the cell from Glycolysis and Krebs cycle generates an electrochemical gradient

Question 33

what is the electrical potential from the proton motive force used for

Answer 33

to do work…
generate ATP
turn flagella
move solutes
oxidative phosphorylation

Question 34

potential production from one molecule of glucose

Answer 34

6 CO2, 10 NADH, 2 FADH2, 38 ATP

Question 35

aerobes

Answer 35

oxygen is essential because it serves as the final electron acceptor of the electron transport chain

Question 36

anaerobes

Answer 36

oxygen is toxic because of their inability to eliminate toxic forms of oxygen generated by some redox reactions

Question 37

fermentation

Answer 37

reducing power generated by oxidative reactions is re-oxidized by metabolites

no oxidative phosphorylation: ATP is produced solely from substrate-level phosphorylations

Question 38

acid production through fermentation

Answer 38

bacteria produce organic acids from fermentable carbohydrates
-heterofermentative bacteria: produce a mixture of metabolites… organic acids, ethanol
-homofermentative bacteria: produce > 90% lactic acid

Question 39

_______ ferments sucrose to lactic acid

Answer 39

streptococcus mutans

Question 40

how does streptococcus mutans ferment sucrose to lactic acid

Answer 40

sucrose —> fructose + glucose
glucose —-> lactic acid, sticks back onto pyruvate and makes lactic acid to demineralize enamel
fructan + glucan (mutan) —> dental plaque matrix