Mid Term 1 Review Questions (Part 4)

Question 1

what is an operon, what do it do?

Answer 1

a unit of linked genes under the control of one promoter

Question 2

what do you call the kind of message that an operon sends?

Answer 2

polycistronic messages

Question 3

what kind of messaging do prokaryotes use?

Answer 3

polycistronic

Question 4

what kind of messaging do eukaryotes use?

Answer 4

monocistronic

Question 5

what is quorum sensing?

Answer 5

bacterial cells sensing the density of nearby cells

Question 6

what is a 2 component system?
aka, what are the two parts, and what is the function?

Answer 6

1. sensor and responder
2. sense environment and respond to it

Question 7

pretty please give an example of two component regulatory systems. who are the players, and what happens?

Answer 7

efflux pump operon expression.
- sensor baeS and responder baeR
- baeR is phosphorylated

Question 8

what is the difference between phase variation and antigenic variation, and how are they used to evade the immune system?

Answer 8

• PHASE: on/off
• ANTIGENIC: change
• EVADE: take off the hat vs. change to a green hat

Question 9

which type of variation involves switching genes on and off

Answer 9

phase

Question 10

which type of variation involves changing the genes

Answer 10

antigenic

Question 11

how is HGT different from mutation?

Answer 11

Generation: HGT occurs within the same generation, whereas mutation is passed from parent to offspring.
Change: mutation yields 1/2 mutated and 1/2 not mutated, HGT yields 100% recipient
Time: HGT brings about more change faster than mutations

Question 12

what changes can HGT bring about?

Answer 12

disease-causing traits

Question 13

in which methods of HGT does the donor survive?

Answer 13

conjugation

Question 14

in which methods of HGT does the donor not survive?

Answer 14

transformation and transduction

Question 15

what happens to donated DNA if no origin of replication?

Answer 15

has to be integrated into recipient DNA

Question 16

what is competence?

Answer 16

the ability to uptake naked DNA

Question 17

how do scientists study transformation if a cell is not inherently competent?

Answer 17

by changing the surface charge of the recipient cell (from negative) to something else in the lab

Question 18

what charge does DNA have?

Answer 18

negative

Question 19

what charge does the surface of a cell have?

Answer 19

negative

Question 20

why does the charge of DNA and surface of a cell present a problem?

Answer 20

means that not all cells are inherently competent

Question 21

are any methods of HGT resistant to DNase?

Answer 21

yes, transformation

Question 22

why is transformation sensitive to DNase?

Answer 22

it’s the only method of HGT that has free DNA. the other two either never leave the cell or are protected by bacteriophages.

Question 23

how does plasmid transfer via conjugation take place?

Answer 23

F+ x F- = F+ x F+

Question 24

F+ x F- = F+ x F+
is what kind of transfer

Answer 24

plasmid transfer via conjugation

Question 25

Hfr x F- = Hfr x F-
is what kind of transfer

Answer 25

plasmid transfer via conjugation

Question 26

what is the formula for plasmid transfer via conjugation?

Answer 26

Hfr x F- = Hfr x F-

Question 27

what do we mean by antibiotics?

Answer 27

a compound naturally produced by molds or bacteria that inhibits the growth of or kills other microorganisms

Question 28

who produces antibiotics?

Answer 28

soil microbes

Question 29

what do antibiotics act on?

Answer 29

bacterial growth

Question 30

what do antibiotics not work on?

Answer 30

eukaryotic growth

Question 31

what is selective toxicity?

Answer 31

causing a greater harm to the pathogen than the host

Question 32

what are the two main groups of soil microbes

Answer 32

bacteria and fungi

Question 33

what are the five targets of antibiotic drugs?

Answer 33

great wall!
1. cell wall (peptidoglycan synthesis)
2. nucleic acid synthesis
3. cell membrane integrity
4. metabolic pathways (folate biogynthesis)
5. protein synthesis

Question 34

how do antimicrobial drugs target the cell wall?

Answer 34

by targeting peptidoglycan synthesis

Question 35

how do antimicrobial drugs target metabolic pathways?

Answer 35

folate biosynthesis

Question 36

how to calculate the therapeutic index?

Answer 36

lowest dose toxic to the patient / dose typically used

Question 37

which is safer, a drug with a therapeutic index of 2, or one with a therapeutic index of 100?

Answer 37

100. larger TI = safer drug.

Question 38

given the choice between a therapeutic index of 2 or 100, why would a doctor use a drug with a therapeutic index of 2?

Answer 38

because the 100 wasn’t working.

Question 39

what’s one way that antimicrobial drugs target cell wall synthesis?

Answer 39

B-lactam drugs

Question 40

what is the target of B-lactam drugs?

Answer 40

peptidoglycan synthesis

Question 41

what does penicillin bind to?

Answer 41

penicillin-binding proteins, aka PBPs

Question 42

what is transpeptidase?

Answer 42

a penicillin-binding protein

Question 43

what do B-lactam drugs do in general?

Answer 43

inhibit cell wall synthesis

Question 44

how do B-lactam drugs inhibit cell wall synthesis?

Answer 44

by inhibiting the enzymes that form cross links between adjacent glycan chains. if penicillin can’t form to PBP, new peptidoglycan can’t be formed, so you’ve got chains but no linkage and they fall apart.

Question 45

what eventually happens to a cell that’s been personally affected by B-lactam drugs?

Answer 45

the cell membrane gets bigger but the cell wall doesn’t, so eventually the cell explodes!