Microbial Genetics

Question 1

What is a conjugative plasmid?

Answer 1

carries genes necessary for transfer of plasmid to another cell

Question 2

Dissimliation plasmid are?

Answer 2

encodes for enzymes that catabolize unusual compounds.
Some species of Pseudomonas can actually use such exotic substances as toluene, camphor, and hydrocarbons of petroleum as primary carbon and energy sources because they have catabolic enzymes encoded by genes carried on plasmids.

Question 3

R Factors are?

Answer 3

encoding resistance to antibiotics and or heavy metals

Question 4

Bacteriocins are proteins made by?

Answer 4

Ribosomes.

Question 5

Bacteriocins and antibiotics are different how? Similar?

Answer 5

Bacteriocins are made by ribosomes. Similar by killing species.

Question 6

Lac - Means?

Answer 6

Cannot utilize lactose or lacking lactose

Question 7

Str(r) Means?

Answer 7

Resistant to the antibiotic streptomycin

Question 8

Deletion of a gene is denoted by?

Answer 8

Triangle (delta)

Question 9

Plasmid C has a defect in rsp43 and is resistant to streptomycin. What function does rsp43 have?

Answer 9

A function that streptomycin would attack.

Question 10

What is ORF?

Answer 10

Open-Reading Frame.

Question 11

What do the numbers represent in the genetics map of the chromosome of E. Coli?

Answer 11

Time of conjugation

Question 12

Why use a RNA primer?

Answer 12

To make sure the DNA polymerase removes it.

Question 13

Which topoisomerase uses ATP?

Answer 13

Topo II (gyrase)

Question 14

What do DNA gyrase and Histones have in common?

Answer 14

DNA gyrase compacts the bacterial DNA. Eukaryotes use histones to compact DNA.

Question 15

Table 8.1

Answer 15

Important Enzymes

Question 16

How are bacterial organisms capable of doubling replication time? (E. Coli 40 mins to 20 mins)

Answer 16

They can begin another replication of their DNA when they are halfway through.

Question 17

The terminator site is mediated by Rho. What mechanism does it have?

Answer 17

It’s a specific sequence that terminates transcription in prokaryotes.

Question 18

Rho-independent has what mechanism?

Answer 18

creates a loop with a stem of UUU’s and the polymerase falls off.

Question 19

Stop Codons (3)

Answer 19

UAA, UAG, UGA

Question 20

What does “degenerate” mean?

Answer 20

Multiple codons can code for the same amino acid

Question 21

80% of the codons found in genome X, code for CCU, 20% code for CCA. What explains the frequency if they both code for Proline?

Answer 21

Codon Bias- the frequency of different codons for the same amino acid could be different?

Question 22

In Prokaryotes: What is the Shine–Dalgarno (SD) sequence

Answer 22

A region before translation leading to the start codon,

Question 23

Repressor gene?

Answer 23

The default position is on.

Question 24

Inducible gene?

Answer 24

The default position is off. It binds the repressor protein and takes it off.

Question 25

The operator is?

Answer 25

Where the repressor binds.

Question 26

Beta-Galactosidase

Answer 26

Cleaves the Beta linkage in lactose to form glucose and galactose.

Question 27

Cleaving galactose can switch the bond between two sugars and create?

Answer 27

Allolactose.

Question 28

If Lactose and glucose are present…?

Answer 28

There will be no transcription.

Question 29

If Lactose is present and glucose is not

Answer 29

Transcription will occur.

Question 30

Low glucose means the activator will bind, what does that mean?

Answer 30

More cAMP (activator), more transcription.

Question 31

(Trp Operon) what regulates it?

Answer 31

Tryptophan.

Question 32

What does Allolactose regulate?

Answer 32

The repressor.

Question 33

What can activators do?

Answer 33

Recruit the polymerase to bind.

Question 34

What do CG nucleotides cause in the eukaryotes?

Answer 34

methylation (silencing genes)

Question 35

What do GA/TC nucleotides cause in the prokaryotes?

Answer 35

methylation and is important for restriction-modification.

Question 36

Post-transcriptional control in bacteria? (4)

Answer 36

1) mRNA stability
2) Translation
3) Protein stability
4) Regulatory RNA molecules; miRNA (Euk) and sRNA (Prok)

Question 37

Transitions are?

Answer 37

Purine to Purine

Question 38

Transversions are?

Answer 38

Purine to Pyrimidine vice versa

Question 39

Point Mutations are?

Answer 39

One base pair change.

Question 40

Base modifiers are

Answer 40

nitrous acid; change the nucleotide to bind a new nucleotide. C to A.

Question 41

Base analogs are

Answer 41

intercalation of the planar molecule can distort base stacking

Question 42

What is the use of velveteen?

Answer 42

Used in indirect and direct selection to imprint colonies.

Question 43

What does the AMES test do?

Answer 43

Testing for cells that do not have a functional histidine gene.
It looks for gene mutations in bacteria. If the substance has the ability to cause a mutation in the bacteria, it might be able to cause mutations in humans as well, and should therefore undergo further testing to determine whether it is safe or not.

Question 44

What is a highly competent bacterial cell capable of doing?

Answer 44

Greatly able to take up genetic information in transformation.

Question 45

Hfr stands for what?

Answer 45

High-frequency recombination.

Question 46

Why don’t [F-] cells become Hfr cells?

Answer 46

There is no homology for the F region in the chromosome found in the Hfr cell.

Question 47

Generalized transduction is?

Answer 47

Phages packages (any) piece from the chromosome.

Question 48

Specialized transduction is?

Answer 48

Phage packages only specific genes and creates a hybrid and a normal bacterial cell, creating two different phages.

Question 49

Cotransduction is the frequency of?

Answer 49

Two genes transducing together.

Question 50

Transposons are?

Answer 50

jumping genes can carry antibiotic resistance move via gene transfer.

Question 51

E. Coli 0157:H7 acquired the toxin gene by?

Answer 51

Specialized transduction.