Chapter 8 Microbial Genetics Pt2

Question 1

What is gene regulation, why is it important

Answer 1

Cells turn enzymes on and off to control metabolism; prevents synthesis of unneeded enzymes
Save energy

Question 2

What are constitutive genes and what % of all genes are constitutive

Answer 2

Their products are constantly produced at a fixed rate (60-80% of genes) always turned on

Question 3

Genes that code for products cell doesn’t always need; not always turned on

Answer 3

Inducible genes

Question 4

Genes that are normally on, which are usually the constitutive genes, are called

Answer 4

Repressible genes

Question 5

Repression vs induction (to control gene regulation)

Answer 5

Repression: inhibits gene expression and decreases synthesis of enzymes
Induction: turns on transcription of gene(s)

Question 6

What is a silent mutation

Answer 6

Doesn’t result in change of amino acid

Question 7

2 different kinds of base substitution mutations

Answer 7

Missense- results in change of 1 amino acid

Nonsense- results in change of 1 of stop codons ( May create a stop codon in middle of mRNA)

Question 8

Which base substitution is almost always lethal

Answer 8

Nonsense mutation

Question 9

A frame shift mutation is what kind mutation

Answer 9

Base insertion or deletion

Question 10

What Ames test determines

Answer 10

Whether a substance was mutanegenic, and therefore carcinogenic

Question 11

How come when a known mutagen, like salmonella that cannot produce histidine, is added to an unknown mutagen grows (even without histidine present)

Answer 11

This means that the unknown mutagen is mutangenic, it caused mutations in the salmonella so it could begin producing histidine

Question 12

3 natural types of recombination in bacteria

Answer 12

Transformation , conjugation, transduction

Question 13

What is transformation

Answer 13

Genes transferred from one bacteria to another (pick up from environment) incorporate into own genome

Question 14

The experiment that proved transformation also proved that

Answer 14

DNA is the genetic material

Question 15

In the experiment that proved transformation, how come the 4th mouse died? Even tho it was only injected w living nonencapsulated bacteria and heat killed encapsulated bacteria

Answer 15

While only live encapsulated bacteria are able to evade the immune system and kill the mouse, the killed encapsulated bacteria transformed capsule forming genes to the live unencapsulated bacteria

Question 16

What is conjugation

Answer 16

Recombination via a sex pili or making bridge (physical connections )

Question 17

Which cell is the recipient cell during conjugation (F pos or neg)

Answer 17

F- (becomes F+)

Question 18

During conjugation, the Plasmid contained within the F+ cell is also called

Answer 18

The F factor

Question 19

When the F factor becomes integrated into the chromosome of an F+ cell it becomes a

Answer 19

Hfr cell (High frequency of recombination cell)

Question 20

What is a bacteriophage

Answer 20

A virus that infects bacteria

Question 21

How transduction works

Answer 21

1) bacteriophage injects DNA into cell and takes over host
2) new phages begin forming inside host, during assembly pieces of bacterial DNA are packaged into phage capsids
3) when host lyses, releases phages (some only have bacteria DNA rather than viral)
4) infect other hosts and incorporated into chromosome