Bacterial Genetics & Gene Regulation

Question 1

Describe the genetics of bacteria

Answer 1

haploid due to single bacteria chromosome

Question 2

What are the advantages of using bacteria for genetic analysis

Answer 2

easy to maintain in labs, gene transfer, mutant bacteria possible

Question 3

TRUE or FALSE - Bacteria can produce gametes

Answer 3

FALSE

Question 4

What do E.Coli grow on

Answer 4

simple liquid broth and solid agar petri dishes

Question 5

What do wild type bacteria grow well on

Answer 5

minimal media

Question 6

What is in minimal media

Answer 6

salt water and sugar

Question 7

What do wild type bacteria synthesise

Answer 7

amino acids and nucleotides themselves

Question 8

What do mutations in bacteria that block bio-synthetic pathways prevent

Answer 8

growth on minimal media

Question 9

Describe complete media

Answer 9

contains amino acids, vitamins, etc

Question 10

How can you identify mutations in bacteria

Answer 10

observe which bacteria grow on complete medium but NOT minimal medium

Question 11

What is an auxotroph

Answer 11

mutants that X synthesise essential nutrients

Question 12

What does changing composition identify

Answer 12

which pathways are affected

Question 13

What are prototrophs

Answer 13

wild types for a specific biosynthetic process - can synthesise

Question 14

What does gene transfer between bacteria require?

Answer 14

cell-cell contact

Question 15

How do we know gene transfer requires cell-cell contact?

Answer 15

block physical contact between bacteria

Question 16

Describe the direction of genetic exchange between bacteria

Answer 16

unidirectional

Question 17

How is DNA transferred between bacteria

Answer 17

Across a physical bridge from donor to recipient

Question 18

What enables bacteria to transfer genetic material

Answer 18

Fertility factor - F plasmid

Question 19

What is the function of the fertility factor?

Answer 19

enables carriers to conjugate with other cells without the F factor

Question 20

What is oriT

Answer 20

DNA sequence where transfer begins

Question 21

What do tra genes encode

Answer 21

components of transfer machinery

Question 22

What is F pilus

Answer 22

cytoplasmic bridge between two bacteria

Question 23

What creates the F pilus

Answer 23

transfer machinery

Question 24

Describe the fertility factor

Answer 24

Circular DNA

Question 25

What happens when bacteria with and without the F factor mate

Answer 25

F factor pulls across entire donor chromosome or fuses with chromosome

Question 26

Describe integration of the F plasmid with host chromosome

Answer 26

high frequency recombination event

Question 27

When do Hfr strains arise

Answer 27

when F plasmid recombines with host chromosomal DNA

Question 28

What causes the emergence of phototrophic colonies

Answer 28

formation of Hfr donor chromosomes

Question 29

Describe feedback inhibition

Answer 29

turns down genes

Question 30

How is transcription regulated

Answer 30

controlling DNA sequence next to the promoter

Question 31

What do repressors block the passage of in transcription

Answer 31

RNA polymerase

Question 32

What is the controlling site in transcription

Answer 32

operator

Question 33

How is transcription induced

Answer 33

dissociation of repressor from the operator

Question 34

What are lac genes required for in E.Coli

Answer 34

metabolism of lactose

Question 35

What is the lac operon

Answer 35

cluster of adjacent genes with closely related biochemical functions

Question 36

When is the lac operon activated

Answer 36

presence of lactose

Question 37

When is the lac operon inhibited/blocked?

Answer 37

presence of glucose

Question 38

What does the lac repressor block?

Answer 38

RNA synthesis of downstream genes

Question 39

What binds to the lac operon

Answer 39

lac repressor

Question 40

What can bind to the lac repressor

Answer 40

lactose

Question 41

What happens when lactose binds to the lac repressor

Answer 41

dissociation of repressor from operator

Question 42

What drives synthesis when bound to promoter

Answer 42

RNA polymerase and CAP protein

Question 43

What makes up the Trp operon

Answer 43

5 enzymes

Question 44

TRUE or FALSE - Trp operon is an activator

Answer 44

FALSE

Question 45

What suppresses transcription of the Trp operon

Answer 45

biosynthetic product of trp operon encoded enzymes - tryptophan