class #4- bacterial genetics

Question 1

what is a bacteriophage

Answer 1

a virus that parasitizes a bacterium by infecting it and reproducing inside it

Question 1

what is the lytic cycle

Answer 1

-injection of phage dna
-replication & synthesis of new phage particles
-packaging of DNA into heads
-lysis
-infection (start again)

Question 2

what is lysis

Answer 2

disintegration of cell by rupture of cell wall or membrane (killing)

Question 3

what is the hershey heaven and the waring blender experiment

Answer 3

an experiment to prove dna is genetic material using s35 (radioactive sulfur) and p32 (radioactive phosphorus)

Question 4

what was the role of s35 in hershey ex

Answer 4

to label protein

Question 5

what was the role of p32 in hershey ex

Answer 5

to label the dna

Question 6

what happened in the hershey ex

Answer 6

1. let phage absorb to bacteria then put in blender
2. separate phage from bacteria: s35 went with phage(virus) and p32 when with bacteria

Question 7

how did the hershey experiment prove that dna was genetic material

Answer 7

p32 was detected in cells (was in dna) s35 was not detected in cells (was in protein)

Question 8

what is a phage plaque

Answer 8

zone of lysed bacteria

Question 9

what is a turbid plaque

Answer 9

created by a lysogenic phage

Question 10

what is turbidity caused by

Answer 10

Caused by bacteria that have been infected and the phage has integrated into the genome

Question 11

what is generalized transduction

Answer 11

The process by which phages can package any bacterial DNA (chromosomal or plasmid) and transfer it to another bacterium.

Question 12

where does generalized transduction occur

Answer 12

during the lytic cycle

Question 13

what happens during generalized transduction

Answer 13

host dna is degraded and bits are mistakenly packaged along with phage dna, host dna is now transferred to another host

Question 14

is generalized transduction efficient

Answer 14

no, b/c only a single phage is getting packaged with dna from host

Question 15

what is transformation

Answer 15

the uptake of naked dna.

Question 16

what important experiment used transformation to show that DNA is genetic material?

Answer 16

Griffiths experiment (rats, s strain and r strains)

Question 17

what are the most desperate ways to transform DNA

Answer 17

-biolistic transformation
-electroporation

Question 18

what is naturally competent bacteria

Answer 18

bacteria that are naturally “competent” to take up DNA, they have structures & systems dedicated to taking up dna

Question 19

who is Joshua Lederberg

Answer 19

he coined the term “plasmids”, nobel prize for conjugation 1959

Question 20

what is conjugation

Answer 20

bacterial “sex”, where one bacterium transfers genetic material to another through direct contact

Question 21

what are self-transmissable plasmids

Answer 21

they encode machinery to iniate conjugation and transfer plasmid

Question 22

what is a mobilizable plasmid

Answer 22

can be transferred but need Tra functions supplied in trans

Question 23

role of donor and recipient in conjugation

Answer 23

donor- has plasmid
recipient - gets plasmid

Question 24

how is dna transferred in conjugation

Answer 24

rolling circle replication, direct contact between 2 bacteriums

Question 25

what is CRISPR

Answer 25

adaptive immunity for bacteria
Clustered Regularly Interspaced Short Palindromic Repeats

Question 26

what are CAS

Answer 26

CRISPR associated genes

Question 27

how does CRISPR work

Answer 27

1. the array is transcribed
2. Cas gene products process array
3. crRNA has a piece that is bound by the Cas9
4. crRNA-Cas9 complex can recognize specific DNA sequences

Question 28

what are transposons

Answer 28

DNA elements that ecode transposase,
they insert randomly

Question 29

role of transposase

Answer 29

they copy a short sequence of DNA and allows DNA to ‘jump’

Question 30

what is Barbara McClintock’s main contribution

Answer 30

she developed notion of gene regulation

Question 31

what is target duplication

Answer 31

it follows after insertion, duplicates a small genetic sequence

Question 32

what aids in duplicating a target sequence

Answer 32

transposase

Question 33

what is a promoter

Answer 33

A region of DNA upstream of a gene where relevant proteins bind to initiate transcription of that gene.

Question 34

what does a promoter drive

Answer 34

drives the expression of a single gene, or mulitple genes (co-expression)

Question 35

what is an operon

Answer 35

where genes that are co-expressed are found

Question 36

what is an activator

Answer 36

proteins that bind to DNA at sequence sites to promote RNA polymerase function

Question 37

who is Jacques Manod and what did he contribute

Answer 37

-founder of molecular bio
-worked out lac operon and trp operon

Question 38

what is a repressor

Answer 38

they block binding of RNA polymerase to promoter
their ability to bind DNA is often regulated by cofactors (sugars or other metabolites)

Question 39

in the lac operon, what is the uninduced state

Answer 39

lacl (repressor) binds to operator
no transcription

Question 40

what is a non-inducible mutant

Answer 40

lacZ, the Lacl repressor can no longer bind to lactose

Question 41

in the lac operon, what is the induced stat:

Answer 41

-the inducer (lactose) binds Lacl (repressor)
-and Lacl cannot bind to operator
-transcription of operon

Question 42

what is a constitutive mutant

Answer 42

when lacl: no repressor, no repression
and Oc: repressor binding site damaged, Lacl is made but cannot bind

Question 43

what is a cis mutation

Answer 43

cis-acting locus: a genetic region affecting the activity of genes on that same DNA molecule

Question 44

what is a trans mutation

Answer 44

trans-acting locus: encodes for a factor that can act else where