FINAL EXAM P2

Question 1

DNA to DNA

Answer 1

is standard in all cells and is done by DNA polymerase
process is called replication
is done to reproduce the genome

Question 2

DNA to RNA

Answer 2

is done by RNA polymerase
process is called transcription
is done by every cell on Earth

Question 3

RNA to RNA

Answer 3

is done by RNA replicase

is only found in viral replication

Question 4

RNA to DNA

Answer 4

is done by reverse transcriptase

is only found in retroviruses

Question 5

lytic infection (T4 phage)

Answer 5

in every case where a phage infects a cell, the end result will by lysis and cell death
not all phages kill cells
early middle and late steps must happen in order or reproduction will not be efficient
99.9% of cells choose this pathway

Question 6

early gene expression

Answer 6

takes over the cellular machinery

Question 7

middle gene expression

Answer 7

has nucleic acid replication

Question 8

late gene expression

Answer 8

has capsomers, assembly, packaging, and lysis

Question 9

takeover

Answer 9

part of lytic cycle
done with the production of nucleases
drives it away from the host to transcribe phage genes. after it makes several copies of its own DNA, late expression begins

Question 10

nuclease

Answer 10

degrades the host cell genome/DNA
produces its own DNA polymerase
makes its own sigma factor

Question 11

sigma factor

Answer 11

binds to the host cell RNAP to direct it to a specific set of promoters found on the phage DNA

Question 12

T4 lysozyme

Answer 12

makes the protein that breaks down PG

can never be lysogenic

Question 13

lysogenic/temperate phage

Answer 13

aka lambda phage
shuts itself down, turning off its own gene expression so it doesn’t kill the cells. instead, it inserts its genome into the host genome. it stays there silently, not harming the cell; it’s part of the genome
every time the cells replicates its genome, it also replicates the phage genome, passing it on to its progeny
0.1% of cells choose this pathway

Question 14

prophage

Answer 14

phage is called this when it is inserted into the host cell genome

Question 15

lysogen

Answer 15

the host strain that carries the prophage
the prophage is in the lysogen
it can be induced, causing the prophage to unsilence itself and start expressing its genes
it will then be excised out of the host DNA and go back into the lytic cycle

Question 16

induction

Answer 16

caused by DNA damage to the host cell when UV light or chemicals that damage the host DNA
if the cell carrying the prophage is endangered, that cell may die. if it dies, than the phage is dead and will never be able to replicate again. this makes it the right time for the prophage to come out and produce progeny that can hopefully go on and infect other cells

Question 17

RNA phage (MS2)

Answer 17

an E. coli phage
only has 4 genes. they encode a maturation protein, a coat protein (encodes the capsomer), a lysis protein (eventually lyses the cell), and one for RNA replicase
some of the genes are overlapping into different reading frames. lysis overlaps into the coat and replicase regions. allows for more coding capacity

Question 18

+RNA in virion

Answer 18

serves as mRNA and as a template for -RNA
key for making the RNA replicase
is packaged into new virus capsids