Exam 2 Lecture 16

Question 1

Which end of the plasmid DNA is inserted first into recipient cell?

Answer 1

The 5’ end

Question 2

Does the donor cell donate the RNA polymerase to make the new DNA plasmid strand?

Answer 2

No the recipient cell uses it’s own RNA to make the new strand.

Question 3

Which kind of synthesis leading or lagging is used in each cell?

Answer 3

Leading is used in donor cell and lagging in the recipient

Question 4

What religates the DNA after new 2nd strands have been made?

Answer 4

Relaxase religates DNA at OriT

Question 5

Examples of common bacterial plasmids and their sizes and copy numbers?

Answer 5

F 100 kb/1

R100 94 kb/1

Ti 200 kb/1

RP4 60 kb/4

ColEl 9kb /30

Question 6

What does the R100 plasmid do and what is it’s host range?

Answer 6

Give resistance to drugs and Hg

Host range- Enterics (Shigellla)

Question 7

What does the Ti plasmid do and it’s host range?

Answer 7

Causes a plant tumor

Host Agrol/Rhizo

Question 8

What was the first known inter-kingdom DNA transfer?

Answer 8

The Ti plasmid from bacteria A. tumefaciens to plants via a Type IV conjugative pili where it integrates and causes tumors.

Question 9

What is a mobilizable plasmid and an example of one?

Answer 9

Mobilizable plasmids use other plasmids like the F plasmids encoded T4S/conjugative system to transfer themselves. If there is not an F plasmid in the new cell they can’t transfer again.

ColEl is an example

Question 10

Name some F plasmid relatives i.e. F-like plasmidsand some extra traits they might have?

Answer 10

pEK499, R100, and pEC985

Addition of tra genes that encode for antibiotic resistance to drugs such as Amp, Tet, and Amikacin.

pEC985 has IS/Tns and 13 antibiotic resistance genes in it.

Question 11

Do all Type IV systems transfer DNA?

Answer 11

No there are two branches of evolution in the Type 4 systems.

Some like B pertussis transfer pathogens and secrete only proteins.

Other do protein/DNA like in conjugative/mobilization

Question 12

Does both transformation and conjugation require ATP?

Answer 12

Yes both require ATPases

Question 13

Are bacterial viruses (phages) involved in remodeling bacterial DNA? If so how?

Answer 13

Yes via transduction and lysogeny

Question 14

Do bacterial genomes ever have viral DNA?

Answer 14

Yes often 10-15%

Question 15

How abundant are viruses?

Answer 15

Most abundant microorganisms on earth- about 10³¹ of them

Question 16

Describe a virus?

Answer 16

A non-cellular particle that must infect a host cell to survive.

Obligate intracellular parasites

Question 17

What do phages use and hosts?

Answer 17

Bacteria and Archaea

Question 18

What kind of genomic material is found in phages?

Answer 18

ssRNA, dsRNA (rare), ssDNA, dsDNA

Linear or circular

Question 19

Are phages and viruses the same size?

Answer 19

No phages tend to be smaller but both can vary widely in size

Question 20

How are viruses packaged?

Answer 20

Enclosed in a protein capsid made up of capsomers

Question 21

Two types of viral packaging?

Answer 21

Just a capsid- Naked

Capsid surround by an Envelope

Question 22

Envelopes are more common in phages or eukaryotic viruses?

Answer 22

Eukaryotic

Question 23

Does an envelope confer extra protection?

Answer 23

Not always, it can often make a virus more susceptible

Question 24

Common viral structures?

Answer 24

Naked viruses often exhibit icosahedral heads.

Others are filamentous helical with capsids in a helix around the genome

Question 25

True/ False Many tailed phages have dsDNA in head?

Answer 25

True

Question 26

True/ False Size of the genome is proportional to size of viral capsid

Answer 26

True

Question 27

What are tail structures used for?

Answer 27

To bind to host cell and inject DNA into it

Question 28

What bacterial secretion system are many tails similar to?

Answer 28

Type 6

Question 29

What is a unique Archaea virus morphology?

Answer 29

An unusual spindle shape but they also exhibit a wide variety of other shapes too

Question 30

How much of the viruses mass is genomic material?

Answer 30

25-50%

Question 31

Do viruses have a lot of “junk” noncoding DNA?

Answer 31

No, the material is tightly packed with not many extraneous non-coding areas.

Question 32

What % of M13 genome is coding regions?

Answer 32

90%

Question 33

Are phages metabolically active?

Answer 33

No, but they can contain enzymes needed for proliferation such as lysozyme or RNA/DNA polymerase

Question 34

How do most phage viruses replicate?

Answer 34

By killing/lysing host cell and releasing progeny

Question 35

How fast do phages kill host cells in some environments?

Answer 35

At a rate of 1-5% a day!

Question 36

Different ways phages recognize particular host cells?

Answer 36

Chi phage- Flagellum

MS 13 or MS2- F pilus

T1- Iron transport terminal

T4 or øX174- Lipopoly saccarides

On Gram+ peptidoglycan can act as receptor (not gram neg)

Question 37

Some major differences between Euk and bact viruses?

Answer 37

Eukaryots- capsid often enter host, often long latency periods and prolonged association

Bacterial Phage- most lyse host quickly not always