Lecture 10-MT2

Question 1

What is an enterotube?

Answer 1

Quick detection tool that is used in clinics to perform many biochemical tests in 1 tube
-entero = GI tract

Question 2

What are bacteriophages?

Answer 2

Viruses that infect bacteria

Question 3

What is CRISPR (Clustered regularly interspaced short palindromic repeat)?

Answer 3

An adaptive immune response in prokaryotes

Question 4

Steps of lytic cycle

Answer 4

1. attachment
2. virus infects phage
3. synthesis of viral DNA
4. Assembly
5. release by LYSIS

Question 5

What happens if the phage does not kill the host?

Answer 5

The host keeps a mugshot of virus by using Cas enzyme to cut piece of viral DNA & inserts it into CRISPR locus

Question 6

What is a CRISPR locus made of?

Answer 6

-Semi-palindromic repeats
-Spacers (DNA sequence from invader)
-CAS gene

Question 7

A DNA sequence coming from a phage is integrated into the
CRISPR locus of the host DNA where other phage sequences
are already present as spacers. In particular, considering those
spacers in the locus, the new sequence is integrated …
A) at the 5’ end
B) at the 3’ end
C) upstream of the most recent spacer already incorporated
D) randomly on the locus as long as a palindromic repeats
separate it from another spacer
E) A and C
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Answer 7

-at the 5’ end
-upstream of the most recent spacer already incorporated

Question 8

3 stages of CRISPR?

Answer 8

1. Adaptation
2. Expression
3. Interference

Question 9

What is Adaptation?

Answer 9

Host integrates & keeps a short sequence of phage DNA into CRISPR

Question 10

What is Expression?

Answer 10

Sequences are transcribed/processed to make cRNA which do surveillance around cell for specific invader
-cRNA–>has snapshot of specific invader

Question 11

What happens if a similar phage attacks the bacterium again?

Answer 11

Interference happens

Question 12

What is interference?

Answer 12

if the cRNA sequence matches the new phage DNA then the cRNA can bind to it
-cRNA recruits Cas9 protein which cuts phage into double strand break–>infection is blocked

Question 13

What is natural immunity?

Answer 13

Acquired through normal life experiences of human and does not come from medical means

Question 14

Active immunity (Natural)

Answer 14

Develop antibodies against a pathogen
-from infection

Question 15

Passive Immunity (Natural)

Answer 15

Receiving immunity from another person
-Breastfeeding

Question 16

What is artificial immunity?

Answer 16

Immunity that comes from medical procedures
-Immunization

Question 17

Active immunity (Artificial)

Answer 17

Developing own immune response to microbe
-Vaccine–>immune system makes antibodies from acquiring microbe artificially

Question 18

Passive immunity (Artificial)

Answer 18

One person receiving preformed immunity made by another person
-Immune globulin therapy

Question 19

How common is for bacterium to acquire spacers from natural environments?

Answer 19

It is rare in natural environments
-in lab it is common

Question 20

True or false: CRISPR is common in gut microbiome

Answer 20

False
CRISPR spacer acquisition is a rare event in human gut microbiome

Question 21

How can a bacterium get CRISPR locus (acquired immunity)?

Answer 21

-Natural infection
-Vaccines

Question 22

What does pasteurization do?

Answer 22

Heats and cools milk to kill pathogenic bacteria like M.tuberculosis & M.bovis

Question 23

What kind of bacteria survive pasteurization?

Answer 23

Thermoduric/thermophilic bacteria survive

Question 24

How to prevent phage infections in dairy industry?

Answer 24

Dairy companies, vaccinate (pre-expose) bacterial strains with phages
-bacterial strains become resistant to phage infections b/c they have CRISPR locus and are used in yogurt/cheese production