Lecture 10-MT2 Flashcards
What is an enterotube?
Quick detection tool that is used in clinics to perform many biochemical tests in 1 tube
-entero = GI tract
What are bacteriophages?
Viruses that infect bacteria
What is CRISPR (Clustered regularly interspaced short palindromic repeat)?
An adaptive immune response in prokaryotes
Steps of lytic cycle
- attachment
- virus infects phage
- synthesis of viral DNA
- Assembly
- release by LYSIS
What happens if the phage does not kill the host?
The host keeps a mugshot of virus by using Cas enzyme to cut piece of viral DNA & inserts it into CRISPR locus
What is a CRISPR locus made of?
-Semi-palindromic repeats
-Spacers (DNA sequence from invader)
-CAS gene
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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-at the 5’ end
-upstream of the most recent spacer already incorporated
3 stages of CRISPR?
- Adaptation
- Expression
- Interference
What is Adaptation?
Host integrates & keeps a short sequence of phage DNA into CRISPR
What is Expression?
Sequences are transcribed/processed to make cRNA which do surveillance around cell for specific invader
-cRNA–>has snapshot of specific invader
What happens if a similar phage attacks the bacterium again?
Interference happens
What is interference?
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
What is natural immunity?
Acquired through normal life experiences of human and does not come from medical means
Active immunity (Natural)
Develop antibodies against a pathogen
-from infection
Passive Immunity (Natural)
Receiving immunity from another person
-Breastfeeding
What is artificial immunity?
Immunity that comes from medical procedures
-Immunization
Active immunity (Artificial)
Developing own immune response to microbe
-Vaccine–>immune system makes antibodies from acquiring microbe artificially
Passive immunity (Artificial)
One person receiving preformed immunity made by another person
-Immune globulin therapy
How common is for bacterium to acquire spacers from natural environments?
It is rare in natural environments
-in lab it is common
True or false: CRISPR is common in gut microbiome
False
CRISPR spacer acquisition is a rare event in human gut microbiome
How can a bacterium get CRISPR locus (acquired immunity)?
-Natural infection
-Vaccines
What does pasteurization do?
Heats and cools milk to kill pathogenic bacteria like M.tuberculosis & M.bovis
What kind of bacteria survive pasteurization?
Thermoduric/thermophilic bacteria survive
How to prevent phage infections in dairy industry?
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
