Lecture 20 - Viruses pt 2 Flashcards
What are 3 Prokaryotic defenses?
- evolution of host cell surface receptors
- restriction enzymes
- CRISPR-Cas9 immune system
What is the cycle of evolution between prokaryotes and viruses?
- host evolves to prevent attaching
- viruses evolve to attach anyway
What are restriction enzymes?
enzymes that cut the genome at a particular spot in the sequence
Why are restriction enzymes used against viruses?
cuts the viral sequence into 2
How do restriction enzymes not eat its own genome?
-methylates its own DNA
What does a phage do in response to the host methylating?
phage methylates its own restriction sites
What does the host do in response to the virus methylating?
host detects and cuts methylated sites into phage via MDS
How does the phage protect its methylated sites?
glusoclation
What is CRISPR-Cas9?
specific gene editing system
What are the 4 steps to CRISPR?
- virus invades bacterial cell
- new spacer derived from virus, integrated into CRISPR
- CRISPR RNA formed
- CRISPR RNA guides molecular machinery to target + destroy viral genome
What are 4 defenses Humans have against viruses?
- evolution
- immune system
- vaccines
- antiviral drugs
viruses are a dominant driver of _____ ______ in mammals
protein adaption
What is a vaccine?
- harmless variant/derivative of a pathogen
- stimulates the immune system to mount defenses
What is herd immunity?
- if most individuals in herd are vaccinated
- can prevent spread of virus
- chance lowered
How does the immune system work?
- WBC
- macrophages swallow up germ (leave antigen)
- evoke antibody response
