Biology Midterm #2

CRISPR - Cas

encodes a spacer sequence between repeats from previous phage DNA, these are used to identify, transcription and processing makes there RNA which is a complement to the phage DNA. Then the Cas protein uses the complement RNA to bind to the DNA and cas protein cuts it out.

CRISP-Cas and miRNA-RISC

both use RNA guided endonucleases which means that proteins (Cas and protein complex) use RNA to recognize RNA from the phages and attach and cut out

RdRp

It’s a protein. Made from positive ssRNAs by ribosomes when it enters and is translated. Used to make the negative sense from the positive sense which is used to make positive sense. Essentially RNA makes RNA. In negative sense it needs to be brought in with the phage genome because it cannot be made from a negative strand.

Retroviruses

HIV which causes aids. Uses Reverse transcriptase to copy RNA into double stranded DNA which insets into the host chromosomes and never exists, RNA polymerase transcribes it into the host cells.

RISC

RNA induced silencing complex (regulates gene expression and is a protein)

Restriction Modification (EUKARYOTES)

RNA interference (RNAi) recognizes intermediate in virus replication that is double stranded RNA (dsRNA) and processes into short RNAs small interfering RNAs (siRNAs) that is made form the dsRNA these bind to the RISC that can target the viral RNAs for degradation.

Restriction Modification (PROKARYOTES)

identifies and cuts out by restriction enzymes. DNA in the host is methylated so that the restircion enzymes won’t but themseelcs. CRISPR-Cas encodes spacer which is made into RNA that compliments the phage DNA and uses the Cas protein to recognize and cut out.

COVID 19

SARS-CoV-2, large positive sense, ssRNA. Spike Protein helps enter the cell via ACER2 when protease cleaves the spike.

COVID 19 Vaccine

paxlovid targets Mpro. VACCINE is derived from pathogenic microbes and targets SPIKE proteins. vaccine that encodes spike but is synthesized with pseudouridine isntead of uridine which means that it’s not harmful to the cells. Encapsulated mRNA in lipid nanoparticle which can fuse to cells one of the lipids is ionizable which allows that can cling to the negative mRNA but it looses charge in alkaline like the blood to reduce toxicity.