<span>The lytic cycle is a six-stage cycle. In the first stage, called "penetration", the virus injects its own nucleic acid into ahost cell. In some viruses this genetic material is circularand mimics a bacterial plasmid. The virus hijacks the cell's replication and translation mechanisms, using them to make more viruses.</span>
B. There are several new ideas about the causes of rise in sea level.
Answer:
B) Viruses are killing some of his B cells and becoming incorporated into the genomes of others.
Explanation:
Epstein-Barr virus causes infectious mononucleosis by following mechanism.
1) Epstein-Barr virus attaches to and infects epithelium of the throat where it replicates and causes pharyngitis.
2) Virions enter the lymphoid vessels and are carried to the lymph nodes. Some virions escape the lymphnode trap and are carried to the bloodstream.
3) Virions attach specifically to B lymphocytes and infect them, producing either latent infection or productive infection.
4)The infected B lymphocytes actively replicate and differentiate into cells producing random immunoglobulins.
5)T cells respond to infection and destroy the lymphocytes replicating EBV vitus.
6) Latently infected B lymphocytes become immortal. They are not attacked by T cells.
Answer:
The correct answer is b. recognizes foreign DNA sequences that have previously entered the cell and directs the Cas proteins to destroy them.
Explanation:
Clustered regularly interspaced short palindromic repeats (CRISPER) is the sequences of DNA found in the genome of prokaryotes and archaea. These sequences are added at a crisper locus in DNA by bacteria through capturing bacteriophage DNA during infection.
Then this sequence is used to detect a similar sequence of bacteriophage during subsequent infection and destroy them by Cas9 enzyme. Cas 9 enzyme uses a crisper sequence as a template to destroy similar phage DNA.
So the CRISPER Cas system provides an adaptive defense mechanism to bacteria against foreign DNA coming from bacteriophage. Therefore the correct answer is b.
