Question

Strain R of E. coli has an RM system that modifies/cleaves the sequence GAATTC. Sometimes invading phage DNA is methylated by the strain R methylase before the endonuclease can cleave the viral DNA, and then replicates in the methylated form and forms viral particles. If you add some of these viral particles to uninfected bacteria of strain R, what will happen? Select one: a. The invading phage DNA is methylated and thus cleaved by the strain Rendonuclease b. The invading phage DNA is unmethylated and is protected from the strain Rendonuclease C. Strain Ris resistant to all phage, no matter the source d. The invading phage DNA is unmethylated and will be cleaved by the strain Rendonuclease e. The invading phage DNA is methylated and protected from the strain Rendonuclease

Answer 1

Answer:

2). D. The X and Y chromosomes separate at Anaphase I

Explanation:

b. The X and Y chromosomes line up independently at the metaphase plate of mitosis.

c. The sister chromatids of the X and Y separate at Anaphase II

e. Males have only one X-chromosome.