Be sure to answer all parts. imagine conducting the meselson and stahl experiment on dna that is replicated by the dispersive mechanism. after 3 rounds of replication, what percentage of the dna would contain exclusively 15n, exclusively 14n, or a mix of 14n and 15n?

25% mixture of N15 and N14 and 75% of exclusively N14.

Explanation:

In the Meselson and Stahl experiment a double DNA chain formed by N15 is placed in a medium with only N14. Therefore, when replicated, the new chains will be synthesized with N14 (lighter). This can be corroborated by centrifuging the sample.

Before replication, a single band corresponding to the double helix of N15 DNA is observed.

After a single replication, only one band corresponding to DNA is observed with 1 strand N15 and 1 strand N14.

After the second replication, two bands will be observed. One for DNA of 1 strand N15 and 1 strand N14 and the other for DNA of 2 strands N14.

The same will happen for the third replication. At this point, the DNA present will consist of a 25% mixture of N15 and N14 and 75% of exclusively N14.

This experiment proves that DNA replication is semi-conservative.

i believe the correct answer is the virus gets an envelope that contains host molecules when it leaves the host cell.

explanation:

during the bidding/release stage of a virus, it encapsulates itself with part of the membrane of the host cells in this case the cells of the monkey and is the reason as to why the scientist found the genetic material of the monkey on the viral cell surface.

further explanation

to understand this answer, we have to know the cycle a virus undergoes to replicate. a virus is basically a bunch of genetic material enclosed in a capsule and lacks any machinery or organelles to ensure their survival so they must enter a host cell in order to get the environment needed to survive. some viruses enter and lyse(destroy) the host cell after they have replicated and undergo the lytic cycle while some enter and leave the cell intact after replicating and these undergo a lysogenic cycle. to enter the cell, they undergo the first process called attachment by binding to specific receptors and co-receptors on the surface of the host cell. after attaching to the cell, they start the second phase called penetration where virus enters or is engulfed whole by the host cell through a process called endocytosis. it is the same process that a cell takes up materials it needs or pathogens around it. uncoating of the virus then happens after the virus has been engulfed and is the third stage. the virus then undergoes releasing of its genetic material in the host's matrix.   the materials then enter the nucleus and undergo biosynthesis by adding themselves in strands of rna being translated and then copies of the virus are produced in addition to the host genetic material. the material/newly formed viral material then undergoes assembly inside the host cell and form a capsule around them. the virus undergoes the last release/budding stage by binding to the host membrane and pushing outwards. in doing so when they tear away from the host membrane, they pick up the genetic material from the membrane of the host cell to form their envelope.

learn more:

1.

2.

3.

level: high school