) Imagine that you are studying a newly discovered bacteria from a hot spring in Yellowstone National Park. You examine the nitrogenous bases of this organism, and find that 10% of the nitrogenous bases in its DNA are adenine. What percentage of nucleotides are cytosine

Cytosine- 40%

Explanation:

DNA is the genetic material in virtually all living organisms. It is a molecule made up of long chains of nucleotides, which are its building block. Four types of nucleotides make up the DNA molecule viz: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).

According to Erwin Chargaff in his rule regarding DNA composition, he stated that in a DNA molecule, the amount of adenine must equal thymine while that of guanine must equal cytosine. In a nutshell, the total of all the base pair must equally be 100% i.e. (A + T) + (G + C) = 100%.

In this case where a newly discovered bacteria from a hot spring in Yellowstone National Park was found to contain 10% of adenine in its DNA. Since Adenine is 10%, Thymine base must also be 10% in accordance to Chargaff's rule.

Hence, 10% + 10% + (G + C) = 100%.

20% + G + C = 100%

G + C = 100 - 20

G + C = 80%

Since, G and C must be equal, then G = C = 80% ÷ 2 = 40%. This means that the percentage of cytosine will be 40%.

you are certainly talking about this picture:

a: is the label of the white square, it is showing the  replication fork, formed by helicase (d) ==> so it is the site of dna separation and replication 

b: is a new dna brand that is following directly the replication fork, so it is continuous ==> built continuously from 5' to 3

c: dna polymerase cannot replicate dna on its own, it needs the of their proteins, and one of them plays the role of a clamp which fixes  the dna with the dna template and increases  the processivity of the enzyme. ==>   stops polymerase from falling off the  template.

d: is the enzyme responsible for forming the replication fork (helicase) ==> unwinds and separates dna into two strands

e: is the delayed strand, it is built  in the opposite sense of the helicase, so dna will be built in fragments ==> built  fragments from 5' to 3 joins

and finally f: is the enzyme that builds  the new dna strand (dna polymerase) ==>   adds nucleotides to make a new dna helix.

credit: gradman555p98x9p

read more on -