1. What cause eyes to be different colors?

The color of our eyes comes from the appearance of the pigment that is present in the iris, the central part of the eye. Brown eyes are rich in melanin pigment deposits, making them darker, while blue eyes lackmelanin. Heterochromia happens when the concentration and distribution of melanin isn't uniform.

Explanation:

Eye color is determined by genetics. The eyes can naturally change their color as a response to the iris expanding or contracting in the presence of light or as the iris ages. This results in the eyes gradually becoming darker or lighter in color.

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

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