Eukaryotic vs. Prokaryotic genes

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Eukaryotic vs. Prokaryotic genes?
What are the differences?

How do eukaryotic genes make up a chromatid/chromosome? Do they coil around the chromatid/chromosome? Do they lie in straight rows to make a chromatid/chromosome? How?
Answer -
In prokaryotic cells (think bacteria), the genome (set of all the organism's gene's) is usually circular. They usually have only one chromosome, and it is not protected by any type of membrane, but rather floats in an irregularly shaped region of the cytoplasm called the nucleoid. The circular shape of the bacterial chromosome allows for the efficient replication of the genome during binary fission, as well as allows the chromosome to not need telomeres (regions of repetitive DNA the eukaryotic cells need at the end of their chromosomes protecting it from being destroyed).

In eukaryotic cells, the chromosome tends to be much larger and essentially linear. While bacterial cells have one chromosome, eukaryotic cells can have many and they are protected within a membrane-bound organelle called a nucleus.

The eukaryotic cell's DNA coils up around proteins called histones, which helps compress the DNA into a smaller volume. The histone proteins also play a role in eukaryotic gene regulation. This repeating unit of the chromatin, comprised of a histone and it's coiled DNA, is called a nucleosome. This level of structure looks much like beads on a string, and it in turn will coil up into a helical structure called a fiber. The fibers will also compress, and eventually become the linear structure you usually picture. Aiding in this coiling of DNA will be additional proteins

[Prof. Nagwa Aref]

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Dr. Nagwa