Chromosome Structure Flashcards

Where is the bacterial chromosome located?

The nucleoid.

Is the bacterial nucleoid surrounded by a membrane?

No.

What is bacterial DNA in direct contact with?

The cytoplasm.

How is bacterial DNA organized inside the cell?

It is highly folded into twisted loops.

What is supercoiling?

Additional twisting of DNA that helps organize and compact it.

What does negative supercoiling promote?

DNA strand separation.

What enzyme introduces negative supercoils in bacterial DNA?

DNA gyrase.

What is another name for DNA gyrase?

Topoisomerase II.

Does DNA gyrase require ATP?

Yes.

What enzyme relaxes negative supercoils?

Topoisomerase I.

What are the 3 important DNA sequences required for eukaryotic chromosome replication and segregation?

Origins of replication, centromeres, and telomeres.

What is the function of an origin of replication?

It is a site where DNA replication begins.

What is the function of the centromere?

It plays a role in chromosome segregation.

Where are telomeres located?

At the ends of chromosomes.

Why are telomeres important?

They are important for replication and chromosome stability.

What is chromatin?

DNA associated with proteins.

What important proteins are associated with DNA in chromatin?

Histones.

What charge does DNA have?

Negative.

What charge do histones have?

Positive.

Why are DNA and histones attracted to each other?

Their opposite charges attract.

What would happen if the positive charges on histones were neutralized?

Histones would separate from DNA.

What is a nucleosome?

DNA wrapped around core histone proteins.

How many core histones are in one nucleosome?

8.

What is the fundamental repeating unit of chromatin?

The nucleosome.

What does "beads on a string" describe?

Nucleosomes connected by linker DNA.

What are the "beads" in beads on a string?

Nucleosomes.

What is linker DNA?

DNA connecting neighboring nucleosomes.