DNA Packaging | Overview & Levels

What is the main goal of cell division?

To ensure that each daughter cell receives one copy of every chromosome.

Why is DNA important in cell division?

DNA serves as the blueprint for building a cell, and errors in DNA can lead to defective cells, diseases, or death.

How long is the DNA in a single human cell if stretched end to end?

Approximately 2 meters (7 feet).

How does DNA fit inside the small nucleus of a cell?

DNA is wrapped around proteins called histones to form chromatin, which is further compacted into structures like nucleosomes.

What process compacts DNA to make it easier to move during cell division?

Chromosome condensation.

What is the final level of DNA compaction during mitosis?

A mitotic chromosome structure that's approximately 10,000 times more compact than the original DNA strand.

What are histones, and why are they important?

Histones are proteins around which DNA wraps to form chromatin, helping compact DNA and regulate gene expression.

Name three common types of histone modification.

Histone acetylation, histone methylation, and histone phosphorylation.

What is histone acetylation, and what does it do?

The addition of an acetyl group to histones, leading to open chromatin structure and increased gene expression.

What is histone methylation, and how does it affect gene expression?

The addition of methyl groups to histones, which can increase or decrease gene expression depending on the location of the modification.

What is a karyogram?

An organized picture of all mitotic chromosomes, used to study the karyotype of an organism.

How many pairs of chromosomes do humans have, and what is special about the 23rd pair?

Humans have 23 pairs of chromosomes. The 23rd pair determines sex and is not identical in males (XY).

Why are condensed chromosomes easier to study than chromatin?

Condensed chromosomes are highly organized and easier to distinguish, while chromatin is a less structured mass.

What is the purpose of staining chromosomes in a karyogram?

To give each chromosome a unique pattern, making it easier to differentiate between them.

What is mitosis?

The process of separating nuclear DNA into identical complements for new daughter cells.