DNA to Chromosomes

Eukaryotic cell: Hierarchy of Biological Information

Human body cells each contain about 2 meters of DNA.

• If all the DNA in every cell of a person was stretched out it would reach to the sun and

back about 70 times!

Length of Human DNA

How can 2 meters of DNAfit here?!

Chromatin

• In eukaryotic cells, DNA is found in the form of chromatin during Interphase (living, functional phase)

• Euchromatin = loosely packed, “active” DNA segments

• Heterochromatin = tightly packed, inactive regions of DNA

Chromatin

Chromatin

• Chromatin = complex of DNA, proteins, and RNA with nucleosomes as the basic structural & functional unit.

The DNA Nucleosome and

Supercoiling

The answer is:

The DNA nucleosome

DNA actually occurs in units called nucleosomes during interphase.

Basic unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound in sequence around histone protein cores.

• Histone proteins = small positively charged proteins that compact DNA into the space of the eukaryotic nucleus

The DNA nucleosome: More images

Prokaryotic DNA organization

DNA to Chromosomes (Eukaryotic Cells)

"Chromatin Structures" by Original uploader was Richard Wheeler at en.wikipedia Later version(s) were uploaded by Seans Potato Business at en.wikipedia. - Transferred from en.wikipedia; Transfer was stated to be made by User:sevela.p.. Licensed under CC BY-SA 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Chromatin_Structures.png#mediaviewer/File:Chromatin_Structures.png

Chromosomes form when cells are preparing to reproduce!

Chromosomes are passed from one cell to the next!

DNA to Chromosomes Video Animation

Human Chromosome