DNA to Chromosomes

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 more than 300 times!

How can 2 meters of DNAfit here?!

The DNA Nucleosome and

Supercoiling

The answer is:

Eukaryotic cell

The DNA nucleosome

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

The DNA nucleosome

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

Chromatin• Chromatin = complex of

DNA, proteins, and RNA with nucleosomes as the basic structural & functional unit.

• 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

• Non-histone proteins = other proteins in nucleus that are not associated with nucleosomes

Chromatin

Prokaryotic DNA organization

DNA to Chromosomes (Eukaryotic Cells)

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Chromosomes form when cells are preparing to reproduce!

Chromosomes are passed from one cell to the next!

Human Chromosome