Cellular Division

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Cellular Division

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Cell Division

All cells are derived from pre-existing cells

New cells are produced for growth and to replace damaged or old cells

Differs in prokaryotes (bacteria) and eukaryotes (protists, fungi, plants, & animals)

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Keeping Cells Identical

The instructions for making cell parts are encoded in the DNA, so each new cell must get a complete set of the DNA molecules

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DNA Replication

DNA must be copied or replicated before cell division

Each new cell will then have an identical copy of the DNA

Original DNA strand

Two new, identical DNA strands

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Identical Daughter Cells

Parent Cell

Two identical daughter cells

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Chromosomes

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Prokaryotic Chromosome

The DNA of prokaryotes (bacteria) is one, circular chromosome attached to the inside of the cell membrane

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Eukaryotic Chromosomes

All eukaryotic cells store genetic information in chromosomes

Most eukaryotes have between 10 and 50 chromosomes in their body cells

Human body cells have 46 chromosomes or 23 identical pairs

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Eukaryotic Chromosomes

Each chromosome is composed of a single, tightly coiled DNA molecule

Chromosomes can’t be seen when cells aren’t dividing and are called chromatin

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Compacting DNA into Chromosomes

DNA is tightly coiled around proteins called histones

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Chromosomes in Dividing Cells

Duplicated chromosomes are called chromatids & are held together by the centromere

Called Sister Chromatids

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Karyotype

A picture of the chromosomes from a human cell arranged in pairs by size

First 22 pairs are called autosomes

Last pair are the sex chromosomes

XX female or XY male

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