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Cell Division Occurs
in All Organisms
Chapter 3.1C
Cell Division is involved in
many functions
Unicellular organisms reproduce through
cell division
Multicellular organisms: cell division is
involved in growth, development & repair, &
reproduction
How does cell division differ for unicellular
and multicellular organisms?
The genetic material of eukaryotic
cells is organized in chromosomes
 When a cell divides into two new cells, each
cell receives a full set of genetic material.
 The genetic material in cells is contained
in DNA molecules.

DNA: deoxyribonucleic acid
 DNA is a chemical that contains
information for an organisms growth and
function
 What is DNA and what purpose does it
serve?
DNA’s Discovery
 Watson and Crick built a DNA model
in 1953
 They showed that DNA is
made of two strands of
molecules joined in a structure
that resembles a twisted
ladder or double helix.
 How was DNA discovered?
Eukaryotic Cells
 In Eukaryotic cells, the cell’s DNA is found in
the nucleus
 DNA is wrapped around a protein core and
compacted into structures called chromosomes.
 Chromatids: two identical structures in a
chromosome
 Centromere: connect chromatids
 Humans have 46 chromosomes
 Describe how DNA is organized inside the
Nucleus
Cell division is involved in
growth, development, & repair
 Through cell division, a single cell becomes two cells, two
cells become four, and so on.
 Cell division is always occurring.
 As the cells divide what happens to some of them?
 They
specialize……this is what makes organisms different
 Cells have different life spans; Throat cells last 2-3 days
(about 60 hours)

You lose about 40,000 skin cells every minute
 At adulthood, you will have about 100 trillion cells
 Describe the purpose of cell division