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