Importance of Cell Division

Importance of Cell Division You began life as a single cell: a fertilized egg Now your body is made up of trillions of cells How?? Cells divide to for 3 main reasons 2

1. Reproduction Involves the transfer of genetic information from parents to offspring Single cell organisms Asexual reproduction = 1 parent, offspring are exact genetic copies 3

1. Reproduction Multicellular Organisms Sexual Reproduction = cell from each parent containing 1/2 DNA (gametes) combine Offspring inherits traits from both parents 4

2. Repair When part of an organism is damaged the remaining cells divide to repair injury 6

2. Repair Every day your body sheds millions of dead skin cells Blood cells are replaced every 120 days Bones break and are healed Cells fill in gaps caused by cuts Lysosomes = search and destroy Ability to repair self keeps organism alive 5

Which organism has larger cells? 7

3. Growth As multicellular organisms grow, the number of cells increases Cells divide rather than grow beyond a certain size Why? 8

3. Growth Why? All cells need nutrients, water, energy & gases Large cell = increased volume Diffusion of these materials into and out of the cell would not happen fast enough Therefore cell would not function properly 9

What Limits Cell Size? Lab Monday Read over lab on page 38-39 Testable question: How does the size of a cell affect the distribution of chemicals throughout a cell? Come up with hypothesis/prediction - Ticket into Lab 10

Homework Questions Page 37 # 2-6 HAVE A GREAT WEEKEND! 11