Importance of Cell Division Importance of Cell Division

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 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 3

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

2. Repair • When part of an organism is damaged the remaining cells divide to repair injury 6 5

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 6

Which organism has larger cells? 7 7

3. Growth • As multicellular organisms grow, the number of cells increases • Cells divide rather than grow beyond a certain size • Why? 8 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 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 10

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