Cell Division Chapter 3

Do Now What happens when you get a cut? Use pictures, symbols, words, etc. to explain.

Objectives To list and explain the different reasons cells must divide. To define chromosomes and all their counterparts. To determine different things that limit cell size.

Cellular Division A. Cell division is involved in many functions. 1. Unicellular division= “binary fission” 2. Multicellular division = “mitosis”

Binary Fission http://www.youtube.com/watch?v=J6akNYlkehY

Multicellular Division http://www.youtube.com/watch?v=AhgRhXl7w_g

Why do we need cell division? Cell division is involved in many processes. a. Growth- get bigger b. Development- change c. Repair- fix damaged/old cells, cuts d. Reproduction- make new cells

B. Cell Division is involved in growth, development, and repair… All organisms start as a single cell Growth- limited by surface area ( needs high ratio of surface area to volume) High SA allows nutrients in & waste out

Surface area vs. volume http://www.brown.edu/Courses/BI0020_Miller/week/10/web-1/4-2-2007_10-20-26/Chapter_41/Present/Animations/41_A01/41_A01s.html

B. Cell Division is involved in growth, development, and repair… c. Development i. makes cells that are specialized ex: nerve, blood, muscle, bone

B. Cell Division is involved in growth, development, and repair… i. healing of cuts and wounds ii. Cells divide to fill space and close wound.

C. The genetic material of eukaryotic cells is organized in chromosomes. DNA (Deoxyribonucleic Acid) Discovered by Watson, Crick, and Franklin 1. purpose: hereditary material (what makes you you!) Shape: Double Helix 1. Repeating units of nucleotides

C. The genetic material of eukaryotic cells is organized in chromosomes. c. How does all of this DNA fit in a cell? 1. Loose= chromatin 2. Coiled around proteins- chromosome a. chromosome = 2 chromatids -connected by a centromere