Cell DivisionCells & Heredity Chapter 2.3

Pages 61-68

The Cell Cycle

• The sequence of growth and division of cells is called the Cell Cycle.

Consists of 3main stages… Mitosis

Cytokinesis

Interphase

Stage 1 - Interphase

• Cell grows to maturity, completely forming its functional structures

• Doubles in size• Copies its DNA in the

nucleus via Replication• Cell prepares to divide.

Stage 2 - Mitosis

• A copy of DNA is distributed to each of 2 daughter cells

• Four Phases– Prophase– Metaphase– Anaphase– Telophase

Key Terms

• Chromatin: Material in cells that contain DNA• Chromosome: doubled rod of condensed

chromatin• Chromatid: identical strands held together by

a centromere.

1. Prophase– Chromatin condenses to

chromosomes– Spindle fibers form bridge

2. Metaphase– Chromosomes align in

center– Attach to spindle fibers

3. Anaphase– Chromosomes split as

spindles retract– Cell begins stretching

4. Telophase– Chromosomes stretch out– Nuclear membrane forms

Stage 3 - Cytokinesis

• Cytoplasm separates organelles as it divides into two cells

• The membrane pinches off– Plant cells can not

pinch, instead form a cell plate.

Round & Round

• Duration of Cell Cycle varies on type of cell being created– Liver cells take 22

hours– Brain cells never

divide.

What to Work On

• Read Section 2.3 in the textbook– Pages 61 to 68

• Answer the Section Review questions– Page 68– Numbers 1 through 4.

What to Work On

• Complete the following Section Reviews– Page 44, #1-4– Page 54, #1-4– Page 59, #1-5