Cellular Reproduction Chapter 6: pp. 116-137

Definitions Related to Cell Division Gene-a segment of DNA that codes for a protein or RNA molecule Chromatid- one pair of strands of DNA that make up a chromosome Centromere-

Chromosomes- DNA tightly coiled around proteins Humans have 46

Chromosomes affect Development Homologous Chromosomes- Similar in shape size and genetic content Diploid 2 sets of chromosomes Haploid One set of chromosomes Zygote Fertilized egg cell, the first cell

Chromosomes affect Development Autosomes Chromosomes that do not determine sex Sex Chromosomes Contain genes that determine male or female Karyotype A picture of the chromosomes in a dividing cell that shows the chromosomes arranged by size.

The Cell Cycle (Fig 6-6) Interphase: 90% of time First Growth (G1) In your book The Cell Cycle (Fig 6-6) Interphase: 90% of time First Growth (G1) Cell grows rapidly Synthesis Phase (S) Cell’s DNA copied Second Growth (G2) Prepare for Mitosis                                               

Cell Division- 3 types 1. Binary Fission- asexual reproduction that produces identical offspring

Cell Division 2. Mitosis – (Fig 6-9) Nucleus of cell divides In your book Cells must divide because Surface Area to Volume ratios get too small Skin Cells

Cellular Reproduction Link!Mitosis animation

Prophase Chromosomes coil up and become visible. The nuclear envelope dissolves and a spindle forms.

Metaphase Chromosomes move to the middle of the cell and line up along the equator. Spindle fibers link the chromatids of each chromosome to opposite poles.

Anaphase Centromeres divide Chromatids (now called chromosomes) move toward opposite poles

Telophase A nuclear envelope forms around the chromosomes at each pole Chromosomes uncoil LAST step in mitosis

Cytokinesis (Fig 6-10) Cytoplasm is divided in half. In your book Cytokinesis (Fig 6-10) Cytoplasm is divided in half. Cell membrane encloses each cell