Chromosomes and cell reproduction

Why does a cell reproduce?  Growth  Repair  Gamete production

What is the one thing each new cell must contain?

DNA Why?

Prokaryotes Reproduce by binary fission asexual produces an exact copy (clone) have one chromosome that is circular (a ring)

Eukaryotes Multiple, paired chromosomes Rod shaped (kinda) Sexual

Chromosome numbers for different organisms mosquito6 House fly12 corn20 human46 dog78

Things to remember  Each chromosome contains thousands of genes  Humans must have all 46 chromosomes in order to survive  Having extra chromosomes usually results in death. At the very least, development is impaired

Examples of trisomy Down’s Syndrome (#21) Patau’s Syndrome (#13) Edwards Syndrome (#18) Most include physical deformities (cleft palate, small eyes, enlarged tongue, clenched fingers, heart problems, etc.

Mutations These involve missing portions of chromosomes, or chromosomes that have broken fragments rearranged in a new order

Mutation Types Deletion – a chromosome is missing a segment Duplication – a chromosome has a duplicated segment (like a stutter, or repeated portion) Inversion – a chromosome fragment breaks off, and reattaches in reverse order Translocation – a chromosome fragment breaks off, and reattaches to a non- homologous chromosome