6.1 Chromosomes and Meiosis
UNIT 3: GENETICS:
The study of genes, heredity, and variation.

6.1 Chromosomes and Meiosis
• Onion Root Mitosis Lab

6.1 Chromosomes and Meiosis
• Onion Root Mitosis Lab

6.1 Chromosomes and Meiosis
• Onion Root Lab Makeup Grade:
– See Biology calendar on my web site (click Friday 10/24) for a makeup assignment that will replace lab grade
– Make-up assignment due by Wednesday 10/29

6.1 Chromosomes and Meiosis
CHAPTER 6: MEIOSIS
Process that creates sex cells (sperm/eggs)

6.1 Chromosomes and Meiosis
SECTION 6.1: CHROMOSOMES :
Bundles of DNA that form during mitosis

6.1 Chromosomes and Meiosis
Human cells contain 46 chromosomes (23 pairs)
• 22 of these pairs are homologous pairs
– One came from Mom, one from Dad
– They are almost identical

6.1 Chromosomes and Meiosis
Chromosomes that are NOT sex chromosomes are called
AUTOSOMES
• Humans have 44 autosomes

6.1 Chromosomes and Meiosis
Sex Chromosomes (X and Y) determine gender
• XX = GIRL
• XY = BOY

6.1 Chromosomes and Meiosis
Two Types of Cells in your body
1. Somatic Cells
• Normal body cells
• Found everywhere in body
2. Gametes
• Sex cells
• Found in ovaries and testes

6.1 Chromosomes and Meiosis
Two Types of Cells in your body, continued
1. Somatic Cells
• Diploid: they have 2 copies of each chromosome (46 total)
2. Gametes
• Haploid: They have only 1 of each chromosome (23 total)

6.1 Chromosomes and Meiosis
• Fertilization occurs when a sperm and egg combine
– Sperm (23 chromosomes/haploid) + Egg (23) = New human! (somatic cell, diploid, 46 chromosomes)

6.1 Chromosomes and Meiosis
Different species have different numbers of chromosomes (whatever works!!)
• Fruit fly, 8
• Human, 46
• Goldfish, 100
• Tongue fern, 1,200

6.1 Chromosomes and Meiosis
6.1 Study Guide due @ end of class

6.1 Chromosomes and Meiosis
• Contrasting MITOSIS and MEIOSIS