Chromosomes

Chromosomes Defined: Tightly coiled DNA Form when cells divide Chromosomes created for the new cells 2 Parts: 1) Chromatids: two identical parts of a chromosome 2) Centromere: Joins chromatids together Chromosomes

Karyotype Female Male Defined: Picture of an individuals chromosomes Help identify sex & chromosome defects Size of final pair identifies sex Same size: XX = female Different size: XY = male Normal human will have 46 chromosomes Female Male

Down Syndrome: What’s Wrong? Writing notation: 1st: total chromosome # 2nd: Sex chromosomes 3rd: extra or missing Down Syndrome 47, XY, +21

Turner’s Syndrome: What’s Wrong? Write the notation for Turner’s Syndrome. 45, X, -23 or 45, XO, -23

Patau’s Syndrome: What’s Wrong? Write the notation for Patau’s Syndrome. 47, XY, +13

Klinefelter’s Syndrome: What’s Wrong? Write the notation for Klinefelter’s Syndrome. 47, XXY, +23

Diploid Cells Diploid Cells = Cells with the full set of chromosomes Paired chromosomes Half of our chromosomes come from each parent (23 from each parent) Somatic (non-sex) cells are diploid Created by mitosis Ex: Skin, Muscle, Nerve, Blood Cells

Haploid Cells Haploid Cells = Cells with ½ the total number of chromosomes Gametes (sex cells) are the only haploid cells Ex: Sperm, Egg, Pollen Created by meiosis Chromosome number reduced by 1/2 How do humans get 46 chromosomes? Haploid sperm cell (23) + Haploid egg cell (23) = Diploid zygote (46)

Diploid Karyotype Haploid Karyotype Because diploid cells have the full set of chromosomes, you will see chromosomes paired.

Rat Karyotype Is this a male or female rat? male

Rat Karyotype What is the diploid chromosome number? 42

Rat Karyotype What is the haploid chromosome number? 21

Rat Karyotype How many chromosomes would be in somatic cells? 42

Rat Karyotype How many chromosomes would be in brain cells? 42

Rat Karyotype How many chromosomes would be in gamete cells? 21

Rat Karyotype How many chromosomes would be in egg cells? 21

Rat Karyotype How many chromosomes would be in muscle cells? 42

Rat Karyotype How many chromosomes would be in sperm cells? 21

Review 1) What is the difference between chromatin, chromatids, and chromosomes? 2) Name the location where chromatids connect. 3) Examine the karyotype. What the haploid number? Diploid number? Somatic number? Gamete number? 4) Which of the following cells are created by mitosis? Skin Nerve Sperm Brain Kidney Stomach Pollen 5) Which of the following cells are created by meiosis? 6) Which of the following cells are haploid? 7) Which of the following cells are diploid?