Chromosomes

Defined: Tightly coiled DNA Chromosomes

Chromosomes Defined: Tightly coiled DNA Form when cells divide Chromosomes created for the new cells 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 centromere left chromatid right chromatid

Karyotype Female Male Defined: Picture of individual 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 per cell Female Male

Types of chromosomes

I’m seeing something that concerns me a little bit I’m seeing something that concerns me a little bit. I think we should consider a karyotype. It’s hard to know. Once we examine the baby’s chromosomes we will have more information. Oh no! Is it serious?

Doctor: I’m gonna insert this needle and suck up some fluid. Cells from the baby should be in this fluid. Now that cells have been obtained, chromosomes can be seen and photographed

Under a microscope, the stained chromosomes are randomly scattered.

The lab technician arranges the chromosomes into pairs so the karyotype can be analyzed.

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: 30 seconds to discuss with your neighbor. Write the notation for Turner’s Syndrome. 45, X, -23 or 45, X0, -23

Patau’s Syndrome: 30 seconds to discuss with your neighbor. Write the notation for Patau’s Syndrome. 47, XY, +13

Klinefelter’s Syndrome: 30 seconds to discuss with your neighbor. Write the notation for Klinefelter’s Syndrome. 47, XXY, +23

Diploid Cells Diploid Cells: Cells with full set of chromosomes Paired chromosomes Humans: 23 pairs; 46 total Somatic (non-sex) cells are diploid Ex: Skin, Muscle, Nerve, Blood Cells Created by mitosis

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 half

I’m half mom and half dad. How do humans get 46 chromosomes? These 23 chromosomes are in the egg cell of mom. These 23 chromosomes are in the sperm cell of dad.

Zygote (fertilized egg) is created 23 chromosomes 23 chromosomes 46 23 chromosomes 23 chromosomes 23 chromosomes 23 chromosomes Zygote (fertilized egg) is created

46 46 46 46 Zygote divides by mitosis 9 months later…

Diploid karyotype: Chromosomes in pairs Haploid Karyotype Diploid karyotype: Chromosomes in pairs Haploid karyotype: Single chromosome

1 Minute: Discuss this rat karyotype with your neighbor. Gender? Number of chromosomes in a somatic cell? In a skin cell? In a gamete? In a diploid cell? In a sperm cell? female 42 42 21 42 Notice there are 21 pairs of chromosomes 21

1 Minute: Discuss this gorilla karyotype with your neighbor. Number of chromosomes in a haploid cell? gamete? In a muscle cell? In a zygote? In an egg cell? 24 24 48 48 Notice there are 24 pairs of chromosomes 24

Quiz 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?

8) Left, Middle, or Right: Which karyotype is from a diploid cell? 9) Left, Middle, or Right: Which karyotype could be from a muscle cell? 10) Left, Middle, or Right: Which two karyotypes could be from a sperm cell? 11) Left, Middle, or Right: Which karyotype is from an egg cell? 12) Left, Middle, or Right: Which two karyotypes are from a haploid cell?