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

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 per cell

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

I’m gonna use ultrasound to help guide the needle. I don’t want to accidentally hit the baby. Then I’ll suck up some of the baby’s cells from the fluid in the womb. Now that cells have been obtained, their chromosomes can be seen and photographed

Under a microscope, the stained chromosomes are randomly scattered.

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

Down Syndrome: What’s Wrong? Writing notation: –1 st : total chromosome # –2 nd : Sex chromosomes –3 rd : 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 = 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 = 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?

That one magical night!

23 chromosomes 23 chromosomes 23 chromosomes 23 chromosomes 23 chromosomes 23 chromosomes 46 Chromosomes (diploid)

Zygote divides from mitosis 9 months of cells dividing later…. Typical human has about 100 trillion cells

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

Is this a male or female rat? male

What is the diploid chromosome number? 42

What is the haploid chromosome number? 21

How many chromosomes would be in somatic cells? 42

How many chromosomes would be in brain cells? 42

How many chromosomes would be in gamete cells? 21

How many chromosomes would be in egg cells? 21

How many chromosomes would be in muscle cells? 42

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? Skin Nerve Sperm Brain Kidney Stomach Pollen 6) Which of the following cells are haploid? Skin Nerve Sperm Brain Kidney Stomach Pollen 7) Which of the following cells are diploid? Skin Nerve Sperm Brain Kidney Stomach Pollen

REview 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 karyotype is 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?