Chromosomes
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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. Karyotype. Female. Defined : Picture of an individuals chromosomes

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Chromosomes

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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


Karyotype

Female

  • 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

Male


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?


Then I’ll suck up some of the baby’s cells from the fluid in the womb.

I’m gonna use ultrasound to help guide the needle. I don’t want to accidentally hit the baby.

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:

    • 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?


That one magical night!


23 chromosomes

23 chromosomes

23 chromosomes

46

Chromosomes (diploid)

23 chromosomes

23 chromosomes

23 chromosomes


Zygote divides from mitosis

Typical human has about 100 trillion cells

9 months of cells dividing later….


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?

    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?


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