• 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
individual’s 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
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
• We inherit half our
chromosomes from each
parent (23 from mom; 23
from dad)
• 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 = 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
• How do humans get 46
chromosomes?
Diploid Karyotype
Diploid karyotype = Chromosomes
in pairs
Haploid Karyotype
Haploid karyotype =
Single chromosome
1 Minute: Discuss this rat
karyotype with your neighbor.
1) Gender?
2) Number of
chromosomes in
a somatic cell?
3) In a skin cell?
4) In a gamete?
5) In a diploid cell?
6) In a sperm cell?
Notice there are 21 pairs of chromosomes
1 Minute: Discuss this gorilla
karyotype with your neighbor.
1) Number of
chromosomes in
a haploid cell?
2) gamete?
3) In a muscle cell?
4) In a zygote?
5) In an egg cell?
6) In a somatic cell?
Notice there are 24 pairs of chromosomes
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) What is the difference between autosomes and sex chromosomes?
5) 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) A, B, or C: Which karyotype is from a diploid cell?
9) A, B, or C: Which karyotype could be from a muscle cell?
10) A, B, or C: Which two karyotypes could be from a sperm cell?
11) A, B, or C: Which karyotype is from an egg cell?
12) A, B, or C: Which two karyotypes are from a haploid cell?