Chromosomes

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Chromosomes
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Chromosome

• Long molecule of DNA
• 46 human chromosomes
• 23 pair
• Inherit 23 from each parent

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Single Chromosome
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Doubled Chromosome
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Doubled Chromosome
Telomeres
q arm
Telomeres
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Types of Chromosomes
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Homologous chromosomes line up in a double file
in metaphase I of meiosis
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Homologous Pairs Separate
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Four Gametes With Single Chromosomes
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Fertilization
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Nondisjunction
One pair of chromosomes fails to separate during
meiosis
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Trisomy
Zygote ends up with 3 chromosomes instead of 2
for a given pair of chromosome.
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Karyotype

• Picture of chromosomes
• Often arranged with autosomes in descending
  order and sex chromosomes separate

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Normal Male
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Normal Female
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Trisomy 21Down Syndrome
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Down Syndrome

• Large tongue
• Flat face
• Single crease across palm
• Slanted eyes
• Usually Mental retardation

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Maternal Age Down Syndrome
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Trisomy 18Edward Syndrome
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Edward Syndrome

• Heart defects
• Displaced liver
• Abnormal hands
• Low-set ears
• Severe retardation
• 98 abort
• Lifespan lt 1 year

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Trisomy 13Patau Syndrome
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Patau Syndrome

• Cleft lip and palate
• Extra fingers toes
• polydactylism
• Defects
• Heart
• Brain
• Kidney
• Most abort
• Live span lt 1 month

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Klinefelter Syndrome
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Klinefelter Syndrome

• Breast development
• Small testes
• Sterile
• Low intelligence

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Turner Syndrome
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Turner Syndrome

• Short
• Not go through puberty
• Produce little estrogen
• Sterile
• Extra skin on neck

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Jacobs Syndrome
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Jacobs Syndrome

• Xyy
• Tall
• Acne
• Slightly lower average IQ than Xy

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Abnormal Chromosome Numbers

• Aneuploidy
• Missing or extra chromosome
• Polyploidy
• Extra set of chromosomes
• Usually lethal
• Common in cancer
• Common in plants

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Fetal testing can determine abnormal karyotypes
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Map of Chromosome 3

• Shows location of genes
• 3q26 has sucrose intolerance gene
• Kidney cancer gene in 3p14

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Terminology
3q26
Chromosome 3
Region 26
q arm
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9p21
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(No Transcript)
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Leukemia

• Cancer that is often the result of various
  chromosomal aberrations

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Translocation

• Part of a chromosome attaches to a nonhomologous
  chromosome

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Translocation of Between Chromosomes 1 and 3

• Part of chromosome 3 attached to chromosome 1
• Acute myeloid leukemia

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Inversion
A
B
C

• Part of a chromosome is inverted

D
E
F
I
H
G
J
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Inversion of Chromosome 16

• Inversion between p13 and q22
• Chromosome on right
• Acute myeloid leukemia

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Deletion

• Part of a chromosome is deleted

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Cat Cry Syndrome

• Deletion of q arm on chromosome 5
• 5p-
• High-pitched cry like a cat
• Large ears
• Retarded

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Duplication

• Part of a chromosome is duplicated

I
J
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Chromosome 10q duplication syndrome

• Mental retardation
• Defects in many organs
• Heart
• Kidneys
• Bones
• Muscles
• Life span less than 1 year

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The End