Chromosomes and Inheritance Chapter 12 231241

1
Chromosomes and InheritanceChapter 12 (231-241)
2
Parts of Chromosomes

• Telomeres
• Centromeres
• Locus

3

• Picture of chromosomes
• Homologous chromosomes contain the same genes
• Often arranged with autosomes (found in both
  sexes) in descending order and sex chromosomes
  separate

Karyotype
4
X-Linked Inheritance
Color blindness
(X-linked recessive)
Hemophilia
(X-linked recessive)
5
Autosomal Recessive Disorders
Sickle-Cell Anemia Red blood cells take on a
curved shape Clot in the capillaries Decreased
oxygen supply to brain muscles
Werner Syndrome Premature
aging Begins during adolescence Mapped to
chromosome 8
6
Autosomal Dominant Disorders
Polydactyly
Extra fingers or toes
Achondroplasia
Growth related defect Cartilage growth in
the long bones is slow Results in short stature
7
Retinitis Pigmentosa
X-linked recessive, Autosomal dominant or
Autosomal recessive Eye diseases that affect the
retina Degeneration of cones and rods in the
eye Loss peripheral vision
8
Pedigree Analysis
Diagrams of family history Used to determine if a
disease or condition is dominant, recessive, or
X-linked Use symbols to represent individuals
9
(No Transcript)
10
(No Transcript)
11
Polyploidy The addition of one or more sets of
chromosomes to a genome Malfunction in
meiosis Egg or sperm end up with two sets of
chromosomes Detrimental in humans Preferred in
some plant species
12
Aneuploidy One chromosome too many or missing one
chromosome Common in humans Common in
miscarriages Ex. Down syndrome Result of
nondisjunction
13
Nondisjunction
14
(No Transcript)
15
Most result in a miscarriage, except for those
that occur on chromosome 13, 18, or 21
16
Trisomy
Zygote ends up with 3 chromosomes instead of 2
for a given pair of chromosome.
17
Down Syndrome (Trisomy 21)

• 1 in 800-1,000 births
• Large tongue
• Flat face
• Single crease across palm
• Slanted eyes
• Mental retardation -Some are not
• Increased risk for congenital hear defects and
  leukemia

18
Edward Syndrome (Trisomy 18)

• 1 in 3,000 births
• Affects more girls than boys
• Heart defects
• Displaced liver
• Clenched hands
• Low-set ears
• Severe retardation
• 98 abort
• Lifespan

19
Patau Syndrome (Trisomy 13)

• 1 in 10,000 births
• Cleft lip and palate
• Small eyes
• Extra fingers toes
• polydactylism
• Defects
• Heart
• Brain
• Kidney
• Most abort
• Live span

20
Klinefelter Syndrome

• 1 in 500-1,000 births
• Breast development
• Small testes
• Sterile
• Autoimmune disorders
• Low intelligence
• Not retarded

21
Turner Syndrome

• 1 in 2,500 births
• Short
• Not go through puberty
• Webbed neck
• Dropping eyelids
• Produce little estrogen
• Sterile
• Increased risk for obesity, cataracts, arthritis,
  scoliosis

22
Aberrations within chromosomes
Deletions
Ex. Cri-du-chat
syndrome Inversions
Ex. Acute Myeloid Leukemia
Translocations Duplications
23
Deletion

• Part of a chromosome is deleted

24
Cat Cry Syndrome

• Deletion on chromosome 5

Prader-Willi Syndrome

• Deletion on chromosome 15

25
Inversion

• Part of a chromosome is inverted

26
Inversion of Chromosome 16

• Inversion between chromosome 13 and 22
• Acute myeloid leukemia

27
Translocation

• Part of a chromosome attaches to a nonhomologous
  chromosome

28
Translocation of Between Chromosomes 1 and 3

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

29
Duplication

• Part of a chromosome is duplicated

30
Chromosome 10q duplication syndrome

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