Chapter 14: Human Genetics
Human Chromosomes Autosome - any
chromosome other than the X & Y
Sex chromosomes–
23rd pair of determine sex in organism
Karyotype
A picture of chromosomes arranged based on size and shape.
Karyotypes can identify abnormal number of chromosomes due to mistakes during meiosis.
Nondisjunction: the failure of chromosomes to separate properly during Anaphase I or II.
Anaphase 1Anaphase 2
As a result of nondisjunction:
Can lead to a number of disorders in the baby. Trisomy (extra chromosome) or Monosomy (one less chromosome).
• Down’s syndrome• Klinefelter’s syndrome• Turner’s syndrome• Edward’s syndrome
Karyotyping & Disease
Sex: Female # of
chromosomes=46
Diagnosis: healthy
Karyotyping & Disease
46 Male Healthy
Karyotyping & Disease
Male 47 Klinefelters
Karyotyping & Disease
Female 45 Turners
Karyotyping & Disease
Female 47 Downs Syndrome
Karyotyping & Disease
Male 47 Edward’s
syndrome
Edward’s syndrome
Pedigree A chart that shows the relationships within a
family that can be used to trace inheritance.
How to draw a pedigree
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A circle represents a female
A square represents a male
A horizontal line connecting a male and female represents a marriage
A vertical line and a bracket connect the parents to their children.
A shaded circle or square indicates that a person expresses the trait.
A circle or square that is not shaded indicates that a person does not express the trait.
Ms. Pitt’s pedigree:
Laura Tom Arlene Tom Joann Chuck Diane Jack
TammyNicole Tom Jeff Matt Jess Jodie Ms. PittMonica Candice Kayla
Mae Tom
X-Chromosomes Inactivation
In female cells, one X chromosome is randomly switched off.
The turned off X chromosome forms a dense region in the nucleus called a Barr body.
Human Genome Project An ongoing effort to analyze the
human DNA sequence.
End of their Notes
Slide 23-38 I will do when I return.
Autosomal Recessive DisordersTay - Sachs Disease More common
among Jewish populations
Young children begin showing signs of slowed development
Severe impairment and death
Build up of lipids in the body – lysosomes do not function properly
Autosomal Recessive Disorders
Cystic Fibrosis More common in
Caucasians Mucus in
respiratory tract, difficulty breathing
Extreme salty sweat
Mucus may cause secondary infections
Autosomal Recessive Disorders
Phenylketonuria (PKU) Lack enzyme for
normal metabolism Phenylalanine builds
up and causes brain damage
Newborns are routinely tested
Changes in diet lead to normal life
PKU
Can be managed if caught early
Autosomal Recessive Disorders
Sickle Cell Disease More common
in Africans (African-Americans)
Causes blood to be sickle shaped
Affects oxygen flow to organs, causing weakness, pain, anemia, etc
Heterozygotes are resistant to malaria
Sickle-Cell Anemia
Autosomal Dominant Disorders
Affected children usually have an affected parent
Heterozygotes are effected
Two heterozygotes (Hh x Hh) can produce a normal (hh) child
Autosomal Dominant DisordersHuntington Disease Neurological disorder, progressive
degeneration of the brain Symptoms appear later in life (40s,
50s)
Huntington’s Disease
Huntington’s Disease
Autosomal Dominant Disorders
Achondroplasia Common form of Dwarfism Short arms and legs, normal
torso Homozygotes (AA) do not
survive
Achondroplasia
Autosomal Dominant DisorderHypercholesterolemia Incomplete dominance Caused by a recessive allele, however in
the heterozygous form (Hh), individuals have 2x the normal blood cholesterol levels
Can lead to Atherosclerosis