Download ex. AA, Aa, aa

Chapter14: Human Heredity
Making a Pedigree
• Pedigree
– A graphic representation of genetic inheritance.
– Track genotypes by looking at their phenotypes
– Genotype- allele combination for genes that
express a trait (ex. AA, Aa, aa)
– Phenotype- physical traits caused by a
genotype( ex. AA= red flowers, aa= white flowers
Carrier- person who
can pass on a disease
but it not effected by it
Reading a Pedigree
• Is this a dominate
or recessive disease?
• Which individuals
MUST be carriers?
• I-1,2; II-1 or 2; III3,4
• What are the
possible genotypes
for III-1?
• AA or Aa
Recessive (aa)
Aa
Aa
AA
or
Aa
Aa
Aa
aa
Aa
Aa
aa
aa
Reading a Pedigree
• Is this a dominate
or recessive disease?
• Which individuals
MUST be carriers?
aa
AA
or
Aa
Dominate (AA, Aa)
Aa
Aa
-None. Cannot have
carries for a simple
dominate disease
• What are the
possible genotypes
for IV-1?
-AA or Aa
Aa
AA
or
Aa
aa
Aa
aa
Simple Recessive Heredity
• Recessive traits can
remain dormant and
can appear suddenly;
carriers
• Tend to skip
generations
• Some recessive
disease are fatal and
have late onset;
disease starts when
you are an adult
Simple Recessive Heredity
• Cystic fibrosis disease
• 1/28 Americans are
carriers
– Thick mucus builds in
the lungs
– Makes physical activity
difficult
– Must be treated with
medication
Simple Recessive Heredity
• Phenylketonuria (PKU)
– Body lacks enzyme to
change phenylalanine to
tyrosine
– Build up in the body
leads to a damaged
nervous system
– Fetuses are tested to
treat with diet
Simple Dominant Heredity
• Heredity of many
physical characteristics
– Widow’s peak hairline
– Darwin earlobes
– Hitchhiker’s thumb
• Traits appear in every
generation and is
equally spread between
males and females
Complex Patterns of Inheritance
• Multiple phenotypes from
multiple alleles
• Traits controlled by more than
two alleles have multiple alleles
• Blood Type IA, IB, or I,
different combinations make
blood types
Complex Patterns of Inheritance
• Polygenic inheritance
– Polygenic inheritance is the inheritance pattern of a
trait that is controlled by two or more genes.
– Alleles are not dominate or recessive; they represent
degrees of expression
– All heterozygotes are intermediate in phenotype.
Complex Patterns of Inheritance
• Sex determination :
– chromosomes, which determine the sex of an
individual, are called sex chromosomes.
– All other chromosomes are called autosomal
chromosomes .
Complex Patterns of Inheritance
• Sex-linked inheritance
W+W+
WW
WW+
Results not possible using Mendel…
WW+
WW+
WW+
WW?
Genes linked to X and Y Chromosomes
Complex Patterns of Inheritance
• Sex-linked traits:
• Traits controlled by genes located on sex
chromosomes are called sex-linked traits.
– Red-green color blindness
– Hemophilia
Complex Patterns of Inheritance
X Chromosome Inactivation
–Females only need one X
chromosome to survive
–Inside each cell of a female, one of
the two X chromosomes are
randomly deactivated (barr body)
–Females Calico Cats random
Complex Patterns of Inheritance
• Environmental Factors:
– Temperature, nutrition, light, etc… can effect the phenotype of an
individual by changing the expression of the genes
– Ex. Arctic Fox
• Internal Factors:
– Hormones regulate gene expression so a genotype may not express the
same phenotype it different individuals
– Ex. Peacocks
Human Genetic Disease Presentations
• Next Week: PPTs in groups of 4
Disease to Pick:
– Select a genetic disease from the list today 1)Angelman
Syndrome
– NO LONGER THAN 10 MINUTES!!! 2) Cri du chat
3) Down Syndrome
– Tell explain the following:
4) Neurofibromitosis
5) Prader-Wili
• What causes the disease?
Syndrome
6) Tay-Sachs Disease
• What are the symptoms?
7) Turner Syndrome
8) Albinism
• How common is the disease?
9) Canavan Disease
• How can the disease be treated? 10) Haemochromatosis