Transcript Mendelian Inheritance of Human Traits

Simple Inheritance,
Pedigrees, & Karyotypes
Pedigrees
• Similar to family trees
• A graphic representation of
genetic inheritance
Pedigree Symbols
Female
Affected
Carrier
Female
Female
Mating
Male
Affected
Carrier
Male
Male
Example of Pedigree
Simple Recessively Inherited
Disorders
• Disorder only seen if two recessive alleles
are inherited.
Cystic Fibrosis
• Leads to excess amounts
• of mucus in the digestive and
respiratory tract
• Can be treated
Sickle-Cell Anemia
• Proteins on blood are changed, thus
changing the shape of the blood
• Abnormal red blood cells they are shaped
like a sickle, or half –moon.
Tay-Sachs Disease
• Leads to lipids accumulating in the
central nervous system
• Children with disease can not control
their bodily functions (muscles)
Tay-Sachs Disease
problem breaking down
lipids; change diet to fix
Phenylketonuria (PKU)
• Body can’t break down an enzyme found
in milk; causes nerve damage
• PKU children appear normal at first
• Leads to the build up of the amino acid:
phenylalanine
• Can lead to mental retardation
Albinism
•
lacking melanin in skin
Dominantly Inherited Traits
• Trait or Disorder seen if one
dominant allele inherited
Different Dominantly
Inherited Traits
• Free Earlobes
• Hitchhiker’s Thumb
Cleft Chin
Widow’s Peak
Polydactyly –
presence of more
than 5 fingers and
toes
Huntington’s Disease
• Dominantly Inherited
• Neurological disorder that causes
lack of muscular control
• Onset around age 30
Sex-Linked Traits
• Traits determined by genes carried on
the sex chromosomes (X-chromosome)
• Ex: colorblindness, hemophilia,
muscular dystrophy
Red-Green Color Blindness
• Common in males
• People who have red-green color
blindness can’t differentiate these two
colors
What
Colors
Do
You
See?
Hemophilia
• More common in males
• Causes a problem with blood clotting
Carrier: an
individual
heterozygous
for a specific
trait…(carries
the trait can
pass to their
offspring)
Chromosomal Mutations
• Mutation: change in the DNA
• Nondisjunction: chromatids or
homologous chromosomes stick together
instead of separating…they do not disjoin
or come apart
• Trisomy: has one extra chromosome
• Monosomy: missing one chromosome
Nondisjunction
•Down Syndrome – trisomy 21
(extra chromosome on 21st)
•Turner Syndrome – XO
(missing sex chromosome)
Klinefelter’s Syndrome
XXY males
XYY Condition
Tests to Detect
Inherited Disorders
Amniocentiesis
Ultrasound
Fetoscopy
Karyotypes
• Chart of chromosomes used to diagnosis
chromosomal disorders.
• Chromosomes are arranged in order
from the largest to the smallest
• Also used to determine gender
Example Karyotype