chapter 11 -1complex inheritance
TRANSCRIPT
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Chapter 11 Complex Inheritance
Section 11-1
Bio30
NWRC
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Section 11-1 Recessive Genetic
Disorders
Two copies of the gene must be mutated for a
person to be affected by a recessive disorder.
An affected person usually has unaffected
parents who each carry a single copy of themutated gene (and are referred to as carriers).
Two unaffected people who each carry one
copy of the mutated gene have a 25% chance
with each pregnancy of having a child affectedby the disorder
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Autosomal Recessive Disorders
Both parents are carriers
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Autosomal Recessive Disorders
One parent is a carrier one is normal
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Autosomal Recessive Disorders
One parent has condition one is normal
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Recessive Disorders
Cystic fibrosis (CF) is caused by adefect in a gene called the cysticfibrosis transmembraneconductance regulator (CFTR) gene.This gene makes a protein thatcontrols the movement of salt andwater in and out of the cells in yourbody. In people with CF, the genedoes not work effectively. Thiscauses the thick, sticky mucus andvery salty sweat that are the mainfeatures of CF. Each of us inheritstwo CFTR genes, one from eachparent.
Children who inherit an abnormalCFTR gene from each parent willhave CF.
Children who inherit an abnormalCFTR gene from one parent and anormal CFTR gene from the otherparent will not have CF. They will be
CF carriers.
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Recessive Disorders
AlbinismThe word "albinism"refers to a group of inheritedconditions. People with albinismhave little or no pigment in theireyes, skin, or hair. They haveinherited genes that do not makethe usual amounts of a pigmentcalled melanin.
Albinism affects people from allraces. Most children with albinismare born to parents who havenormal hair and eye colour for theirparticular ethnic backgrounds.
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Recessive Disorders- galactosemia
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Recessive Disorders- Tay Sachs
Disease Tay-Sachs disease is a rare inherited
disorder that causes progressivedestruction of nerve cells in the brainand spinal cord (the central nervoussystem).
The most common form of Tay-Sachsdisease begins in infancy. Infants with
this disorder typically appear normaluntil the age of 3 to 6 months, whendevelopment slows and muscles usedfor movement weaken. Affectedinfants lose motor skills such asturning over, sitting, and crawling.They also develop an exaggeratedstartle reaction to loud noises. As thedisease progresses, children with Tay-Sachs disease experience seizures,vision and hearing loss, mentalretardation, and paralysis.
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Dominant Genetic Disorders
Only one mutated copy of the gene is
needed for a person to be affected by an
dominant disorder. Each affected person
usually has one affected parent. There is a50% chance that a child will inherit the
mutated gene.
There are no carriers
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Dominant Genetic Disorders
One parent has condition and the other
does not
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Dominant Genetic Disorders
Both parents have a condition
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Pedigree Charts (link to
pedigree analysis)
http://www.youtube.com/watch?v=HbIHjsn5cHohttp://www.youtube.com/watch?v=HbIHjsn5cHo -
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Assessment
1.
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2.
Huntingtons (nervoussystem disorder)and
Achondoplasia(dwarfism) are bothDominant
The affected parent has asingle defective gene (D),which dominates its normal
counterpart (n). Each child hasa 50 percent risk of inheritingthe faulty gene and thedisorder.
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3.
They cannot since albinos would only
have recessive alleles.
Heres an albino squirrel
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4.
tt
Tt