Chapter 11 -1Complex Inheritance

7/31/2019 Chapter 11 -1Complex Inheritance

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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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One parent is a carrier one is normal


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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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One parent has condition and the other

does not


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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.

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Tt

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Chapter 11 -1Complex Inheritance