Cystic Fibrosis

Casey Kriak Joe Scalora

Seyi Akinsola

January 27, 2010Period 9-10

Summary of Cystic Fibrosis • A genetic disorder that affects your respiratory and

digestive system • Cystic fibrosis is a autosomal recessive trait; meaning it

requires to lower case letters• You can be a carrier without having the disease; this

means that your kids can have it• Symptoms: coughing or wheezing, respiratory sickness,

weight-loss, greasy stool, and salty tasting skin • Cystic fibrosis causes 2 to 5 times more salt in your sweat • There is no known treatment, but there is medicine that

clears up the mucus from the lungs to prevent lung infection; which can extend the life of a patient

What Chromosome is it on?

• Cystic Fibrosis is located on the defected gene on chromosome 7.

• CFTR (Cystic Fibrosis Transmembrane conductance Regulator

Mode of Inheritance

• Cystic Fibrosis is an autosomal recessive disease, meaning both parents must pass on the defective gene to their child in order to get the disorder. If the child inherits only one copy of the bad gene, he/she is a carrier. Carriers don’t usually have the disease, but they could pass it onto their kids.

What are Alleles?• Alleles are traits that each gene carry represented with letters (eye, hair

color etc.)• Half of the alleles come from your mother and half of the alleles come

from your father• Each parent gives 2 alleles. The alleles are combined like a multiplication

table and the new-born baby’s odds are made. • Alleles could either be dominant or recessive. Brown eyes and right

handed are examples of dominant and green eyes and left handed are examples of recessive.

• The traits are resembled in letters. F-dominant f-recessive. Two of the possible are combined in a punnet square. Ex. FF Ff, or ff. Any time a dominant allele is matched with a recessive allele the dominant wins

• Sex linkage uses X and Y’s. This determines what gender your child will be. A female is a homozygous link(XX) and a male is a heterozygous link (XY)

What is a Punnett Square?

• A Punnett square is a diagram that predicts to offspring of two parents using alleles.

ANOTHER PREDICTION

b b

B Bb Bb

B Bb Bb

A a

A AA Aa

a Aa aa

ANOTHER PREDICTION

c c

C Cc Cc

c cc cc

HOMOZYGOUS DOMINANT

HETEROZYGOUS DOMINANT

HOMOZYGOUS RECESSIVE

PROBABILITY

• RATIOs: The Homozygous Dominant is (AA), the heterozygous Dominant is (Aa), the Homozygous Recessive is (aa).- ¼ is (AA): ½ is (Aa): ¼ is (aa)

• PERCENTAGES: The Homozygous Dominant is (AA), the heterozygous Dominant is (Aa), the Homozygous Recessive is (aa).- 25% is (AA), 50% is (Aa), 25% is (aa)

A aA AA Aaa Aa aa

Phenotype/ Genotype• What these letters Mean? BB? Bb? Bb?• Let’s say A was brown eyes and a was blue eyes and A is the dominant trait

while a is recessive. (dominant trait shown on the organism.)• Phenotype is what is shown on the organism.

- AA=brown eyes- Aa=brown eyes (with a blue eyes carrier)- aa=blue eyes

• Genotype is what is in the genes of the organism- AA= HOMOZYGOUS DOMINANT- Aa= HETEROZYGOUS DOMINANT- aa= HOMOZYGOUS RECESSIVE

Cystic Fibrosis is aa because it is a recessive trait.

A aA AA Aaa Aa aa

Possibilities • Phenotype:

- Ratios: ¾ chances the child would have brown eyes, ¼ chances the child would have blue eyes.- percentages: 75% out of 100% the child would have brown eyes, 25% out of 100% the child would have blue eyes.

• Genotype:- Ratios: ¼ is HOMOZYGOUS DOMINANT (AA) , ½ is HETEROZYGOUS

DOMINANT( Aa), and ¼ is HOMOZYGOUS RECESSIVE (aa)- Percentages: 25% is HOMOZYGOUS DOMINANT(AA) , 50% is

HETEROZYGOUS DOMINANT (Aa), 25% is HOMOZYGOUS RECESSIVE (aa)

A aA AA Aaa Aa aa

Student Practice

Autosomal Recessive Pedigree

Generation 1

Generation 2

Generation 3

1 2

1 1 22 2 1

1 12 12 2 3

-Male

-Female

No Fill- Carrier of Cystic FibrosisFilled- Has cystic Fibrosis

Now you try!Generation 1

Generation 2

Generation 3

1 2

1 22 1

1 2 3 1 2

-Male

-Female

No Fill- Carrier of Cystic FibrosisFilled- Has cystic Fibrosis

1. If the parents have two kids, how many will have cystic fibrosis?

2. The one kid with CF marries a carrier how many of her 2 kids have cystic fibrosis?

3. What do you think would happen if the female on the right in G3 married a male with CF?