Transcript Pedigrees and Sex linked Traits

Pedigrees and Sex linked Traits
Part 4
What is a PEDIGREE
• A chart used to
trace traits
throughout a family
• Parts of the chart
– Circle = females
– Squares = males
– Half-filled in/Dotted
= carrier
• Have the gene but
do not show signs of
it
– Filled-in = affected
• Have both the gene
and symptoms of
that trait
Pedigrees - A chart used to trace
traits through generations of a
family
-
How can a pedigree trace a trait ?
– Circle = females
– Squares = males
– Half-filled in= carrier –
• they have the gene but do not show signs of the disorder
• Heterozygous – they can pass it on to their offspring
– Filled-in = affected
• Have both the gene and symptoms of that trait
Bellwork: 10/30
Ifc:
The following pedigree shows cystic fibrosis
1.Does anyone in generation 3 have cystic fibrosis?
2. Does generation 3 have any carriers?
3. How many female offspring did the first generation have?
How many of the offspring in generation 2 were affected?
4. Describe individual 4 in generation 3
Sex chromosomes and sex linked
disorders
How is the sex of offspring
determined?
Sex chromosomes – determine the sex
of an individual
Y or X
Males = X and Y - XY
Female = X and X- XX
Which parent determines the sex of the
offspring?
XY
male
X
XX
Y
X
Female
X
It is the male that determines the sex of
the offspring.
What are Sex-Linked Traits?
Traits controlled by genes
located on sex chromosomes
(X or Y)
Most are on X chromosome
Traits on the sex
chromosomes are passed on
differently than traits on the
rest of the chromosomes.
What are sex linked disorders – a
disease or trait on the sex
chromosomes
• XX - female can be a carrier or
have the trait if she has the gene
on both
• XY male – if it is on the x
chromosome, they only need 1
allele to get the disorder.
• They show up more in males
because they only need one
gene to get it and females
need both.
Red-green color blindness
Can not distinguish red from green.
Normal red-green
Red-green colorblind
What a red-green colorblind person would see
Normal
Red-green colorblind