pedigrees and sex linked traits outcome i will explore how traits are inherited through generations...
TRANSCRIPT
Pedigrees and Sex Linked Traits
OutcomeI will explore how traits are inherited through generations by solving autosomal and sex-linked pedigrees.
Sex Chromosomes
X and Y are sex chromosomes The other 22 pairs are
autosomal(body) chromosomes Males = XY Females = XX Not true homologous pairs
– X has more genes
Hemophilia Video
https://www.phd.msu.edu/divisions/pediatric-adolescent-hematology-oncology/educational-videos-about-hemophilia.html
XH Xh
Xh XH Xh Xh Xh
Y XH Y Xh Y
X-Linked Punnett Square
• What is the chance that their son will have hemophilia?
• What is the chance that their daughter will have hemophilia?
50%
50%
Sex linkedH=normal & h=hemophilia
Cross: XHXh x XhY
Sex-linked worksheet
Working with your table, complete the sex linked worksheet in your notes.
You will have 6 minutes!
Pedigrees
circles: females squares: males shaded: individual
with trait/disease Half-shaded: carriers
for a trait but does not express the trait.
Generation / Individual Practice
Generations are the rows in a pedigree
Individuals are labeled across a pedigree
Lines down represent offspring
I
II
III
1 2
1 2 3
1 2 3 4
Quick Quiz
Individual A is
a. A male who expresses the trait
b. A female who does not express the trait
c. A male who does not express the trait
d. A female who does express the trait
What do we call this individual? Carrier
Quick Quiz
Individual D is
a. A male who expresses the trait
b. A female who does not express the trait
c. A male who does not express the trait
d. A female who does express the trait
Quick Quiz
Individual H is
a. A male who expresses the trait
b. A female who does not express the trait
c. A male who does not express the trait
d. A female who does express the trait
Outcome
I will explore how traits are inherited through generations by solving autosomal and sex-linked pedigrees.
Fugates of Kentucky: Skin Bluer than Lake Louise
Methemoglobinemia blood disorder with an abnormal amount of
methemoglobin - a form of hemoglobin reduced ability to release oxygen to tissues - gives
blood a bluish color
Autosomal Recessive
Trait appears only when two parents by chance carry the hidden allele
Affected individual inherits both recessive alleles
Example: sickle cell disease Who could be a carrier?
Autosomal Dominant
Trait appears in every generation, in about half of descendants (assuming a heterozygous carrier)
Affected individual has at least one dominant allele
Example: Huntington’s disease
X-linked Recessive
Mother passes on to half of sons;half of daughters carry it. Father never passes on trait.
Examples: Hemophilia, color blindness Why do more men have it? Who could be a carrier? Can men be carrier?
X-linked Dominant
Father passes trait to all daughters; no sons. Mother passes on to half of children.
Example: Rett syndrome