Sex Linked Genes - Mrs. Connor's Website St. James Collegiate · 2018-09-10 · Sex Linked Genes...
Transcript of Sex Linked Genes - Mrs. Connor's Website St. James Collegiate · 2018-09-10 · Sex Linked Genes...
Sex Linked Genes The Xs and Ys of Genetics
Sex Linked Genes There are 23 pairs
of chromosomes and one of those pairs are the sex chromosomes.
There are either X chromosomes or Y chromosomes.
Sex Linked Genes These
chromosomes not only carry the genes that determines male and female traits, but also those for some other characteristics as well.
Genes that are carried by either sex chromosome (X or Y) are said to be SEX LINKED
Males Men normally have
an X and a Y combination of sex chromosomes.
Since only men inherit the Y chromosome, they are the only ones that inherit Y-linked traits.
Females
Women have 2 X chromosomes
X Linked Traits Men and
Women can get the X-linked traits since both inherit X chromosomes.
Sex inheritance patterns for male and female children
X Chromosome Traits
Men only have one X chromosome
Therefore genes on that chromosome are expressed in the male phenotype, even if it is a recessive gene.
X-linked traits In women, a
recessive allele on one x chromosome is often masked on their phenotype
May have a dominant normal allele on the other carriers of X-linked traits but more rarely have them expressed in their own phenotypes
X-linked traits In humans, at least
120 genes are know to be X-linked.
Genes for hemophilia, red-green color blindness, congenital night blindness, and Duchene muscular dystrophy
Hemophilia An X-linked
genetically inherited recessive disease
Can not clot their blood
Severe bleeding from minor cuts
Mostly in males
Red-Green Color Blindness X-linked Cannot perceive red and green in the same Most often afflicts males
Muscular Dystrophy (MD) Characterized by a gradual irreversible
wasting away of skeletal muscle. An X-linked trait most often passed on to
sons from their mothers. Begins to weaken the legs of boys by age
3 and gets worse every year. No cure and inflicted usually die by age
30.
Y-linked Traits The Y chromosome is small and therefore
does not contain many genes Y linked diseases are very rare Only passed from father to son. Example: Male infertility
Hypertrichosis Pinnae. Hairy ears Can happen later in
life. Y-linked