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Extending Mendelian Genetics
How traits are inherited
Sections 7.1, 7.2
Terms for this chapter
please define these as homework
1.
Carrier
2.
Sex-linked gene
3.
Incomplete dominance
4.
Codominance
5.
Multiple allele
6.
Polygenic traits
7.
Pedigree
8.
karyotype
How Sex is determined
the difference
in the X and Y
chromosome
leads to a
difference in
the
inheritance of
traits located
on the sex
chromosomes
Sex-linked Genes
Most sex-linked traits are
considered to be influenced by
the X chromosome
The Y chromosome does carry
some but it only affects the
males
Genotype
Phenotype
XRXR
Normal
female
Carrier
female
Affected
female
Normal
male
Affected
male
XRXr
XrXr
XRY
XrY
Punnett Squares
&
sex-linked traits
Males statistically have a higher
incidence of sex-linked traits
because only one chromosome
needs to carry the recessive allele
Hemophilia
is
sex-linked
Incomplete dominance
Heterozygous individual shows a blend of two traits
Codominance
Heterozygous individual expresses both alleles
Polygenic traits
Trait is determined by the
combined effect of one or more
genes
Human skin, hair, height, and eye
color