Transcript Non Mendelian Genetics - Goshen Community Schools

Chapter 14 & 15
Non-Mendelian Inheritance
&
Human Genetics
Human Karyotype
Autosomes
• Chromosomes that are
not sex cells.
• Pairs #1 - #22 in
humans
Sex Chromosomes
• X and Y
chromosomes.
• Pair #23 in humans.
Beyond Mendelian Genetics:
Incomplete Dominance
• Mendel was lucky!
• Traits he chose in the pea plant showed up very
clearly…
• One allele was dominant over another, so phenotypes
were easy to recognize.
• But sometimes phenotypes are not very obvious…
Non-Mendelian Inheritance
• Alleles are not simply dominant or recessive.
• 5 Types
– Co-dominance
– Incomplete Dominance
– Multiple Alleles
– Sex-Linked
– Polygenic
Co-dominance
• Both traits expressed at the
SAME time in the
heterozygote.
• NO blending!
• Example:
– Red x White = Red & White
Red x white  red-and-white-spotted
Incomplete Dominance
• A blending of traits in
the heterozygote.
• Example:
– Red x White = Pink
R
RR = Red
Rr = Pink
rr = white
R
r
r
R R Rr
Rr
rr
Multiple Alleles
• More than 2 alleles.
• Example:
– Human blood has A, B,
and O
• A and B are equal.
• O is recessive.
Sex-Linked
• Found only on sex
chromosomes (X & Y)
• Example:
XN
XN
Xn
XN XN
XN Xn
XN Y
XnY
– Hemophilia is on the X
• N = Normal
• n = Hemophilia
Y
Polygenic
• Many genes are involved.
(Poly = many & genic = genes)
• Produces a bell curve.
• aaBbCCDdee is darker than
aabbCcDDee
• AABBCCDDEE is darkest
• aabbccddee is lightest
HINT: Just count the # of upper case letters!
What type of inheritance?
NN = normal blood
Nn = partially sickle cell
nn = sickle cell
Incomplete Dominance
What type of inheritance?
Polygenic
What type of inheritance?
Sex-linked
Pedigree
Males =
Females =
Has trait =
Carrier =
• Chart showing
inheritance of a trait
from generation to
generation.
Generic Pedigree
Is the trait dominant or recessive?