Download - Non mendelian genetics(roel)
Non-Mendelian Genetics(Non-Mendelian Patterns of
Inheritance)-Incomplete dominance
-Codominance-Sex determination-Sex-linked traits
Roel R. Maraya
BEEdBSEd 4-1 (Natural Sciences)
January 19, 2010
Answer this!?
A homozygous round seed crosses with a homozygous
wrinkled seed. Give the genotype and the phenotype
of the offspring.
What if you marry an American man o woman? What do you think would be your children look like?
Think! Think! Think!
Non-Mendenlian Inheritance
is a general term that refers to any pattern of inheritance in which traits do not segregate in accordance with Mendel’s laws.
Incomplete Dominance
is a form of intermediate inheritance in which one allele for a specific trait is not dominant over the other allele.
Example
Remember!
“With incomplete dominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype that is a blending of the parental traits.”
Codominancethe "recessive" & "dominant" traits
appear together in the phenotype of hybrid organisms.
•Both alleles contribute to the phenotype of the organism by showing up simultaneously (at the same time) in heterozygous individuals.
Example
R = allele for red flowers W = allele for white flowers red x white ---> pink RR x WW ---> 100% RW
Remember!
“With codominance, a cross between organisms with two different phenotypes produces offspring with a third phenotype in which both of the parental traits appear together. ”
Sex Chromosomes
MALES: - have non-identical sex
chromosomes (XY).
FEMALES:- have identical sex
chromosomes (XX).
Sex Determination
Sex-linked traits
• This is also referred to as “x-linked traits”.
• These are determined by genes that are carried on the X chromosomes.
• This is determined also in the sex chromosomes of an individual.
Genotypes and Phenotypes of Color Blindness in
HumansGenotypes Phenotypes
1. XX Normal female
2. XXc Normal female,carrier of the
gene
3. XcX
c Color-blind female
4. XY Normal male
5. XcY Color-blind male
Sex-linked trait
Sex-influenced traits
• The traits produced here is not sex-linked, but is carried by the body chromosomes or AUTOSOMES.
– Example of this is Baldness.
Assignment # 1Directions: Answer the following questions. Write your
answers on a short bond paper. COPY and ANSWER.
1. Suppose a heterozygous woman (genotype XcX)
marries a color blind man (genotype XcY), determine
the phenotypes of their children using a Punnett square.
2. Suppose a color-blind woman (XcX
c) th a normal
marries a man with a normal vision (XY), determine the phenotypes of their children using a Punnett square.