GENETIC
INHERITANCE
subtopi
cs
Mendelian
Genetics
(C1)
Deviations From The
Mendelian Inheritance
(C1)
Genetic
Mapping
(C1)
4.1
4.2
4.3
Learning
outcomes
4.1: Mendelian Gene
a)Define the terminologies
b)State the characteristics of Mandel’s pea plants
c)State Mendel’s first law
d)State Mendel’s second law
4.2: Deviations from the Mendelian Inheritance
- Define types of inheritance that deviate from
Mendelian
4.3: Genetic Mapping
- Define genetic mapping
Deviations from the
Mendelian inheritance
Codominant alleles
Incomplete
dominant alleles
Multiple alleles
Linked genes
sex-linked genes
polygenes
Both alleles of a
pair are fully
expressed in a
heterozygote.
Codominant Allele
Roan coat color:
Both alleles are
equally expressed
in the heterozygot
A form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele.
Incomplete dominant
allele
Snapdragons show incomplete dominance in the inheritance of
flower color. The heterozygous flower has a phenotype that is in
between that of the two homozygotes
MORE THAN TWOalleles control forparticular trait OF ACHARACTER
Multiple allele
Coat Color in Rabbits Different combinations of two
alleles give different coat colors and pigment distributions.
Each chromosome carries a number of genes in
particular locus
Linked gene
Genes that are
carried by either
sex chromosomes
( X or Y) are said to
be Sex-Linked
Sex- Linked gene
An additive effect of TWO or
MORE genes on a single
phenotypic character
Eg; skin colour, body height
Polygene
GENETIC MAPPING
Polygene• Genetic map - A graphic representation of the arrangement
of a gene or a DNA sequence on a chromosome.
GENETIC MAPPING
Polygene
• genetic mapping - Process of locating the relative
position & sequence of gene on a chromosome.
• Can be carried out when the genes are linked and
crossing over has taken place
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