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Laws and Mechanism of Inheritance - Coggle Diagram
Laws and Mechanism of Inheritance
Mendel's Laws
Law of Dominance
In a
hybrid individual two different genes for a character are present
Only one gene expresses itself
and
the other one is not allowed to be expressed
The
one which expresses itself
is called the
dominant gene
while
the one that isn't expressed
is called the
recessive gene
Law of Segregation
The
2 alleles of a gene do not get mixed up
and
retain their indentity
They
separate during gamete formation
such that
each gamete only gets one allele for that gene
Also called the
principle of purity of gametes
Each factor appears with
equal frequency in males and females
Law of Independent Assortment
The
genes for any character get assorted into gametes regardless of the genes of any other character
The
genes get randomly rearranged in the offspring
Inheritance of Traits
Genes control inheritance
Since both parents contribute equally during reproduction
, each
progeny must have 2 sets of all genes
For this mechanism to work
, the
progeny must have only one gene set
If progeny inherit a whole gene set
, then the
law of independent assortment won't work
as
the genes would be linked
Each gene set is not a single piece of DNA
, but as
independent pieces called chromosomes
Thus
each progeny cell will have two copies of each chromosome, one from each parent
Each gamete takes one chromosome
from
either mother or father
When the two gametes fertilize
, the
number of chromosomes is restored to normal
Somatic cells have 2n chromosomes and are diploid
while
germ cells are haploid and have n chromosomes
Features of the Mechanism
Characters are controlled by genes on chromosomes
There
may be 2 or more alleles of a gene
1 allele is dominant over the other
The 2 alleles separate out during gamete formation
such that
gametes have only one allele
The
2 alleles from the mother and father are brought together during fertilisation