Please enable JavaScript.
Coggle requires JavaScript to display documents.
4.2a - Deviations from Mendel's Ratio - Coggle Diagram
4.2a - Deviations from Mendel's Ratio
Autosomal
Autosomal recessive inheritance
Pair of inherited factors
Alleles
Alleles pass
from generation to next
alleles may be:
homozygous
heterozygous
Trait that is expressed
Dominant Allele
Masked trait
Recessive Allele
Mendel's first law
dominance
Gamete formation
pair of alleles
segregate
Mendel's first law
segregation
pairs of alleles
separate independently of the other
Mendel's second law
Independent Assortment
Non-sex chromosomes
Sex-Linkage
Genes carried on X and Y chromosomes
code for characteristics
Gene occurs on X
females
2 alleles for that gene
males
will only have 1
Has one X
recessive disorders
more frequent
does not code for the gender of individual
Gene occurs on Y
'Y-linked'
appear in males only
less common
example
Y chromosome infertility
Example
Humans
Gene for Red-Green Colour vision
carried on X
Haemophilia
Bleeding disorder
X-linked disorder
alleles for gene occur on X
Co-Dominance
Both alleles expressed
new phenotype
alleles behave as dominant
hence, both expressed
Hybrid Individuals
Heterozygotes
Example
Roan calf
appearance
red and white hairs are present
received from
red bull
white cow
Incomplete Dominance
Blending of two alleles
hybrid
example
flowers
pink flowers
white snap dragon
#
red snap dragon
#
intermediate
Multiple Alleles
3 or more alleles
For a single gene trait
termed multi-allelic
Example
Humans
Gene
Human Blood Type
3 alleles
A
B
O
i allele
produces no molecular marker
recessive to both A and B
Gene is denoted as I
A and B are codominant
each produce
molecular marker
on red blood cells
4 possible phenotypes
A
B
AB
O
Rabbits
Gene for coat colour
4 alleles
Normal
Chinchilla
Himalayan
Albino
Many different versions
Of the same gene
Whereas polygenic traits
Many genes
Determine 1 trait