Mendel's Principles Flashcards
Mendels law?
Law of segregation (monohybrid cross)
- each individual posses 2 allele of a particular characteristic. At time of gamete formation allele seperate and gamete= pure allele.
-tall and dwarf plant
Law of independent assortment (dihybrid cross-2 independent traits were considered)
- assortment of one gene occurs independently of other gene (gene at different locus) at time of gamete formation. Therefore results in different combinations
-round/wrinkleed seed and green/yellow seed
- yellow and round dominant
Ratio of law of segregation
Geno- 1:2:1
Pheno- 3:1
Total combination -4
Ratio of independent assortment
Geno-1:2:1:2:4:2:1:2:1
Pheno- 9:3:3:1
Total combination - 16
Test cross
F1 individual × recessive homozygous
- can be used to where two genes are linked
Back cross
F1 × parental genotype
Incomplete/partial dominance
Neither allele is completely dominant over the other
intermediate phenotype of parents are observed
FOUR O’CLOCK PLANT
red×white=pink
Ratio of incomplete dominance
Geno- 1:2:1
Pheno- 1:2:1
Codominant
No dominant or recessive allele
Both expressed equally in offspring
MN BLOOD GROUP
Multiple allele
More than 2 different allele form of a gene
ABO BLOOF GROUP
IF AB+ BOTH A AND B ANTIGEN
NO OF DIFFERENT GENOTYPE POSSIBLE
= n(n+1)/2
= n no of allele
Rh antigen is present on?
RhD (carry antigen D) and CE (carry antigen Ce) encoded by RHD AND RHCE
+/- depends on D ag on rbc
Lethal alleles
Loss of mutation occurs in essential gene (imp for survival) they for lethal alleles.
Can be recessive or dominant
Types of lethal alleles
Early- death at embryogenesis
Late- death after some time
Conditional- death when exposed to certain environment
Semilethal- kill some other survive
Penetrance
Proportion of genotype that express in expected phenotype
Incomplete penetrance
Trait is present but not expressed in phenotype.
When penetrance less than 100%
