Inheritence Flashcards
In the result of self-fertilization of dihybride cross the ratio of seeds which contain both dominant characters is
9/16
RrYy × RrYy
=> Cross them by using punet’s square
Then:
=> Phenotype: 9 : 3 : 3 : 1
9 = Round Yellow
3 = Round green
3 = Wrinkle yellow
1 = Wrinkle green
The distance between gene A and B is 9 centiMorgan and B and C is 9.5 the actual distance between A and C will be
9+9.5 = 18.5% = actual distance
=> 17% Recombinant frequency
The property due to which offspring show similarities with their parents is called
heredity
=> Characters transfer from parent called inheritance.
=> If phenotype of parental same as in offspring, then it is called hereditary.
genetics is variation and heredity
If phenotype is O because of recessive H gene the possible I gene may be
any of them
Hh, HH => h substance present so antigen present
hh => h substance absent so antigen is absent
=> If H substance is missing it masks the effect of the (I gene) and genotype will be A, B, AB but phenotype will be O Blood group.
Blood group O is universal donor because of
antigen
=> Donor depends on Antigen
=> Recipient depends on antibody
↳ Both for blood transfuse
no antigen ← O -ive = universal donor
AB +ive = universal acceptor
During determination of gene linkage the ratio of recombinant is similar to parental , the genes are
{Parental = Recombinant} → No linkage
{All parental} → complete linkage
{More parental, Less recombinant} → incomplete linkage
Interaction between alleles of different genes is called
non allelic and epistasis
both are intergenic interactions
Epistasis occurs when two or more different gene loci contribute to the same phenotype, but not additively. Epistasis is often described as occurring when one gene locus masks or modifies the phenotype of a second gene locus. The epistatic gene pair is present on non-homologous chromosomes, an interaction that is termed as non-allelic.
XXY in drosophila represent
fertile female
Male ← XXY = Kline filter syndrome in human
Female ← XXY = in drosophila fertile
Female
In a dominant relation the interaction is
inter allelic
=> According to Mendelian inheritance there is inter allelic interaction
=> Non Mandelian inheritance have intergenic interaction (interaction b/w alleles of different genes)
The genotypic ratio of F2 generation in monohybrid cross is
1:2:1
Genotype in F2:
RR Rr rr
1 : 2 : 1
Phenotype in F2
3 : 1
Number of linkage groups in drosophila are
4
No of linkage groups in an organism are equal to number of homologous pair of chromosomes.
⟹ Drosophila has 4 homologous pair of chromosomes so 4 linkage groups.
Linkage groups
Linkage group refers to a group of genes which are present in one chromosome. In other words, all those genes which are located in one.
Chromosome constitute one linkage group. The number of linkage groups is limited in each individual. The maximum number of linkage groups is equal to the haploid chromosome number of an organism.
For example: There are ten linkage groups in corn (2n = 20), seven in garden pea (2n = 14), seven in barley (2n = 14), four in Drosophila melanogaster (2n = 8) and 23 in man (2n = 46).
what were the characteristics studied by mendel
in a pea plant
Following seven characteristics were studied by Mendel:
1) Flower color 2) Flower position
3) Seed shape 4) Seed color
5) Pod shape 6) Pod color
7) Stem height
conducted exp on 29,000 pea plants
The contrasting pair of a factor in Mendelian crosses are called:
alleles
The contrasting pairs of factors in Mendelian crosses are called allelomorphs or Alleles.
Y-linked, or holandric genes include the gene that initiates
differentiation of the embryo into a male, several genes that encode testis specific spermatogenesis factors, a minor histocompatibility antigen (termed HY), and a gene in which mutations can cause hearing loss (DFNY1).
♦ Y-linked or holandric inheritance implies that only males are affected.
♦ Male-to-male transmission. An affected male transmits Y-linked traits to all of his sons but to none of his daughters.
According to modern concept, Mendel’s factor is called as ________.
genes
Mendel’s law of segregation is also known as _________________
Law of purity of gametes
When a pair of alleles is brought together in a hybrid (F1) they remain together without contaminating each other and they separate or segregate from each other into a gamete during the formation of gametes
Which law states that the inheritance of one trait is independent on the inheritance of another trait?
Law of independent assortment
the allele a gamete receives for one gene does not influence the allele received for another gene.
According to the law of dominance, a trait is represented by two contrasting factors of a gene in a heterozygous individual; the allele/factor that can express itself in a heterozygous individual is called as a dominant trait. Whereas the law of segregation states that the two factors for a trait, present together in a heterozygous individual, do not get mixed and are separated during gametogenesis.
ratio is 9:3:3:1
◉ Using a dihybrid cross, Mendel developed the law of independent assortment.
◉ The law of independent assortment states that each pair of alleles segregates independently of each other pair of alleles during gamete formation.
◉ Strictly speaking, this law applies only to genes on different, nonhomologous chromosomes.
◉ Genes located near each other on the same chromosome tend to be inherited together.
Which of the following crosses and ratio best demonstrates the law of segregation?
Aa×Aa
3:1
applies to non homologus chromosomes
The Mendelian principle which has always stood true is
The law of segregation
n these principles, the law of dominance and Law of Independent assortment have deviations or exceptions. Law of segregation does not have any deviations of exceptions. So it always stands true.
Law of segregation is the universally accepted law of inheritance. It is the only law without any exceptions. It states that each trait consists of two alleles which segregate during the formation of gametes and one allele from each parent combines during fertilization, both parents contribute to the factors of offspring equally. In case, alleles of a pair are heterozygous, one is dominant and other recessive, alleles are not mixed up, the dominant one gets expressed. The recessive traits tend to reappear in the subsequent generation.
There is no such contrary model indicating that alleles mix up in the progeny so far, hence it is accepted and applicable
Occasionally, a single gene may express more than one trait or effect. The phenomenon is called
This phenomenon is called pleiotropy, Polygeny refers to a single characteristic that is controlled by more than two genes
ABO blood grouping in human is an example of
co dominance and multiple allelism
Mendelian recombination’s are due to
Independent assortment of characters
All genes located on the same chromosome
Form one linkage group
Mendel’s perform series of experiments on pea plant because it’s _________?
Flowers were hermaphrodite
Had sharply distinct trait
Self-fertilization is easy
