Principles of Inheritance and Variations Flashcards
what is Filial progeny?
1st generation progeny of cross breeding two true-breeds.
its usually refered as F1.
what is Gene?
A unit of inheritance.
they contain the information that is required to express a particular trait in an organism.
What is an allele?
Allele are the variance of gene for a particular unit of inheritance. They are slightly different forms of the same gene.
what is a genotype?
Genotype is the genetic constitution of a trait.
what is a phenotype?
A set of observable charecters of an individual resulting from the interaction of its genotype with the environment.
What is a difference between dominance and recessive?
A gene comes in a pair of alleles and it could be homozygous or hetrozygous. in the case of hetrozygous the one allele(the dominant) overrules the other (recessive).
for the recessive gene to show up on the phenotype, the pair of alleles should be homozygous of the recessive gene.
what is monohybrid and dihybrid?
monohybrid is an organism with only one gene controlling charecter is hetrozygous.
dihybrid is an organism with only two gene controlling charecter is hetrozygous.
what is an monohybrid cross?
when you cross two true beed organism that has one different traits.
what is the binomial equation of writing the punnet squares ratio of f2 generation?
(ax+by)2
whats a test cross?
test cross is an a test conducted to find if genotype of a plant is homozygous or hetrozygous by cross breeding the genotype unknown plant with know recessive phenotype plant and using the result of the progeny to interpret the genotype.
what are the 2 laws of inheritance?
Law of Dominance & Law of Segregation.
what is the law of dominance?
- The charectors are controlled by discrete units of factors
- The factors occur in pair
- In dissimilar pair of factors one member of the pair dominate the other.
What is the law of segregation?
- Alleles do not blend
- The alleles are segregated in the process of meiosis before transfering to gamete.
- only one allele is tranfered to the gamete.
in homozygous its all the same but in an hetrozygous plant 2 kinds of gametes are produced each having one allele with an equal propotion.
What is in incomplete dominance?
when the dominant allele doesnt completely overrule the recessive allele.
The f1 generation of monohybrid cross results in progenies that are dissimalr to either of its parents.
when the genotype is hetrozygous the phenotype is different from both parents.
Explain how an allele become dominant?
dominant allele are the normal allele and the recessive allele is the modified version of the normal allele.
normal alleles usually means there is product that has a certain function and the modification of that allele can cause the allele (1)to have a product that does same/less efficiant function (2) to have the product but no funtion (3) or no product at all.
the modified (1) allele wont cause any change to the phenotype but the 2 & 3 can affect the phenotype.
What is Co-dominance and give an example?
Co-dominance occur when the traits of both the alleles show in the phenotype.
eg: Blood type ABO
gene - IA, IB, I. there are 3 alleles for blood type gene
If IAIB is the allele the traits of both AB is shown in blood type.
Law of Independent assortment?
When 2 pairs of allele are combined in a hybrid, segregation of charector in one pair is independent of the other pair.
Chromosomal Theory of Inheritance?
- Segregate at the time of gamete
formation such that only one of each
pair is transmitted to a gamete. - Independent pairs segregate
independently of each other.
who were the other scientist that discovered mendels principles of inhertitance
Hugo de vries, Carl corren, and Erich Von Tschermak. All 3 of them discovered mendels principle independently around 1900.
Who came up with the chromosomal theory of inheritance?
Walter sutton & Theodore Boveri
What organism did Thomas Hunt morgan experimented with?
Drosophila melanogaster (common fruit fly)
Why was fruit fly used in Morgans experiment?
- They are easy to grow in the lab
- The complete life cycle in 2 weeks
- Single mating produces large number of progeny
- Clear distinction btw Males & Females
- they form many types of Heriditary variations.
What is Linkage?
The physical association of genes on a chromosome.
What is recombination?
The process by which peices if DNA are broken and recombined to produce new combination of alleles.
whats the relation btw Linkage and recombination?
the stronger the Linkage the lower the possibility of recombination.
Who is Alfred Stuartevent and what did he do?
Alfred was a student of Morgan who worked with him on the experiment of drosophila melanogaster.
He used the frequancy of recombination occured between gene pairs on the same chromosome and used it as a measure of the distance between the genes in the chromosome. then mapped the genes position on the chromosome.
This technique was the basis for gene mapping.
What is Polygenic Inheritance?
Polygenic traits are traits that are controlled by 3 or more genes and they are influneced by the environment. such traits are usually seen as a gradient trait.
eg:- height
the alleles in polygenic traits are additive.
What is Pleiotropy?
A gene that has multiple phenotypic expression.
The reason for that is it usually affects a gene on the metabolic pathway.
eg :- Phenyl ketonuria
What are the different types of sex determination?
XY type - humans
XO type - certain insects
ZW type - birds (Female heterogamety
Haplodiploid (number of chromosome) - Honey bee
Fun fact about bees?
Bees cannot have father or son but can have grandfather and grandson.
What is Mutation?
its a phenomenon that results in the alteration of DNA sequance which results in the change of genotype & phenotype of an organism.
mutation leads to variation in DNA.
types of mutation?
deletion and Insertion/duplication of a Segment of DNA
What is point mutation?
Mutation caused due to a change in a single base pair of DNA
eg:- Sickle-cell anemia
What is a Mutagen?
Chemical & physical factors that induce mutation.
eg:- UV radiation
What is pedigree Analysis? what is it used for?
Study of inheritance of gene over generations of a family.
it can be used as a tool to trace the inheritance of a specific trait, abnormality or disease.
What are the 2 types of genetic disorder?
Mendelian disorder & chromosomal dissorder?
What is mendelian dissorder?
Alteration or mutation in a single gene.
eg:- Haemophilia, cystic fibrosis, sickle cell anemia
Are mutated/altered gene dominant or recessive?
it can be both dominant and recessive.
What is chromosomal disorder?
Such disorders are caused due to absence/excess/abnormal arrangement of one or more chromosomes.
Mention the advantages of selecting pea plant for experiment by Mendel.
- Easy to breed and cross
- Easily distinguishable phenotypes
- quick growth
A diploid organism is heterozygous for 4 loci, how many types of gametes can be produced?
16 gametes.
