Principles Of Inheritance And Variation Flashcards
Well known Indian breed of cow in Punjab -
Sahiwal
Gregor Mendel conducted hybridisation experiments on GARDEN PEA for _____years . From _to ____ .
7 yrs
1856-1863
During Mendel’s investigations into _____ it was for the first time that statistical analysis and mathematical logic were applied to biology .
Inheritance patterns
Mendels laws of inheritance
Mendels experiments had a _____ ,which gave greater credibility to the data he collected .
Large sampling size
Mendel conducted_______ experiments on ____breeding pea lines .
Artificial pollination /cross pollination experiments
True breeding
A true breeding line is one that , having undergone _________ , shows stable _____and _____for several generations .
Continuous self pollination
Stable trait inheritance
Expression
Mendel selected _____true breeding pea plant varieties as pairs , which were similar except for 1 character with contrasting traits .
14
Name the contrasting traits studied by Mendel in pea -
Stem height Flower colour Flower position Seed colour Seed shape Pod colour Pod shape
In F1 generation , ___trait as observed and in F2 , both the traits were expressed in the ratio_____ ( phenotypic ratio in monohybrid cross )
One of the parental trait only
3:1
Segregation meaning -
Separation ; isolation
Recessive parental trait is expressed without any _____ in the ____generation .
Blending
F2
When plants produce gametes by meiosis , the alleles of the parental pair ___ from each other and only 1 allele is transmitted to a gamete .
Segregate /separate
Segregation of alleles is a _____process .and there is ___chance of a gamete containing either allele .
Random
50%
Punnett square was developed by a ____ , named Reginald C Punnett .
British geneticist
When Mendel self -pollinated the F2 plants , he found that -
Dwarf F2 continued to generate dwarf plants in F3 and F4 .
Test cross is used to determine __composition .
Genotypic
______can be calculated using mathematical probability , by simply looking at the phenotype of a dominant trait , it is not possible to know ______ .
Genotypic ratios
Genotypic composition
Whether a tall plant from F1 or F2 has TT or Tt composition can be predicted using -
Test cross
In a typical test cross ,an organism showing a _____ and whose ____is to be determined , is crossed with the _____ instead of self-crossing
Dominant phenotype
Genotype
Recessive parent
Based on his observations on monohybrid cross , Mendel proposed 2 rules to consolidate his understanding of inheritance. These rules are called _____ . Name them .
Principles or Laws of Inheritance
1st law -law of inheritance
2nd law - law of segregation
Give the 3 postulates of LAW OF DOMINANCE -
1) chars are controlled by discreet units called FACTORS .
2) factors occur in pairs
3) in a dissimilar pair of factors one member if a pair dominates the other .
____law states that the ALLELES do not show any blending and that both the chars are recovered as such in F2 gen , though one of these is not seen at the F1 stage .
Law of segregation
Though the parents contain 2 alleles during gamete formation , the factors or alleles of a pair _____ from each other such that a gamete receives only one of the 2 factors .
Segregate
Sometimes the F1 had phenotype that did not resemble either of the 2 parents and was in btw the 2 . This phenomenon is called -
Incomplete dominance
The inheritance of flower colour in ______is a good example to understand incomplete dominance .
Dog flower /snapdragon/ Antirrhinum sp .
Ina cross btw true-breeding red-flower and true-breeding white flower , the ____ generation was ____.
The F1 gen
Pink ( all )
When the F1 gen ( all pink ) , were SELF POLLINATED , then F2 resulted in -
1 red : 2 pink : 1 white
If we talk about a gene that contains info for producing an enzyme , the modified allele (of the gene) could be responsible for production of -
Normal or less efficient enzyme
A non-functional enzyme
No enzyme at all
If the allele produces normal or less efficient enzyme , the modified allele is equivalent to the ____ i.e. , it will produce the ____ i.e., results in the transformation of substrate .
Unmodified allele
Same phenotype /trait
The ____allele which represents the original phenotype is the dominant allele and. The __is generally the recessive allele .
Unmodified /functioning
Modified
In the enzyme functioning , recessive trait is seen due to ____ or _____ .
Non-functional enzyme
Becoz no enzyme is produced
In case of ______, the______ resembles both the parents .
Codominance
F1 gen
Examples of codominance -
ABO blood grps
ABO blood grps are controlled by the gene ____.
I
The ____of the RBCs have _____that protrude from its surface and the _____is controlled by the gene .
plasma membrane
Sugar polymers
Kind of sugar
The gene I has __alleles . Name -
3
IA
IB
i
The kind of sugar produced by the 3 alleles is -
IA ad IB - produce a slightly diff form of sugar
i-does not produce any sugar
When ____and __are present together , they both express their own types of sugars .
IA
IB
Becoz of codominance , RBCs have ____types of sugars .
Both A and B
A total of ___genotypes of the human ABO blood types are possible .
6
ABO blood grouping also provide a good example of ______.
Multiple alleles (And codominance)
ABO show multiple allelism , becoz ?
Here , 3 alleles ( more than 2) are governing the same char .
Since in an individual only 2 alleles can be present , multiple alleles can be found occasionally only when ____are made .
Population studies
___is not an autonomous feature of a gene or the product that it has info for .
Dominance
Dominance depends as much on the ________and the production of _____.
Gene produce
Particular phenotype from this product
Occasionally , a single gene product may produce more than one effect . For example -
Starch synthesis in pea seeds -controlled by 1 gene
Starch is synthesised effectively by homozygotes (BB) , therefore ____starch grains are produced . After maturation , BB seeds are rounded and bb wrinkled . B is the dominant allele . But starch grain produce ____ size in Bb .
Large
Intermediate size
If starch grain SIZE is considered as the PHENOTYPE , then form this angle , the alleles show _____ .
Incomplete dominance ( in size )
When mendel self -hybridised the F1 plants , he found that ____ of F2 had yellow seeds and ____had green seeds. Therefore the yellow and green colour segregated in a _____ratio .
3/4th
1/4th
3:1
In a di hybrid cross , the PHENOTYPES round yellow ;wrinkled yellow ;round green ;wrinkled green appeared in the ratio -
9:3:3:1
Based on the observations on the di hybrid crosses , mendel proposed a second set of generalizations , that we call -
Law of independent assortment
State law of independent assortment -
When 2 pairs of traits are combined in a hybrid , segregation of one pair f characters is independent of the other pair of chars .
Mendel published his work on inheritance in ____ , but it remained unrecognised till ____ .
1865
1900
Give 3 reasons why mendels work remained unrecognised for several years -
1) communication was not easy
2) his concept of genes (or factors ) as stable and discreet units that controlled the expression of traits and of th pair of alleles that did not blend with each other was not accepted by his contemporaries .
3) mendels approach of using maths to explain biology was totally new .
In _____ , 3 scientists ____, ____ and ___ rediscovered mendels results on inheritance of chars .
1900
De vries
Correns
Von tschermak
The 3 scientists jointly /independently rediscovered mendels results .
Independently
By 1900 , due to advancements in microscopy scientists were able to observe ______ . This led to the discovery of structures in the nucleus that appeared to double and divide just before cell division . They were called _____ .why ?
Cell division
Chromosomes / coloured bodies
Becoz they were visualised by staining
B ___ , the chromosome movement during meiosis had been world out .
1902
__and ___noted that behaviour of chromosomes was parallel to the behaviour of genes .
Walter Sutton
Theodore boveri
Walter Sutton and Theodore boveri used __to explain __.
Chromosome movement
Mendels laws
__As well as _____occur in pairs .
Chromosomes
Genes
(Sutton and boveri )
The ____ of ___are located on homologous sites on homologous chromosomes .
2 alleles
A gene pair
During ____of ____ , the 2 chromosome pairs are aligned at the metaphase plate independently of each other .
Anaphase 1
Meiosis 1
___and ___ argued that the pairing and separation of a pair of chromosomes would lead to segregation of a pair of factors they carried .
Sutton
Boveri
Sutton united the knowledge of________ with______ principles and called it _______.
Chromosomal segregation
Mendelian principles
Chromosomal theory of inheritance
Who gave the chromosomal theory of inheritance ?
Sutton
Experimental verification of chromosomal theory of inheritance was done by -
Thomas hunt morgan
______led to discovering the basis for VARIATION that sexual reproduction produced .
Experimental verification of chromosomal theory of inheritance by Morgan and his colleagues
Morgan worked with the _____flies .
Fruit -drosophila melanogaster
Why were fruit flies found very suitable for Morgan’s study ?
1) could be grown on simple synthetic medium in the laboratory
2) they complete their life cycle in about 2 weeks
3) a single mating could produce a large number of progeny flies
4) clear differentiation of sexes
5) it has many types of hereditary variations that could be seen with a low power microscope
Morgan carried out several ___ crosses in drosophila to study genes that were ______.
Dihybrid
Sex-linked
The crosses carried out by Morgan were similar to the dihybrid crosses carried out by _____ in ____ .
Mendel
Peas
Morgan hybridized ____ females to ____males and ____their progeny .
Yellow bodied -white eyed females
Brown bodied -red-eyed males
Intercrossed
When Morgan performed the dihybrid cross , he observed that the 2 genes __________ and the F2 ratio deviated very significantly from the ______ .
Did not segregate independently of each other ( separated depending on each other )
9:3:3:1 ratio ( expected )
Morgan and his group knew that the genes were located on the _____.
X-chromosome
Morgan saw that when the 2 genes were situated on the same chromosome , the proportion of ____Were much higher than the _____ .
Parental gene combination
Non-parental type
Morgan coined the term ___ to describe the physical association of genes on chromosomes and the term ____ to describe the NON-PARENTAL gene combinations .
Linkage
Recombination
Morgan found that genes __ and __were tightly linked ( on drosophila ) and showed only ___% recombination .
White
Yellow
1.3%
Morgan found that ____and __wing were linked more tightly and showed ____% recombination .
White
Miniature
37.2%