The classical example of point mutation is
Sickle cell anaemia
A point mutation is a change in a single base pair of DNA. Sickle-cell anaemia is the classical textbook example of such a mutation.
In sickle-cell anaemia, a single base substitution in the gene for the β-globin chain changes the sixth codon from GAG to GUG. As a result, glutamic acid (Glu) is replaced by valine (Val) at the sixth position of the β-globin chain. The mutant haemoglobin (HbS) polymerises under low oxygen tension, and the red blood cells become elongated and sickle shaped.
Haemophilia is a sex-linked recessive disorder of blood clotting and is not cited as the classical point-mutation example. Cystic fibrosis is an autosomal recessive disorder, most often caused by a small deletion in the CFTR gene. Phenyl ketonuria is an inborn error of metabolism caused by the lack of the enzyme that converts phenylalanine into tyrosine; it is not the textbook example of a single base substitution.
Sickle cell anaemia option is correct.
Similar Questions
In a practical examination, the below given pedigree chart was given as spotter for identification.
The students identified the pedigree chart as ________
Identify the correct order of stages in Human evolution.
a) Homo habilis
b) Homo erectus
c) Australopithecus
d) Neanderthal man
e) Dryopithecus
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Select the statement which is ‘NOT’ true about Big Bang Theory.
Arrange the below given steps of DNA fingerprinting in sequence by selecting the appropriate option.
a) Digestion of DNA by restriction endonucleases
b) Autoradiography
c) Blotting of DNA fragments to nitrocellulose membrane
d) Isolation of DNA
e) Separation of DNA fragments by electrophoresis
In a DNA molecule, cytosine is 28%. Calculate the percentage of adenine.
Who amongst the following scientist/s had no contribution in the development of the double-helix model for the structure of DNA?
Thalassemia and Sickle cell anaemia are due to a problem in globin molecule synthesis.
Select the correct statement.
Read the following statements.
Statement I: In a typical test cross, an organism showing a dominant phenotype is crossed with the recessive parent.
Statement II: The ratio of organisms showing dominant and recessive traits in F1 generation of a test cross indicates that the organism with unknown genotype is homozygous dominant.
Choose the correct option.
The genotypes of husband and wife are IAIB and IAIO. Among the blood groups of their children, how many different genotypes and phenotypes are possible?
Important Questions from Genetics and Evolution
- Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : Forelimbs of human and bats are homologous.
Reason R : Forelimbs of humans and bats have similar anatomical structure.
In the light of the above statements, choose the most appropriate answer from the options given below : - Given below are two statements :
Statement I : Modern *Homo sapiens* arose in Australia and moved across continents.
Statement II : *Homo sapiens* arose around 75000 to 10000 years ago.
In the light of the above statements, choose the most appropriate answer from the options given below : A population of diploid organisms is at Hardy-Weinberg equilibrium. If the frequency of allele A is 0.1, the frequency of AA is ____________ .
Adaptive radiation in placental mammals and Australian Marsupials leading to similarity between distant species is an example of ___________
- Natural selection can lead to
(a) stabilisation
(b) genetic drift
(c) directional change
(d) disruption
Choose the correct answer from the options given below :
