RECESSIVE MUTATION
A recessive mutation is a kind of mutation whereby both alleles must be mutant in order for the mutant phenotype to be observed. This means that the individual must be homozygous for the mutant allele to show the mutant phenotype. on the contrary, the phenotypic expression of a dominant mutation are observed in a heterozygous individual which carries one mutant and one normal allele.
For a recessive mutation to give rise to a mutant phenotype in a diploid organism (Humans), both alleles must carry the mutation.
Factors that influence the frequency of common recessive mutation
Selection – Actually, this is the major force that keeps lethal alleles from frequency increase in a population. It is preferential survival or elimination of individuals with certain genotypes, either naturally or artificially control factors. Due to this, detrimental genes are reduced across generations.
Mutation – Mutations are constantly occurring, hence, mutant allele is never completely eliminated. The increased mutation rate result to the production of more mutant allele across generations.
Improvement in medical care – the frequency of these diseases could rise also because of improved medical care that enables affected individuals to survive and reproduce.
Inbreeding – production of offspring or new ones from within a limited genetic pool often increase the incident of recessive diseases.
Genetic recombination (also known as genetic reshuffling) is the exchange of genetic material between different organisms which leads to production of offspring with combinations of traits that differ from those found in either parent. The mechanism of general recombination ensures that two DNA double helices undergo an exchange reaction only if they contain an extensive region of sequence similarity (homology). The formation of a long heteroduplex joint requires such homology because it involves a long region of complementary base-pairing between a strand from one of the two original double helices and a complementary strand from the other double helix. But how does this heteroduplex joint arise, and how do the two homologous regions of DNA at the site of crossing-over recognize each other? As we shall see, recognition takes place during a process called DNA synapsis, in which base pairs form between complementary strands from the two DNA molecules.
EBONYI STATE UNIVERSITY ABAKALIKI, EBONYI STATE
AN ASSIGNMENT SUBMITTED
BY
NWEKE CHIDERA BENEDICTA
REG.NO: EBSU/2021/101387
QUESTION
RECOMBINATION WITH A STRUCTURE.
Genetic recombination (also known as genetic reshuffling) is the exchange of genetic material between different organisms which leads to production of offspring with combinations of traits that differ from those found in either parent. The mechanism of general recombination ensures that two DNA double helices undergo an exchange reaction only if they contain an extensive region of sequence similarity (homology). The formation of a long heteroduplex joint requires such homology because it involves a long region of complementary base-pairing between a strand from one of the two original double helices and a complementary strand from the other double helix. But how does this heteroduplex joint arise, and how do the two homologous regions of DNA at the site of crossing-over recognize each other? As we shall see, recognition takes place during a process called DNA synapsis, in which base pairs form between complementary strands from the two DNA molecules.
Interesting.. Thanks for the input.