Please enable JavaScript.
Coggle requires JavaScript to display documents.
Genetics (Replication of DNA (DNA is replicated during S phase of the cell…
Genetics
Replication of DNA
-
after cell division, each chromosome consists of single DNA which is double stranded helix in structure.
DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule
DNA is made up of a double helix of two complementary strands. During replication, these strands are separated
unwinding of DNA at the origin and synthesis of new strands, accommodated by an enzyme known as helicase, results in replication forks growing bi-directionally from the origin. A number of proteins are associated with the replication fork to help in the initiation and continuation of DNA synthesis. Most prominently, DNA polymerase synthesizes the new strands by adding nucleotides that complement each (template) strand.
Mutation
mutation is a change, large or small, in DNA.
-
Causes of Mutation
-
some factors that causes mutation are chemicals, ultraviolet light, x- rays and radiation from radioactive substances.
insertion mutation is caused by cutting of DNA by a enzyme and rejoining with a foreign DNA as repair process.
transposition mutagenesis, is a biological process that allows genes to be transferred to a host organism's chromosome, interrupting or modifying the function of an extant gene on the chromosome and causing mutation
-
Monohybrid cross
monohybrid cross is a mating between two organisms with different variations at one genetic chromosome of interest
A cross between two parents possessing a pair of contrasting characters is known as monohybrid cross.
In the organism there is a pair of factors that controls the appearance of a given characteristic called gene. The organism inherits these factors from its parents, one from each. A factor is transmitted from generation to generation as a discrete, unchanging unit. When the gametes are formed, the factors separate and are distributed as units to each gamete. This statement is often called Mendel's rule of segregation. If an organism has two unlike factors (called alleles) for a characteristic, one may be expressed to the total exclusion of the other (dominant vs recessive).
Dihybrid cross
Dihybrid cross is a cross between two different genes that differ in two observed traits. In the Mendelian sense, between the alleles of both these loci there is a relationship of complete dominance - recessive.
In the name "Dihybrid cross", the "di" indicates that there are two traits involved (e.g. R and Y), the "hybrid" means that each trait has two different alleles (e.g. R and r, or Y and y), and "cross" means that there are two individuals (usually a mother and father) who are combining or "crossing" their genetic information.
For genes on separate chromosomes, each allele pair showed independent segregation. If the first filial generation (F1 generation) produces four identical offspring, the second filial generation, which occurs by crossing the members of the first filial generation, shows a phenotypic (appearance) ratio of 9:3:3:1
-
-
-
-
