Linkage refers to the tendency of inhertance of the DNA sequences that are close together on a chromosome during the meiosis of sexual reproduction. It can be measured by the recombination frequency.
Recombination frequency describes the proportion of recombinant offsrpring produced in a genetic cross between two organisms. It is the frequency with which a single chromosomal cross over takesplace between two genes during the process of meiosis. Recombination frequency (RF) is given by
RF= Recombinants /total offspring x 100.
In the above example, the number of recombinant offspring is 20 and the total offspring is 400. By substituting these values,
RF= 20/400 x100
= 5.
The recombination frequency for the above cross is 5.
Answer:
The correct option is A.
Convergent evolution is one of the defined type of evolution and it is shown by the species belonging to different ancestors show similar characteristics due to the same residing environmental condition.
Explanation:
The creation of analogous structure takes place in the process of convergent evolution. This is illustrated by the occurrence of similar structure in two different species which were not observed in their respective ancestor. This is due to the residence of the associated species in the same environmental condition and facing the same problems of livelihood. One of the most common example is the flying ability of the insects, bats and birds.
Chinese hamster ovary cell production of recombinant tissue‐type plasminogen activator (t‐PA) was increased by amplification of cotransfected dihydrofolate reeducates cDNA using stepwise adaptation to increasing methotrexate (MTX) concentrations. The highest producing clones were isolated at 5 μM MTX and yielded 26,000 U/106 cells/day t‐PA (43 μg/106 cells/day). Above 25 μM MTX, cell specific t‐PA production rates became increasingly variable and the cDNA copynumbers decreased. No apparent correlation between the cell specific t‐PA production rate and the growth rate was observed upon sub cloning of the amplified cells. When MTX selection was removed, the t‐PA production rate decreased up to tenfold within 40 days; this was accompanied by an up to 60% drop in cDNA copynumber. Subclones isolated after 108 days of culture in the absence of MTX were, on average, sixfold more stable than their parental cells. In culture without MTX, the maximum stable t‐PA production rate obtained (over 250 days) was 7000 ± 750 U/106cells/day (∼12 μg/106 cells/day), approximately threefold lower than the maximum unstable levels of production reached under selective pressure. Taken together, these results define a wide range of the highest t‐PA expression rates obtained under MTX selection, for which stable expression without selection has not been reported
Answer:
ok
Explanation:
Hi I think the answer is bit C but I am not sure
