B) Replication of their genomes does not involve the proofreading steps of DNA replication.
Explanation:
RNA viruses have upto 1 billion time higher mutation rate than their host. As RNA is more fragile than DNA so these mutations are associated with the adaptability of RNA viruses in changing environment as well with their virulence. The higher mutation rates in RNA are the consequences of following factors.
The DNA of eukaryotes as well as of some viruses have the proofreading mechanism to repair mutations. Even some very high RNA viruses also poses this ability. But most of the viral RNA polymerases lack the ability of proofreading i. e. it cannot rectify the replication errors in RNA. It causes the higher mutation rate in viral RNA.
Another comparatively small cause is the presence of uracil base in RNA instead of thymine. Sometime cytosine base changes to uracil and this is detected in DNA because DNA don't contain uracil while it cannot be detected in RNA because it already contains uracil.
B) Replication of their genomes does not involve the proofreading steps of DNA replication.
Explanation:j
1. This is because RNA polymerase do not proofread proteins or polymerase components to check for errors and repair.
2.Because RNA viruses usually encoded their replication machinery, therefore they have the ability to replication at high rate which increases chances for mutation, to any length and extent to suits their needs.
Therefore,since there is no check for the number of replication they can go through and no need for correction of replication errors, they have rapid chances for mutation and therefore virulence. Different offspring, with distinct genetic composition from wrong bases insertion and translation and therefore of virulence totally different from the parents will be produced. Thus mutagensis, and virulence continues to increase.
In light-dependent reactions, the energy from sunlight is absorbed by chlorophyll and converted into chemical energy in the form of electron carrier molecules like ATP and NADPH. Light energy is harnessed in Photosystems I and II, both of which are present in the thylakoid membranes of chloroplasts.
Base on studies and researches and the DRI guidelines in
which had provided factual and evidence, the desirable intake of dietary fiber
among women who is under at the age of fifty years old is that they should have
twenty five grams of fiber daily.
