The process of RNA editing is the alteration of the sequence of nucleotides in the RNA after it has been transcribed from DNA, but before it is translated into a protein. RNA editing occurs by two distinct mechanisms:<em><u /><u>Substitution</u> <u>editing </u></em>and <u><em>Insertion/</em></u><em></em><u><em>deletion</em></u><em> <u>editing</u></em>.
<u><em>Substitution editing</em></u> is the chemical alteration of individual nucleotides. These alterations are catalyzed by enzymes that recognize a specific target sequence of nucleotides:
*Cytidine Deaminases that convert a C in the RNA to uracil.
*<em />adenosine deaminases that convert an A to inosine,which the ribosome translates as a G.<span>Thus a CAG codon</span><span> (for Gln) can be converted to a CGG codon (for Arg).
<em><u>*Insertion/deletion editing</u></em><em><u /></em><u /> is the insertion or deletion of nucleotides in an RNA.
These alterations are mediated by guide RNA molecules that base-pair as best they can with the RNA to be edited and serve as a template for the addition( or removal) in the target.</span>
the three kinds of nitrogenous wastes based on the energy required to synthesize them are arranged; Ammonia < urea < uric acid.
Nitrogenous wastes are the nitrogen compounds that organisms use to get rid of excess nitrogen. Ammonia, urea, and uric acid are the most common nitrogenous wastes that animals excrete. Protein metabolism generates all of these nitrogenous wastes.
Ammonia is the most toxic of these nitrogenous wastes, and it is the most common but requires the least energy. Urea is more harmful than uric acid, but it is less harmful than ammonia, reducing the amount of energy required to synthesize it. Uric acid is the least harmful, a non-poisonous particle with four nitrogen molecules. This is useful for birds and reptiles that lay hard eggs because it eliminates the most nitrogen, uses the least amount of water, and is not toxic. It also takes the most energy input.
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Answer:
Analogous structures are structures which serve similar function in different organisms and evolved independently in two living organisms while homologous structures are the structures which are similar in related orgnanism due to inheritance.
The wings of Pterodactyl, bats and birds are conisdered as analogous structure. <u>they are similar in structure and same in function and evolved independently in the two groups of animals.</u>
Bones in forelimbs of pterodactyl, bats and birds are considered homologous structures as <u>they inherited the pattern from a common ancestor and have different functions.</u>
asexual reproduction is when 2 of the same sex create more of asexual babies