THIS IS MY ASSIGNMENT 3
- 3af_z1.zip
- N-PHENYLACETAMIDE.PDB
- N-PHENYLACETAMIDE.XYZ
- VRML images
- ABOUT RIBONUCLEIC ACID (RNA)
Ribonucleic acid (RNA) is a nucleic acid polymer consisting of nucleotide
monomers. RNA nucleotides contain ribose rings and uracil unlike
deoxyribonucleic acid (DNA), which contains deoxyribose and thymine.
It is transcribed from DNA by enzymes called RNA polymerases and further
processed by other enzymes. RNA serves as the template for translation of
genes into proteins, transferring amino acids to the ribosome to form
proteins, and also translating the transcript into proteins.
CHEMICAL STRUCTURE
RNA is primarily made up of four different bases: adenine, guanine,
cytosine, and uracil. The first three are the same as those found in DNA,
but in DNA thymine replaces uracil as the base complementary to adenine.
This base is also a pyrimidine and is very similar to thymine. Uracil is
energetically less expensive to produce than thymine, which may account for
its use in RNA. In DNA, however, uracil is readily produced by chemical
degradation of cytosine, so having thymine as the normal base makes
detection and repair of such incipient mutations more efficient.
Thus, uracil is appropriate for RNA, where quantity is important but
lifespan is not, whereas thymine is appropriate for DNA where maintaining
sequence with high fidelity is more critical.
There are also numerous modified bases found in RNA that serve many
different roles. Pseudouridine (Ø) and the DNA base thymidine are
found in various places (most notably in the TØC loop of every tRNA).
There are nearly 100 other naturally occurring modified bases,
many of which are not fully understood.
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