1.5.4 The Structure of RNA Flashcards
Like DNA, the nucleic acid RNA (ribonucleic acid) is
a polynucleotide – it is made up of many nucleotides linked together in a chain
Like DNA, RNA nucleotides contain the nitrogenous bases
adenine (A), guanine (G) and cytosine (C)
Unlike DNA, RNA nucleotides never contain the nitrogenous base
thymine (T)
Unlike DNA, RNA nucleotides never contain the nitrogenous base thymine (T) – in place of this they contain the nitrogenous base
uracil (U)
Unlike DNA, RNA nucleotides contain the pentose sugar
ribose (instead of deoxyribose)
Unlike DNA, RNA molecules are only made up of one
polynucleotide strand (they are single-stranded)
RNA polynucleotide chains are relatively short compared to
DNA
Each RNA polynucleotide strand is made up of alternating
ribose sugars and phosphate groups linked together
Each RNA polynucleotide strand is made up of alternating ribose sugars and phosphate groups linked together, with the nitrogenous bases of each nucleotide
projecting out sideways from the single-stranded RNA molecule
The sugar-phosphate bonds (between different nucleotides in the same strand) are covalent bonds known as
phosphodiester bonds
These bonds form what is known as
the sugar-phosphate backbone of the RNA polynucleotide strand
The phosphodiester bonds link
the 5-carbon of one ribose sugar molecule to the phosphate group from the same nucleotide
The phosphodiester bonds link the 5-carbon of one ribose sugar molecule to the phosphate group from the same nucleotide, which is itself linked by another phosphodiester bond to
the 3-carbon of the ribose sugar molecule of the next nucleotide in the strand
An example of an RNA molecule is
messenger RNA (mRNA
An example of an RNA molecule is messenger RNA (mRNA), which is
the transcript copy of a gene that encodes a specific polypeptide
Messenger RNA (mRNA) provides a good example of the structure of RNA
