5. Nucleic acids. Structure of RNA. RNA types and functions.

Question 1

Structure of RNA

Answer 1

Similar structure to DNA, but with these key differences.

-Ribose instead of deoxyribose
Uracil (U) instead of thymine (T). (complementary to adenine)

-RNA molecules are smaller to DNA
-RNA molecules exist as single stranded (except in double- stranded region, called loops in rRNA, tRNA and RNA viruses)

Similar to DNA, RNA also has a tertiary structure.
-Some RNA molecules, called ribozymes, function as enzymes. e.g the intron RNA functions as a ribozyme and catalyzes its own removal during the mRNA splicing.

Question 2

RNA types and functions - rRNA

Answer 2

Ribosomal RNA (rRNA)
-TYPES of rRNA:
–Three types in prokaryotes
–Four types in eukaryotes.
-STRUCTURE – single stranded, but large part of molecule forms double-stranded stem-loop regions for binding to regulatory proteins.
-FUNCTION
–Structural- in combination with proteins forms the two subunits of ribosomes.
–Prokaryotic 23S pPHK has a catalytic function in the formation of the peptide bond during the translation