THE THREE MAJOR KINDS OF RNA AND THEIR FUNCTION
The main points of this lecture are:
there are 3 major forms of RNA
mRNA which is the "message"
rRNA which is the machinery/enzyme
tRNA which brings in the amino acids and
|1. mRNA is
- it is the actual linear "message" that
is TRANSLATED into protein
- the base sequence specifies which proteins
will be made during translation
|2. rRNA is
- the RNA that is the "machinery"
that makes proteins
- it is structural in that proteins and
the rRNA are assembled together into a globular structure like an enzyme
- it is composed of 2 subunits
|3. tRNA is
- There are 32 different tRNAs and each
one binds a SPECIFIC one of the 20 amino acid
- it holds the amino acid in a physical
position so it can be added onto the developing protein polymer chain
- each tRNA is the product of a separate
gene or section of DNA containing 73-93 nucleotides
– each has a "loop and stem" structure
- the stems are hydrogen bonded
to give structure
– the paired and H bonded stems can form
sections of double helix
- the unpaired regions form 3 loops
- each tRNA carries (at its 3' end)
the amino acid specific to that tRNA
- the middle loop has the 3 unpaired bases
that form the anticodon base
- it is the anticodon that pairs with
the complementary codon on the mRNA molecule and brings the correct amino
acid into alignment to be added to the growing polypeptide chain.
What are the 3 kinds of RNA?
What is their function and how are they
different from each other?
Describe what the different RNAs look