In this lecture you will learn:
|1. mRNA is messenger RNA
- it is the actual "message" that is TRANSLATED into protein
- the base sequence specifies which proteins will be made during translation
|2. rRNA is ribosomal RNA
- the RNA that is the "machinery" that makes proteins
- it is structural, proteins and the rRNA are assembled into a globular structure like an enzyme
- it is composed of 2 subunits
|3. tRNA is transfer RNA
- There are 32 different tRNAs and each
one binds a SPECIFIC amino acid
In order to make proteins it is necessary to faithfully TRANSLATE from the language of RNA to the language of amino acids.
Through experimentation scientists discovered that it requires 3 RNA bases to code for a single amino acid.
HERE ARE TWO DICTIONARIES FOR ALL 20 AMINO
|There are 3 letter abbreviations to each
and "speaks" the amino acid language on the other end --------->
|The first step was making the RNA required
in the nucleus (previous lecture), the mRNA, tRNA, rRNA and processing
it for being translated. The RNAs move out of the nucleus and into
b. The tRNA carrying the anticodon UAC binds firmly to the codon AUG by hydrogen bonds. This tRNA carries the amino acid MET (methionine) on the other end.
c. The large ribosome subunit now joins the small subunit.
b. An enzyme now forges the covalent bond between the two amino acids, MET and the 2nd one in line. The formation of the covalent bond is called "dehydration synthesis".
c. The amino acid MET is released from the tRNA.
d. The tRNA for MET is ejected from the ribosome and floats free to go pick up another MET.
e. The ribosome moves down the mRNA to the next codon.
f. Elongation repeats until it runs into a stop codon.
b. An enzyme separates the chain of amino acids (polypeptide/protein) from the last tRNA.
c. The ribosome comes apart and translation ends.
|Please understand this picture, will be in quiz|
|What you are likely to see in exam|
What is translation?
How many different letters are there in the RNA alphabet?
How many different letters are there in the protein alphabet?
How many of the 4 bases are needed to code for 1 amino acid?
Be able to read the RNA codon to amino acid table.
Where are codons found?
Where are anticodons found?
What is the start codon for all proteins? Which amino acid does it code for?