Translation Flashcards
DNA - RNA
RNA - ?
protein
what is the point of translation?
to make a polypeptide that corresponds to the sequence in the mrna
what are the components of translation?
- mrna
- ribosomes
- trna
- aminoacyl-trna synthetase
- various protein factors
ribosomes are made up of?
they are made up of ribosomal rna and proteins.
in shape they have 2 subunits: large and small subunit
the subunit numbers?
small subunit: 40s
large subunit: 60s
together: 80s
where is the ribosome assembled in eukaryotes?
in eukaryotes the ribosome is assembled in the nucleus
once the ribosomes are made, they move into?
the cytoplasm
the subunits are found where? they come together when?
the subunits are found free in the cytoplasm, they only come together when translation occurs.
what are the 4 sites on the ribosome that are important for protein synthesis?
- one mrna binding site
- 3 trna binding sites
APE
Aminoacyl trna binding site, peptidyl trna binding site, exit site
what is trna?
trna is transfer rna. it is the carrier of amino acids.
- the trna binds to a specific amino acid and brings it to the mrna based upon the appropriate codon.
there is a specific trna molecule?
for each codon
what is an anticodon?
an anticodon is a nucleotide triplet that base pairs with a complementary sequence on the mrna.
what is aminoacyl trna synthetase?
this is the enzyme responsible for attaching the correct amino acid to its corresponding trna molecule. 20 different kinds.
once the amino acid is attached, the trna is called?
an aminoacyl trna or charged trna
there are various protein factors required for?
initiation, elongation, and termination.
examples: ifs, efs, release factors
the translation initiation codon is 5’ aug 3’ by way of genetic code, this codon codes for?
methionine
what does the initial assembly require?
- mrna
- small ribosomal subunit
- initiator trna met
once assembled, what next?
the large subunit comes in and binds.
= translation initiation complex
what position is trna met in?
p site.
step 2: elongation
- trna met is in p site
- a site is open
there are 3 phases of elongation?
first: aminoacyl trna binding. incoming aminoacyl trna is bought to the a site of the ribosome.
then: transpeptidation reaction: the formation of a peptide bond between the amino group of the new amino acid in the a site and the carboxyl group of the amino acid on the growing chain.
then: translocation: the ribosome moves one codon along the mrna. the trna in the p sie moves to the e site and the trna in the a site moves to the p site and a nre trna enters the a site
what are polyribosomes?
string of ribosomes along the mrna.
allows the cell to make many copies of a polypeptide quickly.
how does the ribosome know when to stop?
elongation proceeds until one of the three possible stop codons are reached. they are recognized by proteins called release factors which bind to the codon and trigger the release of the polypeptide from the trna.
what happens to the released polypeptides?
the released polypeptides are then folded into their 3d conformation.
correct folding is aided by ?
proteins called molecular chaperones
polypeptide vs protein?
a polypeptide refers to the immediate polymerization of amino acids.
a protein is a polypeptide or several that has folded itself into a functional conformation
