Translation Flashcards
What happens to mRNA in eukaryotic cells?
mRNA leaves nucleus + binds to specific site on smaller subunit of ribosome
Ribosomes found free in cytoplasm or on surface of RER
How does translation start?
When mRNA bounds to smaller subunit, larger ribosomal subuniy attaches + process of translation can begin
What is the 1st step in translation?
Each triplet codon on mRNA molecule attracts specific tRNA molecule that has a complementary anticodon
E.g. mRNA codon AUG binds with tRNA anticodon UAC
What is tRNA?
Form of RNA composed of single-stranded RNA molecule that forms hydrogen bonds within itself
What is the tRNA structure?
Clover-leaf structure, and anticodon + amino acid attachment site
How many tRNA molecules have specific anticodons?
64
What happens at the ribosome?
Max of 2 tRNA molecules can bind to mRNA strand. As they do, peptide bond forms between 2 amino acids
This is catalysed by enzyme peptidyl transferase
What is the purpose of transcription + translation?
To make proteins - sequence of amino acids
What happens at the end of translation?
Ribosome moves along mRNA molecule, with 1st tRNA leaving. 2nd mRNA molecule becomes 1st + new tRNA molecule arrives
Continues until ribosome reaches stop codon
Then, subunits of ribosome dissociate + polypeptide (or protein) is released
What is a polysome?
Several ribosomes binding to single mRNA molecule at same time
What does it mean when ribosomes are closer to 3’ end?
The more translation has occurred, + the longer the polypeptide chain
What structure is the protein in when 1st formed?
Primary structure - specific sequence of amino acids
What happens after the primary structure?
Protein folds into secondary + tertiary structure
This depends on primary structure + type of R-groups it contains
Where is any further modification of proteins done in eukaryotic cells?
Golgi apparatus
E.g. Prosthetic groups can be added to make conjugated proteins
