Proteins Flashcards
What enzymes bind amino acids to tRNA?
Aminoacyl-tRNA synthetases
What 2 molecules are used as energy sources during translation?
ATP and GTP
What is the first stage of tRNA to amino acid binding?
Aminoacyl-tRNA synthase for a specific enzyme binds to ATP and the amino acid
What is the second stage of tRNA to amino acid binding?
ATP bound to the activating enzyme is hydrolysed to form AMP and a pyrophosphate
What is the third stage of tRNA to amino acid binding?
The amino acid specific tRNA molecule binds to the enzyme
What is the fourth stage of tRNA to amino acid binding?
The AMP is lost from the molecule leaving just the enzyme, tRNA and amino acid
What is the fifth stage of tRNA to amino acid binding?
The tRNA and amino acid detach from the enzyme
What size of ribosome is found in a prokaryote?
70S
What size of ribosome is found in a eukaryote?
80S
What are the 3 binding sites of ribosomes?
Exit
Peptidyl
Aminoacyl
What is required for the initiation of translation?
Initiation factors
GTP
Methionine tRNA
40S subunit
What is required to move the first methionine from the A binding site to the P binding site
ATP
What allows for the binding of the large 60S subunit to the small 40S subunit?
The methionine initiator RNA
What brings the second base of translation to the A site of the ribosomes?
An elongation factor (EF-1α)
What enzyme catalyses the formation of peptide bone between amino acids?
Peptidyl transferase
What moves the mRNA along the ribosome by 1 triplet?
EF-2
What releases EF-1α from the aminoacyl-tRNA after it has been moved?
The hydrolysis of GTP
What regenerates EF-1α to pick up the next aminoacyl-tRNA?
EFβγ
What binds to stop codons to terminate translation?
A release factor
What is a polysome?
A chain of ribosomes in which the same mRNA strand can move through to form many copies of the same protein
Where do proteins formed by free ribosomes move to?
Cytosol
Nucleus
Mitochondria
Where do proteins formed by bound ribosomes move to?
Plasma membrane
ER
Golgi apparatus
Secretion
When are proteins from free ribosomes translocated?
Post-translationally (After translation)
When are proteins from bound ribosomes translocated?
Co-translationally (During translation)
What is I-cell disease/mucolipidosis II?
An inherited disease in which proteins normally destined for ribosomes are not sorted in the golgi, so they are secreted from the cell. This means lysosomes can’t properly digest material
What is glycosylation?
Addition and processing of carbohydrates in the ER and golgi
