Genetic code/protein synthesis Flashcards
How many bases code for one amino acid?
3
How many possible amino acids can the genetic code make?
64
Aug codes for?
Methionine and it is a start codon
What are the three stop codons?
UAA, UGA and UAG
Ugg codes for what amino acid?
trp
The first column is green which means they are?
hydrophobic
The yellow amino acids have what quality?
they are polar, have H bonds
the pink amino acids are?
charged
What is the most common amino acid for e. coli?
leucine at CUG
what is the most common amino acid for humans?
leucine for CUG
how many of the 64 codons make amino acids?
61
All living systems do not use the same genetic code and it is not universal.
FALSE IT IS UNIVERSAL
mitocondrial genomes show some differences, for example ____ specifies TRp rather than stop
UGA
Are prokaryotic or eukaryotic ribosomes bigger?
eukaryotic
What is found in the gap between the 50S and the 30S of the ribosome in E. coli?
mRNA is found
initiation in protein synthesis involves….?
binding of mRNA to the small and large ribosomal
subunits, and binding of an initiator tRNA
Elongation in protein synthesis involves….?
the formation of all peptide bonds of the growing
polypeptide chain
Elongation in protein synthesis involves….?
the formation of all peptide bonds of the growing
polypeptide chain
Termination in protein synthesis occurs when….?
Occurs when a “stop” codon is reached along the mRNA, which leads to the release of the completed polypeptide.
In protein synthesis, a new aminoacyl-tRNA binds to the _________ site and then the
growing polypeptide at the P (peptidyl) site is transferred to the A site with the formation
of a peptide bond.
A (acceptor)
is this in eukaryotes or prokaryotes?
Small subunit (30S)
16S rRNA
21 proteins
60% RNA/ 40% protein
prokaryotes
is this in eukaryotes or prokaryotes?
Large subunit (50S)
23S and 5S rRNAs
31 proteins
70% RNA
prokaryotes
is this in eukaryotes or prokaryotes?
Small subunits (40S)
18S rRNA
33 proteins
50% RNA/ 50% protein
eukaryotic
is this in eukaryotes or prokaryotes?
Large subunits (60S)
28S, 5.8S, and 5S rRNAs
49 proteins
65% RNA/ 35% protein
eukaryote
Rat liver ribosomes (80S) have a mass that is _____ times that of E. coli ribosomes
1.7
Protein synthesis has three phases: initiation, elongation, and termination.
true
what is initiation in protein synthesis
Involves binding of mRNA to the small and large ribosomal
subunits, and then binding of an initiator tRNA
what is elongation in protein synthesis
Includes the formation of all peptide bonds of the growing
polypeptide chain
what does termination do in protein synthesis
Occurs when a “stop” codon is reached along the mRNA
what 5 factors are needed for peptide chain initiation.
(a) mRNA
(b) 30S and 50S ribosomal subunits
(c) initiation factors
(d) GTP
(e) initiator tRNA (f-Met-tRNA)
what is needed for elongation in protein synthesis
(a) mRNA/ribosome/peptidyl-tRNA complex
(b) aminoacyl-tRNAs
(c) elongation factors
(d) GTP
For peptide chain termination, the components include:
(a) release factors
(b) GTP
Initiation begins with the binding
of _____ and the initiator _____
(f-Met-tRNA) to the 30S
ribosomal subunit. Initiation
factors IF-1, IF-3, IF-2, and GTP
are also required
mRNA and tRNA
The initiator tRNA binds to the _____ _____ on the 30S subunit, and the
50S subunit joins the 30S subunit.
P site
The 70S initiation complex
consists of the 30S and 50S
ribosomal subunits, mRNA,
and the initiator tRNA bound to
the P site. The mRNA and the
tRNA are in the ____ _________
the two subunits
gap between
the _______ blocks it so no more amino acids can be added.
formyl group
in elongation in protein synthesis: Binding of a new aminoacyl-tRNA to the A site is brought about by elongation factor EF-___.
Tu
Elongation factor EF-__ recycles EF-Tu
Ts
in elongation______ __________ is the step that forms the peptide bond between the new amino acid and the growing polypeptide chain
Peptidyl transfer
in elongation: The peptidyl transferase activity is not due to a protein enzyme, but to
an ______ ________ activity of the “peptidyl transferase center” of the 23S
rRNA of the 50S subunit.
RNA enzyme
RNA enzymes are known as _________
“ribozymes”
in elongation: Translocation of the peptide chain back to the P site is brought
about by elongation factor EF-_
G
In termination: The binding of ______ _____ to the A site transforms the ribosomal peptidyl transferase, that forms the peptide
bond between amino acids, into a ______
release factors and hydrolase
in termination: The peptidyl transferase then hydrolyzes the bond linking the polypeptide to its ______ _______, thereby releasing the polypeptide
tRNA carrier
in termination:The presence of a _________ ______ at the A
site brings about the binding of
release factor RF-1 or RF-2
plus RF-3
stop codon
(UAA, UAG, or UGA)
in termination: The binding of the release
factors transforms the
ribosomal ______ _______
into a hydrolase that breaks
the bond between the
polypeptide and its tRNA
carrier
peptidyl transferase
The polypeptide is released,
and the ____ ribosome
dissociates from the mRNA
70S
The proper folding of
newly synthesized
_______in the cell
may require molecular
__________ such as
Hsp70 and GroES/GroEL
polypeptides and chaperones
