Translation Flashcards
is a process wherein the information contained within the order of nucleotides in messenger RNA (mRNA) transcribed from the genes is interpreted to produce the linear sequences of
amino acids in polypeptides/proteins.
Translation
proposed that before their incorporation into
polypeptides, amino acids must attach to a special adaptor molecule that is
capable of directly interacting with and recognizing the three-nucleotide-long
coding units of the mRNA.
Francis H. Crick
It was shown by those amino acids
are attached Blank and Blank to a class of RNA molecules before they are incorporated into
proteins.
Paul C. Zamecnik and Mahlon B. Hoagland
proposed the concept of a codon, the idea that three nucleotides could code for one amino acid.
* He got a Nobel Prize for “genetic regulation of organ development and programmed cell death“.
Sydney Brenner
Won the Nobel Prize in Physiology or Medicine 1968 for their interpretation of the genetic code and its function in protein synthesis.
Robert W. Holley, Har Gobind Khorana, Marshall W. Nirenberg
Four primary components compose the
machinery responsible for translating the
language of mRNAs into the language of
proteins.
mRNAs, tRNAs, aminoacyl-tRNA synthetases, and the ribosomes.
The Blank carries the information to be interpreted by the translation
machinery and serves as the template for the translation process.
mRNA
The Blank provide the physical link between the amino acids being added to the growing polypeptide chain and the codons in the mRNA.
tRNAs
The mRNA region that codes for the protein consists of an ordered series of three-nucleotide units called Blank that
specify the sequence of amino acids.
codons
Enzymes called Blank couple amino acids to specific tRNAs that recognize the appropriate codon/s.
aminoacyl-tRNA synthetases
It coordinates the correct recognition of the mRNA by each tRNA and catalyzes peptide-bond formation between the growing polypeptide chain and the amino acid attached to the selected tRNA
Ribosome
The protein-coding region of each mRNA is composed of a continuous, non-overlapping chain of codons called the Blank, which specifies a protein.
open reading frame (ORF)
The first and last codons of an ORF are known as the Blank and Blank.
start and stop codons
Eukaryotes always use Blank as their start codon.
5’-AUG-3’
Bacteria also usually use this, but they could also use Blank and sometimes even Blank.
5’-GUC-3’, 5’-UUG-3’
The Blank functions for specifying the first amino acid to be incorporated into the growing polypeptide chain, and it also defines the reading frames for all subsequent codons.
start codon
On the other hand, the stop codons Blank, Blank, and Blank define the end of the ORF and signal the termination of the polypeptide synthesis.
5’-UAG-3’, 5’-UGA-3’, and 5’-UUA-3’
True or False
In all organisms, mRNAs contain at two ORF
False: least one ORF.
True or False
The ORFs’ number per mRNA is the same
between prokaryotes and eukaryotes.
False: different
Eukaryotic mRNAs almost always contain a
single ORF.
○ This is referred to as Blank
monocistronic mRNAs
In contrast, prokaryotic mRNAs frequently
contain two or more ORFs and hence can
encode multiple polypeptide chains.
○ These types of mRNAs are known as
Blank
polycistronic mRNAs
To facilitate binding by a ribosome, many prokaryotic ORFs contain a ribosome binding site (RBS), which is a short sequence upstream of the start codon and is also referred to as
Blank.
Shine-Dalgarno sequence
Unlike that of prokaryotes, eukaryotic mRNAs
recruit ribosomes through a specific post
transcriptional chemical modification called
the Blank, which is located at the extreme 5’
end of the mRNA (please recall the previous
lesson).
5’ cap
True or False
The core of this region of the 16S rRNA has the sequence 5’-AGGAGG-3’ while prokaryotic RBS is most often a subset of the sequence 5’-CCUCCU-3’.
False: 5’-CCUCCU-3’, 5’-AGGAGG-3’
Once the ribosome is bound to the mRNA, it
moves in a 5’ -to- 3’ direction until it encounters
a 5’-AUG-3’ start codon.
* This process is called Blank.
scanning
This process is done by Blank molecules, which
act as adaptors between the amino acids they
specify and the codons.
tRNA
show a characteristic and highly conserved pattern of single stranded and double-stranded regions (due to self-complementarity) that can be illustrated as a cloverleaf.
tRNA molecules
The Blank is the attachment site for the cognate amino acid.
○ It is formed by pairing between the 5’- and 3’-ends of the tRNA
molecule.
○ The 5’-CCA-3’ end protrudes from this double-stranded stem and is
preceded by the unpaired discriminator base.
acceptor stem
The Blank is the most 3’ proximal loop and contains pseudouridine frequently found within the sequence 5’-TYUCG-3’.
ѰU loop
The Blank is the most 5’-proximal loop and contains dihydrouridine
residues.
D loop
The Blank contains the anticodon sequence that is complementary
to the codon in the mRNA.
○ Codon and anticodon triplets interact by RNA-RNA base pairing.
○ Because codons in the mRNA are read from 5’ -to- 3’, anticodons are
oriented and written in the 3’ -to- 5’ direction.
anticodon loop
The Blank is located between the anticodon loop and the YU loop.
○ It varies in size from 3 to 21 nucleotides.
variable loop
Cells do not have a specific tRNA for every codon as this would
require 61 tRNAs.
● Instead, it was discovered that certain tRNA species of known
sequence can recognize several different codons.
● Thus, the genetic code is described as Blank.
degenerate
True or False
Furthermore, some tRNAs do not have one of the four classical bases but have inosine instead in the second position of the
anticodon.
False: first
Like all the other minor tRNA bases (modified bases), Blank arises through enzymatic modification of a base in a completed
tRNA chain (it is not directly incorporated during transcription of
the tRNA gene).
inosine
The Blank (developed by F. Crick in 1966) states that the base at the
5’-end of the anticodon is not as spatially confined as the other two, allowing
it to form hydrogen bonds with any of several bases located at the 3’-end of
the codon.
wobble theory
True or False
The wobble theory rules permit any single tRNA molecule to recognize
four different codons.
False: do not permit
True or False
The “wobble movement” is restricted to the second position of the anticodon
because the other two positions are more “stacked” and surrounded by
modified, bulky purine residues that further restrict their movement.
False: first position
Blank molecules are those
tRNAs with an already attached amino
acid.
Charged tRNA
The enzyme called Blank is responsible for this
catalysis
aminoacyl-tRNA synthetase
True or False
It is uncommon for one synthetase to recognize and charge more than one tRNA (known as isoaccepting tRNAs) because
most amino acids are specified by more than one codon.
False: not uncommon
Studies have indicated that the determinants for the specificity of tRNA recognition by aminoacyl-tRNA synthetase are found at two distant sites on the molecule.
* These are the Blank and the Blank.
acceptor stem, anticodon loop
Directing the synthesis of proteins is the macromolecular machine called the Blank.
ribosome
The ribosome is composed of an assembly of RNA and protein known as the Blank and Blank
large and small subunits.
The Blank contains the peptidyl transferase center, which is responsible for the formation of peptide
bonds.
large subunit
The Blank contains the decoding center in which charged tRNAs read or decode the codon units of the mRNA.
small subunit
The unit of measure sedimentation velocity is the Blank.
Svedberg
The ribosome also catalyzes the formation of a peptide bond which is called Blank reaction.
peptidyl transferase
The growing chain attached to tRNA is called the Blank
peptidyl-tRNA
a tRNA with attached amino acid is called Blank.
aminoacyl-tRNA
is the site for the binding of the aminoacyl-tRNA
The A-site
is the binding site for the peptidyl-tRNA
P-site
is the site for binding the tRNA that is released after the growing polypeptide chain has been transferred to the aminoacyl-tRNA.
E-site
