Protein Synthesis Flashcards
Genes encode for…
proteins
Alkaptonuria is caused by a mutation in the gene…
HGD
What is the Central Dogma?
DNA, RNA, protein
What is the function of RNA polymerase II?
synthesizes an RNA from a DNA template
What is the function of RNA polymerase I?
synthesizes ribosomal RNA
What is the function of RNA polymerase III?
synthesizes transfer RNA
What is a chemical language created through sequencing nucleotides reading from left to right where 3 DNA nucleotides become an RNA codon (in a gene)?
transcriptional unit
What is a primary transcript?
a completed array of three-letter codons that are sent to the ribosome to be transformed as a polypeptide
Where does translation occur?
the ribosome
What is mRNA?
when the gene codes for the synthesis of a protein
How many different combinations of mRNA codons are possible?
64
Cells can build __ mRNA sense codons- which implies_____
61, redundancy
What is life’s primary start codon?
AUG (met)
What are the stop codons?
UAA, UAG, UGA
permease
allows lactose in the cell
beta-galactosidase
cleaves the bond between glucose and galactose monomer allowing glucose to move into glycolysis
Ribosomes consist of two parts…
large and small ribosomal subunit
Large ribosomal subunit
contains catalytic chambers where translation takes place
Small ribosomal subunit
initially binds to the mRNA
Transfer RNAs
bring amino acids coded for by the mRNA to the ribosome
tRNAs have an active site called…
anti-codon
tRNAs have another active site for the placement of an amino acid by an additional enzyme called…
amino-acetyl transferase
Where are the amino acids bound on a tRNA?
a CCA on a 3’ end
What part of the tRNA binds to the ribosome?
the left part of the tRNA aka the T-arm binds to the ribosome
What is opposite the T-arm on a tRNA? What is the function?
the D-arm; the region where aminoacyl-tRNA synthetase binds and attaches the correct amino acid to the CCA (leaves the tRNA charged- uses ATP to charge)
what is the function of the anticodon?
anticodon recognizes the mRNA sequence in translation
Ribosomes are…
a complex of proteins and ribosomal RNA
tropomyosin
protein involved in muscle contraction
promoter
control sequence for transcription
transcription
the mechanism by which information encoded in the DNA template strand is copied into a complementary RNA strand
translation
uses the information encoded in the RNA copy to assemble amino acids into a polypeptide
a protein-coding gene is transcribed into…
mRNA
What is the genetic code?
the nucleotide information that specifies the amino acid sequence of a polypeptide
What are the 3 stages of transcription?
Initiation, Elongation, Termination
Initiation (transcription)
Molecular machinery assembles at the promoter and being synthesizing an RNA copy of the gene
Transcription factor
bind to the promoter in the area of a special sequence known as the TATA box
TATA box
where a genetic sequence can be read and decoded It is able to define the direction of transcription and also indicates the DNA strand to be read.
elongation (transcription)
RNA polymerase II moves along the gene extending the RNA chain; DNA continues to unwind ahead of the enzyme
termination (transcription)
the RNA transcript and RNA polymerase II are released from the DNA template
Uracil pairs with
adenine
Genes encoding RNAs that are not translated are called…
noncoding RNA genes
A eukaryotic protein-coding gene is transcribed into a _________ that must be processed in the nucleus to produce the translatable mRNA
precursor-mRNA (pre-mRNA)
The ____ is the site where ribosomes attach to mRNAs at the start of translation
5’ cap
proteins bind to a _________ transcribed near the 3’ end of the pre-mRNA and cleave the pre-mRNA downstream of that sequence
polyadenylation signal
what enzyme adds a chain of 50 to 250 adenine nucleotides (poly-A tail) to the 3’ end of the pre-mRNA
Poly(A) polymerase
exons
the amino acid coding sequences that are retained in finished mRNAs
mRNA splicing
removes introns from pre-mRNAs and joins exons together
where does mRNA splicing take place?
spliceosome
Which gene is alternatively spliced in smooth muscle, skeletal muscle, fibroblast, liver, and brain?
the alpha-tropomyosin gene
exon shuffling
a process by which existing protein regions or domains are mixed into novel combinations
How is mRNA read?
5’ end to the 3’ end
How is a polypeptide assembled?
N-terminus end to the C-terminus end
Francis Crick’s Wobble Hypothesis
the pairing of the anticodon with the first two nucleotides of the codon is always precise, but the anticodon has more flexibility in pairing with the third nucleotide of the codon
aminoacylation
addition of the correct amino acid to a tRNA
ribosomes
ribonucleoprotein particles that translate mRNA into chains of amino acids
tRNAs interact with mRNA at three binding sites on the ribosome, what are they?
A site, P, site, E site
A site
aminoacyl-tRNA carrying the next amino acid to be added to the polypeptide binds here the aminoacyl site
P site
tRNA carrying the growing polypeptide chain is bound here the peptidyl site
E site
tRNA without an amino acid binds here at the exit site before exiting the ribosome
Initiation (Translation)
components assemble on the start codon of the mRNA
Elongation (Translation)
assembled complex reads the string of codons in the mRNA one at a time while joining specified amino acids into the polypeptide
Termination (Translation)
complex disassembles after the last amino acid specified by the mRNA has been added to the polypeptide
aminoacyl-tRNA binds to the codon in the A site of the ribosome- facilitated by a protein…
elongation factor
a peptide bond forms between a C-terminal end of the growing polypeptide on the P site tRNA and the amino acid on the A site tRNA, catalyzed by…
peptidyl transferase
_______ takes place when the A site arrives at one of the stop codons on the mRNA
termination (translation)
The stop codon is read by a protein…
release factor or termination factor
ribosomes continue to attach as translation continues and become spaces along the mRNA like beads on a string, forming a _____
polysome
chaperones
helper proteins that help with folding other proteins into their functional 3-D shapes
What 3 compartments are finished proteins sorted into within the cell?
the cytosol, the endomembrane system, membrane-bound organelles
