LO13 Day 2 Flashcards
translation goes from what to what
RNA to polypeptide
Are ribosomes fully assembled prior to the start of translation?
Yes
Where does the initial assembly of the ribosomal units occur in a eukaryotic cell?
cytoplasm
Where are the two locations that ribosomes can be found in a eukaryotic cell?
Cytoplasm or RER
Which amino acid is always bonded to the initiator tRNA?
Methionine (AUG) start codon
What are the event of initiation of translation 1-5
- Initiation factors bind to a small ribosomal subunit
- Small ribosomal subunit binds to a mRNA molecule at its 5’ end near the AUG codon
- An initiator tRNA molecule binds to the AUG codon
- large ribosomal subunit binds to the initiation complex
- Initiation factors are released from the complex
elongation adds what to form a polypeptide?
amino acids
during elongation a ribosome moved down mRNA from its __ end to it ____ end
5 to 3
definition: movement where a ribosomes moves down an mRNA one codon at a time
translocation
What is the name of the enzyme that catalyzes peptide bond formation?
peptidyl transferase
What type of molecule is peptidyl transferase?
ribozyme
Where is peptidyl transferase located?
large subunit
When a tRNA recognizes the codon in the A site what happens?
base pairing between the mRNA codon and its complementary anticodon occurs
What bond forms between the amino acids in the A site and the last amino acids of the growing polypeptide in the P site?
polypeptide bond
What happens after the peptide bond formation?
- bonding transfers the polypeptide to the tRNA in the A site
- the tRNA in the A site moves to P site
- The tRNA that was in P site moves to E site and exits ribosome
- A site is not ready to accept the next tRNA
When does elongation end?
When it reaches a stop codon
during termination what happens to the ribosome?
it reaches a stop codon and a release factor protein binds to the A site
What does the ribosome reaching a stop codon trigger?
the release of the polypeptide from the tRNA in the P site
when a polypeptide is released from the ribosome is it immediately ready to function?
No
When a polypeptide is released only its ______ structure has been completed
tertiary
In prokaryotes what genetic processes are coupled?
transcription and translation
Why can prokaryotes start translation before an mRNA is completely transcribed?
because they do not modify their mRNA molecules prior to translation
In eukaryotes what must mRNA do before they can be translated on ribosomes in the cytoplasm or on the RER?
leave the nucleus
Where do transcription and translation occur in prokaryotes?
cytoplasm
Where do transcription and translation occur in eukaryotes?
cytoplasm and nucleus
How mutations occur?
when incorrect base pairings are not corrected by DNA polymerase or other repair mechanisms
When a mutation occurs in reproductive cells what will happen?
they will be passed off to offspring
are all mutations harmful?
no some are beneficial
definition: mutation that has no effect on phenotype and does not alter amino acid sequence
silent mutation
definition: mutation that affect one pair of dna nucleotides and may alter or destroy protein function
base-pair substitution mutations
definition: base pair substitution mutation the changes a codon resulting in a different amino acid being specified
missense mutation
definition: base pair substitution mutation where a codon become a stop codon
nonsense mutation
definition: mutation that involves the insertion or deletion of 1-2 nucleotide pairs
frameshift mutations
what do frameshift mutations result in
either a different polypeptide sequence or an early stop codon
during translocation what moves down an mRNA molecule one codon at a time?
a ribosome
