lecture 17,18 Flashcards
what is the decoding machine for translation?
tRNA + Ribosome (Protein and RNA)
what is the information used for translation?
mRNA
what is the result of translation?
a peptide chain and/or a protein
what are the building blocks of protein?
amino acids
how many amino acids are there?
20
what does it mean for an amino acid to be degenerate?
some amino acids have more than one codon assignment
how many bases encode for 1 amino acid?
3
DNA mutation
permanent change in the DNA sequence
base substitution mutation
when a base pair is swapped for a different base pair
insertion mutation
when a base pair is added into the DNA sequence
deletion mutation
when a base pair is removed from the DNA sequence
do insertion/deletion mutations have an upstream or downstream mutation?
downstream
overlapping genetic codes
When a single base substitution alters multiple amino acids
what connects the mRNA to the protein during translation?
tRNAs
wobble
refers to the flexibility of the third position of a codon in mRNA and the first position of an anticodon in the tRNA
what is the purpose of wobble?
helps optimize and simplify protein synthesis by reducing the minimal number of tRNAs required
what are some pairings allowed by wobble rules?
G can pair to U, U can pair to G, and I can pair to U,C, and A
what is inosine?
a rare based used in tRNA
what is the ribosome unit for prokaryotes?
70S ribosome
what is 70S ribosome broken into in prokaryotes?
50S and 30S ribosomal subunits
what is the ribosome unit for eukaryotes?
80S ribosome
what is 80S ribosome broken into in eukaryotes?
60S and 40S ribosomal subunits
how often should a random mRNA sequence have a start codon?
Every 64 codons
in prokaryotes, what helps the initiator codon start in the right place for translation?
Shine-Dalgarno sequence
where can the Shine-Dalgarno sequence be found?
about 8-10 nucleotides upstream from the start site AUG
how is the start codon inserted into the ribosome?
by a special tRNA called an initiator
what is the initiator in translation?
tRNA (Meti)
what do initiation factors do in prokaryotes?
it keeps the ribosome subunits apart and ensure that only a tRNA (fMet) is brought in
what do initiation factors do in eukaryotes?
They associate with the 5’ cap, 40S subunit, and initiator tRNA to form an initiation complex and remove secondary RNA structures
EF-Tu
an elongation factor that brings Aminoacyl tRNA to the ribosome
aminoactyl-tRNA?
the tRNA that carries the amino acid
EF-G
an elongation factor that moves the ribosome to the next codon for translation
what happens when the ribosome reaches the stop codon?
water molecules get into the peptide transfer center and releases the peptide, before disassembling itself
what does Shine-Dalgarno sequence do?
It serves as a ribosome binding site that helps position the ribosome in the correct location for translation to start
release factors
ribosome components that recognize stop codons at the A site
what are the tRNA binding sites?
aminoacyl, peptidyl, exit
