RNA Translation Flashcards
3 stop codons
UAA (U Are Away)
UGA (U Go Away)
UAG (U Are Gone)
redundancy
Having different codons that code to the same thing
What is the difference between the coding and template strand
All T’s are turned to U’s
What is the Anti-Codon on a tRNA base complimentary strand?
Changes from AUG —> UAC
tRNA (3)
-Brings amino acids to ribosome
-Cloverleaf shape
-Contains an anticodon sequence that pairs with codons in mRNA
Wobble Hypothesis
The first 2 nucleotides must match between codon and anticodon, but the 3rd had flexibility
Aminoacylation
Adds amino acids to tRNA
Ribosome sites
exit
peptidyl
aminoacyl
What is peptidyl
the site where polypeptides bind together on the chain
Stages of Translation
Initiation
Elongation
Termination
Initiation of translation (4)
-Ribosomes assembled with mRNA molecules
-tRNA binds to small subunit
-Complex binds to 5’ cap and scans for start codon
-Large subunit binds to complete initiation
Elongation of translation (3)
-Amino acids are linked to tRNAs and added to polypeptide chain
-The A site matches the next codon
-Peptide bond is cleaved off in the P site
Termination of translation (2)
-New polypeptide put on ribosome
-Ribosome separates from mRNA
Polysomes
Multiple ribosomes simultaneously translating a single mRNA
points of polypeptide processing (5)
-Processing reactions convert polypeptides into finished form
-Removal of one or more amino acids from protein chains
-Addition of organic groups
-Folding guided by chaperones
-Alternative pathways to different mature polypeptides
Sorting signals and where
how proteins are distributed within the cells, signals are coded in DNA and when protein is made
sorted at the rough ER
signal peptide
beginning of the polypeptide chain
signal recognition particle
binds to signal peptide
SRP receptor
bind to protein receptors in ER membrane, and growing polypeptide is pushed into the ER lumen
Signal peptidase
removes signal sequence
peptidase
mean enzyme
Misfolded proteins what happens, and what diseases it can cause
once folded the wrong way, all the same proteins will fold in the same way
can cause Creon disease, Mad Cow, and Alzheimer’s
Mutations
changes in genetic material
only in DNA
nonsense mutation
changes a normal codon to a stop codon
silent mutation
Changes a codon nucleotide to a different one, but it still codes for the same polypeptide
frameshift mutation
base pairs are inserted or deleted
Sickle-cell disease
mRNA strand changes from GAG to GUG which changes the polypeptide from glutamine to valine
promotor mutation
Could increase or decrease rate of transcription
Transcriptional response element mutation
Alter regulation of transcription
Splice junction mutation
Alter ability of pre-mRNA to be spliced properly
germ-line mutation
Happens to the whole body and carries onto half the next generation of gametes
Somatic mutation
Happens to part of the embryo like the head and then it will only happen to the head of the person and not be passed on
EX: birthmark
Direct repair
Repair enzyme recognizes an incorrect structure in the DNA and directly converts back to the correct structure
Base excision and nucleotide excision repair
Abnormal base is recognized and removed. The complimentary DNA strand is used as a template to synthesize a normal DNA strand
Methyl-directed mismatch repair
A base pair match is in the wrong spot and once recognized a section is removed and replaced
missense mutation
Same as a silent mutation where one codon is switched with another one, but it codes for a different polypeptide
