Chapter 14 Flashcards
Define translation
Use of mRNA as instructions to make a protein
What 4 things does translation (eukaryotic) use?
mRNA, ribosomes, amino acids, and tRNAs.
Define ribosome
Machine that reads mRNA and combines amino acids
Define amino acids
Monomers of proteins
What does mature eukaryotic mRNA contain (7 things)
5’ cap
5’ untranslated region (5’ UTR)
Start codon
Open reading frame
Stop codon
3’ untranslated region (3’ UTR)
Poly-A tail
What does mature prokaryotic mRNA contain (6 things)
5’ UTR
Shine-Delgarno Sequence
Start codon
Open reading frame
Stop codon
Poly-A tail
What does 5’ cap do?
Protection and translation initiation in eukaryotes
What does 5’ untranslated region do?
Helps control initation of translation in both eukaryotes and prokaryotes
What does a 3’ UTR do?
Helps control the amount of translation in eukaryotes
What does the poly-A tail do?
Proides stability and protection
What are the differences in prokaryotes and eukaryotes mRNA?
Prokaryotes do NOT have a 5’ cap
Prokaryotes contain a Shine-Delgarno sequence and additional ORFs
Define small subunit
Helps initiation of translation by finding and binding to the start codon
Made up of multiple proteins and RNA molecules.
Define the large subunit
accepts tRNAs and makes polypeptides.
Made up of multiple proteins and RNA molecules.
Define a dalton
The mass of 1 Hydrogen. Used to measure protein size.
What are the 3 main components of the large subunit and what do they do?
- Acceptor (A) Site - new tRNAs bind here
- Peptide (P) Site - Polypeptide elongates here
- Exit (E) Site - Old tRNA leaves from here
What does rRNA do?
In the large subunit, the rRNA catalyzes polypeptide formation.
Define ribozymes
rRNA molecule that catalyzes a reaction
How many amino acids are there? What are the unconventional amino acids?
20 conventional.
2 unconventional: selenocysteine in humans, and pyrrolysine in bacteria.
What do all amino acids contain?
An amino group, carboxyl group, central carbon, and a chemically distinct side chain (R-group).
How does the ribosome link multiple amino acids together?
Peptide bond, with Carboxyl group being attached to the amino group of the next.
Define N terminus
Front end of polypeptide - the exposed amino group
Define C terminus
Back end of polypeptide - exposed carboxyl group
Like a DNA strand going 5’ -> 3’, the polypeptide goes ….
N terminus -> C terminus
Define tRNA
Transfer RNA reads the codon and brings the corresponding amino acid.