Chapter 9 Flashcards
All amino acids have…
1) central carbon
2) amino group
3) carboxyl group
4) R-group
Explain the three different sites of ribosomes
1) A Site: entry for charged tRNA
2) P Site: holds tRNA to which polypeptide is attached
3) E Site: exit of uncharged tRNA
The eukaryotic ribosome is ______ with a _____ large subunit and _____ small subunit. The bacterial ribosome is _____ with a _____ large subunit and _____ small subunit
Eukaryotic ribosome: 80S, 60S (5S, 5.8S, 28S rRNA subunits) & 40S (18S rRNA subunit)
Bacterial ribosome: 70S, 50S (5S, 23S rRNA subunits) & 30S (16S rRNA subunit)
In bacterial translation, the ___________ sequence helps initiate translation but in eukaryotic translation, the __________ sequence helps identify the start codon. The first amino acid in eukaryotes and bacteria is ___________________ and ____________ respectively.
Shine-Delgarno, Kozak, N-formylmethionine, methionine
What happens when a release factor (RF) enters the A site of a ribosome?
1) polypeptide release
2) RF ejection
3) separation of ribosomal subunits
In polycistronic mRNA in bacteria, there are multiple polypeptide-producing segments each separated by an ____________________, each has its own _________________.
intercistronic spacer, Shine-Dalgarno site
T or F: the same amino acid can be encoded by several codons but genetic code is “unambiguous”, “universal”, and “degenerate” in the sense that each codon codes for only one amino acid
True
What are two pieces of evidence that point towards a single origin of all life?
1) ribosomes are strongly conserved across all three domains of life
2) genetic code is also conserved across the domains
tRNAs that are charged with the same amino acid but have different anticodons are known as ________________. some tRNAs can recognize multiple mRNA codons that differ only at their 3rd base, this is known as _____________. These are both reasons why the genetic code is ________________.
Iso-accepting tRNAs, third base wobble, degenerate
Synonym Order VS Relatedness Order
Synonym Order: codons assigned to the same amino acid are generally “mutationally” close to one another
Relatedness Order: codons assigned to different amino acids with the same chemical properties are generally “mutationally” close to one another
___________________ catalyze the addition of amino acids to tRNAs
aminoacyl-tRNA synthetases
What are methods of post-translational polypeptide processing?
removal of fMet or Met after translation, phosphorylation, dephosphorylation, methylation, acetylation, addition of hydroxyl groups, forming glycoproteins, proteolysis, lipidation, ubiquifination
T or F: proteins that are translated on the surface of the endoplasmic reticulum are shuttled to the Golgi apparatus where they can be exported in vesicles
True
