Question | Answer |
The transfer of genetic information from nucleotide language into AA language of proteins | Translation |
Genetic coding includes__ nucleotides and __ AAs, __ combinations | 4, 20, 64 |
Stop codons | UAA, UGA, UAG |
____ mutations – one base is altered | point |
_____ (point) mutation – changed codon may code for the same AA | Silent |
______ (point)mutation – changed codon may code for different AA | Missense |
_____ (point)mutation – changed codon may become a termination codon | Nonsense |
In the sickle cell gene, GTG (Val) replaces the normal GAG (Glu) | Missense mutation |
The number of inserted or deleted nucleotides is not multiple of three | Frameshift mutation |
Components req. for translation | 1)mRNA and tRNAs 2)Ribosomes Protein factors3) Amino Acids 4)energy sources |
Has an attachment site for specific AA at 3’-end,Contains anticodon that recognizes codon on mRNA, Specifies insertion of AA into growing peptide | tRNA |
Has an attachment site for specific AA at 3’-endContains anticodon that recognizes codon on mRNASpecifies insertion of AA into growing peptide | Aminoacyl-tRNA synthetases |
Ribosome has __ sites for tRNA molecules | 3 (A, P, and E) |
__ site binds incoming aminoacyl-tRNA and specifies next AA to be added | A |
__ site is occupied by peptidyl-tRNA, this tRNA carries synthesized peptide | P |
__ site is occupied by empty tRNA as it is about to exit | E |
Energy used to attach AA to tRNA? | ATP |
Energy use for binding of aminoacyl-tRNA to A site and for translocation step? | GTP |
tRNA can recognize more than one codon for specific AA | – wobble hypothesis (Nontraditional base-pairing) |
Prokaryotic mRNAs often have several coding regions | - polycistronic |
Eukaryotic mRNA codes for only one polypeptide chain | – monocistronic |
Translation is divided into three separate steps: | initiation, elongation, and termination |
_________ involves the assembly of components of translation system | initiation |
___ codon at the beginning of message is recognized by initiator tRNA that enters __ site | AUG, "P" |
In ___________ and mitochondria, initiator tRNA carries N-formylated methionine | prokaryotes |
In ________ , Met in initiator tRNA is not formylated | eukaryotes |
binds to the 30S subunit,Interferes with initiation,Causes misreading of mRNA,Can cause permanent hearing loss | Streptomycin |
binds to 30S subunitInhibits binding of aminoacyl-tRNA to A site | Tetracycline |
Interferes with peptidyltransferase of 50S bacterial subunit | Chloramphenicol not used in humans |
Most protein synthesis occurs in ________ of eukaryotic cell | cytoplasm |
Nuclear proteins used for | nuclear localization signal |
Mitochondrial proteins used for | – mitochondria entry signal |
Use to regulate the rate of translation | Rare codons , binding of regulatory proteins ,Small interfering RNA can target mRNA for degradation |
Trimming of large inactive precursor proteins by specific proteases | postranlational modification |
Covalent alterations | postranlational modification |
Proteins that are defective or destined for rapid turnover are often marked by ________ | ubiquitination |
Proteins marked by ubiquitin are rapidly degraded by ____________ | proteosome |