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31 Cards in this Set
- Front
- Back
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Translation
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proteins encoded by RNA
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codon
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64 triplets:
combination of four bases (A, G, C, U) of mRNA |
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What is the start codon?
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AUG=Met
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What are the stop codons?
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UAA
UAG UGA |
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codon sequence (5'-3') in mRNA is ____ with amino acid sequence in the protein
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colinear (n-term to c-terminus)
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commaless
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the code is not punctuated...the codons around could be altered via insertion or deletion
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1 codon=
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1 aa
except: AUG-> n-romylmethionine and methionine UGA: stop and selenocyteine UAG: stop and pyrrolysine |
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1 aa can correspond to ...
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up to 6 codons depending on the aa
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silent mutation
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produce no change in phenotype (activity of protein or RNA remains unaltered)
generelly mutations in the 3rd position of a codon-> no change in aa |
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Missense mutation
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substitution of one amino acid for another
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Nonsense
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replacement of a sense codon with a stop codon
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frameshift
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insertion or deletion of base will change the reading frame
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tRNA is an _____ between RNA sequnece and ____ sequence.
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adaptor
aa |
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position 1 of the codon base pairs with the _ postion of the anticodon
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3
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one amino acid attached where on the tRNA?
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3' end
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What are some key features of the structure of a tRNA?
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a clover leaf
D-loop: UH2 T-loop: TYC anticodon |
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what are two modified bases encountered in tRNAs?
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pseudouridine
ribothymidine dihydrouridine |
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In a tRNA, half the bases are ___ base paired.
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intra-strand
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some tRNAs recognize ___ codons.
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multiple
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Wobble base pairing
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occurs at 1st poition of anticodon...do not form standard pase pairing...I
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Inosine
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one of the modified bases in tRNA is especially promiscuous in base pairing to A, C, U in bacteria and just U,c in eukaryotes
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What catalyzes the amino acid activation?
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aminoacyl tRNA synthetase
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How does aminoacyl-tRNA synthetase ensure the incorportaion of the right amino acid?
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There is an editing site to remove the incorrect amino acid in addition to the synthesis site
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How does the aminoacyl-tRNA synthase recognize tRNA?
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1. binding of anticodon to a 3 nucleotide binding pocket on the enzyme
2. making contact with the sequence in the acceptor stem 3. both of the above... makes only 1 mistake per 40,000 couplings |
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selenocysteine (Sec) is a component of ....
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selenoproteins
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Mutations in selenoprotein N gene may cause...
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autosomal recessive muslce disorders such as congenital muscular dystrophy with spinal rigidity (RSMD1) and a variety of related myopathies
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What does the r of rRNA stand for?
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rogue, no retrograde, no reverse.....=ribosomal
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ribosome
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ribonucleoprotein with large "surface" and catalytic activity for protein synthesis
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What are the subunits of ribosome?
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prokaryotic: 50s and 30s=70s
eukaryotic : 60s and 40s= 80s |
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What are three site of the ribosomes?
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APE
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______ end of tRNA is on the large subunit.
_____end of tRNA is on the small subunit. the _____-binding site is on the small subunit of the ribosome. |
aminoacyl-large
anticodon-small mRNA-small |
