




Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
Material Type: Exam; Professor: Chen; Class: Biochemistry; Subject: Chemistry and Biochemistry; University: University of Delaware; Term: Spring 2010;
Typology: Exams
1 / 8
This page cannot be seen from the preview
Don't miss anything!
(I) Fill in the blanks (20%)
both coding called exons_, and noncoding, called introns, sequences. Before it can be
translated into protein, the two ends of the RNA are modified, the noncoding sequences
are removed by an enzymatically catalyzed splicing reaction, and the resulting
mRNA is transported from the nucleus to the cytoplasma.
initiate splicing, while the group II intron sequences use an especially reactive A_
nucleotide in the intron sequence itself for the same purpose.
the correct amino acids to their tRNAs. Then, a _Met amino acid initiates protein
synthesis. Unlike eucaryotic ribosomes, which typically require a capped 5'end,
procaryotic ribosomes initiate transcription at ribosome-binding sites called
Shine-Dalgarno, which can be located anywhere along an mRNA molecule.
of the following enzymes involved in what repair pathway. (a) AP endonuclease BER (b) mutS-mutL complex MMR
(c) ABC excinuclease NER
(d) DNA photolyase Direct reversal
protein rapidly attains a “Molten Globule” state. Subsequent folding occurs more
slowly and by multiple pathways, often involving the help of a _chaperone.
Some molecules may still fail to fold correctly; these are recognized and degraded
by_proteasome_.
(II) Pick “one” correct answer from each question (12%)
A) A naturally occurring tRNA exists in yeast that can read both arginine and lysine codons. B) A tRNA can recognize only one codon. C) Some tRNAs can recognize codons that specify two different amino acids, if both are nonpolar. D) The “wobble” occurs only in the first base of the anticodon. E) The third base in a codon always forms a normal Watson-Crick base pair. D
A) All codons recognized by a given tRNA encode different amino acids. B) It is absolutely identical in all living things. C) Several different codons may encode the same amino acid. D) The base in the middle position of the tRNA anticodon sometimes permits “wobble” base pairing with 2 or 3 different codons. E) The first position of the tRNA anticodon is always adenosine.
C
A) A, C, G, and U are the only bases present in the molecule. B) Although composed of a single strand of RNA, each molecule contains several short, double-helical regions. C) Any given tRNA will accept only one specific amino acid. D) The amino acid attachment is always to an A nucleotide at the 3 ' end of the molecule. E) There is at least one tRNA for each of the 20 amino acids.
A,
A) “recognize” specific tRNA molecules and specific amino acids. B) in conjunction with another enzyme attach the amino acid to the tRNA. C) interact directly with free ribosomes. D) occur in multiple forms for each amino acid. E) require GTP to activate the amino acid.
A
(B) A duplex DNA to be sequenced is shown below. If the primer you decided to use for
the sequence reaction is 5’ACGATTGC3’. Please draw an imaginary sequencing gel that
shows the expected results of the following 4 reactions with different nucleotide mixtures
(6%):
Four,
A. Suppose mRNA is transcribed from this DNA using the complementary strand as a template. What will be the sequence of the mRNA?
5’-GUA, UCC, CAU, AAG,UAG, G-3’
B. What peptide would be made if translation started exactly at the 5' end of this mRNA? (Assume no start codon is required, as is true under certain test tube conditions.)
Val-Ser-His-Lys-STOP
polymers of RNA containing known ratios of nucleotides (e.g., 70% A and 30% T) generate only certain codons in predictable ratios. The identities and ratios of the amino acids specified by such polymers provided important clues that helped solve the genetic code. (2) Trinucleotides of known sequence were used to stimulate aminoacyl-tRNA binding to ribosomes. Because only that aminoacyl-tRNA whose anticodon matched the trinucleotide “mRNA” was bound, the coding specificity of each sequence of three bases could be determined by determining which of the 20 aminoacyl-tRNAs bound. (3) Additional assignments were made possible using synthetic oligonucleotides containing repeats of specific two, three, or four base pair sequences.
Mutant 1 MET-Ser-Ile-Arg 2 Leu-TRP-Ile-Arg 3 Leu-Ser-ARG-Arg 4 Leu-Ser-Ile-PRO 5 Leu-Ser-Ile-TRP
What was the nucleotide sequence of the region of mRNA that coded for the amino acid sequence in the wild-type organism? (Refer to Fig. in 6)
2 or 4
*(5 ' )GGATTCTAATAAAGT|AACGCGTT|ACGACTTGG CCTAAGATTATTTCA|TTGCGCAA|TGCTGAACC binding site