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65 Cards in this Set
- Front
- Back
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Semiconservative replication |
Half of the parental DNA molecule is conserved in each new double helix. This replication transfers genetic info from one generation to the next with high fidelity |
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Helicase |
unzips the DNA into two strands to start replication |
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Melting Temp (Tm) |
Temp at which half of the helical structure of DNA is lost. This is monitered by measuring absorbance at 260 nm. single stranded DNA absorbs more UV light than double stranded. Temp at the midpoint of the transition on a graph is Tm. |
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Tm depends on |
pH, ionic strength, the size, base composition of DNA |
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It is possible to convert the Cys that is a part of Cys-tRNA to Ala a catalytic reduction. If the resulting Ala-tRNA were added to a mixture of ribosomes, all theother tRNA's and amino acids, all of the cofactors and enzymes needed to make protein in vitro, and mRNA for hemoglobin, where in the newly synthesized hemoglobin would the Ala from Ala-tRNA be incorporated? |
Whereever Cys normally occurs |
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What do Souther, Norther, and Western blots detect, respectively? |
Southern Northern Western DNA RNA Protein |
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Which of the following statements about aminoacyl-tRNA syntetases is false? |
a. some of the enzymes have an editing/proofreading capability. b. the enzyme attaches an amino acid to the 3' end of a tRNA. C. The enzyme will usa any tRNA species d. There is a different synthetase for every amino acid |
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What is the order of the tRNA binding sites on the 70S ribosome with respect to the 5'-3' direction of the mRNA? |
A. EPA b. PAE c. AEP d EAP |
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In protein syntesis, 61 codons specify the 20 amino acids. Base pairing between the codon and the tRNA anticodon assures that the correct amino acid will be inserted intothe nascent polypeptide chain. Why then does the cell require only 32 different tRNAs to recognize 61 codons? |
Some codons code for the same aa, the tRNA's 3rd base can sometimes pair with a different base, still creating the aa but with a different triplet codon. |
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True or False
15% of all genetic diseases are caused by mutations that affect RNA splicing |
True |
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Which metabolism is blocked by mushroom toxin (a-amanitin)? be specific.... |
The alpha-amanitin blocks the inhibition of RNA polymerase II, causing it to not synthesize mRNA. Without mRNA, protein synthesis and hence cell metabolism comes to a halt and the cell dies. |
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mRNA's are synthesized in the .............. direction |
a. carboxy to amino b. amino to carboxy c. endo to exo D. 5' to 3' e. 3' to 5' |
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In rho-independent termination, the termination sequence is on the .......... and the hairpin is formed by the ............ |
A. DNA; RNA b. RNA; DNA c. DNA; rho protein d. RNA; RNA |
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What would be the sequence of the anticodon of tRNA that binds to UCC on mRNA? |
3' --------- 5' 3' GGA 5' G G A 5'--U-C-C--3' |
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What distinguishes whether an AUG serves as an intiation codon or a codon for an internal methionine? |
a. nothing B. a base sequence preceding an AUG which base pairs with 16 S rRNA indicates that the AUG will be an initiation codon c. an AUG codon preceded by a three base sequence which specifies another amino acid must be an internal Met. D. In bacteria, the first AUG codon on the 3' side of a shine delgarno is the initiation codon and any AUG's on the 5' side will be ignored. |
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Number the following steps in the proper order with regard to protein synthesis. ....Aminoacyl-tRNA binds to the A site .... Deactlated tRNA is released from ribosome ....Peptide bond formation sifts the growing peptide from the P to the A site. ....The 50S subunit binds to the initiation complex of the 30S subunit and mRNA. |
2 4 3 1 |
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What are some of the features common to tRNA molecules? |
a. each is a single chain between 73 and 93 ribonucleotides. b. They contain many unusual bases. c. About half the nucleotides in tRNA are base-paired. d. They usually have a pG at the 5' terminal. E. All of the above |
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The E. coli protein carrying out translocation of the mRNA is |
a. serine proteas B. elongation factor G (translocase) c. TATA factor d. Shine-Delgarno e. None of the above |
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A new antibiotic was recently discovered that inhibits prokaryotic protein synthesis. in the presence of the antibiotic, protein syhtesis can be initiated, but only dipeptides that remain bound to the ribosome are formed. What specific step of protein sythesis is likely to be blocked by this antibiotic? |
Chain elongation, the chain terminates protein synthesis stops |
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Fill in the blanks.
A) A reaction can occur spontaneously only if delta G is ............ B) When delta G for a system is zero, the system is at ............. |
A) negative B) equillibrium
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IN order to get 256 fold of a target DNA by PCR method, how many cycles are needed? |
8 |
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The processing of transfer RNA involves all of the following except: |
A. Addition of a methylated guanosine at the 5' end (cap) b. Cleavage of extra bases from both the 3' and 5' ends. c. Nucleotide sequence-specific methylation of bases (modification of bases) d. Addition of the sequence CCA by a nucleotidyl transferase |
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Ragents necessary for sequencing by chain termination (Sanger's method) include |
a. template DNA, deoxyribonucleoside triphosphates (dNTPs), primer, dideoxy nucleotide analogs, DNA polymerase, and radioactive probe B. template DNA deoxyribonucleoside triphosphates (dNTPs), primer, dideoxy nucleotide analogs, and DNA polymerase. c. template DNA, deoxyribonucleoside triphosphates (dNTPs), primer, dideoxy nucleotide analogs, and RNA polymerase d. All of the above |
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Restriction enymes: |
a. are very specific proteases that cleave peptides at only certain sequences. b. are highly specialized ribonucleases that degrade mRNA soon after its synthesis C. are sequence-specific DNA endonucleases d. catalyze the addition of a certain amino acid to a specific tRNA e. act at the membrane to restrict the passage of certain molecules into the cell |
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Which one of the following DNA sequences contains a 4-8 base palindromic site? (Note: only one strand is shown) |
a. CAGTCC b. GCATCC c. CGATTAGC d. GAGAGAGA E. GCATATGC |
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Increasing the concentration of which of the following would most effectively antagonize he inhibition of protein synthesis by puromycin? |
a. ATP b. GTP C. Aminoacyl-tRNA d. Peptidyl-tRNAs e eIF3 |
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Suppose that you need to determine the DNA sequence of 5'-CTGATCGA-3' by the Sanger dideoxy method. Write the fragments formed after treatment with the ddTTP |
5' CTGAddT 5' CddT |
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Which of the following statements is true regarding the role an enzyme plays in catalysis? |
a. An enzyme increases the equilibrium constant. B. An enzyme decreases the activation energy c. An enzyme increases the energy of the transition state so that it breaks down more rapidly. d. None of the above
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Match the factor or enzyme (on the right) with the stages of protein synthesis (on the left) at which it acts. If a factor or enzyme participates in two stages of protein synthesis, indicate all of them. Charged tRNA UAA Initiation Translocase Elongation Aminoacyl-tRNA synthetase Termination 16S |
Aminoacyl-tRNA synthetase 16S Translocase UAA |
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Which of these statements regarding the active (catalytic) site of enzymes is correct? |
a. Upon substrate binding it remains rigid and does not change shape. b. It is made up of adjacent residues of linear enzymes c. It contains amino acids without side chains d. It is composed of only non-polar residues E. None of the above are correct |
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The 5' terminal cap structure of eukaryotic mRNAs is a(n) |
a. 7methylcytosine joined to the mRNA via 2'3'-cyclic linkage b.7-methylguanosine joined to the mRNA via a 5' to 3' diphosphate linkage. C. 7-methylguanosine joined to the mRNA via a 5' to 5' triphosphate linkage |
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Is RNA synthesis of greater or lesser fidelity that DNA synthesis? why? |
RNA is made slower, but has less modifications and is easily broken apart because it isnt always in base pairs, allowing for mutation and insertions. DNA has greater fidelity than RNA |
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The processing of a primary mRNA transcript in a eukaryotic cell does not normally involve: |
a. attachment of a long poly(A) tail at the 3' end b. methylation of guanine nucleotides at the 5' end (cap) c. excision of intervening sequences (introns) D. conversion of normal bases to modified bases such as inosine and pseudouridine e. joining of adjacent exons |
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As you know, bacterial protein synthesis is initiated by formylmethionyl transfer RNA. Initiator tRNA is first charged with Met, and then a formyl group is attached to Met. What is the role for formylation? |
UG |
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IN a multi step biochemical reaction the rate-limiting step is the ....... step and requires the ........ activation energy and determines the overall rate of the reaction |
a. slowest, lowest b. fastest, lowerst c. fastest, highest D. slowest, highest e. None |
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Which of the following is required for initiation of protein synthesis in prokaryotes? |
a. mRNA b. the 30S subunit c. met-tRNA d. GTP E. All of the above |
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The double-reciprocal transformation of the Michaelis-Menten equation, is also called the Lineweaver-Burk plot. To determine Km from a double-reciprocal plot, you would: |
a. take the x-axis intercept where V0=1/2Vmax b. take the reciprocal of thex-axis intercept C. multiply the reciprocal of the x-axis intercept by -1 d. take the reciprocal of the y-axis intercept e. multiply the reciprocal of the y-axis intercept by -1 |
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Which one of the following is not among the six internationally accepted classes of enzymes? |
a. Hydrolases b. Ligases c. Oxidoreductases D. Polymerases e. Transferases |
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codons for Isoleucine |
ATT, ATC, ATA |
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codons for Leucine |
CTT, CTC, CTA, CTG, TTA, TTG |
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codons for Valine |
GTT, GTC, GTA, GTG |
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codons for pheylalanine |
TTT, TTC |
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Methionine |
ATG |
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Cysteine |
TGT, TGC |
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Alanine |
GCT, GCC, GCA, GCG |
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Glycine |
GGT, GGC, GGA, GGG |
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Proline |
CCT, CCC, CCA, CCG |
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Threonine |
ACT, ACC, ACA, ACG |
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sERINE |
tct, tcc, tca, tcg, agt, agc |
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Tyrosine |
TAT, TAC |
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Tryptophan |
TGG |
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Glutamine |
CAA, CAG |
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Asparagine |
AAT, AAC |
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Histidine |
CAT, CAC |
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Glutamic acid |
GAA, GAG |
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Aspartic acid |
GAT, GAC |
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Lysine |
AAA, AAG |
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Arginine |
CGT, CGC, CGA, CGG, AGA, AGG |
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Stop codons |
TAA, TAG, TGA |
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THe following figure shows the possible base pairing between I and C, U, and A. What is the benefit of this multi-pairing of I? Where do we find I usually? |
Makes what is normally a 3-H bond between C-G into a 2-bond between C-I ususally in tRNA, can be used during modification. |
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What toxin covalently binds ADP-ribose to the EF(translocase) in eukaryotes |
Diphtheria toxin |
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In order to get 256 fold of a target DNA by PCR method, how many cycles are needed? |
dived 256 by two until you get one. The number of times that you divided by two is your number of cycles. so for 256 it is 8 cycles |
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Benefits of PCR |
- HIV-1 can be detected -Finding Mycobacterium tuberculosis in tissue specimens is slow; PCR redily detects 10 bacilli/million cells -Early detection of cancer is possible -Mutations in ras genes can be identified -Forensic medicine -Ancient DNA studied |
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palindrome |
Sequence that reads the same both ways. So GCATTACG is a palindrome. |
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Southern Blot Northern Blot Western Blot |
DNA; Complementary 32P-DNA strand RNA; Comp 32P-RNA strand Proteins; Antibody attached to radiactive label or enzyme |
