1. All of the molecular models shown are serine. Which one is L-serine?
2. Which one of the following is L-alanine?
3. How many peptide bonds are there in a pentapeptide?
4. In a strongly acidic solution the amino acid lysine exists as the dication? As the pH is raised, what monocation is formed by loss of a proton from the dication?
5. Which of the amino acids shown at the right have the S configuration?
a. A only
b. B only
c. A and B
d. Neither A nor B
6. The major species present at the isoelectric point of glycine is:
7. Which nucleoside is incorporated into DNA?
8. Which of the following are purines?
9. Watson and Crick's proposal for the structure of DNA made use of data derived by Chargaff on the composition of DNA from different species. Which statement below best summerizes Chargaff's findings with amounts expressed in mole percentages?
a. The amount of guanine plus adenine is about equal to that of cytosine plus thymine.
b. The amount of guanine plus cytosine is about equal to that of adenine plus thymine.
c. The amount of adenine is about equal to that of guanine.
d. The amount of cytosine is about equal to that of thymine.
10. In which of the following is a sequence of bases termed an anticodon located?
b. Messenger RNA
c. Ribosomal RNA
d. Transfer RNA
This solution explains a variety of problems dealing with amino acids, proteins, and nucleic acids.
Molecular Biology (Nucleic Acids and the Genetic Material) Multiple Choice
1. Which scientists first gave experimental evidence that DNA is the genetic material?
A Avery, MacLeod, and McCarty who repeated the transformation experiments of Griffith, and chemically characterized the transforming principle.
B Garrod, who postulated that Alcaptonuria, or black urine disease, was due to a defective enzyme.
C Beadle and Tatum, who used a mutational and biochemical analysis of the bread mold Neurospora to establish a direct link between genes and enzymes.
D Meselson and Stahl who showed that DNA is replicated semiconservatively
E Watson and Crick who gave a model for the structure of DNA
2. In the Meselson-Stahl DNA replication experiment, what percent of the DNA was composed of one light strand and one heavy strand after one generation of growth in N-14 containing growth media?
3. In this diagram of the process of DNA replication at a replication fork, the strand labeled B is the:
A template strand
B lagging strand
C leading strand
D Okazaki fragment
E RNA primer
4. In this diagram of the process of DNA replication at a replication fork, the newly synthesized DNA strand labeled C is the:
A coding strand
B parental DNA
C leading strand
D lagging strand
5. In this diagram of the process of DNA replication at a replication fork, the black boxes labeled D and E are:
A RNA primers
B DNA template strands
C Okazaki fragments
D DNA polymerase
E Newly synthesized DNA strand
6. In the Meselson-Stahl DNA replication experiment, if the cells were first grown for many generations in N-15 containing media, and then switched to N-14 containing media, what percent of the DNA had 1 light strand and 1 heavy strand after 2 generations of growth in N-14 growth media? A 0
Frederick Griffith accidentally discovered transformation when attempting to develop a vaccine for pneumonia. He injected mice with samples from S-strain (virulent) and/or R-strain (non-virulent) pneumococci bacteria. Which of the following results is NOT consistent with Griffith's experiments?
A injected S-strain; mouse dies.
B injected R-strain; mouse lives.
C injected heat-killed S-strain; mouse lives.
D injected mixture of heat-killed S-strain and live R-strain; mouse lives.
E injected mixture of heat-killed R-strain and live S-strain; mouse dies.
8. Complementary bases:
For the DNA strand 5'-TACGATCATAT-3' the correct complementary DNA strand is:
9. Problems on transcription: Three types of RNA involved in comprising the structural and functional core for protein synthesis, serving as a template for translation, and transporting amino acid, respectively, are:
A mRNA, tRNA, rRNA
B rRNA, tRNA, mRNA
C tRNA, mRNA, rRNA
D tRNA, rRNA, mRNA
E rRNA, mRNA ,tRNA
10. Protein amino acids from translated mRNA
A messenger acid is 336 nucleotides long, including the initiator and termination codons. The number of amino acids in the protein translated from this mRNA is:
11. Products after protein synthesis
A synthetic mRNA of repeating sequence 5'-CACACACACACACACAC... is used for a cell-free protein synthesizing system like the one used by Niremberg. If we assume that protein synthesis can begin without the need for an initiator codon, what product or products would you expect to occur after protein synthesis.
A. one protein, consisting of a single amino acid
B. three proteins, each consisting of a different, single amino acid
C. two proteins, each with an alternating sequence of two different amino acids
D. one protein, with an alternating sequence of three different amino acids
E. one protein, with an alternating sequence of two different amino acids
12. mRNA and protein coding
Under conditions where methionine must be the first amino acid, what protein would be coded for by the following mRNA?5'-CCUCAUAUGCGCCAUUAUAAGUGACACACA-3'
A. pro his met arg his tyr lys cys his thr
B. met arg his tyr lys cys his thr
C. met arg his tyr lys
D. met pro his met arg his tyr lys cys his thr
E. arg his ser glu tyr tyr arg leu tyr ser
13. mRNA polypeptide code:
Which mRNA codes for the following polypeptide?
met arg ser leu glu
14. Codon-anticodon base pairing:
With what mRNA codon would the tRNA in the diagram be able to form a codon-anticodon base pairing interaction?
15. DNA template for mRNA synthesis
You have obtained a sample of DNA, and you transcribe mRNA from this DNA and purify it. You then separate the two strands of the DNA and analyze the base composition of each strand and of the mRNA. You obtain the data shown in the table to the right. Which strand of the DNA is the coding strand, serving as a template for mRNA synthesis?
A G C T U
DNA strand #1 19.1 26.0 31.0 23.9 0
DNA strand #2 24.2 30.8 25.7 19.3 0
mRNA 19.0 25.9 30.8 0 24.3
A. Strand 1
B. Strand 2
C. Both Strands 1 and 2
D. Neither Strand 1 or 2
E. Too little information to tell
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