Molecular Biology Chapter Quiz
1 / 14
Which scientist confirmed a double helix structure with the X-ray pattern in Photo 51?
The correct answer is D. Rosalind Franklin reportedly was "two steps away" from solving the DNA structure. Crick and Watson gained knowledge from Franklin's work, solved the mystery, published the findings, and received the recognition. Chargaff contributed to the discovery of the double helix with his earlier research.
2 / 14
Which scientist theorized that DNA composition varies from one species to another?
B is the correct answer. Miescher isolated a DNA sample from salmon sperm. His student, Altmann, later named it nucleic acid. Alfred Hershey and Martha Chase were a scientific team that showed that DNA is the genetic material.
3 / 14
Which of the following describes the flow of information in a cell?
The correct answer is B. DNA produces RNA that codes for proteins. Choices A, C, and D are all out of sequence.
4 / 14
Two mRNAs, produced by the same DNA segment, translated two different proteins with different amino acid sequences. How can this be explained?
B is the correct answer. It is possible for different proteins to be produced by assembling the exons in a different sequence. Mutations do occur, but are less likely than re-sequencing exons. Transcription is not likely to start at the wrong place. Different ribosomes will produce the same proteins.
5 / 14
What part of DNA stores the information on how to make proteins?
C is the correct answer. Genetic information is coded in the nucleotide sequences, specifically the triplets of bases called codons. DNA contains nucleotide bases, not amino acids. The sugar-phosphate backbone does not contain the variety of molecular structure necessary to carry genetic information. There is no RNA strand in the DNA molecule.
6 / 14
During DNA replication, what is the result of a T base occurring where a G base had been?
The correct answer is D. Most of the nucleotide sequences in human DNA are non-coding. Each gene sequence codes for a different protein. At most, only one protein would be affected. All codons code for some amino acid. A mistake is most likely to be in a non-coding section.
7 / 14
After an mRNA molecule is transcribed from a eukaryotic gene, it is processed. The resulting mRNA strand is
D is the correct answer. Processing of mRNA after transcription removes the non-coding introns. While it is true that a cap and tail are added, the additional length is small compared to the length of the excised introns. A gene sequence codes for a single strand of mRNA that is processed, but not combined.
8 / 14
Which of the following molecular structures carries the information for making a specific polypeptide?
B is the correct answer. mRNA contains the transcribed information for a specific polypeptide. Ribosomes, tRNA, and rRNA are all part of the mechanism for assembling all polypeptides.
9 / 14
Based on studies of other animals, which of the following is the likely role of homeotic genes in humans?
D is the correct answer. Homeotic genes are expressed early in embryonic development and are responsible for overall body plans, including placement of limbs and anterior versus posterior ends. Choices A, B, and C are regulated by other genes.
10 / 14
Which of the following processes can increase genetic variability in bacteria?
B is the correct answer. During conjugation, one bacterium extends a tube of cytoplasm to temporarily join with another bacterium. The tube is used to transfer a replica of the original cell's plasmid. Transfection refers to the introduction of DNA into eukaryotic cells. Transcription refers to the process of DNA being copied by RNA to produce a complementary RNA. Translation is preceded by translation; it is the decoding of mRNA to produce a specific polypeptide.
11 / 14
What is the name of the piece of DNA that confers the ability on some E. coli to carry out conjugation?
The correct answer is C. Conjugation occurs in cells that have the F plasmid form of the F factor. All bacterial cells contain plasmids, but not all have the F factor on the plasmid. The R plasmid (not factor) is the gene that conveys antibacterial resistance. There is no C factor.
12 / 14
What proteins switch genes on by binding to DNA and enhancing the interaction between RNA polymerase and a promoter?
B is the correct answer. Specificity factors alter RNA polymerase, making it less likely to bind to promoters. Housekeeping genes are always turned on. Operators are sites on DNA where repressor proteins bind.
13 / 14
A section of human DNA is inserted into a bacterial plasmid, which is inserted into a bacterium. The bacterium synthesizes protein, but nothing like the human cell. Which of the following is the most likely explanation for this phenomenon?
B is the correct answer. Most of the nucleotide sequences in human DNA are non-coding. If these non-coding sections, or introns, are included in the plasmid, they will also be turned on and begin coding for amino acids, producing a completely different protein. Although the plasmid is, in a sense, artificially mutated by the insertion of the human DNA, this does not explain the different protein synthesis. Choice D is incorrect because the inserted DNA is spliced into the plasmid by an enzyme.
14 / 14
What is Southern blotting used for?
The correct answer is D. Southern blotting is a means of transferring DNA markers from a gel to special paper, then tagging these DNA markers with a radioactive tag so they can be photographed.
Your score is
The average score is 41%
1123 Zonolite Road, Suite 29, Atlanta, GA 30306