Biology 210A – Sample/Practice Quiz (Chapters 16-18) Miramar College Dr. Hurley
The following is meant to provide a familiarity with the general format and style/types of questions you may see on the actual quiz.
Multiple choice – choose the single best answer
1) A codon
A) consists of two nucleotides.
B) may code for the same amino acid as another codon.
C) consists of discrete amino acid regions.
D) catalyzes RNA synthesis.
2) Which of the following is true for both prokaryotic and eukaryotic gene expression?
A) After transcription, a 3' poly-A tail and a 5' cap are added to mRNA.
B) Translation of mRNA can begin before transcription is complete.
C) RNA polymerase binds to the promoter region to begin transcription.
D) mRNA is synthesized in the 3' → 5' direction.
3) Which of the following is not a part of the eukaryotic transcription initiation complex?
A) promoter C) transcription factors
B) RNA polymerase D) snRNA E) TATA box
4) Which of the following helps to stabilize mRNA by inhibiting its degradation in the cytoplasm?
A) TATA box C) 5' cap
B) spliceosomes D) poly-A tail E) both C and D
5) What is a ribozyme?
A) An enzyme that uses RNA as a substrate
B) An catalytic molecule made up of RNA
C) An enzyme that catalyzes the association between the large and small ribosomal subunits
D) An enzyme that synthesizes RNA as part of the transcription process
6) What are the coding segments of a stretch of eukaryotic DNA called?
A) exons
B) introns
C) codons
D) replicons
7) Introns are significant to biological evolution because
A) their presence allows exons to be moved around more easily, creating proteins with new combinations of functional domains.
B) they protect the mRNA from degeneration.
C) they are translated into essential amino acids.
D) they maintain the genetic code by preventing incorrect DNA base pairings.
8) What is an anticodon part of?
A) DNA C) mRNA
B) tRNA D) a ribosome
9) What are ribosomes composed of?
A) rRNA only C) both rRNA and protein
B) proteins only D) mRNA, rRNA, and protein E) mRNA, tRNA, rRNA, and protein
10) Which of the following is not involved in the process of protein synthesis?
A) ligase C) rRNA
B) tRNA D) mRNA E) aminoacyl-tRNA synthetase
11) During translation, chain elongation continues until what happens?
A) No further amino acids are needed by the cell.
B) All tRNAs are empty.
C) The polypeptide is long enough.
D) A stop codon is encountered.
E) The ribosomes run off the end of mRNA.
12) As a ribosome translocates along an mRNA molecule by one codon, which of the following occurs?
A) The tRNA that was in the A site moves into the P site.
B) The tRNA that was in the P site moves into the A site.
C) The tRNA that was in the P site moves to the E site and is released.
D) Both A and B are correct.
E) Both A and C are correct
13) What are polyribosomes?
A) groups of ribosomes reading a single mRNA simultaneously C) multiple copies of ribosomes associated with giant chromosomes
B) ribosomes containing more than two subunits D) aggregations of vesicles containing ribosomal RNA
14) When translating secretory or membrane proteins, ribosomes are directed to the ER membrane by
A) a specific characteristic of the ribosome itself, which distinguishes free ribosomes from bound ribosomes.
B) a signal-recognition particle that brings ribosomes to a receptor protein in the ER membrane.
C) moving through a specialized channel of the nucleus.
D) a chemical signal given off by the ER.
15) What enzyme catalyzes the attachment of an amino acid to tRNA?
A) aminoacyl-tRNA synthetase C) dextrinase
B) nuclease D) argininosuccinate lyase
16) What is the effect of a nonsense mutation in a gene?
A) It changes an amino acid in the encoded protein.
B) It has no effect on the amino acid sequence of the encoded protein.
C) It introduces a premature stop codon into the mRNA.
D) It alters the reading frame of the mRNA
17) A frameshift mutation could result from
A) a base insertion only.
B) a base deletion only.
C) a base substitution only.
D) either an insertion or a deletion of a base.
18) A base-pair substitution mutation in a germ cell line is likely to have no effect if the substitution _____.
A) forms a new stop codon C) changes a stop codon to a codon specifying an amino acid
B) occurs in an intron D) prevents the initiation of transcription of the DNA sequence that codes for ATP synthase
19. All of the following are true except: general transcription factors
A) are required for the expression of all protein-encoding genes.
B) bind to other proteins or to a sequence element within the promoter called the TATA box.
C) help RNA polymerase bind to the promoter and begin transcribing.
D) usually lead to a high level of transcription with or without additional proteins called specific transcription factors.
E) all of the above are true
20. A eukaryotic gene typically has all of the following features except
A) control elements. C) a promoter.
B) an operator. D) TATA box. E) introns.
21. In eukaryotes, what binds to a site in the DNA far from the promoter to stimulate transcription?
A) repressor C) enhancer
B) terminator D) activator
22. A lack of this small molecule would result in the loss of repressor inactivation:
A) co-repressor C) repressor
B) inducer D) promoter
23. This protein is produced by a regulatory gene:
A) repressor C) inducer
B) promoter D) operator
24. A mutation in this section of DNA could influence the binding of RNA polymerase to the DNA:
A) co-repressor C) repressor
B) inducer D) promoter
25. In a nucleosome, what is the DNA wrapped around?
A) polymerase molecules C) mRNA
B) histones D) ribosomes
26. Ubiquitination is an example of:
A) post-translational modification C) transcriptional modification
B) post-transcriptional modification D) chromatin modification
27. What does the operon model attempt to explain?
A) how genes move between homologous regions of DNA
B) bacterial resistance to antibiotics
C) the coordinated control of gene expression in bacteria
D) the mechanism of viral attachment to a host cell
28. If you were to observe the activity of methylated DNA, you would expect it to
A) be replicating.
B) be improving conditions for maximum transcription.
C) have turned off or slowed down the process of transcription.
D) be very active in translation.
29. For a repressible operon to be transcribed, which of the following must be true?
A) A corepressor must be present.
B) RNA polymerase and the active repressor must be present.
C) RNA polymerase must bind to the promoter, and the repressor must be inactive.
D) RNA polymerase cannot be present, and the repressor must be inactive.
30. This segment of DNA is the site of attachment for an active repressor:
A) operon C) operator
B) promoter D) regulatory gene
31. If you were to observe DNA actively being transcribed, histones would be:
A) methylated C) ubiquitinated
B) acetylated D) unmodified
32. A proteasome is a protein complex that:
A) phosphorylates a protein C) degrades a protein
B) assists with protein folding D) ubiquitinates a protein
33. Human liver cells and kidney cells are different from one another due to
A) having different genes. C) using different genetic codes.
B) having different chromosomes. D) differential gene expression.
34. A new DNA strand elongates only in the 5' to 3' direction because
A) DNA polymerase begins adding nucleotides at the 5' end of the template.
B) Okazaki fragments prevent elongation in the 3' to 5' direction.
C) the polarity of the DNA molecule prevents addition of nucleotides at the 3' end.
D) replication must progress toward the replication fork.
E) DNA polymerase can only add nucleotides to a free 3' end.
35. Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?
A) 12 B) 24 C) 31 D) 38 E) It cannot be determined from the information provided.
36) Which of the following is true?
A) The uracil nucleotide consists of the uracil nitrogen base, a deoxyribose sugar, and a phosphate group.
B) When tRNA attaches to mRNA during translation, cytosine pairs with guanine and adenine pairs with thymine.
C) Ribosomes contain RNA nucleotides and amino acids.
D) Only A and B are true E) A, B, and C are true
37) RNA polymerase moves along the template strand of DNA in the direction, and adds nucleotides to the ______end of the growing transcript.
A) 3' to 5'; 3' C) 3' to 5'; 5'
B) 5' to 3'; 3' D) 5' to 3'; 5'
38) Which of the following is not true of a tRNA molecule?
A) tRNA carries amino acids to ribosome C) tRNA has a short lifespan and is used only once in translation
B) tRNA’s anticodon is complementary to a particular codon D) tRNA is transcribed within the nucleus of eukaryotic cells
39) Which of the following is not true of RNA processing?
A) Introns are spliced together before transcript encounters a ribosome C) Nucleotides may be added to both ends of a transcript
B) This process is unique to only eukaryotic cells D) A primary transcript (pre-mRNA) is longer than the mRNA molecule
40) The DNA of an elephant and DNA of a cherry tree will probably differ in all of the following ways except for the
A) length of the DNA molecules B) number of DNA molecules
C) gene products for which the DNA codes D) sequence of the DNA molecules
E) amino acids coded for by each codon
41) Which of the following is not a part of the eukaryotic transcription initiation complex?
A) mRNA C) transcription factors
B) RNA polymerase D) promoter E) TATA box
Matching (use each choice only once):
42) ____ adds replacement DNA nucleotides to the 3' end of Okazaki fragments. A. helicase
43) ____ separates the DNA strands during replication. B. RNase H
44) ____ covalently connects disjointed segments of DNA. C. ligase
45) ____ synthesizes short segments of RNA. D. DNA polymerase I
46) ____ removes the RNA nucleotides from the primer. E. primase
47) ____ catalyzes the elongation of a DNA strand in the 5'à 3' direction. F. DNA polymerase III
Short Answer
48) Briefly outline the major historical events that led to the discovery of DNA’s role in inheritance and its structure – be sure to note the major contributing scientists and what they did to identify either DNA’s role or its structure.
1928 –
1944 –
1952 –
1952-1953 –
49. At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork:
3' C C T A G G C T G C A A T C C 5'
A primer is formed starting at the underlined T (T) of the template – write the sequence of the resulting primer, appropriately labeling each end.
50. Once mRNA, encoding for a particular protein, reaches the cytoplasm, what are four mechanisms that can regulate the amount of protein that is active in the cell?