24 October 2012

Unit 2 Practice Test

Click Answers to check  yourself:

1. How do we describe transformation in bacteria?
a. The infection of cells by a phage DNA molecule
b. The creation of a strand of DNA from an RNA molecule
c. Assimilation of external DNA into a cell
d. The creation of a strand of RNA from a DNA Molecule
e. The type of semiconservative replication shown by DNA

2. In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts?
a. DNA Contains purines, whereas protein includes pyrimidines
b. DNA contains sulfur, whereas protein does not.
c. RNA includes ribose, whereas DNA includes deoxyribose sugars
d. DNA Contains phosphorus, whereas protein does not
e. DNA contains nitrogen, whereas protein does not

3. Replication in prokaryotes differs from replication in eukaryotes for which of the following reasons?
a. Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not.
b. Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many
c. Prokaryotes have telomeres, and eukaryotes do not
d. Prokaryotic chromosomes have histones, whereas eukaryotic chromosomes do not.
e. The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes.

4. In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?
a. The DNA will supercoil
b. Replication will require a DNA template from another source
c. No replication fork will be formed
d. No proofreading will occur
e. Replication will occur via RNA polymerase alone

5. At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork:    3' CCTAGGTGCAATCC 5'
An RNA primer is formed starting at the underlined T of the template. Which of the following represents the primer sequence?
a. 3' GCCTAGG 5'
b. 5' ACGUUAGG 3'
c. 5' GCCUAGG 3'
d. 5' GCCTAGG 3'
e. 5' ACGTTAGG 3'

6. Which of the enzymes removes the RNA nucleotides from the primer and adds equivilent DNA nucleotides to the 3' end of Okazaki fragments?
a. helicase
b. DNA Polymerase
c. ligase
d. primase

7. Which of the enzymes separates the DNA strands during replication?
a. helicase
b. DNA Polymerase
c. ligase
d. Primase

8. Which of the enzymes covalently connects segments of DNA?
a. Helicase
b. DNA Polymerase
c. ligase
d. Primase

9. Which of the enzymes synthesize short segments of RNA
a. helicase
b. DNA Polymerase
c. ligase
d. primase

10. What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?
a. The origins of replication occur only at the 5' end.
b. Helicase and single-strand binding proteins work at the 5' end.
c. DNA ligase works only in the 3' ----> 5' direction
d. Polymerase can work on only one strand at a time.
e. DNA polymerase can join new nucleotides only to the 3' end of a growing strand

11. In a nucleosome, the DNA is wrapped around
a. histones
b. satellite DNA
c. Ribosomes
d. a thymine dimer
e. polymerase molecules

12. Which of the following does not occur in prokaryotic gene expression, but does in eukaryotic gene expression?
a. RNA polymerase binds to the promoter.
b. mRNA, tRNA, and rRNA are transcribed.
c. A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end.
d. Transcription can begin as soon as translation has begun even a little.
e. RNA polymerase requires a primer to elongate the molecule.

13. Transcription in eukaryotes requires which of the following in addition to RNA polymerase?
a. start and stop codons
b. the protein product of the promoter
c. aminoacyl synthetase
d. several transcription factors (TFs)
e. ribosomes and tRNA

14. The TATA sequence is found only several nucleotides away from the start site of transcription. This most probably relates to which of the following?
a. The number of hydrogen bonds between A and T in DNA
b. the ability of this sequence to bind to the start site
c. the triplet nature of the codon
d. the 3-D shape of a DNA molecule
e. the supercoiling of the DNA near the start site

15. What is a ribozyme?
a. an enzyme that uses RNA as a substrate
b. an enzyme that synthesizes RNA as part of the transcription process
c. an RNA with enzymatic activity
d. an enzyme that synthesizes RNA primers during DNA replication

16. Alternative RNA splicing
a. can allow the production of similar proteins from different RNAs
b. increases the rate of transcription
c. is due to the presence of absence of particular snRNPs
d. is a mechanism for increasing the rate of transcription
e. can allow the production of proteins of different sizes from a single mRNA

17. Which of the following is the first event to take place in translation in eukaryotes?
a. The small subunit of the ribosome (and the tRNA holding Met) recognzies and attaches to the 5' cap of mRNA
b. elongation of the polypeptide in the 5' ---. 3' direction
c. binding of the larger ribosomal subunit to smaller ribosomal subunits
d. covalent bonding between the first two amino acids
e. base pairing of activated methionine-tRNA to AUG of the messenger RNA

18. Which of the following is a function of a signal peptide?
a. To bind RNA polymerase to DNA and initiate transcription
b. to direct an mRNA molecule into the cisternal space of the ER
c. to terminate translation of the messenger RNA
d. to be recognized by SRP and then translocate the polypeptide across the ER membrane
e. To signal the initiation and elongation (transcription) of a polypeptide in the cytoplasm of a eukaryote


19. What amino acid sequence will be generated, based on the following mRNA codon sequence?
a. met-leu-phe-arg-glu-glu
b. met-arg-glu-arg-glu-arg
c. met-ser-ser-leu-ser-leu
d. met-ser-leu-ser-leu-ser
e. met-glu-arg-arg-glu-leu

20. Which of the following is a function of the plasma membrane?
a. Fat synthesis
b. Protein synthesis
c. control center of the cell
d. intracellular digestion
e. regulation of the passage of material into and out of the cell

21. In euakryotic cells, what name is given to the region between the nucleus and the plasma membrane?
a. nucleoplasm
b. cytoplasm
c. gene
d. phospholipid bilayer
e. cytosol

22. in eukaryotic cells, organelles are suspended within the_____?
a. nucleoplasm
b. gene
c. cytoplasm
d. phospholipid bilayer
e. cytosol

23. You find a cell of a type you have never seen before. The cell has both a nucleus and a cell wall. Therefore, you conclude that it must be a ______ cell.
a. plant
b. prokaryotic
c.  bacterial
d. liver
e. animal

24. ________ are the major lipids of plasma membranes.
a. phospholipids
b. steroids
c. prostaglandins
d. triglycerides
e. mosaics

25. The extracellular coats of cells _____.
a. are warehouses for the storage of extra lipids and carbohydrates
b. protect and support cells and facilitate interactions between adjascent cells
c. are primarily sites of dead matter and waste materials
d. provide avenues for the exchange of DNA
e. none of the above

26. Cells are often bound to the extracellular matrix by _____ in the plasma membrane
a. ribosomes
b. proteins
c. cholesterol
d. phospholipids
e. carbohydrates

27. ________ code for the structure of proteins
a. ribosomes
b. lysosomes
c. genes
d. phospholipids
e. carbohydrates

28. The nuclear envelope is composed of _________.
a. carbohydrates
b. genes
c. a single membrane
d. a double membrane
e. DNA

29. The structural combination of DNA and protein forms
a. nucleoplasm
b. ATP
c. chromatin
d. ribosomes
e. nucleoli

30. What name is given to the organelle that manufactures the components of ribosomes
a. chromosome
b. nucleus
c. nucleolus
d. cytoplasm
e. endoplasmic reticulum

31. Which of the following organelles is NOT defined by a membrane
a. endoplasmic reticulum
b. chloroplast
c. lysosome
d. Golgi apparatus
e. ribosome

32. Where does protein synthesis take place?
a. in the nucleolus
b. in the golgi apparatus
c. on ribosomes
d. in the nucleus
e. on smooth endoplasmic reticulum

33. Many antibiotic drugs are effective against bacteria without harming humans because the antibiotics rely upon differences in the structure of human and bacterial ______
a. chromosomes
b. ribosomes
c. mitochondria
d. lysosomes
e. carbohydrates

34. The endomembrane system includes:
a. Golgi apparatus, lysosomes, ribosomes, and the endoplasmic reticulum.
b. Golgi apparatus, lysosomes, vacuoles, and ribosomes
c. Golgi apparatus, lysosomes, vacuoles, and the endoplasmic reticulum
d. Golgi apparatus, ribosomes, vacuoles, and the endoplasmic reticulum
e. ribosomes, lysosomes, vacuoles, and the endoplasmic reticulum

35. A hormone is destined for secretion from the cell would be manufactured by ribosomes ____.
a. suspended in the cytosol
b. attached to the Golgi apparatus
c. attached to the endoplasmic reticulum
d. suspended in the nucleoplasm
e. attached to the plasma membrane

36. What structures move proteins from the ER to the Golgi apparatus?
a. ribosomes
b. peroxisomes
c. transport vesicles
d. lysosomes
e. nucleosomes

37. Functions of the smooth endoplasmic reticulum include ______.
a. lipid synthesis, steroid synthesis, and drug detoxification
b. lipid synthesis, steroid synthesis, protein synthesis, and drug detoxification
c. lipid synthesis, protein synthesis, and drug detoxification
d. lipid synthesis, steroid synthesis, and protein synthesis
e. steroid synthesis, protein synthesis, and drug detoxification

38. Which of the following is a function of the Golgi apparatus?
a. drug detoxification
b. protein modification
c. intracellular digestion
d. cellular respiration
e. protein synthesis

39. Lysosomes are responsible for _______.
a. cellular respiration
b. protein modification
c. intracellular digestion
d. cellular respiration
e. protein synthesis

40. In plant cells, _______ contain organic nutrients, pigment, and poisons.
a. ribosomes
b. mitochondria
c. chloroplasts
d. central vacuoles
e. lysosomes

41. Which organelle is responsible for photosynthesis?
a. chloroplasts
b. mitochondrion
c. nucleolus
d. smooth endoplasmic reticulum
e. lysosomes

42. Similar to the nucleus, chloroplasts and mitochondria are ______.
a. green
b. able to synthesize lipids
c. not bounded by membrane
d. manufactured by the nucleus
e. surrounded by two membranes

NOTE: Metaphysical questions
Read the following scenario to answer the following question(s).
The earliest cells detectable in fossils were different from the cells in animals, plants, fungi, and protists living today. These first prokaryotic cells gave rise to eukaryotic cells approximately 1.7 billion years ago. The structure of eukaryotic cells today suggests how they might have evolved from their prokaryotic ancestors. Scientists examining mitochondria and chloroplasts now think that these organelles were probably free-living prokaryotes before becoming a part of eukaryotic cells long ago.

43. Which of the following is a characteristic of mitochondria that suggests that they might have evolved from free-living bacteria?
a. The plasma membrane of a mitochondrion, forming the surface of this organelle, is the site of many important steps on aerobic metabolism
b. Mitochondria rely upon proteins as their source of food
c. Mitochondria have their own DNA
d. A single, highly folded membrane surrounds mitochondria
e. Mitochondria do not produce ATP.

44. Which of the following is a characteristic of chloroplasts that suggests that they might have evolved from free-living bacteria
a. chloroplasts divide by meiosis
b. chloroplasts contain pigments
c. a single, highly folded plasma membrane surrounds chloroplasts
d. chloroplasts have their own DNA
e. chloroplasts do not produce ATP.

45. Consider the figure of the nucleotide.
a. Circle and label the nitrogenous base, ribose sugar, and phosophate group in the following figure.
b. Accurately number the carbons on the sugar
c. Is the nitrogenous base a pyrimidine or a purine?

46. Draw a diagram indicating the correct direction of the flow of genetic information. Include the following terms: translation, RNA, transcription, protein, reverse transcriptase, replication, DNA

47. Correctly label the following parts of the mRNA shown below.
(Start codon, 5' cap, Stop codon, poly-A tail, 3' UTR, polyadenylation signal, protein-coding segment, 5' UTR)

48. Place the letters associated with each of the phrases in the appropriate locations in the diagram of the DNA replication fork to describe the name or function of each structure.

A. Relaxes supercoiled DNA
B. Coats single-stranded DNA
C. Synthesizes RNA primers on leading and lagging strand
D. Synthesizes DNA 5' to 3' on the leading and lagging strands
E. Breaks hydrogen bonds, unwinding DNA double helix
F. Catalyzes phosphodiester bond formation, joining DNA fragments
G. Replaces RNA primers with DNA nucleotides
H. Leading strand
I. Lagging strand
J. Draw an arrow indicating the overall direction in which the replication fork is moving


49. Label the following structures at least once: nuclear membrane, DNA, tRNA, mRNA, ribosome, RNA polymerase, Aminoacyl-tRNA synthetase, amino acid, cytoplasm, nuclear pore complex.

50. Is this a eukaryotic cell or a prokaryotic cell? Briefly explain


1. C
2. D
3. B
4. C
5. B
6. B
7. A
8. C
9. D
10. E
11. A
12. C
13. D
14. A
15. C
16. E
17. A
18. D
19. C
20. E
21. B
22. E
23. A
24. A
25. B
26. B
27. C
28. D
29. C
30. C
31. E
32. C
33. B
34. C
35. C
36. C
37. A
38. B
39. C
40. D
41. A
42. E
43. C
44. D






This is a Eukaryotic cell:
It contains a nucleus (eu = good/true) (Karyon = Kernel/nucleus)
Also, the mRNA undergoes a splicing (as indicated by the lighter colored areas that are missing in the final mRNA leaving the nucleus). mRNA modifications are primarily eukaryotic.

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