Sample/practice exam 2019, questions and answers PDF

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1. After transferring its peptide, a tRNA exits the bacterial ribosome complex via the __ a. A site b. 50S subunit c. P site d. E site e. 30S subunit 2. The Shine Dalgarno sequence found in prokaryotic systems resides on the ____ end of _____ and is the _____ site. a. 5’; mRNA, ribosome binding b. 3’; rRNA; imitation factor binding c. 3’; peptidyl-tRNA; formyl transferase d. 5’;DNA; polymerase binding e. 3’; aminoacyl-tRNA; formyl methionine binding 3. A micelle is a. A small cellular inclusion found in some plants that have features of both cells and mitochondria b. A cell fraction produced by the dissolution of the nucleus in centrifuge c. A small intracellular vesicle that buds from the Golgi apparatus d. A stable ‘droplet’ of phospholipid under water with the polar heads facing outward e. None of these options 4. DNA ligase would most likely be used in recombinant DNA technology to a. Function as a vector b. Screen for recombinant plasmids c. Cut DNA into fragments with sticky ends d. Stimulate a transformed cell to divide e. Join DNA fragments together 5. The genes of the lactose operon are present in which order on the E. coli chromosome? a. ABCDEF b. AIOPYZ c. IOPAYZ d. EDCBA e. IPOZYA 6. A heterodimer is a. A protein subunit where two identical heteromers bond covalently. b. A disulphide bridge between adjacent base pairs. c. A heterologous protein complex where the subunits are dimerically opposed. d. A dimeric misnomer between two adjacent heteromers. e. A protein building block made of two different subunits

7. Stone wash jeans are now easier to produce (i.e. cheaper) due to the use of a gene originally obtained from which kingdom of life: a. Archaea b. Bacteria c. Fungi d. Plants e. Animals 8. Which function does TFIIH have during the initiation of transcription in eukaryotes? a. TFIIH is a docking station for TFIIE. b. c. d. e.

TFIIH is a TATA binding protein. TFIIH recruits RNA polymerase II to the transcription start site. TFIIH recruits RNA polymerase I to the transcription start site. TFIIH unwinds DNA at the transcription start site.

9. Which of the following answers about histone acetylation is correct? a. HD proteins acetylate histone protein tails. b. Acetylation of histones leads to transcriptionally inactive chromatin. c. Histone tails can be acetylated on lysine residues. d. Histone tails are acetylated on proline residues. e. Amino acids are acetylated on carboxy groups. 10. If a protein were largely composed of a-helices, it would probably reside a. in close association with the hydrophobic tails of membrane phospholipids b. in the nucleus. c. in close association with the hydrophilic heads of membrane phospholipids. d. free in the cytoplasm (as a water-soluble protein). e. in the mitochondria. 11. What is the correct term for the reaction leading to the formation of macromolecules such as carbohydrates, DNA and proteins? a. Multimerisation reaction

b. Hydrolysis reaction c. Condensation reaction d. Ionic reaction e. Oxygenation reaction 12. In the Southern blotting procedure, the gel after electrophoresis is treated with an alkali solution. What is the primary function of this treatment? a. It denatures the duplex DNA to single-stranded DNA. b. It cleaves the DNA into smaller pieces to permit greater efficiency of transfer to nitrocellulose. c. It neutralizes any acidic impurities in the gel. d. It inactivates any restriction endonucleases that may be in the gel. e. It neutralizes any acidic phosphate groups that might be in the gel. 13. A possible DNA sequence for the peptide N-Gly Ile Pro Leu-C is a. 5' GGTATTCCTTTA 3'. b. 5' GGGACUCCUUUA 3'. c. 5' GGGACTCCTTTA 3'. d. 5' GGAAUTCCTTTA 3'. e. 5' GGCAGTCCTTTA 3'. 14. All of the following are components of the PCR except a. dNTPs b. a template DNA c. a restriction enzyme d. a heat stable DNA e. polymerase primers 15. In cell membrane transport, there are three broad categories of transport: a. nuclear transport, membrane transport, and vesicular transport.

b. cytokines, antipores and sympores. c. ribosomal kinesins, flippases and kinases. d. bilayer transport, mitochondrial transport and transport within cristae. e. None of the above is correct. 16. The true “readers” of the genetic code are a. the ribosomal proteins. b. the tRNAs c. the RNA polymerases. d. the mRNAs. e. the ribosomal proteins. 17. Which of the following statements does NOT apply to Cyclin dependent kinases (CDKs)? a. CDKs are protein kinases. b. Access to the T-loop of is blocked in the inactive CDK. c. CDKs are inactivated by ubiquitination. d. CDKs act as the catalytic subunit in a complex with cyclins. e. When active, CDKs are part of a heterodimeric complex. 18. Crossing over and the random distribution of maternal and paternal chromosomes are responsible for a. Genetic variation b. DNA synthesis c. Cell division d. Genetic stability e. None of these options 19. Which of the following statements about prokaryotes is TRUE? a. They include bacteria, yeast and protozoans. b. They are separated into eubacteria and archeabacteria based on phenotype.

c. They are all able to live on inorganic energy sources. d. They have no Golgi apparatus. e. They have no nucleus and hence no DNA. 20. An Okazaki fragment is a. A byproduct of the methylation of viral DNA, present immediately before a replication bubble. b. Partially digested DNA on an electrophoretic gel seen aer  labelling with a fluorescent DNA clone. c. A short-lived complex of tRNA and an amino acid that binds to the ribosomal complex. d. A segment of DNA synthesis on the lagging strand of DNA which is growing in the 5' to 3' direction. e. The short strand of RNA primer synthesized by DNA primase 21. Which of the following statements is FALSE? a. All cells are composed of similar sorts of molecules. b. Prokaryotic cells do not have membranes. c. A cell can divide, grow, convert energy and respond to stimuli. d. Prokaryotic cells are generally smaller and less elaborate than eukaryotic cells. e. Eukaryotic cells contain membrane-bound organelles. 22. Phospholipids can form bilayer membranes because they are a. Hydrophilic. b. Amphoteric. c. Hydrophobic. d. Lipids. e. Amphipathic. 23. What is the correct term for the reaction type leading to the formation of macromolecules such as carbohydrates, DNA and proteins? a. Condensation reaction b. Ionic reaction c. Hydrolysis reaction

d. Multimerisation reaction

e. Oxygenation reaction 24. What is the correct name of the molecule shown below? a. α-D-glucose b. β -D-fructose

c. Sucrose d. β -D-glucose

e. α-D-fructose

25. Which of the following statements about hydrogen bonds is TRUE? a. They are weak bonds formed between nonpolar groups. b. They are weak covalent bonds that are easily disrupted by heat. c. They are weak bonds formed between hydrocarbons in water. d. They are weak bonds involved in maintaining the conformation of macromolecules. e. They are weak bonds only formed in the presence of water. 26. The three major organelles in animals/plants that have a double layered membranes are a. The endosomes, the vesicles and the nucleus. b. The mitochondria, the vesicles and the chloroplasts. c. The nucleus, the chloroplasts and the mitochondria. d. The Golgi apparatus, the endosomes and the nucleus. e. None of the above 27. Atoms form covalent bonds with each other by a. Attraction of positive and negative charges b. Sharing protons c. Sharing neutrons d. Sharing electrons e. Transferring electrons from one atom to another 28. Regarding peroxisomes, which of the following statements is TRUE? a. They are surrounded by a double membrane. b. They have evolved from a photosynthetic prokaryote.

c. They are part of the Golgi apparatus of a eukaryotic cell. d. They contain DNA. e. They are sites of detoxification in a cell. 29. A triglyceride is a molecule a. Of three glycerol molecules joined to form a complex. b. Used by cells in the production of the glycocalyx. c. Formed from three glyceride molecules joined by hydrogen bonding that forms the lipid monolayers in cells. d. With a glycerol backbone and three fatty acid chains attached. 30. Which of the following statements about the plasma membrane is FALSE? a. It mediates the transport of substances into and out of the cell. b. It receives and transmits information from the cell’s surrounding environment. c. It has a bilayer structure. d. It has the capacity to expand during cell growth. e. It is the membrane surrounding the nucleus. 31. Regarding nucleotides, which of the following is FALSE? a. They link together through DNA base pairing to form the backbone of nucleic acids. b. They are the building blocks of DNA and RNA. c. They can act as signalling molecules. d. They can be carriers of chemical energy. e. They are composed of a five carbon sugar, a nitrogenous base, and a phosphate group. 32. Compared to actin filaments, microtubules a. Are composed of protein subunits. b. Are found in all eukaryotic cells. c. Have a larger diameter

d. Are part of the cytoskeleton. e. Are directly involved in muscle contraction.

33. What nitrogenous base is unique to RNA? a. Guanine b. Adenine c. Uracil d. Thymine e. Xanthine 34. Which of the following statements regarding transposition is NOT TRUE? a. The transposase creates double stranded DNA breaks at the site of insertion. b. Transposons insert via a process of non-homologous recombination. c. The transposon is flanked by inverted repeats. d. Short direct repeats are created on either side of the transposon. e. Extensive homology is required between the site of insertion and the original location of the transposon. 35. During the initiation stage of translation in bacteria a. fMet-tRNAi binds to the initiation codon. b. Release factors bind at the A site. c. The two ribosome subunits separate. d. FMet-tRNAi binds at the A site. e. A peptide bond is formed. 36. Antiparallel is a term applied to the double-stranded DNA structure. This refers to the fact that a. Strands are in opposite orientations. b. Strands are based paired via hydrogen bonds.

c. One stand is complementary to the other. d. One strand is coding whilst the other is not. e. Strands form a right-handed helix. 37. The main technique used by Watson and Crick to determine the structure of doublestranded DNA was a. X-ray diffraction b. Gel electrophoresis. c. Restriction enzyme digestion. d. Electron spin resonance. e. Nuclear magnetic resonance. 38. Hypotheses concerning the origin of life on Earth include: a. Lipid membranes being formed inside hot springs b. The first self-replicating entity being RNA c. Panspermia which is the carriage by meteorites of sperm d. An organic soup being struck by lightning e. Organic chemical synthesis in an oxidizing atmosphere 39. A large assembly of several ribosomes on a single mRNA molecule is termed a. Polymer b. Polycistronic c. Polymorphic d. Polyribosome e. Poly-A tail 40. Which of the following classifications is FALSE? a. Tyrosine and threonine are neutral, polar amino acids b. Aspartic acid and asparagine are acidic amino acids c. Alanine and valine are neutral, nonpolar amino acids

d. Lysine and arginine are basic amino acids e. Serine and glutamine are polar uncharged amino acids 41. DNA replication is considered semi-conservative because a. Each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand. b. New DNA strands must be copied from a DNA template. c. Each daughter DNA molecule consists of two new strands copied from the parent DNA molecule. d. After many rounds of DNA replication, the original DNA double helix is still intact. e. An RNA primer must be used to initiate synthesis of the DNA strand. 42. Regarding the role of the helicase enzyme in DNA replication a. It wraps around DNA to ensure the stability of the double helix structure b. It adds nucleotides to the 3’ end of the new strand c. It complexes with histones to produce their standard 9+2 arrangement d. It is often associated with a ribosomal subunit e. It unwinds the DNA double helix during replication 43. If a protein were largely composed of a-helices, it would probably reside a. In close association with the hydrophilic heads of membrane phospholipids. b. In the nucleus. c. Free in the cytoplasm (as a water-soluble protein). d. In the mitochondria. e. In close association with the hydrophobic tails of membrane phospholipids 44. A common _________________ structure of proteins involves a hydrogen bond between the amino group of one amino acid and the carboxyl group of an amino acid farther along the peptide chain. a. Quaternary b. Tertiary

c. Primary d. Secondary e. Pentenary 45. All are characteristic of plasmids except a. Harbour genes for novel metabolic activities b. Can be constructed artificially by restriction enzyme endonuclease digestion, insertion of DNA and ligation. c. Must include an origin of replication to facilitate propagation d. Able to perpetuate themselves without a host organism. e. Naturally occurring, circular extrachromosomal DNA. 46. Reverse transcription (RT)-PCR differs from basic PCR in that a. Reverse temperatures are used for annealing and transcription b. Reverse transcriptase is used to synthesise an RNA strand complementary to a DNA strand c. Transcription is reversed from the 3’ to 5’ ends d. Transcription is reversed from the 5’ to 3’ ends e. Reverse transcriptase is used to synthesise a cDNA strand complementary to an RNA strand 47. The amino acid sequence is NOT a. A distinctive characteristic of a polypeptide. b. Constant for proteins with the same function from different organisms. c. Encoded by the nucleotide sequence of DNA. d. Read from the N-terminal end to the C-terminal end. e. A form of genetic information.

48. All are characteristic of motor proteins EXCEPT a. They transfer ATP energy into mechanical energy.

b. ATP hydrolysis is presumed to drive and control protein conformational changes that result in the movement of one protein relative to another. c. They have tail regions that bind cellular cargo, such as organelles and vesicles, and head regions that reversibly associate with microtubules. d. They are involved in intercellular movement of organelles and vesicles. e. They use chemical energy (e.g. ATP) to coordinate movement. 49. Noncovalent interactions that can form between the atoms of a polypeptide’s backbone and the atoms of its side chain (R) group include all EXCEPT a. Ionic bonds b. Disulphide bonds c. Hydrogen bonds d. Van der Waals attractions e. Hydrophobic interactions 50. Keratin is an example of a(n) _____________ and the lac repressor is an example of a(n) _____________. a. Storage protein; enzyme b. Structural protein; enzyme c. Transport protein; regulatory protein d. Structural protein; regulatory protein e. Protein enzyme; transport protein 51. The number of genes coding for an enzyme is found with ____________, while ______________ determines which tissues express the genes. a. Northern analysis; PCR analysis b. Southern analysis; reverse transcription (RT)-PCR analysis c. Reverse transcription (RT)-PCR analysis; PCR analysis d. Reverse transcription (RT)-PCR analysis; Northern analysis e. PCR analysis; Southern analysis

52. In the Southern blotting procedure, the gel after electrophoresis is treated with an alkali solution. What is the primary function of this treatment? a. It cleaves the RNA into smaller pieces to permit greater efficiency of transfer to nitrocellulose. b. It neutralizes any acidic impurities in the gel. c. It neutralizes any acidic phosphate groups that might be in the gel. d. It inactivates any restriction endonucleases that may be in the gel. e. It denatures the duplex DNA to single-stranded DNA. 53. The foundation of nucleic acid hybridisation is the a. Ability of DNA to be radioactively labelled b. Base-pairing properties of nucleic acids c. Use of plasmids and other vectors d. Activity of restriction enzymes e. Antiparallel nature of the DNA strands 54. Restriction enzymes a. Always leave cohesive ends on DNA molecules after digestion. b. Are exonucleases. c. Digest double-stranded and single-stranded DNA. d. Leave 3'-phosphate and 5'-hydroxyl groups on DNA molecules after digestion. e. Digest double-stranded DNA.

55. What function does TFIIF have during the initiation of transcription in eukaryotes? a. TFIIH recruits RNA polymerase I to the transcription start site. b. TFIIH is a docking station for TFIIE. c. TFIIH is a TATA binding protein. d. TFIIH recruits RNA polymerase II to the transcription start site.

e. TFIIH unwinds DNA at the transcription start site. 56. Positive regulation of gene expression in prokaryotes is defined by the presence of a. An inducer and an antagonist a repressor but no inducer b. An inducer and an antagonist c. A repressor and an inducer d. An activator and a repressor e. An activator but no repressor 57. Which of the following causes 90o bending of the DNA double helix of E. coli? a. Binding of tryptophan to the tryptophan repressor b. Binding of lactose to the lactose repressor c. Binding of CAP-cAMP dimer to CAP-binding site d. Binding of tryptophan repressor to the major groove of DNA e. Binding of CAP to cAMP 58. What are the names given to proteins that control gene transcription and bind to regulatory elements on DNA and how are they categorised? a. They are known as control elements, and are categorised as either general OR cell/tissue specific control elements. b. They are known as transcription factors, and are categorised as either general OR gene specific transcription factors. c. They are known as transcription factors, and are categorised as either general OR cell/tissue specific transcription factors. d. They are known as motifs, and are categorised as either general OR gene specific motifs. e. They are known as morphogens, and are categorised as either general OR gene specific morphogens. 59. For biosynthetic metabolic pathways in prokaryotes, the regulatory molecule is often: a. Any large, complex molecule within the pathway b. The biosynthetic enzyme

c. The first precursor in the pathway d. The final end-product of the pathway e. The operator of the pathway 60. Which of the following answers about histone acetylation is correct? a. b. c. d. e.

Amino acids are acetylated on carboxy groups. Histone tails are acetylated on proline residues. Histone tails can be acetylated on lysine residues. Acetylation of histones leads to transcriptionally inactive chromatin. HD proteins acetylate histone protein tails.

61. What bonds are not formed between prokaryotic DNA binding proteins and DNA a. Covalent bonds b. Hydrogen bonds c. Hydrophobic bonds d. Chemical bonds e. Ionic bonds 62. Bacterial RNA molecules that are translated into more than one protein are called a. Regulatory RNA

c. Polycistronic mRNA

b. Operon RNA

d. Polyprotein mRNA

e. Polygonic tRNA

63. The lactose operon is under a. Only positive transcriptional control b. Only negative translational control c. Both positive and negative translational control d. Only negative transcriptional control e. Both positive and negative transcriptional control 64. Between 25 and 50% of eukaryotic genes are solitary. How are the rest of the genes that have protein products with similar, but not identical, function described? a. They are ubiquitous genes b. They are known as replicated domain genes

c. They belong to gene families d. They form coordinated gene clusters e. None of the above statements are correct 65. Which of the following statements is correct? a. Bicoid is a Hox protein. b. Hox proteins are morphogens. c. Bicoid is a histone deacetylase. d. Hox genes are transcription factors. e. The homeobox is a specific amino acid sequence motif found in Hox proteins 66. Which of the following is NOT a standard type of pre-mRNA processing to produce a mature mRNA in eukaryotes? a. Addition of a polyA tail. b. Addition of a 5’ cap. c. Splicing to remove introns. d. Co-transcriptional modifications. e. Binding of transcription factors. 67. The DNA binding...