Biochem HW 3

A common cloning strategy for introducing foreign genes into plants with Agrobacterium employs all the following features except:

a. active vir gene products from the altered Ti plasmid. b. a shuttle vector with 25 bp T-DNA repeats flanking the foreign gene of choice. c. a selectable antibiotic marker such as kanamycin resistance. d. a Ti plasmid lacking its T-DNA segment.

A common cloning strategy for introducing foreign genes into plants with Agrobacterium employs all the following features except:

a. active vir gene products from the altered Ti plasmid. b. a shuttle vector with 25 bp T-DNA repeats flanking the foreign gene of choice. c. a selectable antibiotic marker such as kanamycin resistance. d. a Ti plasmid lacking its T-DNA segment.

b. a shuttle vector with 25 bp T-DNA repeats flanking the foreign gene of choice.

An example of a glycerophospholipid that is involved in cell signaling is: a. ceramide. b. vitamin A (retinol). c. phosphatidylinositol. d. testosterone. e. arachidonic acid.

c. phosphatidylinositol.

Biological waxes are all: a. semesters of sphingolipids. b. trimesters of glycerol and three long-chain saturated fatty acids. c. none of the above. d. trimesters of glycerol and palmitic acid. e. esters of single fatty acids with long-chain alcohols.

e. esters of single fatty acids with long-chain alcohols.

Hormone-activated phospholipase C can convert phosphatidylinositol 4,5-bisphosphate to: a. glycerol + inositol + phosphate. b. glycerol + phosphoserine. c. diacylglycerol + inositol triphosphate. d. diacylglycerol + inositol + phosphate. e. phosphatidyl glycerol + inositol + phosphate.

c. diacylglycerol + inositol triphosphate.

Identify the molecule(s) derived from sterols. a. Arachidonic acid b. Prostaglandins c. Vitamin D d. Gangliosides e. Phosphatidylglycerol

c. Vitamin D

In genetic engineering, in vitro packaging is used to: a. incorporate recombinant DNA into infectious bacteriophage particles. b. ensure that genetically engineered bacteria are not accidentally released into the environment. c. cut a desired region out of the host bacterium's chromosome. d. place an antibiotic resistance gene in a plasmid. e. splice a desired gene into a plasmid.

a. incorporate recombinant DNA into infectious bacteriophage particles.

In the laboratory, recombinant plasmids are commonly introduced into bacterial cells by: a. electrophoresis - a gentle low-voltage gradient draws the DNA into the cell. b. infection with a bacteriophage that carries the plasmid. c. transformation - heat shock of the cells incubated with plasmid DNA in the presence of CaCl2 d. microinjection. e. mixing plasmids with an extract of broken cells.

c. transformation - heat shock of the cells incubated with plasmid DNA in the presence of CaCl2

Programmed cell death is called: a. ubiquitination. b. oncogenic transformation. c. mitotic termination. d. apoptosis. e. metastasis.

d. apoptosis.

Protein kinase A (PKA) is: a. activated by covalent binding of cyclic AMP. b. allosterically activated by cyclic AMP. c. noncompetitively inhibited by cyclic AMP. d. affected by cyclic AMP only under unusual circumstances. e. competitively inhibited by cyclic AMP.

b. allosterically activated by cyclic AMP.

Proto-oncogenes can be transformed to oncogenes by all of the following mechanisms except: a. during a viral infection cycle. b. chromosomal rearrangements. c. elimination of their start signals for translation. d. chemically induced mutagenesis. e. radiation-induced mutation.

c. elimination of their start signals for translation.

Steroid hormones are carried on specific carrier proteins because the hormones: a. cannot dissolve readily in the blood because they are too hydrophobic. b. require subsequent binding to specific receptor proteins in the nucleus. c. need them in order to pass through the plasma membrane. d. are too unstable to survive in the blood on their own. e. cannot find their target cells without them.

a. cannot dissolve readily in the blood because they are too hydrophobic.

The biological role of restriction enzymes is to: a. degrade foreign DNA that enters a bacterium. b. aid recombinant DNA research. c. restrict the damage to DNA by ultraviolet light. d. make bacteria resistant to antibiotics. e. restrict the size of DNA in certain bacteria.

a. degrade foreign DNA that enters a bacterium.

The E. coli recombinant plasmid pBR322 has been widely utilized in genetic engineering experiments. pBR322 has all of the following features except: a. resistance to two different antibiotics, which permits rapid screening for recombinant plasmids containing foreign DNA. b. a number of conveniently located recognition sites for restriction enzymes. c. a replication origin, which permits it to replicate autonomously. d. a number of palindromic sequences near the EcoRI site, which permit the plasmid to assume a conformation that protects newly inserted DNA from nuclease degradation. e. small overall size, which facilitates entry of the plasmid into host cells.

d. a number of palindromic sequences near the EcoRI site, which permit the plasmid to assume a conformation that protects newly inserted DNA from nuclease degradation.

The G-protein involved in visual signal transduction is: a. a leukotriene. b. rhodopsin. c. arrestin. d. a GTP receptor. e. transducin.

e. transducin.

The inner (plasma) membrane of E. coli is about 75% lipid and 25% protein by weight. How many molecules of membrane lipid are there for each molecule of protein? (Assume that the average protein is Mr 50,000 and the average lipid is 750.) a. 1 b. 10,000 c. 50 d. 200 e. 50,000

d. 200

The PCR reaction mixture does not include: a. oligonucleotide primer(s). b. DNA containing the sequence to be amplified. c. heat-stable DNA polymerase. d. all four deoxynucleoside triphosphates. e. DNA ligase.

e. DNA ligase.

The technique known as two hybrid analysis for detecting interacting gene products depends on: a. direct binding of a Gal4p activation domain to a DNA sequence in the promoter region. b. hybridization of DNA segments corresponding to the two genes being examined. c. activation of DNA polymerase by the nearby binding of hybridizing protein complexes. d. having a promoter that responds directly to one of the two proteins whose interactions is being measured. e. stimulation of transcription by interaction of two Gal4p domains via fused protein sequences

e. stimulation of transcription by interaction of two Gal4p domains via fused protein sequences.

Which of the following contains an ether-linked alkyl group? a. Sphingomyelin b. Platelet-activating factor c. Gangliosides d. Cerebrosides e. Phosphatidyl serine

b. Platelet-activating factor

Which of the following does not involve cyclic AMP? a. Regulation of glycogen synthesis and breakdown b. Signaling by glucagon c. Signaling by acetylcholine d. Signaling by epinephrine e. Regulation of glycolysis

c. Signaling by acetylcholine

Which of the following is not involved in signal transduction by the adrenergic receptor pathway? a. GTP-binding protein b. Cyclic AMP synthesis c. Protein kinase A d. All of the above are involved. e. GTP hydrolysis

d. All of the above are involved.

Which of the following is not involved in the specificity of signal transduction? a. Structure of receptor molecules b. Interactions between receptor and signal molecules c. Transmembrane transport of signal molecules by receptor molecules d. Location of receptor molecules e. Structure of signal molecules

c. Transmembrane transport of signal molecules by receptor molecules

Which of the following is not true of sterols? a. They are more common in plasma membranes than in intracellular membranes (mitochondria, lysosomes, etc.). b. Cholesterol is a sterol that is commonly found in mammals. c. They are commonly found in bacterial membranes. d. They have a structure that includes four fused rings. e. They are precursors of steroid hormones.

c. They are commonly found in bacterial membranes.

Which of the following is true of sphingolipids? a. Phosphatidylcholine is a typical sphingolipid. b. They may be charged, but are never amphipathic. c. They always contain glycerol and fatty acids. d. They contain two esterified fatty acids. e. Cerebrosides and gangliosides are sphingolipids.

e. Cerebrosides and gangliosides are sphingolipids.

Which of the following statements about sterols is true? a. Sterols are found in the membranes of all living cells. b. All sterols share a fused-ring structure with four rings. c. The principal sterol of animal cells is ergosterol. d. Stigmasterol is the principal sterol in fungi. e. Sterols are soluble in water, but less so in organic solvents such as chloroform.

b. All sterols share a fused-ring structure with four rings.

Which of the following statements about the polymerase chain reaction (PCR) is false? a. DNA amplified by PCR can be cloned. b. DNA is amplified at many points within a cellular genome. c. The boundaries of the amplified DNA segment are determined by the synthetic oligonucleotides used to prime DNA synthesis. d. Newly synthesized DNA must be heat-denatured before the next round of DNA synthesis begins. e. The technique is sufficiently sensitive that DNA sequences can be amplified from a single animal or human hair.

b. DNA is amplified at many points within a cellular genome.

Which of the following statements about type II restriction enzymes is false? a. Many make staggered (off-center) cuts within their recognition sequences. b. They are part of a bacterial defense system in which foreign DNA is cleaved. c. They cleave DNA only at recognition sequences specific to a given restriction enzyme. d. Some cut DNA to generate blunt ends. e. They cleave and ligate DNA.

e. They cleave and ligate DNA.

Which of the following statements concerning cyclins is not correct? a. They are activated and degraded during the cell cycle. b. They contain specific amino acid sequences that target them for proteolysis. c. They are regulatory subunits for enzymes that catalyze the phosphorylation of proteins. d. They catalyze the phosphorylation of proteins. e. They can become linked to ubiquitin.

d. They catalyze the phosphorylation of proteins.

Which of the following statements concerning receptor enzymes is correct? a. They contain an enzyme activity that acts upon the extracellular ligand. b. They have a ligand-binding site on the cytosolic side of the membrane. c. They have an active site on the extracellular side of the membrane. d. They contain an enzyme activity that acts upon a cytosolic substrate. e. They are not usually membrane-associated proteins.

d. They contain an enzyme activity that acts upon a cytosolic substrate.

Which of the following statements concerning signal transduction by the insulin receptor is not correct? a. Binding of insulin to the receptor results in a change in its quaternary structure. b. Activation of the receptor protein kinase activity results in the activation of additional protein kinases. c. The receptor protein kinase activity is specific for tyrosine residues on the substrate proteins. d. Binding of insulin to the receptor activates a protein kinase. e. The substrates of the receptor protein kinase activity are mainly proteins that regulate transcription.

e. The substrates of the receptor protein kinase activity are mainly proteins that regulate transcription.

Which of these is a general feature of the lipid bilayer in all biological membranes? a. Individual lipid molecules are free to diffuse laterally in the surface of the bilayer. b. The bilayer is stabilized by covalent bonds between neighboring phospholipid molecules. c. The polar head groups face inward toward the inside of the bilayer. d. Polar, but uncharged, compounds readily diffuse across the bilayer. e. Individual lipid molecules in one face (monolayer) of the bilayer readily diffuse (flip-flop) to the other monolayer.

a. Individual lipid molecules are free to diffuse laterally in the surface of the bilayer.

Which of these statements is generally true of integral membrane proteins? a. They undergo constant rotational motion that moves a given domain from the outer face of a membrane to the inner face and then back to the outer. b. They can be removed from the membrane with high salt or mild denaturing agents. c. They are unusually susceptible to degradation by trypsin. d. A hydropathy plot reveals one or more regions with a high hydropathy index. e. The domains that protrude on the cytoplasmic face of the plasma membrane nearly always have covalently attached oligosaccharides.

d. A hydropathy plot reveals one or more regions with a high hydropathy index.

Which one of the following signaling mechanisms is used most predominantly in plants? a. Protein tyrosine kinases b. Cyclic-nucleotide dependent protein kinases c. DNA-binding nuclear steroid receptors d. G protein-coupled receptors e. Protein serine/threonine kinases

e. Protein serine/threonine kinases