AP Biology Chapter 20
DNA ligase
an enzyme that eventually joins the sugar-phosphate backbones of the Okazaki fragments
genome-wide association studies
A large-scale analysis of the genomes of many people having a certain phenotype or disease, with the aim of finding genetic markers that correlate with that phenotype or disease.
cDNA library
A limited gene library using complementary DNA. The library includes only the genes that were transcribed in the cells examined.
The nucleotide sequence of ACGT will form a pair with a DNA restriction fragment with the sticky end of the nucleotides ______.
A nucleotide sequence of ACGT will pair with a DNA restriction enzyme fragment of TGCA.
Ti plasmid
A plasmid of a tumor-inducing bacterium that integrates a segment of its DNA into the host chromosome of a plant; frequently used as a carrier for genetic engineering in plants.
Where the does the location of restriction enzymes need to be such that you can clone a copy of the gene?
A restriction enzyme needs to be on both sides of the entire gene, but not within the gene, to clone a gene.
RT-PCR
A technique in which RNA is first converted to cDNA by the use of the enzyme reverse transcriptase, then the cDNA is amplified by the polymerase chain reaction.
The transfer of antibiotic-resistant genes from genetically engineered bacteria to disease-causing bacteria _____. A) would, if it occurred, be no cause for concern B) has occurred C) is likely to occur D) can never occur E) seems unlikely
E) seems unlikely It seems unlikely to occur and there is no evidence that it has occurred.
in vitro mutagenesis
A technique to discover the function of a gene by introducing specific changes into the sequence of a cloned gene, reinserting the mutated gene into a cell, and studying the phenotype of the mutant.
electroporation
A technique to introduce recombinant DNA into cells by applying a brief electrical pulse to a solution containing cells. The electricity creates temporary holes in the cells' plasma membranes, through which DNA can enter.
How many DNA molecules would there be after four rounds of PCR if the initial reaction mixture contained two molecules? A) 32 B) 64 C) 8 D) 16
A) 32 Thirty-two DNA molecules are produced if two molecules are doubled four times (2^4 + 2^4 = 32).
What is the polymerase chain reaction (PCR)? A) A method to amplify a fragment of DNA B) A method to propogate a gene in bacteria C) A method to join two fragments of DNA together D) A method to determine the sequence of bases in a gene
A) A method to amplify a fragment of DNA PCR is an in vitro DNA synthesis reaction that produces many copies of a single DNA fragment.
True or False? The Taq enzyme is a type of DNA polymerase that allows researchers to separate the DNA strands used during the annealing step of the PCR cycle without destroying the polymerase.
False Taq polymerase is derived from a species of bacteria living in hot springs, which makes it stable at the high temperature required for the denaturation step of PCR.
True or False? The use of growth hormone isolated from cadavers was banned mainly because there were not enough cadavers to supply the hormone.
False The use of growth hormone isolated from cadavers was banned mainly because the hormone was potentially contaminated with prion proteins.
In order to insert a human gene into a plasmid, both must _______. A) have identical DNA sequences B) originate from the same type of cell C) code for the same gene product D) be cut by the same restriction enzyme E) be the same length
D) be cut by the same restriction enzyme Doing so will result in the formation of complementary sticky ends.
GMO
Genetically modified organism made when DNA is removed from one organism and placed within the DNA of what can be a very different organism.
In gel electrophoresis DNA molecules migrate from _____ to _______ ends of the gel?
In gel electrophoresis DNA molecules migrate from the negative to the positive ends of the gel.
The unpaired nucleotides produced by the action of restriction enzymes are referred to as ____.
The unpaired nucleotides produced by the action of restriction enzymes are referred to as sticky ends. They are called sticky ends because they will "stick" to a complementary single-stranded sequence.
restriction enzyme
any of the enzymes that cut nucleic acid at specific restriction sites and produce restriction fragments
What machine amplifies DNA?
A PCR machine amplifies (produces multiple copies of) a DNA molecule.
expression vector
A cloning vector that contains the requisite prokaryotic promoter just upstream of a restriction site where a eukaryotic gene can be inserted.
biotechnology
A form of technology that uses living organisms, usually genes, to modify products, to make or modify plants and animals, or to develop other microorganisms for specific purposes.
During which step of the PCR cycle are nucleotides used? A) Extension B) Denaturation C) Annealing D) All of these steps
A) Extension Nucleotides are used to synthesize the complementary strand to the DNA template during the extension step.
Which lengths of DNA strands move faster down the gel electrophoresis medium? A) Smaller B) Larger
A) Smaller The shorter the DNA molecule, the farther it moves.
genetic profile
An individual's unique set of genetic markers, detected most often today by PCR or, previously, by electrophoresis and nucleic acid probes.
Gel electrophoresis separates DNA fragments on the basis of what characteristic?
As the DNA fragments move through the gel, the longer fragments are impeded more than shorter fragments, producing characteristic banded patterns in the gel.
Which of the following tools of recombinant DNA technology is incorrectly paired with its use? A) DNA polymerase-polymerase chain reaction to amplify sections of DNA B) DNA ligase-cutting DNA, creating sticky ends of restriction fragments C) reverse transcriptase-production of cDNA from mRNA D) electrophoresis-separation of DNA fragments E) restriction enzymes-analysis of RFLPs
B) DNA ligase-cutting DNA, creating sticky ends of restriction fragments This statement is incorrect because the action described above is the job of restriction enzymes, not DNA ligase. DNA ligase rejoins the recombinant DNA.
What defect causes pituitary dwarfism? A) Lack of a pituitary gland B) Lack of a growth hormone C) One defective allele D) Neurodegeneration
B) Lack of a growth hormone Individuals affected by pituitary dwarfism produce little or no growth hormone.
How can large quantities of a protein be produced from a bacterial colony containing the gene of interest? A) Construct a probe that matches part of the gene's sequence B) Put a cDNA encoding the protein into a plasmid with a bacterial promoter sequence C) Insert the plasmid containing the cDNA into bacteria D) Use reverse transcriptase to make cDNAs.
B) Put a cDNA encoding the protein into a plasmid with a bacterial promoter sequence Once a cDNA is put into a plasmid with a bacterial promoter, the bacteria will transcribe and translate the gene.
nucleic acid hybridization
Base pairing between a gene and a complementary sequence on another nucleic acid molecule.
Which of the following describes the function of reverse transcriptase? A) It synthesizes double-stranded DNA molecules from single-stranded DNA molecules B) It seals the DNA fragments together C) It makes complementary DNA (cDNA) from mRNA D) It cuts DNA strands at specific sequences
C) It makes complementary DNA (cDNA) from mRNA The function of reverse transcriptase is similar to the reverse of transcription; it makes a single strand of complementary DNA (cDNA) from mRNA.
What information can not be obtained from the sequence of a gene? A) Relationship between two species B) Effects of a mutation on gene function C) Whether the gene is methylated D) Amino acid sequence of a gene
C) Whether the gene is methylated Although the gene's sequence may reveal the presence of methylation targets like cytosine (C), it does not give information about whether such bases have been methylated.
What is the process where a recombinant plasmid is replicated?
Cloning is known as the process where a recombinant plasmid is replicated.
During which step in the PCR cycle do primers form bonds with a single-stranded template? A) Extension B) Denaturation C) All of these steps D) Annealing
D) Annealing Primers form hydrogen bonds with the single-stranded DNA template during the annealing step.
Which of the following steps would be performed last when screening a cDNA library? A) Spread bacterial cells containing the library on a plate to form colonies B) Treat DNA on the filter to make it single-stranded C) Incubate the filters with a gene-specific probe D) Match the region of radioactivity on the filter with the corresponding plate
D) Match the region of activity on the filter with the corresponding plate This step allows researchers to match the colony on the filter with the colony of the bacterial plate so the correct colony can be grown for further study. It would be the last step in screening a cDNA library.
recombinant DNA
DNA produced by combining DNA from different sources
What enzyme forms covalent bonds between restriction fragments? A) DNA primase B) DNA helicase C) single-stranded binding protein D) DNA polymerase E) DNA ligase
E) DNA ligase DNA ligase catalyzes the formation of covalent bonds between restriction fragments.
In recombinant DNA experiments, what is used to cut pieces of DNA and what joins the resulting fragments to form recombinant DNA? A) a transposon ... a restriction enzyme B) a plasmid ... DNA ligase C) DNA ligase ... a restriction enzyme D) a transposon ... a plasmid E) a restriction enzyme ... DNA ligase
E) a restriction enzyme ... DNA ligase Restriction enzymes cut DNA molecules at specific points; in most cases, the restriction fragments have sticky ends that can base-pair with complementary sticky ends. The joined segments are then covalently fused by DNA ligase.
What is genetic cloning?
Genetic cloning is the process by which many identical copies of a gene are produced.
BAC
Large circular vectors that can replicate very large pieces of DNA; used to clone pieces of human chromosomes for the Human Genome Project, can clone much larger pieces of DNA but have lower copy number
RNAi
RNA interference; injecting double stranded RNA into a cell turns off expression of a gene with the same sequence as the RNA
STR
Short Tandem Repeating, a region of a DNA molecule that contains short segments consisting of three to seven repeating base pairs.
SNP
Single nucleotide polymorphism, change of base of single DNA nucleotide, makes up 90% of all human genetic variation
totipotent
Stem cells with the potential to differentiate into any type of cell
gene therapy
The insertion of working copies of a gene into the cells of a person with a genetic disorder in an attempt to correct the disorder
What part of the DNA molecule contains a negative charge?
The phosphate group of a nucleotide contains a negative charge.
gene cloning
The production of multiple copies of a gene.
gel electrophoresis
The separation of nucleic acids or proteins, on the basis of their size and electrical charge, by measuring their rate of movement through an electrical field in a gel.
What is the process where a bacterium takes up a plasmid from the surrounding solution?
Transformation is known as the process by which a bacterium takes up a plasmid from the surrounding solution.
True or False? Comparison of the sequences of the same gene across species can give some insight into the existence of a common ancestor with that gene.
True DNA sequence comparisons are a powerful tool by which to estimate how closely related different species are along the evolutionary timeline.
True or false? The term "sticky ends" refers to the overhanging ends on DNA that are generated by restriction enzymes, which can base pair with any DNA molecules that contain complementary sticky ends.
True Restriction enzymes cut DNA and generate "sticky ends" which can then base pair with DNA molecules that contain the same sticky ends.
Sort the four bacterial classes into different categories based on the medium in which they will grow. Given: A) Bacteria with no plasmid (transformation did not occur) B) Transformed bacteria containing a nonrecombinant plasmid C) Transformed bacteria containing a recombinant plasmid without the vgp gene D) Transformed bacteria containing a recombinant plasmid with the vgp gene Based on the categories: ~Will grow only in medium without ampicillin ~Will grow only in medium containing ampicillin ~Will grow in both media
Will grow in both media: B) Transformed bacteria containing a nonrecombinant plasmid C) Transformed bacteria containing a recombinant plasmid without the vgp gene D) Transformed bacteria containing a recombinant plasmid with the vgp gene Will grow only in medium without ampicillin: A) Bacteria with no plasmid (transformation did not occur) Only bacteria that were transformed (picked up a plasmid) can grow in a medium containing ampicillin. Each transformed bacterium reproduces, forming a clone of cells. The complete set of clones is called a plasmid library. Some clones in the library will have recombinant plasmids, some have recombinant plasmids without the vgp gene, and a small fraction have recombinant plasmids with the vgp gene.
cloning vector
a carrier used to clone a gene and transfer it from one organism to another
plasmid
a small cellular inclusion consisting of a ring of DNA that is not in a chromosome but is capable of autonomous replication
PCR
a technique used to create multiple copies of a piece of DNA
sticky end
an end of DNA in which one strand of the double helix extends a few units beyond the other
stem cell
an undifferentiated cell whose daughter cells may differentiate into other cell types (such as blood cells)
northern blotting
combines gel electrophoresis of mRNA followed by hybridization with a probe on a membrane
genomic library
complete collection of cloned DNA fragments from an organism
RFLPs
differences in homologous DNA sequences that are reflected in different lengths of restriction fragments produced when the DNA is cut up with restriction enzymes
nucleic acid probe
radioactively labeled nucleic acid molecule used to tag a particular DNA sequence
microarray
shows which genes are being actively transcribed in a sample from a cell
cDNA
single-stranded DNA that is complementary to messenger RNA or DNA that has been synthesized from messenger RNA by reverse transcriptase
restriction fragment
the fragment of DNA that is produced by cleaving DNA with a restriction enzyme
restriction site
the specific sites at which a restriction enzyme will cleave DNA
genetic engineering
the transfer of a gene from the DNA of one organism into another organism, in order to produce an organism with desired traits
in situ hybridization
uses fluorescent dyes attached to probes to identify location of specific mRNAs in place in intact organism
southern blotting
A hybridization technique that enables researchers to determine the presence of certain nucleotide sequences in a sample of DNA.