20 Practice Test

What is an advantage to using a bacterial artificial chromosome (BAC) for generating a genomic library compared to a plasmid or phage that has historically been used for this process? (eText Concept 20.1)

-BACs carry DNA fragments much larger than plasmids or phages and greatly minimize the number of clones needed to make up the genomic library. -The use of BACs reduces the frequency with which specific genes will be cut within the coding region by restriction enzymes and divided up among two or more clones.

Single nucleotide polymorphisms (SNPs) _____. (eText Concept 20.2)

-are single base-pair variations in the genomes of the human population -are genetic markers used to study the genetic basis for disease -are small nucleotide differences among individuals located in coding and non-coding sequences in the genome -can be the molecular basis for different alleles

Separating DNA fragments by gel electrophoresis is useful for which of the following? (eText Concept 20.2)

-identifying DNA fragments for RFLP analysis -purifying specific DNA fragments -distinguishing between different alleles of a gene -identifying a plasmid or a virus by examining its restriction fragment pattern

Gene cloning is crucial to any application involving one gene because _____. (eText Concept 20.1)

-naturally occurring DNA molecules are very long and contain many genes -it provides a means to produce large quantities of its protein product -genes occupy only a small proportion of the chromosomal DNA in eukaryotes, the rest being noncoding nucleotide sequences -it provides a means to produce many copies of a gene in short period of time

A scientist wishing to create an organism capable of breaking down several kinds of toxic waste combines genes from several species of bacteria to create a single "superbacterium." Which of the following would be needed to do this? (eText Concept 20.1)

-nucleic acid probes -DNA ligase -plasmids -restriction enzymes

To create recombinant DNA with long-term stability, it is necessary to have which of the following in the test tube? (eText Concept 20.1)

DNA ligase

Which of the following enzymes could seal a nick in one strand of a double-stranded DNA molecule by creating a sugar-phosphate bond between the adjacent, unjoined nucleotides? (eText Concept 20.1)

DNA ligase

Human nerve cells differ from human muscle cells because different sets of genes are expressed; in each type of cell, different genes are transcribed into mRNA and translated into protein. Which of the following techniques would be the most efficient way to identify the genes that these cells express? (eText Concept 20.4)

DNA microarray assays

_____ can give rise to any type of cell whereas _____ can give rise to a subset of cell types. (eText Concept 20.3)

Embryonic stem cells ... adult stem cells

Dolly, the sheep, was cloned from an adult cell. She had a number of health problems and died at a relatively young age. Three mules that were born in 2003 were cloned from fetal cells. If it turns out that the mules remain healthy and live normal lives, how would this outcome tie in with Gurdon's observations with tadpoles? (eText Concept 20.3)

Gurdon found that the ability of a transplanted nucleus to direct normal development was inversely related to the age of the donor.

Which of the following enzymes is key to the automation of PCR (polymerase chain reactions)? (eText Concept 20.1)

Taq polymerase

A molecular biologist used a retroviral vector to introduce a gene coding for a certain human enzyme into mouse cells. One cell line was isolated that was able to make the human enzyme, but it had lost the ability to express an endogenous, normally expressed gene in the process. What is the best explanation for these results? (eText Concept 20.4)

The virus inserted the gene encoding the human enzyme within the sequence of a normally expressed endogenous gene.

A genetic marker is _____. (eText Concept 20.4)

a particular nucleotide sequence at a particular locus whose inheritance can be followed

In recombinant methods, the term "vector" refers to _____. (eText Concept 20.1)

a plasmid or other agent used to transfer DNA into a living cell

Which of the following would be considered a transgenic organism? (eText Concept 20.4)

a rat with rabbit hemoglobin genes

An enzyme that cuts DNA at a symmetrical sequence of bases is called _____. (eText Concept 20.1)

a restriction enzyme

What two enzymes are needed to produce recombinant DNA? (eText Concept 20.1)

a restriction enzyme and a ligase

In which of the following would it be advantageous to create and work with a cDNA (complementary DNA) library rather than a genomic library? (eText Concept 20.1)

a study of a protein involved in eye development of a salamander and the regulation of the gene that expresses it

Southern blotting is _____. (eText Concept 20.2)

a technique used to study RFLPs

Gene therapy involves _____. (eText Concept 20.4)

adding a functioning version of a defective gene to the cells of an individual

DNA synthesized using an RNA template is called _____. (eText Concept 20.1)

cDNA

All of the following are current applications of DNA technology in medicine except _____. (eText Concept 20.3)

clinical use of iPS cells harvested from organ-impaired individuals for the culturing and transplantation of a functioning organ in the diseased individual

The efficiency of cloning, and the ability to generate healthy cloned animals, has been largely hampered by the difficulty of _____. (eText Concept 20.3)

completely reversing epigenetic alterations in donor cell nuclei such as DNA methylation and chromatin packing

Bacteria use restriction enzymes to _____. (eText Concept 20.1)

destroy foreign DNA

In the polymerase chain reaction (PCR), the sequence of bases in the primers is important because it _____. (eText Concept 20.1)

determines which segment of the genome will be amplified

Which of the following is the first step of the Southern blotting procedure? (eText Concept 20.2)

digesting the DNA with a restriction enzyme

During the process of differentiation, cells _____. (eText Concept 20.3)

express different genes in response to cell signaling

All of the following are true regarding induced pluripotent stem (iPS) cells except _____. (eText Concept 20.3)

iPS cells have been demonstrated to function identically to embryonic stems cells

A nucleic acid probe is used to _____. (eText Concept 20.1)

identify genes that have been inserted into bacterial plasmids or separated by electrophoresis

In genetic engineering, the highly active plasmid from Agrobacterium tumefaciens is used to _____. (eText Concept 20.4)

insert genes of interest into plant chromosomes

A molecular biologist has isolated a short segment of DNA that she wants to replicate in vitro. First she heats the DNA, which separates the two strands, and then she adds _____. (eText Concept 20.1)

nucleotides, primers, and polymerase

The dideoxyribonucleotide chain-termination method _____. (eText Concept 20.2)

produces a ladder of DNA fragments, with each individual band labeled with one of four different fluorescent tags

Nuclear transplantation involves _____. (eText Concept 20.3)

removing the nucleus of an egg cell and replacing it with the nucleus of a somatic cell

The term "RFLP" stands for _____. (eText Concept 20.2)

restriction fragment length polymorphism

What is the source of the reverse transcriptase used in recombinant DNA technology? (eText Concept 20.1)

retroviruses

Which arrangement of the following four enzymes represents the order in which they would be used in a typical gene-cloning experiment resulting in the insertion of a cDNA into a bacterial plasmid? Begin with the gene's mRNA transcript. (eText Concept 20.1)

reverse transcriptase, DNA polymerase, restriction enzyme, DNA ligase

In genetic engineering, "sticky end" refers to _____. (eText Concept 20.1)

short bits of single-stranded DNA left at the end of DNA molecules cut by restriction enzymes

DNA fingerprints are used to determine whether Sam could be the father of Becky's baby. Sam is not the father if _____ genetic fingerprint shows some bands not present in _____ genetic fingerprint. (eText Concept 20.4)

the baby's ... Sam's or Becky's

The expression of the PAX-6 gene when vertebrate and fruit fly versions of the gene are exchanged between these animal groups illustrates _____. (eText Concept 20.1)

the common ancestry in the evolution of these animal groups

When a typical restriction enzyme cuts a DNA molecule, the cuts are staggered so that the DNA fragments have single-stranded ends. This is important in recombinant DNA work because _____. (eText Concept 20.1)

the fragments will bond to other fragments with complementary single-stranded ends

Transgenic organisms can be scientifically or commercially useful only if _____. (eText Concept 20.4)

the inserted ("foreign") gene is expressed in the host organism

DNA fingerprints used as evidence in a murder trial look something like supermarket bar codes. The pattern of bars in a DNA fingerprint shows _____. (eText Concept 20.4)

the presence of various-sized fragments of DNA

"Therapeutic cloning" refers to _____. (eText Concept 20.3)

the use of cloned embryos as a source of stem cells that could be used to treat disease

RFLPs have been tremendously useful for genomic mapping studies because _____. (eText Concept 20.2)

they are not restricted to genes, and are abundantly scattered throughout the genome

In the polymerase chain reaction (PCR) technique, a heating phase and a cooling phase alternate. An original sample of DNA would have to pass through how many total rounds of heating and cooling before a sample is increased eight times in quantity? (eText Concept 20.1)

three

Because eukaryotic genes contain introns, they cannot be translated by bacteria, which lack RNA-splicing machinery. But if you want to engineer a bacterium to produce a eukaryotic protein, you can synthesize a gene without introns. A good way to do this is to _____. (eText Concept 20.1)

work backward from mRNA to make a version of the gene without introns