Bio 203 ch. 20 Practice Test Questions – Flashcards
Unlock all answers in this set
Unlock answersquestion
Gene cloning is crucial to any application involving one gene because __________
answer
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 a short period of time
question
The expression of the PAX-6 gene when vertebrate and fruit fly versions of the gene are exchanged between these animal groups illustrates __________.
answer
the common ancestry in the evolution of these animal groups
question
Which of the following enzymes is key to the automation of PCR (polymerase chain reactions)?
answer
taq polymerase
question
Bacteria use restriction enzymes to __________.
answer
destroy foreign DNA
question
An enzyme that cuts DNA at a symmetrical sequence of bases is called __________.
answer
a restriction enzyme
question
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
answer
he fragments will bond to other fragments with complementary single-stranded ends
question
In genetic engineering, sticky end refers to __________.
answer
short bits of single-stranded DNA left at the end of DNA molecules cut by restriction enzymes
question
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?
answer
DNA ligase
question
Which of the following is required for the production of recombinant DNA with long-term stability?
answer
DNA ligase
question
What two enzymes are needed to produce recombinant DNA?
answer
a restriction enzyme and a ligase
question
In recombinant DNA technology, the term vector refers to __________.
answer
a plasmid or other agent used to transfer DNA into a living cell
question
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
answer
reverse transcriptase, DNA polymerase, restriction enzyme, DNA ligase
question
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 for this project?
answer
nucleic acid probes DNA ligase plasmids restriction enzymes
question
The dideoxyribonucleotide chain-termination method __________.
answer
produces a ladder of DNA fragments, with each individual band labeled with one of four different fluorescent tags
question
A nucleic acid probe is used to __________
answer
identify genes that have been separated by electrophoresis, or mRNA molecules through in situ hybridization
question
What is the source of the reverse transcriptase used in recombinant DNA technology?
answer
retroviruses
question
Because eukaryotic genes contain introns, their transcripts 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 __________.
answer
work backward from mRNA to make a version of the gene without introns
question
DNA synthesized using an RNA template is called __________.
answer
cDNA
question
In the polymerase chain reaction (PCR), the sequence of bases in the primers is important because it __________.
answer
determines which segment of the genome will be amplified
question
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 __________.
answer
nucleotides, primers, and polymerase
question
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?
answer
three
question
Single nucleotide polymorphisms (SNPs) __________.
answer
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
question
The efficiency of cloning, and the ability to generate healthy cloned animals, has been largely hampered by the difficulty of __________.
answer
completely reversing epigenetic alterations in donor cell nuclei such as DNA methylation and chromatin packing
question
Therapeutic cloning refers to __________.
answer
the use of cloned embryos as a source of stem cells that could be used to treat disease
question
Nuclear transplantation involves __________.
answer
removing the nucleus of an egg cell and replacing it with the nucleus of a somatic cell
question
__________ can give rise to any type of cell whereas __________ can give rise to a subset of cell types.
answer
Embryonic stem cells ... adult stem cells
question
During the process of differentiation, cells __________.
answer
express different genes in response to developmental signals
question
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?
answer
Gurdon found that the ability of a transplanted nucleus to direct normal development was inversely related to the age of the donor.
question
All of the following are true regarding induced pluripotent stem (iPS) cells EXCEPT __________
answer
iPS cells have been demonstrated to function identically to embryonic stems cells
question
All of the following are current applications of DNA technology in medicine EXCEPT __________.
answer
clinical use of iPS cells harvested from organ-impaired individuals for the culturing and transplantation of a functioning organ in the diseased individual
question
A genetic marker is __________.
answer
a particular nucleotide sequence at a particular locus whose inheritance can be followed
question
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?
answer
DNA microarray
question
Gene therapy involves __________.
answer
adding a functioning version of a defective gene to the cells of an individual
question
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?
answer
The virus inserted the gene encoding the human enzyme within the sequence of a normally expressed endogenous gene.
question
Genetic profiles are used to determine whether Sam could be the father of Becky's baby. Sam is not the father if __________ genetic profile shows some bands not present in __________ genetic profile.
answer
the baby's ... Sam's or Becky's
question
Genetic profiles used as evidence in a murder trial look something like supermarket bar codes. The pattern of bars in a genetic profile shows __________.
answer
the presence of various-sized fragments of DNA
question
Which of the following would be considered a transgenic organism?
answer
a rat with rabbit hemoglobin genes
question
Transgenic organisms can be scientifically or commercially useful only if __________.
answer
the inserted ("foreign") gene is expressed in the host organism
question
In genetic engineering, the highly active plasmid from Agrobacterium tumefaciens is used to __________.
answer
insert genes of interest into plant chromosomes
