18. Biotechnology

Introduction to DNA-Based Technology

DNA cloning and recombinant DNA | Biomolecules | MCAT | Khan Academy

it allows a cell to recognize fragments produced by the enzyme

the single-stranded ends serve as starting points for DNA replication

No. Different restriction enzymes produce fragments with different sticky ends, which are unlikely to have the appropriate sequence for the initiation of DNA replication.

it enables researchers to use the fragments as introns

No. Introns are segments of eukaryotic genes that are spliced out of mRNA.

only single-stranded DNA segments can code for proteins

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

These single-stranded ends consist of unpaired nucleotides.

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 __________.

Short Video: Transgenic Mice

No. This would not tell you anything about the gene expression.

Isolating and analyzing all the proteins from each type of tissue

No. This would provide much relevant information, but not as quickly as one of the other choices.

No. The polymerase chain reaction is used to amplify specific segments of DNA, not to study gene expression.

No. This is a technique for expression of eukaryotic genes in bacterial cells.

Consider the end product of each of these techniques.

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?

No. Probes would probably be used for locating certain nucleotide sequences, but there is a better answer.

No. DNA ligase undoubtedly would be used in making recombinant DNA, but there is a better answer.

No. Plasmids would probably be used as gene vectors, but there is a better answer.

No. Restriction enzymes would probably be used in isolating the desired genes and preparing recombinant DNA, but there is a better answer.

Think about the recombination process needed to produce this "superbacterium."

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?

are single base-pair variations in the genomes of the human population

No. This is true, but there is a better answer.

are genetic markers used to study the genetic basis for disease

No. Although this is true, there is a better answer.

are small nucleotide differences among individuals located in coding and noncoding sequences in the genome

can be the molecular basis for different alleles

Consider the meaning of polymorphism."

Single nucleotide polymorphisms (SNPs) __________.

allowing individuals to follow the natural progression of a genetic disorder, accompanied by psychological counseling and then drug treatment when the condition becomes life-threatening

No. This is not the goal of gene therapy.

No. Gene therapy raises many serious ethical issues.

replacing organs affected with genetic disorders by transplants

No. Gene therapy involves replacing genes, not organs.

No. Only one of the other choices is correct.

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

Review the techniques of gene therapy.

Gene therapy involves __________.

the inserted ("foreign") gene is drawn from the human genome

No. Humans are not the only organisms with commercially useful genes.

No. Transgenic plants and animals are useful for agriculture, medicine, and basic research.

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

Getting a gene into another organism's genome is only part of the battle.

Transgenic organisms can be scientifically or commercially useful only if __________.

Contrast technology with science. Give an example of each to illustrate the difference.<img src="https://lightcat-files.s3.amazonaws.com/problem_images/0a7df28604b4fd96-1671986665070.jpg" alt="" />

a technique for finding a gene of interest within a nucleus without destroying the cell

No. Sticky ends are found at the end of certain DNA molecules.

the ability of plasmids to stick to a bacterial cell wall and thus be taken up into the bacterium

the site on mRNA that sticks to the DNA during transcription

No. Sticky ends are products of restriction enzymes.

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

Consider how sticky ends are formed and their role in recombinant DNA technology.

In genetic engineering, sticky end refers to __________.

Plants are more readily manipulated by genetic engineering than are animals because
a. plant genes do not contain introns.
b. more vectors are available for transferring recombinant DNA into plant cells.
c. a somatic plant cell can often give rise to a complete plant.
d. plant cells have larger nuclei.

inserting a sperm cell into an egg cell in vitro

No. This is in vitro fertilization.

placing the nucleus from an egg cell into an enucleated somatic cell

No. This procedure is unlikely to produce anything.

the use of microarray analysis and RNA interference

No. Neither of these techniques is involved in nuclear transplantation.

the use of reverse transcriptase to make copies of the genes that are being expressed

No. Although improper gene expression appears to be a problem in clones, reverse transcriptase is not used in nuclear transplantation.

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

Think about haploid and diploid cells.

Nuclear transplantation involves __________.

“Bt maize”
a. is resistant to various herbicides, making it practical to weed rice fields with those herbicides.
b. contains transgenes that increase vitamin A content.
c. includes bacterial genes that produce a toxin that reduces damage from insect pests.
d. is a “boron (B)-tolerant” transgenic variety of maize.

Gurdon found no correlation between the age of the donor cells and the ability of the transplanted nucleus to direct development.

No. Gurdon found that nuclei from older donor cells were unlikely to correctly direct differentiation.

Gurdon found that nuclei from older donor cells were more likely to correctly direct differentiation and give rise to healthy tadpoles.

Gurdon found a positive correlation between the age of the donor nuclei and the ability of the nuclei to direct differentiation.

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

Does the age of the donor matter in cloning?

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?

A bacterium that has been treated with a compound that affects the expression of many of its genes

No. Transgenic refers to the origin of the genes in the genome, not their expression.

A human treated with insulin produced by E. coli bacteria

No. The human has not received a gene from the bacteria but has received the product of a human gene.

A fern grown in cell culture from a single fern root cell

No. Such a fern would be considered a clone.

No. Only one of the other answers is correct.

What does the prefix "trans-" mean?

Which of the following would be considered a transgenic organism?

Today, it is fairly easy to make transgenic plants and animals. What are some important safety and ethical issues raised by this use of recombinant DNA technology? What are some of the possible dangers of introducing genetically engineered organisms into the environment? What are some reasons for and against leaving decisions in these areas to scientists? To business owners and executives? What are some reasons for and against more public involvement? How might these decisions affect you? How do you think these decisions should be made?

Biotechnology: Crash Course History of Science #40

that the same gene can have very different functions in different types of animals

No. Whether in a vertebrate or an insect, the Pax-6 gene triggers the genetic program that leads to eye formation.

that some coding genes have products other than proteins in different types of animals

No. All coding genes have protein products.

that the mechanisms of gene expression vary among different animal groups

No. Recombinant DNA technology is founded on the fact that the mechanisms of gene expression have deep evolutionary roots and are shared among all living things.

that a gene that plays a major role in the development of one type of organism often has a reduced role in another

No. The Pax-6 gene plays an important and similar role in the eye development of different animals.

the common ancestry in the evolution of these animal groups

Some genes are conserved over time as switches for specific genetic programs.

The expression of the Pax-6 gene when vertebrate and fruit fly versions of the gene are exchanged between these animal groups illustrates __________.

Map of DNA-Based Technology Lesson

the enzyme that cuts DNA into restriction fragments

No. Vectors are not enzymes. DNA polymerase is not required for making recombinant DNA.

a DNA probe used to locate a particular gene

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

A mosquito is considered a vector in infectious diseases because it brings the infectious agent to a person.

In recombinant DNA technology, the term vector refers to __________.

use of genome-wide association studies to identify single-nucleotide polymorphisms (SNPs) linked to disease

No. This statement is true. The genomes of individuals can be screened for the presence of a SNP that is associated with an abnormal allele and can be correlated with increased risk of conditions such as heart disease, Alzheimer's, or different types of cancer.

use of microarray assays to analyze the expression patterns of genes associated with a type of cancer

No. This statement is true. Microarray assays allow researchers to observe gene expression patterns occurring in normal and cancerous tissues.

use of retroviruses to introduce normal alleles of genes into diseased cells for disorders involving one defective gene

No. This statement is true. Gene therapy using retroviruses as vectors to ferry normal alleles into the stem cells producing diseased somatic cells offers great potential to treat a small number of disorders caused by one defective gene, such as severe combined immunodeficiency and cystic fibrosis.

genetically engineering organisms, from bacteria to goats, into protein factories that produce vital human proteins such as insulin, anticlotting agents, and human growth hormone

No. This statement is true. Human genes are routinely cloned in bacterial cells or animals (transgenic) that can function as gene expression systems for the large-scale production of human protein, which can be isolated and purified to pharmaceutical standards.

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

What is currently an obstacle to therapeutic cloning?

All of the following are current applications of DNA technology in medicine except __________.

SCIENTIFIC THINKING Scientists investigate hypotheses using a variety of methods, depending on the circumstances behind the research. Human nutrition studies (such as those studying whether GMO foods have any health effects) are particularly problematic. Can you design a hypothetical human nutrition study to test whether GMO corn is less healthy than traditional corn? Can you identify real-world problems that may interfere with your design and confound your results?

A gene that makes the husk of the corn too tough for insects to penetrate

No. Bt maize contains genes from Bacillus thuringiensis that encode for a protein that causes plant cells to release a protoxin. The protoxin is activated into a harmful toxin in the guts of insects.

A gene that causes the plants to emit a substance that is toxic to weeds

A gene that reduces the amount of water the plants need to grow

A gene that increases the level of vitamin A found in maize

A gene that causes the plants to produce a chemical that becomes toxic within insect guts

Bt maize is a transgenic organism.

What does the "Bt" in Bt maize refer to?

No. Asexual reproduction by cuttings also produces clones.

Generate variability in a population that can be subject to artificial selection

No. Sexual reproduction, particularly open pollination, provides variability for breeders.

Introduce genes into a crop from a related species

No. Some crops hybridize naturally, and others, such as triticale, can be hybridized using cross-pollination.

All of the listed responses can be performed by traditional methods.

No. DNA from nonplants can be introduced into a plant only by using genetic engineering.

The question is what can be done, not how fast or how easily.

Which of the following can be done by using biotechnology but cannot be done using traditional agricultural breeding practices?

HHMI BioInteractive: Microarrays

No. Reverse transcriptase catalyzes the formation of a strand of DNA that is complementary to a strand of RNA.

No. cDNA formation is catalyzed by reverse transcriptase.

No. Ligases catalyze the formation of phosphodiester bonds.

Review the enzymes used in recombinant DNA technology.

An enzyme that cuts DNA at a symmetrical sequence of bases is called __________.

a genetically modified crop from one country were transplanted to another country

No. Transgene escape refers to the transfer of a genetically modified gene from the transformed plant to a neighboring plant, particularly related weedy plants.

a genetically modified crop is allowed to freely self-pollinate

terminator genes also are inserted into a genetically modified crop

a genetically modified crop is hybridized with a local weed

Review some of the concerns about genetic engineering and genetically modified crops.

Transgene escape would occur if __________.

iPS cell technology may provide a more morally acceptable approach to therapeutic cloning

No. This statement is true. Embryonic stem cells have been researchers' stem cells of choice for therapeutic cloning applications because of their pluripotency, but their use has drawn public consternation regarding the morality of using human embryos for scientific endeavors.

the reprogramming of diseased cells in humans to form iPS cells could provide model systems for studying the origins of the disease

iPS cell technology could offer the potential to regenerate nonfunctional or diseased tissues and avoid the risk of transplant rejection in the diseased patient

No. This statement is true. Because the patient's own cells would be reprogrammed into iPS cells to grow the new tissues to replace the diseased ones, the patient's immune system will not reject them upon transplantation.

iPS cells are formed by added genes to the genome of differentiated skin cells

No. This statement is true. Researchers used retroviruses to introduce extra cloned copies of four "stem cell" master regulatory genes into differentiated skin cells, thereby increasing the size of their genome and creating something akin to embryonic stem cells.

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

Is the reprogramming of differentiated cells into stem cells "bug-free"?

All of the following are true regarding induced pluripotent stem (iPS) cells except __________.

What is Biotechnology

Which of the following is not part of the procedure used to make a DNA profile?
a. Short tandem repeat sequences are amplified by PCR;
b. DNA is placed in a gel and subjected to an electric current;
c. The genes that encode DNA sequence are cloned into bacteria;
d. DNA from blood, semen, vaginal fluids, or hair root cells can be used for analysis.

HHMI BioInteractive: Bioinformatics

HHMI BioInteractive: Shotgun Sequencing

Which of the following tools of DNA technology is incorrectly paired with its use?
a. electrophoresis—separation of DNA fragments
b. DNA ligase—cutting DNA, creating sticky ends of restriction fragments
c. DNA polymerase—polymerase chain reaction to amplify sections of DNA
d. reverse transcriptase—production of cDNA from mRNA

Changing the Blueprints of Life - Genetic Engineering: Crash Course Engineering #38

The fruits of wild species of tomato are tiny compared with the giant beefsteak tomatoes available today. This difference in fruit size is almost entirely due to the larger number of cells in the domesticated fruits. Plant biologists have recently discovered genes that are responsible for controlling cell division in tomatoes. Why would such a discovery be important to producers of other kinds of fruits and vegetables? To the study of human development and disease? To our basic understanding of biology?

a place where a restriction enzyme cuts DNA

a chart that traces the family history of a genetic trait

No. Probes are used to recognize specific nucleotide sequences.

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

Consider the meaning of the word marker.

A genetic marker is __________.

Biotechnology: Genetic Modification, Cloning, Stem Cells, and Beyond

No. This is the enzyme that is used to catalyze the formation of DNA from an RNA template.

No. Restriction enzymes cut DNA at specific recognition sites.

No. rDNA may refer to recombinant DNA or to ribosomal DNA.

No. A plasmid is a small, circular piece of bacterial DNA.

Remember that the process still depends on complementary base pairing.

DNA synthesized using an RNA template is called __________.

In the not-too-distant future, gene therapy may be an option for the treatment and cure of some inherited disorders. What do you think are the most serious ethical issues that must be dealt with before human gene therapy is used on a large scale? Why do you think these issues are important?

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