Chapter 12 Biology
restriction fragments
A DNA segment that results from the cutting of DNA by a restriction enzyme.
How does DNA profiling work?
1) DNA samples from the crime scene, suspects, and other evidence is isolated 2) Next, the selected markers from each DNA sample are amplified (copied a lot) to produce a large sample of DNA fragments 3) finally, the amplified DNA markers are compared, proving which samples match the individual DNA profiling is used for investigating murder, paternity, ancient DNA, and even evolution research!
How does a restriction enzyme work?
1) the restriction enzyme cuts the DNA strands between the particular bases within the recognition sequence, producing restriction fragments. The staggered cuts yield 2 double-stranded DNA fragments with single-stranded ends (sticky ends), which are the key to joining DNA restriction fragments originating from different sources. 2) a piece of DNA from another source is added (same restriction enzyme had to have been used on this piece so they fit) 3) the complementary ends stick together by base pairing. The union between them is made permanent by DNA ligase (pastes) 4) this enzyme, which is one of the proteins used in DNA replication, connects the DNA pieces into continuous strands by forming bonds between adjacent nucleotides. The final outcome is a single outcome of recombinant DNA
DNA profiling
A procedure that analyzes DNA fragments to determine whether they come from a specific individual.
Retrovirus
An RNA virus that reproduces by transcribing its RNA into DNA and then inserting the DNA into a cellular chromosome; an important class of cancer-causing viruses.
reverse transcriptase
An enzyme encoded by some certain viruses (retroviruses) that uses RNA as a template for DNA synthesis.
clone
An organism that is genetically identical to the organism from which it was produced
cDNA
Complementary DNA. DNA produced synthetically by reverse transcribing mRNA. Because of eukaryotic mRNA splicing, cDNA contains no introns.
Which enzyme "pastes" DNA fragments together?
DNA ligase
Describe the many ways that DNA profiling can be used in our society.
DNA profiling is used for investigating murder, paternity, ancient DNA, and even evolution research!
restriction enzymes
Enzyme that cuts DNA at a specific sequence of nucleotides; certain restriction enzymes only recognize a particular short DNA sequence (4-8 nucleotides long)
whole-genome shotgun sequencing
Method of sequencing a genome in which sequenced fragments are assembled into the correct sequence in contigs by using only the overlaps in sequence.
transgenic organism
Organisms that contain functional recombinant DNA from a different organism
the most useful method for initially increasing the amount of dodo DNA available testing is
PCR
Explain how recombinant DNA techniques are used to mass-produce a protein from an isolated gene; such as Humulin, human growth hormone, erythropoietin.
PCR can mass clone DNA
gel electrophoresis
Procedure used to separate and analyze DNA fragments by placing a mixture of DNA fragments at one end of a porous gel and applying an electrical voltage to the gel, method for sorting macromolecules by electrical charge and size. A DNA sample from each source is placed in a separate well, and a neg. charged electrode is attached to the DNA end of the gel, and pos. electrode to the other side. The phosphate's neg. charge in the DNA makes it run towards positivity. Bigger fragments move more slowly than shorter fragments
nucleic acid probe
Radioactively labeled nucleic acid molecule used to tag a particular DNA sequence.
Explain how recombinant DNA technology can be used to produce useful products.
Recombinant DNA can create many important proteins via cloning DNA that humans can't by themselves, hence curing many diseases
genetic engineering
The direct manipulation of genes for practical purposes.
Describe the goals of the Human Genome Project. Explain why our genome presents a major challenge.
The main goals of the Human Genome Project were to provide a complete and accurate sequence of the 3 billion DNA base pairs that make up the human genome and to find all of the estimated 20,000 to 25,000 human genes. The Project also aimed to sequence the genomes of several other organisms that are important to medical research, such as the mouse and the fruit fly. The human genome is reapply changing and is extremely vast.
biotechnology
The manipulation of living organisms or their components to produce useful products.
how to use recombinant DNA techniques to produce important proteins on a large scale
To start: the biologist isolates 2 kinds of DNA: plasmid & organism DNA process: 1) bacterial plasmids that will serve as vectors (gene carriers) 2) DNA from another organism that includes the gene of interest, along with other genes. This other DNA may be from any type of organism, even a human. 3) the researcher uses an enzyme to cut the two kinds of DNA. Each plasmid is cut in only one place; the other DNA is cut into many fragments, one of which carries the gene of interest. 4) the other DNA fragments are mixed with the cut plasmids. The two kinds of DNA join together, resulting in recombinant DNA plasmids, some of which contain the gene of interest 5) the recombinant plasmids are then mixed with bacteria. Under the right conditions, the bacteria take up the recombinant plasmids. 6) each bacterium, with its recombinant plasmid, is allowed. to reproduce. This step is the actual gene cloning. As the bacterium forms a clone, any genes carried by the recombinant plasmid are also copied. 7) the biologist finds the few bacterial clones that contain the gene of interest 8) the transgenic bacteria with this gene can then be grown in large tanks, producing the protein in marketable quantities, which can be inserted into organisms or harvested proteins may be used directly
7. What feature of a DNA fragment causes it to move through a gel during electrophoresis?
a
genomic library
a collection of cloned DNA fragments that includes an organism's entire genome
The Human Genome Project
a massive scientific endeavor to determine the nucleotide sequence of all the DNA in the human genome, could potentially help cure many diseases
human gene therapy
a recombinant DNA procedure intended to treat disease by altering an afflicted person's genes. One approach to it: 1) a gene from a normal ind. is isolated and cloned by recombinant DNA techniques 2) the gene is inserted into a vector, such as a harmless virus 3)the virus is injected into the patient.
Human growth hormone
a synthetic version of the growth hormone that is administered to stimulate growth when the natural supply of growth hormone is insufficient for normal development
The Polymerase Chain Reaction (PCR)
a technique by which a specific segment of a DNA molecule can be targeted and quickly amplified in the laboratory. A DNA sample is mixed with nucleotides, DNA polymerase, and a few other ingredients. The solution is then exposed to cycles of heating (to separate DNA strands), and cooling (to allow double-stranded DNA to re-form). During these cycles, specific regions of each molecule of DNA are replicated , doubling the amount of that DNA. The key to automated PCR is DNA polymerase (heat stable), and can help generated hundreds of billions of copies in a few hours
8. After a gel electrophoresis is run, the pattern of bars in the gel shows:
b
Why is an artificial gene that is made using reverse transcriptase often shorter than the natural form of the gene?
because it does not contain introns
put the following steps of human gene therapy in the correct order
c. b. a. d.
suppose you wish to create a large batch of the protein lactase using recombinant DNA. Place the following steps in order you'll perform them
c. isolate gene for lactase d. create recombinant plasmids b. insert plasmids into bacteria a. find the clone with gene for lactase
9. name the steps of the whole-genome shotgun method
chop the genome into fragments, clone and sequence each fragment, and reassemble the short sequences into a continuous sequence for every chromosome
Which of the following choices best defines "recombinant DNA technology"?
combining genes from different species
DNA profiling, a forensic procedure now being utilized to identify individuals, __________________.
compares the DNA banding patterns in small segments of chromosomes
why do DNA fragments containing STR sites from different people to migrate to different locations during gel electrophoresis?
different. people have different numbers of repeats at each STR site, so they will have different lengths
vaccine
harmless variant or derivative of a disease-causing microbe that is used to prevent an infectious disease. One approach to vaccine production is to use genetically engineered years cells to make large amounts of a protein found on the microbe's outer surface
Recombinant DNA technology has provided a mechanism for nonhuman cells to produce
human proteins
Which of these pairs would have exactly the same DNA restriction fragments?
identical twins
DNA profiling determines ____________________
if two samples of DNA are from the same person
humulin
in humans, insulin is a protein made by the pancreas. Functioning as a hormone, insulin helps regulate the level of glucose in the blood. If the body fails to produce enough insulin, the result is type 1 diabetes. There is no cure, so people with this disease must inject themselves with daily doses of insulin for the rest of their lives. Since human insulin is not readily available, diabetes was historically treated using cow and pig insulin. This treatment was not without problems, however. Pig and cow insulins can cause allergic reactions because of the difference in chemical structure. In 1978, scientists chemically synthesized two genes, one for each of the polypeptides of the active forms of human insulin. Since the amino acid sequences of the two insulin polypeptides were already known, it was easy to use the genetic code to determine nucleotide sequences that would encode for them to form the insulin genes.
how common is GMO food?
in the U.S. today, roughly half the corn crop and over three-quarters of the soybean and cotton crops are genetically modified. Corn is genetically engineered to resist attack by an insect known as the European corn borer. growing plants that are resistant to insects by genetic engineering reduces the need for chemical pesticides.
how powerful is DNA technology?
it may eventually replace traditional animal breeding. recombinant DNA technology serves many roles today and in the future
The polymerase chain reaction (PCR) is a useful technique because it can ___________.
make a large amount of DNA from a tiny amount
repetitive DNA
makes up much of the DNA that lies between genes in humans, consists of nucleotide sequences that are present in multiple copies in the genome
DNA technology
methods used to study and/or manipulate DNA, including recombinant DNA technology
genetically modified organisms
organisms that have acquired one or more genes by artificial means
genetic markers
particular stretches of DNA that are variable among individuals
The term "restriction fragments" refers to _________.
pieces of DNA that have been cut into different lengths
How to obtain gene of interest
possible option: send a complementary molecule labeled with radioisotope and see where it pairs. another option: synthesize the gene of interest. use reverse. transcriptase: 1) a eukaryotic cell transcribes the gene of interest 2) process the transcript, removing introns and splicing exons together to produce mRNA. 3) researcher isolates mRNA in a test tube 4) makes single-stranded DNA from it using reverse transcriptase 5: DNA polymerase is then used to synthesize a second DNA strand OR synthesize gene from scratch using automated DNA-synthesizing machines, which can accurately and rapidly produce customized DNA molecules of any sequence
Human insulin is produced in large quantities by
recombinant E. Coli bacteria grown in large fermentation vats
RFLP analysis
restriction fragment length polymorphism; the method for preparing a DNA fingerprint. DNA molecules to be compared are exposed to a restriction enzyme. Resulting restriction fragments are separated and made visible on a gel.
recombinant DNA
results when scientists combine nucleotide sequences from two different sources (usually from different species)
short tandem repeats (STRs)
sections of a chromosome in which DNA sequences are repeated, more likely to match in relatives. Method of DNA profiling that compares lengths of STR sequences at certain sites in the genome.
Electrophoresis is used to ___________.
separate fragments of DNA
plasmids
small circular DNA molecules that replicate separately from the bacterial chromosome, used often to manipulate genes in the lab. They can carry virtually any gene and are passed on from one generation of bacteria to the next.
in making recombinant DNA, what is the benefit of using a restriction enzyme that cuts DNA in a staggered fashion?
sticky ends
proteomics
study of the structure and function of proteins in the human body
genomics
study of whole genomes, including genes and their functions
Transgenic
term used to refer to an organism that contains genes from other organisms
DNA 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.
the baby's.... Sam's or Becky's
DNA profiles used as evidence in a murder trial look something like supermarket bar codes. The pattern of bars in a DNA profile shows ______________.
the presence of various-size fragments of DNA
gene cloning
the production of multiple identical copies of a gene-carrying piece of DNA. Gene cloning methods are central to the production of useful products from GMOs.
Explain how restriction enzymes and DNA ligase are used to create recombinant DNA.
the restriction enzyme cuts the DNA, leaving sticky ends for another segment of DNA cut by the same enzyme, and DNA ligase seals up the bonds
forensics
the scientific analysis of evidence for crime scene investigations and other legal proceedings
Explain how the polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and gel electrophoresis are used in the process of DNA profiling.
they can all compare two samples of DNA
Genetic engineers often insert genetic markers into plasmids containing genes of interest so that ______________.
they will know which bacteria have taken up the plasmid
a carrier that moves DNA from one cell to another, such as a plasmid is called a
vector
