Name:
Biology
Date:
Quiz Prep: Chp 13 – Frontiers of Genetics
1.
What is DNA technology? Explain 3 ways scientists study or manipulate DNA.
Manipulating genomes of organisms at the molecular level in order to use the organisms to perform practical
tasks for humans.
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Sequencing genomes of rice to make it a more nutritious food source
Apply research on genes in simpler organisms to humans when genes are similar (learn how a gene
works by studying its counterpart in another organism)
Gene cloning – inserting desired gene into a bacterial plasmid and using bacteria as a means of copying
the DNA every time they replicate
GMOs – adding genes to an organism to create a desired trait, such as fish that grow larger or plants
that can tolerate colder temperatures.
2. What is a restriction enzyme? Why would different restriction enzymes cut the same DNA molecule into
different numbers of fragments?
“molecular scissors” – cut DNA at a specific restriction site. Each restriction enzyme cuts at a different
restriction site, so different restriction enzymes will cut a given piece of DNA at different places and may also cut
a different amount of times.
3. In the space below, draw two sketches. Show what happens when a restriction enzyme leaves “blunt ends”
and show what happens when a restriction enzyme leaves sticky ends. Label the restriction sites in each
sketch and identify which situation is preferable for genetic engineering and why.
Blunt Ends
No unpaired bases
Sticky Ends
Unpaired bases = sticky ends
Sticky ends are necessary for genetic engineering because they provide an
attachment site for gene being added.
4. What does gel electrophoresis allow scientists to do? How does the process work?
Technique that sorts molecules or fragments of molecules by length.
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DNA is cleaved into fragments with restriction enzymes and added to wells of agarose gel.
Gel is submerged in a buffer fluid and exposed to electrical current.
Since DNA has a negative charge, it will be repelled from the negative end of the gel and attacted to
the positive.
The fragments will move through pores in the gel, with the smallest fragments moving fastest and
therefore traveling farthest.
5. What is PCR (polymerase chain reaction)? How does it work (very general).
A method of rapidly copying a specific DNA segment without using living organisms, using a series of heating &
cooling reactions.
Needed materials: DNA sample to copy, DNA polymerase & nucleotides & primers.
The sample is heated to separate original DNA strands then cooled to build complementary strands. The process
can be repeated over and over to generate a large supply of a DNA sequence in a relatively short period of time.
6. What is genetic engineering? How are recombinant DNA and plasmids related?
Genetic engineering replaces selective breeding to create desired traits in organisms through recombinant DNA technology.
The organism itself may be the desired result (more nutritious crop) or a protein product created by the organism may be
desired (insulin or human growth hormone)
The desired gene is placed into a bacterial plasmid, forming recombinant DNA (combined DNA from two sources). The
plasmid can be used as a vector (transporter) to add genes to plant or animal cells being targeted.
7. What does it mean to say a cell is differentiated? How are stem cells related?
A differentiated cell has taken on a specific role and only has the genes relevant to its role “on”. Cells that are not
differentiated are called stem cells.
8. How do operons regulate gene expression in prokaryotic cells?
Operons control whether or not genes are expressed using repressor proteins. If a repressor protein is bound to
the operator in front of genes, the genes will not be transcribed. Presence or absence of given substance (such as
lactose) dictates whether a gene will be transcribed and a protein will be translated. This prevents unnecessary
protein production to conserve cellular energy/resources.
9. What are Homeotic genes?
“master switches” that direct the development of body parts in an embryo. (Makes sure each body part is
developed in the appropriate location.)
10. What is a GMO? Give two examples of GMOs.
Genetically modified organism or a transgenic organism – has acquired one or more genes by artificial means.
Ex.
Salmon to grow larger
Melons that ripen faster.
Crops that resist bacterial or fungal infections
11. What is epigenetics? Identify the two epigenetic tags discussed and explain how they affect gene
expression.
Epigenetics studies how factors aside from DNA sequence affect our traits by influence gene expression (protein
production. The main epigenetic tags are methyl groups and acetyl groups. When a gene is highly tagged with
(epigenetic marks) methyl groups, they DNA will be more tightly wrapped around histones, harder to transcribe,
and therefore less active. When a gene is has minimal methyl groups or has acetyl groups attached, the DNA will
be coiled less tightly around the histones, allowing transcription to occur more easily and more often, making a
gene more active.