DNA TECHNOLOGY STUDY GUIDE (14.3 + CH 15)
Studying the Human Genome
Since the 1970s, techniques have been developed that allow
scientists to cut, separate, and r
eplicate DNA base
base. Using these tools, scientists can
read the base sequences in DNA from any cell.
cut DNA into smaller pieces, called restriction fragments, which are
several hundred bases in length. Each restriction enzyme cu
ts DNA at
a different sequence
sized DNA fragments by placing them at one end
of a porous gel, then applying an electrical voltage. The e
lectrical charge moves the DNA.
labeled nucleotides, scie
ntists can stop replication at any point along a single
DNA strand. The fragments can then be separated by size using gel electrophoresis and
The Human Genome Project
was a 13
year international effort to sequence all 3
pairs in human DNA and identify all human genes. The
project was completed in
They used “shotgun sequencing,” which uses a comput
er to match DNA base sequences.
The Human Genome Project identified genes associated with many diseases and
From the project came the new science of
, the creation and use
of databases and other computing tools to manage data. Bioinformatics launched
, the study of whole genomes.
The human genome project pinpointed genes and associated par
ticular sequences in those
genes with numerous diseases and disorders. It also found that the DNA of all humans
base at most sites, b
ut can vary at 3 million sites.
The 1000 Genomes Project, launched in 2008, will catalogue t
For Questions 1
4, write True if the statement is true. If the statement is false, change
the underlined word to make the statement true.
Bacteria produce restriction enzymes that cut the
molecule into smal
Restriction fragments are always cut at a particular sequence of
The technique that separates differently sized DNA fragments is
The enzyme that copies DNA is DNA
Complete the graphic organizer to summarize the steps used to determine the sequences
of bases in DNA.
Tool or Technique Used
Large molecule of DNA is cut into
Smaller DNA fragments move
faster on the gel, so fragments are
separated by size
and gel electrophoresis
Labeled nucleotides stop the
synthesis of a new strand at
different lengths. Gel
phoresis then separates
them so they can be read
For Questions 6
10, complete each statement by writing in the correct word or words.
By using tools that cut, separate, and then replicate DNA, scientists can now read the
sequence in DNA from any
Restriction enzymes cut pieces of DNA sometimes called restriction
Each restriction enzyme cuts DNA at a different sequence of
The smaller the DNA, the
and farther it moves during gel electrophoresis.
After chemically dyed bases have been incorporated into a DNA strand, the order of
on the gel reveals the
exact sequence of bases in DNA.
The Human Genome Project
What were the goa
ls of the Human Genome Project?
To sequence the base pa
irs of DNA to identify all human genes
, humans choose organisms with
to produce the next generation.
This takes advantage of
natural variation among organisms and pas
ses wanted traits to
The numerous breeds of dogs and varieties of crop plants and domestic animals are
examples of selective breeding.
crosses dissimilar individuals to bring together the b
est of both parents in the
is the continued breeding of individuals with selected characteristics. It
ensures that wanted traits are preserved, but can also res
ult in defects being passed on.
Mutations are the so
urce of biological diversity. Breeders
introduce mutations into populations to increase genetic variation.
application of a technological process, invention, or method to living organisms. Selective
s one example of biotechno
Radiation and chemicals can increase the mutation rate. Diverse bacterial strains hav
been bred from mutated lines.
Drugs can prevent the separation of chromosomes during mitosis, leading to polyploidy in
plants. Such plants may be larger or stron
r than their diploid relatives.
For Questions 1
5, write True if the statement is true. If the statement is false,
change the underlined word or words to make the statement true.
works because of the natu
ral genetic variation in a
individuals to bring together the best of both.
The individuals produced by crossing dissimilar parents are
The continued cros
sing of individuals with similar characteristics is
the risk of genetic defects.
Complete the table describing the types of selective breeding.
Crossing dissimilar individuals
to bring together the best of
Burbank potatoes that
are disease resistant
The continued breeding of
individuals with similar
Genetic engineers can transfer a gene from one organism to another to
achieve a goal, but first, individual genes must be identified and separated from DNA. The
original method (used by Douglas P
rasher) involved several steps:
amino acid sequence in a
he mRNA code for that sequence.
Use a complementary base sequence
to attract the predicted mRNA.
Find the DNA f
ragment that binds to the mRNA.
Once scientists find a gene, they can use a technique called the
polymerase chain reaction
make many copies.
rates the DNA into two strands.
As the DNA cools, primers are added t
o opposite ends of the strands.
DNA polymerase adds nucleotides between the primers, producing two complementary
he process can be re
peated as many times as needed.
molecules contain DNA from two different sources.
DNA technology can change the genetic c
omposition of living organisms.
are circular DNA molecules fou
nd in bacteria and yeasts; they are widely used
by scientists studying recombinant DNA, because DNA joined
to a plasmid can be
is a gene that is used to differentiate a cell that carries a recombinant
plasmid from those th
at do not.
organisms contain genes from other species. They
result from the insertion of recombinant DNA into the genome of the host organism. A
is a member of a population
of genetically identical cells.
For Questions 1
5, complete each statement by writing in the correct word or words.
Genetic engineers can transfer
from one organism to another.
As a first step toward finding a gene, Douglas Prasher studied the
of part of
Prasher next found the
nce that coded for the protein.
Using the technique of
, Prasher matched the mRNA to a DNA
fragment that contained the gene for GFP.
Southern blot analysis uses
to bind to fragments with complementary
Make a sketch to show the steps in the polymerase chain reaction
(PCR) method of copying genes.
Label each part of your sketch.
For Questions 7
10, write the letter of the correct answer on the line at the left.
Why is DNA ligase so important in recombinant DNA technology?
It causes DNA to make
multiple copies of itself.
It joins two DNA fragments together.
It shapes bacterial DNA into a circular plasmid.
DNA into restriction fragments.
A recombinant plasmid can be used to
vent nondisjunction at meiosis.
the number of chromosomes in a plant cell.
cut DNA into restriction fragments.
transform a bacterium.
What do genetic engineers use to create the “sticky ends” needed to splice two
fragments of DNA together?
an amino acid sequence
Give a reason why a plas
mid is useful for DNA transfer.
It has a DNA sequence that helps promote plasmid replication, helping to ensure
that the foreign DNA will be replicated
Complete the flowchart about how a transgenic plant is produced, using
can cause tumors in plants. The part of the DNA that
causes tumors is deactiv
ated and replaced with
bacteria are placed in a dish with plant cells. The
bacteria infect the plant cells.
Inside a plant cell,
inserts part of its DNA into the host cell
complete or new plan
is generated from the transformed cell.
What is a transgenic organism?
An organism that contains genes from other species
What can happen when DNA is injected into the
ucleus of an animal’s egg cell?
Enzymes that are normally responsible for repair and recombination may help insert the foreign
DNA into the chromosomes of the injected cell.
How is a DNA molecule constructed so that it will eliminate a particula
The DNA molecule is constructed with two ends that will sometimes recombine with specific
sequences in the host chromosomes. The host gene between the two sequences may then be lost or
replaced with a new gene.
What is a clone?
a member of a population of genetically identical cells produced from a single cell
What kinds of mammals ha
ve been cloned in recent years?
Sheep, cows, pigs, mice, and cats have been cloned
For Questions 17
, write True if the statement is
true. If the statement is false, change the
underlined word to make the statement true.
An organism that contains one or more genes from another species is
Transgenic organisms can be made by inserting recombinant DNA
of the host organism.
Examining the properties of a transgenic organism allows scientists to discover
the function of the transferred
Plant cells will sometimes take up DNA on their own if their
Carefully designed DNA molecules can achieve gene
On the lines below, write
next to an example of a transgenic organism, and
next to an example
of a clone.
A goat that produces spider’s silk in its milk
A plant that is grown from a cell into which
A lamb that is born with the same DNA as a donor cell
A colony of bacteria that grows from one bacterium
that can pr
oduce human insulin
Complete the sentences in the diagram below to show the steps in
Applications of Genetic Engineering
Genetic engineers work to improve the products
we get from plants and
Genetically modified crops may be more nutritious or higher yielding. They may be resistant to
insects, diseases, or spoil
age. Some can produce plastics.
modified animals may produce more milk, have leaner meat, or contain higher levels of
nutritious compounds. Transgenic salmon grow rapidly in captivity. Transgenic goats pro
silk in their milk.
Health and Medicine
Recombinant DNA studies are l
eading to advances in the preve
treatment of disease.
Examples include vitamin
rich rice, human proteins made in animals, animal models of human disease
(for research), and bacte
ria that produce human insulin.
is the process of chan
ging a gene to treat a disorder. However, gene therapy is still an
mental and high
Genetic testing can identify h
undreds of inherited disorders.
Not all genes are active in every cell.
technology lets scientists study
thousands of genes
at once to
determine their activity level.
analyzes sections of DNA that may have little or
no function but that vary
from one individual to another.
DNA fingerprinting is used in
e scientific study of crime
criminals. It is also used to identify the biological father
when paternity is in question.
Common ancestry can sometimes be determined using mitochondrial DNA (mt
DNA) and Y
iculture and Industry
Give two examples of how genetically modified organisms lead to more environmentally f
Some GM crops do not need pesticide
Some GM pigs have leaner meat
Name two other benefits that may be
gained from gene
tically engineering food crops.
Less expensive food
Crops resistant to insects, disease, or spoilage
Give two examples of how DNA modification has increased the importance of transge
nic animals to
our food supply.
DNA techniques increase milk production in cows
Transgenic salmon grow faster than wild salmon
Complete the flowchart about how DNA fingerprints are made.
are used to cut the DNA into fragment
containing genes and repeats.
The restriction fragments are separated according to size using gel
The DNA fragments containing repeats are then labeled using
. This labeling produces a serie
the DNA fingerprint.
Study the DNA fingerprint below. Which two samp
les may be from a set of id
entical twins? How do
Samples 1 and 4 may be from identical twins because thy are exactly the same