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13.1 Biologists have learned to
manipulate DNA
I. The beginnings of DNA
technology
A. Biotechnology is the use of
organisms to perform practical
tasks for humans
1. Much of DNA technology has come from use
of bacteria called Escherichia coli or E. coli
2. Three ways bacteria can include new DNA
Beginnings of DNA tech
a. 1940- Joshua Ledgerberg and Edward Tatum
showed two bacteria can form a tunnel-like
connection
b. Viruses can take bacteria DNA from one to
another bacteria
c. Can take up loose bacteria from surroundings
1) This occurred with Griffith’s mice
experiment with harmless strain bacteria
B. Recombinant DNA technology combines genes
from different sources – or species – into a
single DNA molecule
II. DNA technology and frontiers
of research in biology
A. Human genome- map of all humans
genes was completed by 2000
1. Other organisms sequenced: fruit fly,
yeast, E. coli, or rice plant
B. Uses
1. Improve food nutrition
2. Help us understand how our genes
work from others
13.2 Biologists can engineer
bacteria to make useful products
I. Engineering bacteria: an
introduction
A. Plasmids are small circle-shape
DNA molecule separate from
larger bacterial chromosomes
B. Plasmids can be shared between
bacteria, for example to increase
antibiotic resistance
Plasmids
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Engineering bacteria
C. Humans use plasmids to place
DNA to make useful products from
bacteria
1. Plasmid is removed and the desired gene is
placed in the plasmid  recombinant DNA
2. Recombinant plasmid is placed back in
bacteria to replicate over and over- gene
cloning
II. Cutting and pasting DNA
A. Piece of DNA is cut from desired
source by restriction enzymes
1. In nature used to defend bacteria from foreign invading
DNA
2. Restriction enzymes recognize certain sequences to cut
– eg. GATTC cuts after G
3. Usually make staggering cuts exposing a single strand
known as the “sticky end”
Restriction
Enzymes
Cutting DNA
B. DNA fragment from another source
is added
C. The fragments stick together by
base-pairing – a complementary strand
D. DNA ligase pastes the fragments
together to form recombinant DNA
molecule
III. Cloning Recombinant DNA
A. The Process of cloning recombinant
DNA
1. Restriction enzymes cuts plasmid in
one place, human DNA cut in many
places with one fragment code for
protein-V
2. Sticky ends of human DNA and
plasmid pair up by base pairing
Cloning recombinant DNA
3. DNA ligase joins plasmid and human
DNA
4. Bacterial cell takes up recombinant
plasmid
5. Many copies of recombinant bacteria
are made; when human gene expressed
protein V made
Gene
Cloning
Cloning recombinant DNA
B. Libraries of cloned genes
1. Genomic library- the complete
collection of DNA fragments from an
organism
2. The total of all recombinant
plasmids contain the entire genome of
the organism – human
Genomic Library
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Cloning recombinant DNA
C. Identifying specific genes with probes
1. How do biologist locate a specific
gene in the library?
2. Nucleic acid probe- a complementary
radioactive nucleic acid strand used to
find the desired gene sequence
3. Heat or chemicals are used to break
up DNA and probe tags the portion
needed
Nucleic Acid Probe
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13.3 Biologists can genetically
engineer plants and animals
I. Producing Genetically
Modified Plants
A. Genetically modified organism (GMO)any organism that has gotten one or more
genes by artificial means
B. Transgenic- the source of new genetic
material comes from a different species
C. Use in plants for delayed ripening,
increased nutrition, prevent spoiling or
resist diseases
D. Herbicide resistance so they survive when
fields sprayed for weeds; fungi and pest
resistance as well
Transgenic Plants
II. Producing Genetically
Modified Animals
A. More difficult than in plants – egg
and sperm are fertilized and desired
trait added to embryo
B. Use to produce more wool on sheep,
leaner meat, or mature fish in shorter
time
C. Certain human proteins produced in
animals milk for human use after
purification
III. Animal Cloning
A. Plants have been cloned from a
simple cutting of a plant
B. An empty egg and a complete nucleus
from the organism are fused together
exact copy of original organism created
C. Mass production of animals with
desired trait
Animal
Cloning
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IV. The GMO controversy
A. Possible that gene resistance passed
onto other plants through pollen
1. Academy of Science feels that GMO are not a threat
but needs to be regulated and researched
B. GM plants and animal products may
be slightly differ than original –
possible allergies or other negative
effects
13.4 DNA technologies have
many applications
I. Mass-producing DNA
A. Polymerase chain reaction (PCR)makes may copies of certain DNA
segment without living cells
B. Process
1. Targeted DNA, nucleotides, DNA
polymerase and primers are added
together
a. Primers- short strands of DNA that
pair with known targeted DNA
Mass producing DNA
2. Heat is added to separate or denature
the DNA strand
3. Mixture cools and primers bind to
strand
4. DNA polymerase adds nucleotides to
strands producing two DNA molecules
5. Procedure is repeated, 2 strands
becomes 4 becomes 8 and so on
PCR Techniques
II. Comparing DNA
A. Gel electrophoresis- sorting
molecules by or fragments by
length
B. Process
1. DNA samples cut up using restriction enzymes
2. Few drops are placed in pocket called a well at
the end of a thin gelatin-like material called gel
Comparing DNA
3. Other end is (+) charge, so the smaller
pieces of DNA (-) charge move farther
in the gel
4. Gel is stained to make DNA visible
under UV light
5. Fragments show up as bands in the
lanes
Gel Electrophoresis
Comparing DNA
C. Genetic markers
1. Used to tell different in bands between samples
2. May use radioactive DNA labels to tag genetic
markers
3. Genetic markers- specific portion of DNA
varies from individual
a. May analyze to look at recessive disease as a
carrier
Comparing DNA
D. DNA fingerprinting – unique banding
pattern on gel, determined by
restriction fragments of a person’s
DNA
1. Markers found in alleles for disease or in the introns
(noncoding) regions
2. To use DNA he genetic markers that are not shared with
others are used
3. DNA specimen from hair follicle or blood
4. 1 in 100,000 to 1 billion chance that two people have
the same number of genetic markers
13.5 Control mechanisms switch
genes on & off
I. Regulation of Genes in
Prokaryotes
A. Bacteria do not have ability to turn
genes on or off, but can change
functions based on environment
1. E. Coli makes three enzymes
in presence of milk, does not
when milk not present
Gene Regulation in Prokaryotes
B. Genetics of breaking milk sugar /
lactose into an usuable form
(Fig. 13-18)
1.Operon- cluster of genes along
with control sequence genes
a. lac operon includes two control genes and 3
genes for enzyme production are located
Regulation of genes
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Gene Regulation in Prokaryotes
2. Promoter- first control sequence
where RNA polymerase (makes
mRNA) attaches itself to DNA
3. Operator- second control gene,
like a switch, that determines if
RNA polymerase can attach to the
promoter
Lac Operon & repressor
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Gene Regulation in Prokaryotes
C. Activation or Repression of the lac operon
(Fig. 13-19)
1. Repressor- a protein that binds to the operator
and blocks the attachment of RNA polymerase
2. If lactose is absent then repressor is present and
turns off the lac operon
3. If lactose is present then it binds to the
repressor protein and changes the shape of the
repressor
Gene Regulation in Prokaryotes
a. When the repressor changes shape it no
longer binds to the operator
b. The operator is open and RNA polymerase
binds to the promoter
c. The lactose processing genes are turned on
d. When lactose is no longer present – the
repressor can rebind to the operator
D. Prokaryotes waste little energy on unnecessary
reactions due to many different operons
II. Regulation of Genes in
Eukaryotes
A. More elaborate and complicated than in
prokaryotes
B. Eukaryotic DNA includes promoter sequences
before the point that transcription takes place
C. Transcription factors- regulate transcription by
binding to promoters or RNA polymerases
D. Transcription factors are activated and
deactivated by certain chemical signals in the cell
1. Hormones may attach to transcription factors
to signal gene expression- the transcription
and translation of genes into proteins
III. From Egg to Organism
A.Gene expression begins when an egg
is fertilized and divides
1.The position of each new cell in the
embryo promotes expression of
particular groups of genes
2.Genes affecting the head are only
expressed in the “pre-head region”
3.A cell’s position relative to its
neighboring cells affects its gene
expression
Active Genes
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From Egg to Organism
B. Cellular differentiation- cells become
increasingly specialized in structure and
function
1.Glycolysis gene expressed in all cell types,
while insulin gene expressed pancreas cells
2.Hemoglobin gene would not be expressed
in eye lens, nerve cell, or pancreas cell
C. DNA chip- help biologist track which genes
are turned on in a given cel
IV. Stem Cells
A. Stem cells- cells that have the
ability to differentiate into various
types of cells
B. Blastocyst- embryo of about 100
cells, comprised mostly of stem
cells
Stem Cells
C. Most stem cells differentiate into different cell
types, yet bone marrow has them in adulthood
1. Stem cells in bone marrow differentiate into
different types of blood cells
2. Bone marrow transplants help people with
leukemia
D. Stem cells either from embryonic or adult
stem cells may help to fight other disease as
well
1. Ethical debates surround the use of stem
cells
V. Homeotic Genes
A. Homeotic genes- master control genes that
direct development of body parts in specific
locations
1. Homeobox- nucleotide sequence that
codes for a protein that promotes the
transcription ofgenes involved in the
development of specific body parts
2. A mutation in the Drosphila fruit fly
homeobox can lead to eyes developing
where legs or wings or antenna should be.
Homeotic Genes
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