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Chapter 5: DNA, Gene
Expression, and Biotechnology
What is the code and how is it harnessed?
Lectures by Mark Manteuffel, St. Louis Community College; Clicker Questions by Kristen Curran, University of Wisconsin-Whitewater
Learning Objectives
Describe what DNA is and what it does.
 Explain the process of gene expression and
the collaboration of nature and nurture.
 Explain the causes and effects of damage to
the genetic code.
 Describe biotechnology and its implications
for human health.
 Discuss biotechnology in agriculture.
 Discuss biotechnology today and tomorrow.

AIM:
How is DNA structured?
Do Now:
Where is DNA found and why is it
important?
5/23/2017
5.1 “The DNA 200”
Knowledge about DNA is
increasing justice in the world.
What is the most common reason why
DNA analyses overturn incorrect
criminal convictions?
DNA is unique for each individual.
Selfish dictators may owe their behaviour
partly to their genes, according to a study
that claims to have found a genetic link to
ruthlessness.
–Nature, April 2008
Whether a man has one type of gene versus
another could help decide whether he’s good
“husband material,” a new study suggests.
–Washington Post, September 2008
The “Age of the Gene”
Take-home message 5.1
 DNA
is a molecule that all living organisms
carry in every cell in their body.
Take-home message 5.1
 Unique
in virtually every person, DNA can
serve as an individual identifier, left behind
us as we go about our lives.
 This
is a fact that is used increasingly to
ensure greater justice in our society, such
as through establishing the innocence of
individuals wrongly convicted of crimes.
5.2 The DNA molecule contains
instructions for the development
and functioning of all living
organisms.
Two Important Features of DNA
(1) DNA contains the instructions on how
to create a body and control its growth
and development.
(2) The instructions encoded in the DNA
molecule are passed down from parent
to offspring. (Where have we recently
seen this concept?)
DNA “Double Helix”
Nucleic acids and nucleotides
Sugars, Phosphates,
and Bases
A, T, C, and G
Base pairs
All Teachers Go Crazy
Which answer will base pair with
the following sequence?
AGTTCTCATGT
1.
2.
3.
4.
AGTTCTCATGT
ACATGAGAACT
TCAAGAGTACA
UCAAGAGUACA
How does DNA replicate?
Why is this an important process?
DNA replication
1. DNA original strand “unzips” by breaking the
hydrogen bonds between the complimentary base
pairs.
2. New free floating nucleotides form new hydrogen
bonds with the appropriate base pair with the help
of DNA polymerase.
3. Two new identical of DNA molecules result, each
with one strand of the original DNA as one side of
the sugar-phospahate backbone.
Take-home message 5.2
 DNA
is a nucleic acid, a macromolecule
that stores information.
 It
consists of individual units called
nucleotides: a sugar, a phosphate group,
and a nitrogen-containing base.
Take-home message 5.2
 DNA’s
structure resembles a twisted
ladder, with the sugar and phosphate
groups serving as the backbones of the
molecule and base pairs serving as the
rungs.
ACTIVITY
Make your own DNA model.
EXIT SLIP
Answer the AIM
How is DNA structured?
5.3 Genes are sections of DNA that
contain instructions for making
proteins.
Why is DNA considered the
universal code for all life on
earth?
The number of chromosomes varies from
species to species.

Corn has 10 unique chromosomes.

Fruit flies have only four.

Dogs and chickens have 39 different chromosomes.

Goldfish have 47 chromosomes.

Individuals in each of these species inherit one
copy of each chromosome from each parent.
Genes
A
sequence of bases in a DNA molecule
that carries the information necessary for
producing a functional product, usually a
protein molecule or RNA
Different people can have free or attached
earlobes. The DNA that encodes for making
free or attached earlobes is called a(n)
________, and there are two different
versions of it, called __________.
1.
2.
3.
4.
allele; genes
trait; alleles
gene; trait
gene; alleles
Take-home message 5.3
 DNA
is a universal language that provides
the instructions for building all the
structures of all living organisms.
 The
full set of DNA an organism carries is
called its genome.
Take-home message 5.3
 In
prokaryotes, the DNA occurs in circular
pieces.
 In
eukaryotes, the genome is divided
among smaller, linear strands of DNA
called chromosomes.
Take-home message 5.3
A
gene is a sequence of bases in a DNA
molecule that carries the information
necessary for producing a functional
product, usually a protein molecule or
RNA.
Take-home message 5.4
 Only
a small fraction of the DNA in
eukaryotic species codes for genes.
 The
function of the rest is still a mystery.
5.5 How do genes work?
An overview

Genotype
• all of the genes contained in an
organism

Phenotype
• the physical manifestations of the
instructions
Which molecule acts as a “middle man”
between the nucleus, where transcription
occurs, and the cytoplasm, where translation
occurs?
1.
2.
3.
4.
DNA
mRNA
Protein
Choices 1 and 3 are
correct.
Take-home message 5.5
 The
genes in strands of DNA are a
storehouse of information, an instruction
book.
Take-home message 5.5
The process by which this information is
used to build an organism occurs in two
main steps:
 transcription,
in which a copy of the a
gene’s base sequence is made, and
 translation,
in which that copy is used to
direct the production of a protein.
5.6 Transcription: reading the
information coded in DNA
Classroom Catalyst
Transcription Activity
Which answer shows the correct
orientation of the mRNA sequence
(Phosphate (5’)  Oxygen (3’)) given the
DNA sequence below?
5’-TCATCTATCT-3’
1.
2.
3.
4.
5’-UCAUCUAUCU-3’
5’-AGUAGAUAGA-3’
5’-AGAUAGAUGA-3’
5’-AGATAGATGA-3’
Take-home message 5.6
 Transcription
is the first step in the two-step
process by which DNA directs the synthesis
of proteins.
 In
transcription, a single copy of one specific
gene within the DNA is made, in the form of
a molecule of mRNA, which moves where it
can be translated into a protein.
AIM:
How are protein synthesized?
Do Now:
What determines the function of an
enzyme?
5.7 Translation: using information
from DNA to build usable molecules
Several ingredients must be present in the
cytoplasm for translation to occur.
 Free
amino acids
 Ribosomal
 Transfer
units
RNA
Classroom Catalyst
Translation Activity
Translate the following mRNA:
5’-CGAGCAUGGGCUUUAGG...
1.
2.
3.
4.
MET-GLY-PHE-ARG…
ARG-ALA-TRP-ALA-LEU…
GLY-PHE-ARG-VAL-ARG…
ARG-PHE-GLY-MET-SER…
Take-home message 5.7
 Translation
is the second step in the twostep process by which DNA directs the
synthesis of proteins.
 In
translation, the information from a gene
that has been carried by the nucleotide
sequence of an mRNA is read, and
ingredients present in the cell’s cytoplasm
are used to produce a protein.
5.8 Causes and effects of
mutation
 Alteration
DNA
of the sequence of bases in
• can lead to changes in the structure and
function of the proteins produced
• can have a range of effects
Breast Cancer in Humans
 Two
human genes, called BRCA1 and
BRCA2
 More
than 200 different changes in the
DNA sequences of these genes have been
detected,
 each
of which results in an increased risk
of developing breast cancer.
Mutations
 Bad
reputation
 Tend
to be disruptive
 Very,
very rare
Which answer shows the mRNA
transcribed from the DNA sequence
below?
5’-TTA TCC TTT ACT CAT-3’
1.
2.
3.
4.
5’-AUG AGU AAA GGA UAA-3’
5’-AAU-AGG-AAA-UGA-GUA-3’
5’- TTA-TCC-TTT-ACT-CAT-3’
5’-UUA-AGG-AAA-TGA-GUA-3’
Which of the following changes (base
substitutions and insertions are underlined
and in bold) would have the most severe
effect on the protein made from the mRNA in
the last question?
5’-AUG AGU AAA GGA UAA-3’
1.
2.
3.
4.
AUG-AGU-AAG-GGA-UAA
AUG-AGU-AAA-GGA-UAG
AUG-GUA-AAG-GAU-AA
AUG-AGU-AAA-GGA-GUA-A
Why is it dangerous around the
core of a nuclear power plant?
Chemical-induced mutations
Take-home message 5.8
 Mutations
are alterations in a single base
or changes in large segments of DNA that
include several genes.
 They
are rare and when they occur in a
gene usually disrupt normal physiological
functioning.
 They
play an important role in evolution.
From mutation to illness in just
four steps:
(1) A mutated gene codes for a nonfunctioning protein, usually an enzyme.
(2) The non-functioning enzyme can’t
catalyze the reaction as it normally
would, bringing it to a halt.
From mutation to illness in just
four steps:
(3) The molecule with which the enzyme
would have reacted accumulates, like a
blocked assembly line.
(4) The accumulating chemical causes
sickness and/or death.
Why can one change in a nucleotide
sequence of a gene cause a
nonfunctional protein to be produced?
1. The change can cause a stop codon to occur early in
translation and the full length protein is not
translated.
2. A substitution can result in one incorrect amino acid
being present in the protein which can affect the
shape of the protein and therefore its function.
3. An insertion or deletion can occur early in the gene
and result in an incorrect translation of the protein.
4. All of the above.
Take-home message 5.9
 Most
genetic diseases result from
individual mutations that cause a gene to
produce a non-functioning enzyme, which
in turn blocks the functioning of a
metabolic pathway.
5.10 What is biotechnology?
Genetic Engineering
 Adding,
deleting, or transplanting genes
from one organism to another, to alter the
organisms in useful ways
Biotech advances in human health fall into
three categories:
(1) producing medicines to treat diseases
(2) curing diseases
(3) preventing diseases from occurring in
the first place.
If you were trying to identify the gene for
insulin, which particular step of the
procedure outlined below would you use?
1. Cut human DNA into small pieces with a
restriction enzyme.
2. Amplify the DNA pieces with PCR.
3. Insert the gene into a plasmid and insert
into bacteria.
4. Probe a gene library.
Take-home message 5.10
 Biotechnology
is the use of technology to
modify organisms, cells, and their
molecules to achieve practical benefits.
Take-home message 5.10
 Modern
molecular methods make it
possible to cut and copy DNA from one
organism and deliver it to another.
 Biotechnology
has achieved some
important successes in medicine,
agriculture, and forensics.
5.11 Treating diseases and producing
medicines with biotechnology
 cure
diseases
 treating
diseases
• The treatment of diabetes
Why do some bacteria
produce human insulin?
Recombinant DNA technology
Several important achievements followed the
development of insulin-producing bacteria,
including:
(1) Human growth
hormone (HGH)
(2) Erythropoietin
Take-home message 5.11
 Biotechnology
has led to some notable
successes in treating diseases, usually by
producing medicines more efficiently and
more effectively than they can be
produced with traditional methods.
5.12 Curing diseases with
biotechnology
Gene therapy and the
correction of malfunctioning
genes
Stem Cells
 Cells
that have the ability to develop into
any type of cell in the body
Why has gene therapy had
such a poor record of success
in curing diseases?
Gene Therapy Difficulties
(1) Difficulty getting the working gene into
the specific cells where it is needed.
Gene Therapy Difficulties
(2) Difficulty getting the working gene into
enough cells and at the right rate to
have a physiological effect.
(3) Problems with the transfer organism
getting into unintended cells.
Take-home message 5.12
 Gene
therapy has had a poor record of
success in curing human diseases.
 This
stems primarily from technical
difficulties in transferring normalfunctioning genes into the cells of a
person with a genetic disease.
5.13 Preventing diseases
with biotechnology
Intervening to prevent diseases using
biotechnology focuses on answering questions
at three different points in time:
I would want to know if my genome or
that of a loved one carries one or more
copies of a gene that can cause a
genetic disease.
1.
2.
3.
4.
5.
Strongly agree
Agree
Neutral
Disagree
Strongly disagree
(1) Is a given set of parents likely to
produce a baby with a genetic
disease?
(2) Will a baby be born with a genetic
disease?

cystic fibrosis

sickle-cell anemia

Down syndrome

others
(3) Is an individual likely to develop a
genetic disease later in life?
 breast
cancer
 prostate
 skin
cancer
cancer
Ethical Dilemmas
 Discrimination
 Health
 How
insurance
to proceed with the information?
Take-home message 5.13
 Biotechnology
allows us to identify:
• whether a given set of parents is likely to
produce a baby with a genetic disease,
• whether a baby is likely to be born with a
genetic disease,
• and whether an individual carriers certain
disease-causing genes that may have their
effect later in life.
Take-home message 5.13
 These
tools can help us to reduce
suffering and the incidence of diseases,
but they also come with significant
potential costs, particularly the risk of
discrimination.
5.14 Producing
more nutritious
and better food
with
biotechnology
How might a genetically
modified plant help 500
million malnourished people?
Nutrient-rich “golden rice”
Take-home message 5.14
 Biotechnology
has led to important
improvements in agriculture by using
transgenic plants and animals to produce
more nutritious food.
5.15 More efficient and eco-friendly
farming with biotechnology
And he gave it for his opinion, ‘that
whoever could make two ears of corn, or
two blades of grass, to grow upon a spot
of ground where only one grew before,
would deserve better of mankind, and do
more essential service to his country, than
the whole race of politicians put together.’
—Jonathan Swift, Gulliver’s Travels, 1726
Almost everyone in the U.S. consumes
genetically modified foods regularly
without knowing it.
What foods are responsible for this?
Insect Resistance
How can genetically modified
plants lead to reduced pesticide
use by farmers?
Herbicide Resistance
Faster Growth and Bigger Bodies
Take-home message 5.15
 There
has been a revolution through
biotechnology.
 Herbicide-resistant
and insect-resistant
crops help reduce the environmental and
financial costs of producing food.
5.16 Fears and risks: the safety of
genetically modified foods
Fear #1. Organisms that we want to kill may
become invincible.
 Fear #2. Organisms that we don’t want to kill may
be killed inadvertently.
 Fear #3. Genetically modified crops are not tested
or regulated adequately.

Fear #4. Eating genetically modified foods is
dangerous.
 Fear #5. Loss of genetic diversity among crop
plants is risky.
 Fear #6. Hidden costs may reduce the financial
advantages of genetically modified crops.

Which food below does not
potentially contain GMOs?
1.
2.
3.
4.
5.
Nacho chips
Fruit juice
Corn flakes
Rice
All of the above.
Take-home message 5.16
 More
and more genetically modified foods
are being created using modern methods
of recombinant DNA technology.
 Some
legitimate fears among the public
remain, however, as to the safety of these
foods given that their development relies
on such new technology.
5.17 DNA as an individual identifier: the
uses and abuses of DNA fingerprinting
What is a DNA
fingerprint?
Using the DNA fingerprint information
below, determine which suspect was
present at the crime scene?
1.
2.
3.
4.
Suspect #1
Suspect #2
Suspect #3
All of the above.
Crime
Scene
Suspect
#1
Suspect Suspect
#2
#3
Take-home message 5.17
 Comparisons
of highly variable DNA
regions have forensic value in identifying
tissue specimens and determining the
individual from whom they came.
5.18 DNA sequences reveal
evolutionary relatedness
(1) Mapping Genetic Landscapes:
The Human Genome Project
(2) Building Earth’s Family Tree
When we say humans and
chimps are genetically 96%
identical, what do we mean?
Take-home message 5.18
 Comparisons
of sequence similarities
across species reveal the evolutionary
relatedness and make it possible to
construct detailed evolutionary trees.
5.19 The promise and
perils of cloning
From organs to individuals
Are there any medical
justifications for cloning?
Is it possible to clone a dinosaur? How
could it be done?
Take-home message 5.19
 Cloning
of individuals has potential
benefits in agriculture and medicine, but
ethical questions linger.
We should pursue cloning in animals
but not humans.
1.
2.
3.
4.
5.
Strongly agree
Agree
Neutral
Disagree
Strongly disagree
We should pursue cloning in humans
for the purpose of developing or
performing medical treatments.
1.
2.
3.
4.
5.
Strongly agree
Agree
Neutral
Disagree
Strongly disagree