biol 108 chp 5 - dna
TRANSCRIPT
DNA, Gene Expression,DNA, Gene Expression, And BiotechnologyAnd Biotechnology
BIOL BIOL 108 108 Intro to Bio Intro to Bio SciSci
Chapter Chapter 55
Rob Rob SwatskiSwatski Assoc Prof BiologyAssoc Prof Biology
HACCHACC--YorkYork 1
Learning GoalsLearning Goals Learning GoalsLearning Goals
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.
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5.1–5.5
DNA: what is it, and
what does it do?
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5.1 5.1 “The DNA 200”“The DNA 200”
Knowledge about DNA is increasing justice in the world.
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What is the most common reason why What is the most common reason why DNA analyses overturn incorrect DNA analyses overturn incorrect
criminal convictions?criminal convictions?
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The “Age of the Gene”The “Age of the Gene”
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Take-Home Message 5.1
DNA is a molecule that all living organisms carry in every cell in their body.
DNA is a molecule that all living organisms carry in every cell in their body.
Unique in virtually every person, DNA can serve as an
individual identifier, left behind us as we go about our
lives.
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.
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.
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5.2 The DNA molecule contains 5.2 The DNA molecule contains instructions for the development instructions for the development
and functioning of all living and functioning of all living organisms.organisms.
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Two Important Features Two Important Features of DNAof DNA
DNA contains the instructions on how to
create a body and control its growth and development.
The instructions encoded in the DNA molecule are
passed down from parent to offspring.
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NucleotidesNucleotides NucleotidesNucleotides
Sugars, phosphates, &
bases
A, T, C, & G
Base pairs
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Take-Home Message 5.2
DNA is a nucleic acid, a macromolecule that stores
information.
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.
It consists of individual units called nucleotides: a sugar, a phosphate group, and a nitrogen-containing base.
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.
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.
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5.3 Genes are sections of DNA that 5.3 Genes are sections of DNA that contain instructions for making contain instructions for making
proteins.proteins.
Why is DNA considered the universal code for all life on earth?
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Chromosome number varies from species to species
Corn
10 chromosomes
Fruit flies
4 chromosomes
Dogs & chickens
39 chromosomes
Goldfish
47 chromosomes
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GenesGenes GenesGenes
A sequence of bases in a DNA
molecule
Carries the information
necessary for producing a functional
product
…usually a protein
molecule or RNA
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Take-Home Message 5.3
DNA is a universal language that provides the
instructions for building all the structures of all living
organisms.
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.
The full set of DNA an organism carries is called its
genome.
In prokaryotes, the DNA occurs in circular pieces. In prokaryotes, the DNA occurs in circular pieces.
In eukaryotes, the genome is divided among smaller,
linear strands of DNA called chromosomes.
In eukaryotes, the genome is divided among smaller,
linear strands of DNA called chromosomes.
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.
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.
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5.4 Not all DNA contains instructions for making proteins.
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An onion has five times as much An onion has five times as much DNA as a human. DNA as a human.
Why doesn’t that make them more complex than us?
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IntronsIntrons IntronsIntrons
Non-coding regions of DNA
May take the form of short (or long)
sequences that are repeated 1000’s of
times
May also consist of gene fragments,
duplicate versions of genes, and
pseudogenes 25
Take-Home Message 5.4
Only a small fraction of the DNA in eukaryotic
species codes for genes.
Only a small fraction of the DNA in eukaryotic
species codes for genes.
The function of the rest is still a mystery,
although it may play a role in gene regulation.
The function of the rest is still a mystery,
although it may play a role in gene regulation.
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5.5 How do genes work? 5.5 How do genes work?
GenotypeGenotype
All of the genes contained in an
organism
Phenotype
The physical manifestations of the
instructions 27
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Take-Home Message 5.5
The genes in strands of DNA are a storehouse
of information, an instruction book.
The genes in strands of DNA are a storehouse
of information, an instruction book.
The process by which this information is used
to build an organism occurs in two main
steps:
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
…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.
…translation, in which that copy is used to
direct the production of a protein.
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5.6–5.8
Building organisms:
information in DNA
directs the production
of the molecules that
make up an organism.
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5.6 Transcription: reading the information coded in DNA
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Take-Home Message 5.6
Transcription is the first step in the two-step process by
which DNA directs the synthesis of proteins.
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.
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.
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5.7 5.7 In translation, the mRNA copy of In translation, the mRNA copy of the information from DNA is used to the information from DNA is used to
build functional molecules.build functional molecules.
What What ingredients are ingredients are needed in the needed in the cytoplasm for cytoplasm for translation to translation to
occur?occur?
What What ingredients are ingredients are needed in the needed in the cytoplasm for cytoplasm for translation to translation to
occur?occur?
Free amino acids
Ribosomal units
Transfer RNA (tRNA)
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Take-Home Message 5.7
Translation is the second step in the two-step process by which
DNA directs the synthesis of proteins.
Translation is the second step in the two-step 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.
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.
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5.9–5.10
Damage to the
genetic code has a
variety of causes and
effects.
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5.9 Causes and effects of
mutation
5.9 Causes and effects of
mutation
Alteration of the sequence of bases in
DNA
Can lead to changes in the structure and
function of the proteins produced
Can have a range of effects
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Breast Cancer in Humans
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 these changes results in an increased
risk of developing breast cancer
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Mutations Mutations
Bad reputation
Tend to be disruptive
Very, very rare
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Mutations in Sex Cells and Mutations in Sex Cells and NonNon--Sex CellsSex Cells
Differences?
Which may get passed on to offspring?
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46
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Take-Home Message 5.9
Mutations are alterations in a single base or changes in large segments of DNA that
include several genes.
Mutations are alterations in a single base or changes in large segments of DNA that
include several genes.
They are rare, but when they do occur, they may
disrupt normal functioning of the body (although many
mutations are neutral).
They are rare, but when they do occur, they may
disrupt normal functioning of the body (although many
mutations are neutral).
Extremely rarely, mutations may have a beneficial effect. Extremely rarely, mutations may have a beneficial effect.
They play an important role in evolution.
They play an important role in evolution.
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5.10 Faulty genes, coding for faulty enzymes,
can lead to sickness.
5.10 Faulty genes, coding for faulty enzymes,
can lead to sickness.
How can people respond so differently
to alcohol?
A single difference in a single pair of bases
in their DNA.
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(1) A mutated gene codes for a non-functioning protein, usually an enzyme.
(2) The non-functioning enzyme can’t catalyze the reaction as it normally would, bringing it to a halt.
(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.
From mutation to illness in just four steps:From mutation to illness in just four steps:
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Take-Home Message 5.10
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.
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.
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Insert section 5.11-5.13 opener photo
5.11–5.13
Biotechnology is
producing
improvements in
agriculture.
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Genetic Engineering
5.11 5.11 What is biotechnology?What is biotechnology?
Adding, deleting, or transplanting genes
from one organism to another, to alter the
organisms in useful ways 54
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Biotech advances in human Biotech advances in human health fall into three categories: health fall into three categories:
Biotech advances in human Biotech advances in human health fall into three categories: health fall into three categories:
Producing medicines
to treat diseases
Curing diseases
Preventing diseases
from occurring in
the first place
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Take-Home Message 5.11
Biotechnology is the use of technology to modify organisms, cells, and their
molecules to achieve practical benefits.
Biotechnology is the use of technology to modify organisms, cells, and their
molecules to achieve practical benefits.
Modern molecular methods make it possible to cut and copy DNA from
one organism and deliver it to another.
Modern molecular methods make it possible to cut and copy DNA from
one organism and deliver it to another.
The methods rely on naturally occurring restriction enzymes for
cutting DNA, the polymerase chain reaction for amplifying small amounts
of DNA, inserting the DNA into bacterial or viral vectors, and cloning
and identifying the cells with the transferred DNA of interest.
The methods rely on naturally occurring restriction enzymes for
cutting DNA, the polymerase chain reaction for amplifying small amounts
of DNA, inserting the DNA into bacterial or viral vectors, and cloning
and identifying the cells with the transferred DNA of interest.
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5.12 Biotechnology can improve food nutrition and make farming more efficient and eco-friendly.
Insert figure 5-30
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How might a genetically How might a genetically modified plant help 500 million modified plant help 500 million
malnourished people?malnourished people?
Nutrient-rich “golden rice”
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Almost everyone in the United States consumes genetically modified foods regularly
without knowing it.
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How can genetically modified How can genetically modified plants lead to reduced pesticide plants lead to reduced pesticide
use by farmers?use by farmers?
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Insect Resistance Insect Resistance
Insert figure 5-33
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Herbicide ResistanceHerbicide Resistance
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Faster Growth and Bigger BodiesFaster Growth and Bigger Bodies
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Take-Home Message 5.12
Biotechnology has led to important improvements in
agriculture by using transgenic plants and
animals to produce more nutritious food.
Biotechnology has led to important improvements in
agriculture by using transgenic plants and
animals to produce more nutritious food.
Even more significant is the extent to which biotechnology has reduced the environmental and financial costs of
producing food:
Through the creation of herbicide-resistant and insect-resistant crops
Even more significant is the extent to which biotechnology has reduced the environmental and financial costs of
producing food:
Through the creation of herbicide-resistant and insect-resistant crops
The ecological and health risks of such widespread use
of transgenic species are not fully understood and
are potentially great.
The ecological and health risks of such widespread use
of transgenic species are not fully understood and
are potentially great.
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5.13 5.13 Fears and Fears and RisksRisks: : Are Are Genetically Genetically Modified Foods Modified Foods Safe?Safe?
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Fear #1. Fear #1. Organisms that we want to kill may become invincible.
Fear #2.Fear #2. Organisms that we don’t want to kill may be killed inadvertently.
Fear #3.Fear #3. Genetically modified crops are not tested or regulated adequately. 75
Fear #4.Fear #4. Eating genetically modified foods is dangerous.
Fear #5. Fear #5. Loss of genetic diversity among crop plants is risky.
Fear #6.Fear #6. Hidden costs may reduce the financial advantages of genetically modified crops.
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Take-Home Message 5.13
More and more genetically modified foods are being
created using modern methods of recombinant
DNA technology.
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.
Some legitimate fears among the public remain,
however, as to the safety of these foods given that their development relies on such
new technology. 77
5.14–5.17
Biotechnology
has the potential
for improving
human health (and
criminal justice)
78
5.14 The treatment of diseases and 5.14 The treatment of diseases and production of medicines are improved production of medicines are improved
with biotechnology.with biotechnology.
Preventing diseases
Curing diseases
Treating diseases
• The treatment of diabetes
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Why do some bacteria produce human insulin?
Recombinant DNA technology
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Several important achievements followed the development of insulin-producing
bacteria, including:
(1) Human growth hormone (HGH)
(2) Erythropoietin
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What is “blood doping”? What is “blood doping”?
How does it improve some athletes’ performance?
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Take-Home Message 5.14
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.
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. 83
5.15 Gene therapy: Biotechnology can 5.15 Gene therapy: Biotechnology can help diagnose and prevent diseaseshelp diagnose and prevent diseases..
But has had a limited success in curing them
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1. Is a given set of parents likely to produce 1. Is a given set of parents likely to produce a baby with a genetic disease?a baby with a genetic disease?
Insert figure 5-41
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(2) Will a baby be born with a genetic (2) Will a baby be born with a genetic disease?disease?
Cystic fibrosis
Sickle-cell anemia
Down syndrome
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(3) Is an individual likely to develop a (3) Is an individual likely to develop a genetic disease later in life?genetic disease later in life?
Breast cancer
Prostate cancer
Skin cancer
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Ethical DilemmasEthical Dilemmas
Discrimination Health
insurance
How to proceed with the
information?
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Why has gene therapy had such Why has gene therapy had such a poor record of success in a poor record of success in
curing diseases?curing diseases?
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(1) Difficulty getting the working gene into the specific cells where it is needed.
(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.
(4) Difficulty regulating gene expression.
Gene Therapy DifficultiesGene Therapy Difficulties
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Take-Home Message 5.15
Biotechnology allows us to identify:
Biotechnology allows us to identify:
…whether a given set of parents is likely to produce a baby with a
genetic disease,
…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,
…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.
…and whether an individual carriers certain disease-causing genes that may have their effect
later in life.
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.
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.
Gene therapy has had a poor record of success in curing human
diseases, primarily because of technical difficulties in
transferring normal-functioning genes into the cells of a person
with a genetic disease.
Gene therapy has had a poor record of success in curing human
diseases, primarily because of technical difficulties in
transferring normal-functioning genes into the cells of a person
with a genetic disease. 91
Stem CellsStem Cells
Cells that have the ability to develop
into any type of cell in the body
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Take-Home Message 5.12
Gene therapy has had a poor record of success in curing human diseases.
Gene therapy has had a poor record of success in curing human diseases.
This stems primarily from technical difficulties in transferring normal-
functioning genes into the cells of a person with a
genetic disease.
This stems primarily from technical difficulties in transferring normal-
functioning genes into the cells of a person with a
genetic disease. 93
Take-Home Message 5.18
Comparisons of sequence similarities across species
reveal the evolutionary relatedness and make it
possible to construct detailed evolutionary trees.
Comparisons of sequence similarities across species
reveal the evolutionary relatedness and make it
possible to construct detailed evolutionary trees.
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5.16: Cloning5.16: Cloning——ranging ranging from from genes to organs genes to organs to individualsto individuals——offers both offers both promise and promise and perils.perils.
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Are there any medical justifications Are there any medical justifications for cloning?for cloning?
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Is it possible to clone a Is it possible to clone a dinosaur? How could dinosaur? How could it be done?it be done?
98
Take-Home Message 5.16
Cloning of individuals has potential benefits in
agriculture and medicine, but ethical
questions linger.
Cloning of individuals has potential benefits in
agriculture and medicine, but ethical
questions linger. 99
5.17 DNA as an individual identifier: the 5.17 DNA as an individual identifier: the uses and abuses of DNA fingerprintinguses and abuses of DNA fingerprinting
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What is a DNA What is a DNA fingerprint?fingerprint?
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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.
Comparisons of highly variable DNA regions have
forensic value in identifying tissue specimens and
determining the individual from whom they came.
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