Chapter 16 Genetics
What Is a Gene?
Chromosomes: Packages of Genetic Information
The Structure of DNA
DNA Replication
How Proteins Are Built
Genetic Mutations
How Radioactivity Causes Genetic Mutations
Meiosis and Genetic Diversity
Mendelian Genetics
More Wrinkles: Beyond Mendelian Genetics
The Human Genome
Cancer: Genes Gone Awry
Environmental Causes of Cancer
Transgenic Organisms and Cloning
DNA Technology—What Could Possibly Go Wrong?
History of Science: Discovery of the Double Helix
Technology: Gene Therapy
Science and Society: Genetic Counseling
Science and Society: DNA Forensics
Association genetics‟ or ‟association studies,” or ‟linkage disequilibrium mapping”.
Tool to resolve complex trait variation down to the sequence level by exploiting historical and evolutionary recombination events at the population level.
Natural population surveyed to determine MTA using LD.
Genotyping by Sequencing is a robust,fast and cheap approach for high throughput marker discovery.It has applications in crop improvement programs by enhancing identification of superior genotypes.
Association mapping, also known as "linkage disequilibrium mapping", is a method of mapping quantitative trait loci (QTLs) that takes advantage of linkage disequilibrium to link phenotypes to genotypes.Varioius strategey involved in association mapping is discussed in this presentation
Nadia Pisanti - With the recent New Genome Sequencing Technologies, Medicine and Biology are witnessing a revolution where Computer Science and Data Analysis play a crucial role. In this talk, I will give an overview of perspectives and challenges in this field.
Association genetics‟ or ‟association studies,” or ‟linkage disequilibrium mapping”.
Tool to resolve complex trait variation down to the sequence level by exploiting historical and evolutionary recombination events at the population level.
Natural population surveyed to determine MTA using LD.
Genotyping by Sequencing is a robust,fast and cheap approach for high throughput marker discovery.It has applications in crop improvement programs by enhancing identification of superior genotypes.
Association mapping, also known as "linkage disequilibrium mapping", is a method of mapping quantitative trait loci (QTLs) that takes advantage of linkage disequilibrium to link phenotypes to genotypes.Varioius strategey involved in association mapping is discussed in this presentation
Nadia Pisanti - With the recent New Genome Sequencing Technologies, Medicine and Biology are witnessing a revolution where Computer Science and Data Analysis play a crucial role. In this talk, I will give an overview of perspectives and challenges in this field.
Molecular marker technology in studies on plant genetic diversityChanakya P
A molecular marker is a molecule contained within a sample taken from an organism (biological markers) or other matter. It can be used to reveal certain characteristics about the respective source. DNA, for example, is a molecular marker containing information about genetic disorders, genealogy and the evolutionary history of life. Specific regions of the DNA (genetic markers) are used to diagnose the autosomal recessive genetic disorder cystic fibrosis, taxonomic affinity (phylogenetics) and identity (DNA Barcoding). Further, life forms are known to shed unique chemicals, including DNA, into the environment as evidence of their presence in a particular location.Other biological markers, like proteins, are used in diagnostic tests for complex neurodegenerative disorders, such as Alzheimer's disease. Non-biological molecular markers are also used, for example, in environmental studies.
Gene mapping means the mapping of genes to specific locations on chromosomes.
Such maps indicates the positions of genes in the genome and also distance between them.
Molecular marker technology in studies on plant genetic diversityChanakya P
A molecular marker is a molecule contained within a sample taken from an organism (biological markers) or other matter. It can be used to reveal certain characteristics about the respective source. DNA, for example, is a molecular marker containing information about genetic disorders, genealogy and the evolutionary history of life. Specific regions of the DNA (genetic markers) are used to diagnose the autosomal recessive genetic disorder cystic fibrosis, taxonomic affinity (phylogenetics) and identity (DNA Barcoding). Further, life forms are known to shed unique chemicals, including DNA, into the environment as evidence of their presence in a particular location.Other biological markers, like proteins, are used in diagnostic tests for complex neurodegenerative disorders, such as Alzheimer's disease. Non-biological molecular markers are also used, for example, in environmental studies.
Gene mapping means the mapping of genes to specific locations on chromosomes.
Such maps indicates the positions of genes in the genome and also distance between them.
Unit 1 genetics nucleic acids DNA (1) Biology aid Lassie sibanda
These slides will help those who love biology but yet find it so hard to break down see how easy and interesting life science is. hope these improve your knowledge
Classifying Life
The Three Domains of Life
Bacteria
Archaea
Protists
Plants
Moving Water Up a Tree
Fungi
Animals
How Birds Fly
Viruses and Prions
Science and Society: Swine Flu
Chapter 17
Evoution of Life
The Origin of Life
Did Life on Earth Originate on Mars?
Early Life on Earth
Charles Darwin and The Origin of Species
How Natural Selection Works
Adaptation
Staying Warm and Keeping Cool
Evolution and Genetics
How Species Form
Evidence of Evolution
Fossils: Earth's Tangible Evidence of Evolution
The Evolution of Humans
History of Science: The Peppered Moth
Science and Society: Antibiotic-Resistant Bacteria
Chapter 15
The basic unit of life
Characteristics of Life
Macromolecules Needed for Life
Cell Types: Prokaryotic and Eukaryotic
The Microscope
Tour of a Eukaryotic Cell
The Cell Membrane
Transport into and out of Cells
Cell Communication
How Cells Reproduce
How Cells Use Energy
ATP and Chemical Reactions in Cells
Photosynthesis
Cellular Respiration and Fermentation
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
DERIVATION OF MODIFIED BERNOULLI EQUATION WITH VISCOUS EFFECTS AND TERMINAL V...Wasswaderrick3
In this book, we use conservation of energy techniques on a fluid element to derive the Modified Bernoulli equation of flow with viscous or friction effects. We derive the general equation of flow/ velocity and then from this we derive the Pouiselle flow equation, the transition flow equation and the turbulent flow equation. In the situations where there are no viscous effects , the equation reduces to the Bernoulli equation. From experimental results, we are able to include other terms in the Bernoulli equation. We also look at cases where pressure gradients exist. We use the Modified Bernoulli equation to derive equations of flow rate for pipes of different cross sectional areas connected together. We also extend our techniques of energy conservation to a sphere falling in a viscous medium under the effect of gravity. We demonstrate Stokes equation of terminal velocity and turbulent flow equation. We look at a way of calculating the time taken for a body to fall in a viscous medium. We also look at the general equation of terminal velocity.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
What is greenhouse gasses and how many gasses are there to affect the Earth.moosaasad1975
What are greenhouse gasses how they affect the earth and its environment what is the future of the environment and earth how the weather and the climate effects.
Salas, V. (2024) "John of St. Thomas (Poinsot) on the Science of Sacred Theol...Studia Poinsotiana
I Introduction
II Subalternation and Theology
III Theology and Dogmatic Declarations
IV The Mixed Principles of Theology
V Virtual Revelation: The Unity of Theology
VI Theology as a Natural Science
VII Theology’s Certitude
VIII Conclusion
Notes
Bibliography
All the contents are fully attributable to the author, Doctor Victor Salas. Should you wish to get this text republished, get in touch with the author or the editorial committee of the Studia Poinsotiana. Insofar as possible, we will be happy to broker your contact.
Comparing Evolved Extractive Text Summary Scores of Bidirectional Encoder Rep...University of Maribor
Slides from:
11th International Conference on Electrical, Electronics and Computer Engineering (IcETRAN), Niš, 3-6 June 2024
Track: Artificial Intelligence
https://www.etran.rs/2024/en/home-english/
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
2. This lecture will help you understand:
• What Is a Gene?
• Chromosomes: Packages of Genetic Information
• The Structure of DNA
• DNA Replication
• How Proteins Are Built
• Genetic Mutations
• How Radioactivity Causes Genetic Mutations
• Meiosis and Genetic Diversity
• Mendelian Genetics
• More Wrinkles: Beyond Mendelian Genetics
3. This lecture will help you understand:
• The Human Genome
• Cancer: Genes Gone Awry
• Environmental Causes of Cancer
• Transgenic Organisms and Cloning
• DNA Technology—What Could Possibly Go Wrong?
• History of Science: Discovery of the Double Helix
• Technology: Gene Therapy
• Science and Society: Genetic Counseling
• Science and Society: DNA Forensics
4. What Is a Gene?
• A gene is a section of DNA that contains the
instructions for building a protein.
• An organism's genes make up its genotype.
• The traits of an organism make up its phenotype.
5. Chromosomes: Packages of Genetic
Information
• A chromosome consists of a
long DNA molecule wrapped
around small proteins called
histones. Genes are sections
of chromosomes.
6. Chromosomes: Packages of Genetic
Information
• Most cells have two of each kind of chromosome.
These cells are diploid, and their matched
chromosomes are called homologous
chromosomes.
• Sperm and eggs contain only one of each kind of
chromosome. They are haploid.
7. Chromosomes: Packages of Genetic
Information
• Humans have 46 chromosomes (23 pairs).
• One pair—the sex chromosomes—determines the
sex of the person.
• Males have one X and one Y chromosome.
Females have two X chromosomes.
• All the other chromosomes are autosomes.
8. The Structure of DNA
• A molecule of DNA consists of two strands and
looks like a spiraling ladder. It is often called a
double helix.
• The "sides" of the ladder consist of alternating
molecules of deoxyribose sugar and phosphate. The
"rungs" are a series of paired nitrogenous bases.
9. The Structure of DNA
• Four nitrogenous bases are used in DNA:
– Adenine (A)
– Guanine (G)
– Cytosine (C)
– Thymine (T)
• A binds with T, and G binds with C.
10. DNA Replication
• During replication:
– DNA's two strands are
separated.
– Each strand serves as a
template for building a new
partner, following the base-
pairing rules.
– Each new DNA molecule
includes one old strand and one new strand.
– Each new DNA molecule is identical to the
original.
11. How Proteins Are Built
• RNA, or ribonucleic acid,
plays a key role.
• RNA differs from DNA in
several ways:
– Single-stranded instead
of double-stranded
– Uses ribose instead of
deoxyribose sugar
– Uses the nitrogenous base
uracil (U) instead of thymine (T)
12. How Proteins Are Built
• DNA provides instructions for cells to build proteins
through the processes of transcription and
translation.
• During transcription, DNA is used as a template for
making an RNA molecule.
• During translation, this RNA molecule is used to
assemble a protein.
13. How Proteins Are Built
• Transcription
– In eukaryotes, transcription occurs in the cell
nucleus.
– The two strands of DNA separate, and one strand
serves as a template for building the RNA
transcript.
– Transcription follows the usual base-pairing rules
except that RNA uses uracil (U) instead of
thymine (T).
– RNA polymerase adds the free nucleotides to the
growing RNA molecule.
15. How Proteins Are Built
• RNA processing
– Introns are removed.
– Exons remain.
– A cap and a tail are
added.
– The result is an mRNA
molecule ready for
translation.
16. How Proteins Are Built
• Translation
– Translation occurs at ribosomes in the cytoplasm.
– Codons, sets of three nucleotides, are "read"
from the mRNA.
– Most codons represent a single amino acid to be
added to the growing protein.
– Stop codons tell the ribosome that no more
amino acids should be added and that translation
is complete.
18. How Proteins Are Built
• A tRNA molecule has a set
of three nucleotides, called an
anticodon, and carries a single,
specific amino acid.
• A tRNA's anticodon binds to
the mRNA's codon.
19. Genetic Mutations
• Occur when the sequence of nucleotides in an
organism's DNA is changed
• May result from errors during DNA replication or
from exposure to things that damage DNA (UV light,
X-rays, chemicals, etc.)
• May have no effect, some effects, or huge effects
• In eggs or sperm, may be passed down to offspring
• Are the ultimate source of all genetic diversity and
provide the raw materials for evolution
20. Genetic Mutations
• A point mutation occurs when one nucleotide is
substituted for another.
• A nonsense mutation creates a stop codon in the
middle of a gene.
• A frameshift mutation occurs when nucleotides are
inserted or deleted, shifting the codons that are
"read" during translation.
22. How Radioactivity Causes Genetic
Mutations
• Ionizing radiation strikes electrons
in the body, freeing them from the
atoms they were attached to.
• The free electrons may hit and
damage DNA directly.
• Free electrons may hit a water
molecule, producing a free radical,
a group of atoms that has an
unpaired electron and is highly
reactive. The free radical may then
react with DNA and damage it.
23. How Radioactivity Causes Genetic
Mutations
• Frequently dividing cells have less time to repair
DNA damage before passing on mutations and so
are more vulnerable to radiation damage.
– Examples: cells in the bone marrow, lining of the
digestive tract, testes, and developing fetus
• Because cancer cells also divide frequently,
radiation is sometimes used to treat tumors.
24. Meiosis and Genetic Diversity
• Meiosis is a form of cell
division used to make haploid
cells, such as eggs and sperm.
• In meiosis, one diploid cell
divides into four haploid cells.
• During sexual reproduction,
sperm and egg join to
restore the normal diploid
chromosome number.
25. Meiosis and Genetic Diversity
• At the beginning of meiosis, the diploid cell has
already copied its DNA.
• Meiosis takes place in two steps: meiosis I and
meiosis II.
26. Meiosis and Genetic Diversity
• During prophase I of meiosis,
crossing over occurs: Chromosomes
exchange parts with their homologous
chromosomes.
• The chromosomes in the dividing cell
are now different from those in the
original cell.
• Crossing over results in recombination,
the production of new combinations of
genes different from those found in the
original chromosomes.
27. Meiosis and Genetic Diversity
• How does meiosis result in genetic diversity?
1. Crossing over
2.Independent separation of homologous
chromosomes
• The genetic diversity produced during meiosis is
crucial to evolution.
28. Mendelian Genetics
• Gregor Mendel's experiments breeding pea plants
explained many hereditary patterns.
• Mendel demonstrated the existence of dominant
and recessive traits.
29. Mendelian Genetics
• Mendel postulated that the genes that determine
traits consist of two separate alleles. One allele is
inherited from each parent.
• Mendel's principle of segregation: When an
individual makes sex cells (sperm or eggs), half the
sex cells carry one allele, and the other half carry
the other allele.
30. Mendelian Genetics
• Mendel bred two pea plants
that varied in a single trait
--for example, round peas (RR)
and wrinkled peas (rr).
• The offspring inherited
one R (round pea) allele
and one r (wrinkled pea)
allele. They were Rr.
• All of the offspring expressed
the dominant characteristic—
they had round peas.
• In the second generation, self-fertilizing the Rr plants
resulted in a 3:1 ratio of round-pea plants to wrinkled-
pea plants.
31. Mendelian Genetics
• Mendel's principle of
independent assortment:
The inheritance of one
trait is independent of
the inheritance of a
second trait.
• Mendel demonstrated
this by crossing plants
with two different traits.
32. More Wrinkles: Beyond Mendelian Genetics
• In incomplete dominance, there are two alleles and
neither is dominant. The heterozygote has an
intermediate trait.
• Example: snapdragon color
33. More Wrinkles: Beyond Mendelian Genetics
• In codominance, a heterozygote expresses the traits
of both alleles.
• Example: human blood type
34. More Wrinkles: Beyond Mendelian Genetics
• Polygenic traits are determined by more than one
gene. They tend to show more of a continuum than
traits determined by a single gene.
• Examples: human eye color, skin color, and height
35. More Wrinkles: Beyond Mendelian Genetics
• Pleiotropy occurs when a single
gene affects more than one trait.
• Example: sickle cell anemia in
humans
36. More Wrinkles: Beyond Mendelian Genetics
• Linked genes are often inherited together. The
closer two genes are to each other on a
chromosome, the more likely they are to be
inherited together.
• Example: body color and wing size in fruit flies are
linked
37. More Wrinkles: Beyond Mendelian Genetics
• Sex-linked traits are determined by genes found on
the X chromosome. Men, who have only one X
chromosome, need only one recessive allele to
express a recessive sex-linked trait. These traits are
more common in males than females.
• Examples: red-green color-blindness, hemophilia
38. The Human Genome
• A genome is the total genetic material of an
organism.
• The Human Genome Project determined the DNA
sequence of the entire human genome.
• Over 99.9% of the 3.2 billion nucleotide pairs in the
human genome are identical in all humans.
39. The Human Genome
• Humans have about 22,000 genes.
• Many human genes give rise to RNA transcripts that
are processed in different ways. So, one gene can
provide the instructions for building multiple
proteins.
• The function of more than half of our genes is still
unknown.
40. The Human Genome
• Single-nucleotide polymorphisms (SNPs) are
locations in the genome where the nucleotide
sequence differs among humans.
• More than 3 million SNPs are known.
• SNPs may help scientists identify genes related to
human diseases.
41. Cancer: Genes Gone Awry
• Cancer occurs when cells in the body divide out of
control.
• Mutations in the genes that control cell division
result in cancer.
• A mutation in a single gene is not enough to cause
cancer—mutations in many key genes are required.
42. Cancer: Genes Gone Awry
• Over a lifetime, mutations build up until a
combination of mutations in a single cell allows
uncontrolled cell division.
• Further mutations expand the tumor cells' ability to
divide and spread.
• Cancer is most likely to strike older people, those
who have been exposed to mutation-causing
agents, and those who have inherited mutations in
cancer-related genes.
43. Cancer: Genes Gone Awry
• Genes that have been implicated in cancer:
– Proto-oncogenes: When mutated, they become
oncogenes that stimulate abnormal cell division.
– Tumor-suppressor genes: They prevent cancer
by inhibiting cell division.
• Metastasis is the ability of tumor cells to spread
around the body and give rise to secondary tumors.
Cancer is much harder to treat once metastasis has
occurred.
44. Environmental Causes of Cancer
• A person's environment is responsible for about
80%–90% of the mutations that result in cancer.
• Environmental risk factors:
– Smoking
– Diet
– Radiation
– Ultraviolet light
– Chemicals
– Infection by certain viruses and bacteria
45. Transgenic Organisms and Cloning
• A transgenic organism is one that contains a gene
from another species.
• Typical process for developing transgenic bacteria
46. Transgenic Organisms and Cloning
• Examples of transgenic organisms:
– Bacteria that produce insulin and other important
products
– Plants that
• produce medicines
• have resistance to pests, diseases, or
herbicides
• are drought-resistant or able to grow in salty
soils
– Animals that produce products:
• Sheep with increased wool production
• Pork with higher levels of omega-3 fatty acids
• Salmon that grow faster
47. Transgenic Organisms and Cloning
• Cloning is the creation of an organism that is
genetically identical to one that already exists.
• In mammals, cloning is done through the process of
nuclear transplantation.
• Potential uses of cloning:
– A routine part of agriculture
– Could generate herds of identical animals with
desirable traits
– Cloning of endangered species could help
increase their numbers
– Cloning of deceased pets
48. DNA Technology – What Could Possibly Go
Wrong?
• Some bacteria and viruses are a danger to human
health or to natural habitats.
– How likely is an accidental release?
• Potential dangers of genetically modified (GM)
plants and animals:
– Is the safety of GM food adequately tested?
– Should GM foods be labeled?
49. DNA Technology – What Could Possibly Go
Wrong?
• Potential dangers of GM plants and animals
(continued):
– Plants that are toxic to pests also harm nontarget
species --for example, Monarch butterflies
– May lead to the evolution of resistant
"superweeds" that can be controlled only with
very toxic chemicals
– Contamination of natural habitats or populations
by transgenic plants and animals or their genes
– Cost of GM seeds and products
• Effects on human societies
50. History of Science: Discovery of the Double
Helix
• By 1950, scientists knew DNA was the genetic material,
but they did not know the structure of DNA.
• In 1953, Watson and Crick built a model of DNA that was
consistent with available evidence.
• Watson and Crick used X-ray photos of DNA taken by
Franklin and Wilkins as part of their research.
51. Technology: Gene Therapy
• Many genetic diseases
occur when people do not
have a working gene for
making a key protein.
• Gene therapy attempts to
introduce DNA for the
normal, working gene into
a person's cells.
• Some large setbacks have
occurred in gene therapy,
but there are some recent
promising developments also.
52. Science and Society: Genetic Counseling
• A pedigree is a family tree that
shows which relatives are and
are not affected by a particular
genetic disease.
• Medical tests can determine
whether a person is a carrier of a
disease allele.
• Amniocentesis and chorionic villus
sampling can determine whether a
fetus has a genetic disease.
53. Science and Society: DNA Forensics
• Forensic scientists use short tandem repeat (STR) analysis
to determine whether DNA samples match.
• Between 1989 and 2011, DNA evidence exonerated 272
people who were imprisoned for crimes they did not
commit.
• DNA forensics was used to identify the victims of the 2001
World Trade Center terrorist attacks.
• DNA forensics can be used to establish paternity and trace
familial relationships.
• DNA forensics can be used to identify disease-causing
microorganisms or endangered species.
• Ethical concerns – DNA contains a wealth of private
information about family relationships, susceptibility to
diseases, and so on.