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Chapter 12
GENETIC ENGINEERING AND
THE MOLECULES OF LIFE
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Contents
12.1 The Chemistry of Heredity
12.2 The Double Helix of DNA
12.3 Cracking the Chemical Code
12.4 Protein Structure and Activity: Form and Function
12.5 The Human Genome Project
12.6 Genetically Engineered Medical Treatments
12.7 Genetically Engineered Agriculture
12.8 Cloning Mammals and Humans
12.9 The New Prometheus?
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The Chemistry of Heredity
Genetics: Fundamentals
Human Genome:
- 10 million million
(10x1012) cells with a
nucleus
- each cell has a complete
set of genetic
instructions to make
another you(biologically)
- 23 pairs of chromosomes
- 100,000 genes
- def’n: totality of human
hereditary information in
molecular form
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DNA
DNA (deoxyribonucleic acid):
molecule that carries genetic
information in all species
- DNA of one cell unraveled = 2
meters long
3 parts to DNA:
(i) Phosphate group
(ii) Sugar (deoxyribose)
(iii) Nitrogen bases
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DNA
Put all 3 groups together,
called a nucleotide
Adenosine phosphate
A DNA molecule consists of
thousands of nucleotides put
together in a long chain (left)
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The Double Helix of DNA
X-Ray Diffraction of DNA
• R. Franklin
• J. Watson & F. Crick
• 1962 Nobel in Chemsitry
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DNA
Turns out that:
Adenine bonds with
Thymine
Guanine binds with
Cytosine
Called
complementary
bases:
A=T
G=C
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DNA Double Helix
DNA is double stranded and
is shaped like a spiral
staircase.
Ex. What is the
complementary strand of
DNA for the following
sequence:
ATAGCCG
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DNA Replication
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Cracking the Chemical Code
DNA: Blueprint of Life?
How does DNA provide genetic information, where does the
information come from?
Key is in the sequences of nitrogen bases.
DNA: blueprint for making proteins
Proteins: made up of amino acids
consist of/or regulate everything in the
chemistry of life
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DNA to Proteins
OK, the instructions are in the sequence of bases.
There are 20 amino acids
How many bases encode for an amino acid?
if it were 1 base = 1 amino acid, then there would only
be 4 amino acids found in proteins. There are up to 20
amino acids found in proteins.
if it were 2: 42 = 16, not enough
3 bases: 43 = 64
3 bases = codon
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Codon table
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DNA to Proteins
Transcription: DNA to mRNA
Translation: mRNA to protein
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Protein Structure and Activity:
Form and Function
Polypeptide
Backbone
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Protein structure
• The peptide bond allows for rotation around it and
therefore the protein can fold and orient the R
groups in favorable positions
• Weak non-covalent interactions will hold the
protein in its functional shape – these are weak
and will take many to hold the shape
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Secondary structures
• 2 regular folding patterns
have been identified –
formed between the
bonds of the peptide
backbone
• -helix – protein turns like
a spiral – fibrous proteins
(hair, nails, horns)
• -sheet – protein folds
back on itself as in a
ribbon –globular protein
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Tertiary structure
• The overall fold result in increase in stability
• The shape is maintained through H-bond,
intermolecular ionic and covalent bond and
interactions of amino acid residues with water
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Protein function
–
–
–
–
Enzymes, exp : chymotrypsin
Structural, exp: collagen, hair
Transport : hemoglobin
etc
– Sickle cell anemia
differs from normal
blood cell due to
replacement of
hemoglobin amino acid
two glutamic acid by
valine
– Hemoglobin is a
transport protein
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The Human Genome Project
What is the Human Genome Project?
• International effort to map all gene in human organism
• Started in 1989 lead by J. Watson
• Finished June 26, 2000 (co-announced by President Bill Clinton
and PM Tony Blair)
Definition: GENOME – the whole hereditary information of an
organism that is encoded in the DNA.
• Aims of the project:
–
–
to identify the approximate 100,000 genes in the human DNA.
determine the sequences of the 3 billion bases that make up human
DNA.
–
store this information in databases.
develop tools for data analysis.
address the ethical, legal, and social issues that arise from genome
research.
–
–
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Whose genome is being sequenced?
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the first reference genome is a composite genome
from several different people.
generated from 10-20 primary samples taken from
numerous anonymous donors across racial and ethnic
groups.
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Benefits of Human Genome Project research
• improvements in medicine.
• microbial genome research for
fuel and environmental
cleanup.
• DNA forensics.
• improved agriculture and
livestock.
• better understanding of
evolution and human migration.
• more accurate risk assessment.
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Genetically Engineered Medical Treatment
Recombinant DNA: manipulating gene pools
Cut out DNA that encodes for
human insulin
Splice it into E. Coli plasmid
(DNA)
Ecoli reads DNA and starts
making insulin.
Human Growth Hormone
(HGH): previously, a 1 year
supply required harvesting
the pituitary glands from 80
human cadavers
• DNA recombinant
technology offers many
biocatalysis
• Greener reaction
condition
• Atorsvastatin produced from (R)-4-cyano-3hydroxybutyrate which was produced by
process using biocatalyst (enzyme)
• The enzyme was a product of DNA
recombinant
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Genetically Engineered
Agriculture
Transgenic plants (organisms)
• Artificially created higher plants and animals that
share the genes of another species
• The focus of development
– Improve production stability
– Give nutritional benefits to the consumer
– Reduce environmental effect of intensive and
extensive agriculture
– Increase the availability of pharmaceutical and
vaccines
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How to create transgenic plants
Agrobacterium tumefaciens
Plant cell
DNA containing
gene for desired trait
Ti
plasmid
T DNA
Restriction site
Insertion of gene
into plasmid using
restriction enzyme
and DNA ligase
Recombinant
Ti plasmid
Introduction
Regeneration
into plant
of plant
cells in
culture
T DNA carrying new
Plant with new trait
gene within plant chromosome
•Nitrogen fixing corn, corn
that capable in fixing N2
•Contain nitrogen fixing
bacterial genes
•Transgenic soybeans
which is resistance to
herbicides
Mixing Genes: Transgenic Organisms
Cloning Mammals and Humans
Nuclear transfer/ Somatic cell nuclear transfer
(A, B) nucleus is sucked of cell
(C) New nucleus is picked up
(D) Nucleus/DNA is inserted
into the egg
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Dolly, 1996-2003
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Snuppy, 2005
Snuppy and his
“father”
Snuppy and his
surrogate mother
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Human cloning
• Many reports said the success of the somatic
nuclear transfer
• After electrical jolt, the embryo started growing
• No report of embryo development to human
• The intention of researcher is to harvest stem cell
The New Prometheus?
• We have clone animals
• Next logical step would be creating new organism
or cloning human “the super one”
• However we could not removed defective gene
from the pools
• And cloning or creating superman could end up
with creating a new promatheus
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THANK YOU
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