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Genetics 101
By: Wong Wei Cong (32)
Journey into DNA
The genome is here before us;
its chromosomes make me and you.
We see them here in their most condensed state,
each one will in no time be two.
Forty-six of them make up the genome,
half are mum’s and half are pop’s.
They’ll soon split into two when the cell divides;
there will be ninety-two when it stops.
Journey into dna
We zoom in to take a close look at…
a single chromosome?
Didn’t we say there are two here?
Half of this “X” is a clone.
Chromosomes when stained show banding,
or areas of light and dark.
What causes this trait is its structure,
and the denseness of its parts.
Journey into dna
Here we behold a single gene,
the unit of inheritance.
If you’re short of thin or slim or bald,
depends on its transmittance.
Its length can vary greatly,
its intricacy can’t be outdone.
It can be as short as a hundred bases,
Two million is a long one.
Journey into dna
A DNA molecule is very long,
when stretched out end to end.
To fit inside a small cell
it’s developed this knack to bend.
The DNA twists ‘round and ‘round
like countless Hula Hoops.
It creates a cord-like structure,
which we called chromatin loops.
The chromatin scaffold is vital,
providing much-needed support.
From it extend many more loops
that a ruler would measure as short.
Journey into dna
We almost see the DNA strand
as we look at some nucleosomes.
It’s wrapped tightly on those round things,
Which are structures called protein histones.
The histones, they carry a plus charge;
without it the strand’s in distress.
For then the DNA would try to float free,
And become a colossal mess.
“It has a helical structure,”
Watson and Crick forthrightly insisted.
With two sides and the rungs that connect them,
the DNA strand looks like a ladder that’s twisted.
Journey into dna
Here is a small piece of the ladder,
untwisted to better your view.
Please note that the bases displayed here,
are paired up in groupings of two.
Note also that there are four letters;
and that’s all that they’ll ever be.
They comprise the four DNA bases,
and they are A, T, C and G.
Development of life
-Darwin's theory of evolution
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On the Origin of Species by
Means of Natural Selection, or
the Preservation of Favoured
Races in the Struggle for Life
Natural selection
Adaptation
Diversity
Over-reproduction
Development of life
-Darwin's theory of evolution
 Natural selection
 Produces adaptations
 Biodiversity arises by
surviving evolution
Development of antibiotic resistance
in microorganisms
Development of life
-Darwin's theory of evolution
 All living organisms have a single common ancestor
 Each species through time fit somewhere in an
evolutionary Tree of Life.
Darwin’s Tree of Life
Modern Tree of Life
Development of life
-What Darwin didn’t know: Heredity
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Gregor Johann Mendel
“Father of modern genetics”
Australian monk & scientist
Studied the inheritance of certain traits in pea plants
Discovered the Laws of Inheritance
Development of life
-What Darwin didn’t know: Heredity
Parent plants
Development of life
-What Darwin didn’t know: Heredity
2nd Generation
Development of life
-What Darwin didn’t know: Heredity
3:1
3rd Generation
Development of life
-What Darwin didn’t know: Heredity
Parent plants
2nd Generation
3rd
Generation
Development of life
-What Darwin didn’t know: Heredity
DOMINANT
RECESSIVE
Development of life
-What Darwin didn’t know: Heredity
Development of life
-What Darwin didn’t know: Heredity
Parent plants
2nd Generation
3rd
Generation
Development of life
-What Darwin didn’t know: Heredity
Development of life
-What Darwin didn’t know: Heredity
 Punnett Square
Development of life
-We have found the secret of Life
By 1953 Watson and Crick was on the case,
they were the dynamic duo that deciphered DNA.
Must be in double helix like a spiral staircase,
with Gs married to Cs and Ts paired to As.
We see here the famous arrangement
discovered by Watson and Crick.
Based on the work of Ms. Franklin,
Their model was at once declared slick.
Other genetic concepts
 Multiple
alleles
 Incomplete
dominance
Other genetic concepts
 Co-dominance
 Mutation?
Weird Genetics-What is mutation?
 A change in genetic information
 Failure of DNA repair
 Mutate a sentence!
– The fat cat ate the wee rat.
– The fat hat ate the wee rat. (Point mutations)
– The fat caa tet hew eer at. (Frame shift
mutations)
– The fat ate the wee rat. (Deletion)
– The fat cat xlw ate the wee rat. (Insertion)
– The fat tar eew eht eta tac. (Inversion)
Weird Genetics-classification
 Hereditary mutations
 Acquired mutations
 Beneficial mutations
(Murray Grey)
 Harmful mutations
(Down Syndrome)
Weird Genetics-classification
 Natural mutations
 Human intervention
– Selective Breeding
– Genetic Engineering
Weird Genetics-selective breeding
 Breeding plants and animals for particular genetic
traits (desirable characteristics)
 Inbreeding depression
 Reduced genetic diversity
The Liger is the
result of breeding
a female Tiger to
a male Lion.
Weird Genetics-genetic engineering
Ian made a little lamb, little lamb, little lamb.
Ian made a little lamb and Dolly was her name.
When she grew, she was just like Mom.
Just like Mom, just like Mom.
Why was she just like Mom?
Their DNA’s the same!
Weird Geneticsso what is GE?
 Selective change of genetic material by man
 Technique of removing, modifying or adding
genes to a DNA molecule
Scientists successfully
genetically engineered a rat to
grow a human ear on its back.
ANDi (DNA inserted spelled
backwards): The first
genetically modified
monkey
Weird Geneticsgm food for thought
 Advantages:
– Pest resistance
– Herbicide tolerance
– Disease resistance
– Cold tolerance
– Drought tolerance
– Salinity tolerance
– Nutrition
– Medicine
Bright face of genetically modified corn
plant: pest-infected non-GM (left) and
pest-free GM plant (right) planted side-byside in a field trial. (photo: Dr. Yu Jialin,
China Agricultural University)
Weird Geneticsgm food for thought
 Disadvantages:
• Environmental hazards
o Unintended harm to other organisms
o Reduced effectiveness of pesticides
• Human health risks
o
Unknown effects on human health
• Economic concerns
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Corporate monopoly
Dependence on GM companies
Monoculture
Weird Geneticsdesign-a-baby?
 Biotechnology critic Jeremy Rifkin: "It's the ultimate
shopping experience: designing your baby.”
 Using genetic technologies to modify embryos and
choose desirable characteristics
 Spare part children?
Weird Geneticsthe genetic menu
MENU
TODAY’S SPECIAL
• TENNIS CHAMPION
$19,000 (LIMITED OFFER!)
APPETISERS
• EYE COLOUR
BROWN $10,000
BLUE $10,500
BLACK $9,500
• HAIR COLOUR
BLACK $9,000
WHITE $10,000
RED $10,500
GREEN $12,000 (MUST TRY!)
Weird Geneticsthe genetic menu
MENU
SIDE ORDERS
• SKIN TONE
• WEIGHT/HEIGHT
$11,000
ENTREES
• BEAUTY
• INTELLIGENCE
• GENDER
$20,000
$23,000
$19,500
MAIN COURSE
• MUSIC PRODIGY $25,000
$9,50O
Weird Geneticsthe genetic menu
MENU
MAIN COURSE
• GREAT ARTIST
• NOBEL PRIZE-WINNING SCIENTIST
• GENIUS PHILOSOPHER
• NEXT PRESIDENT OF AMERICA
$25,000
$26,000
$26,000
$40,000
DESSERT
• WORLD-CLASS SPORTSMAN
• CANCER-FREE BABY
$25,000
FOR FULL BABY MAKEOVER
$1,500,000
$35.000
TERMS AND CONDITIONS APPLY
Weird Geneticsterms and conditions?
 Safety issues
– Genes introduced at random places in genome
– Many genes have more than one effect
– Many traits we want to select are influenced by multiple genes
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Environmental influence?
Discrimination?
Imbalance between rich and poor?
Loss of humanity?
Is it right to experiment on babies?
Other moral complications?
genetic blueprint- Human Genome Project
• Project goals
– Identify all the approximately
20,000-25,000 genes in human DNA
– Determine the sequences of the 3
billion chemical base pairs that
make up human DNA
– Store this information in databases
– Improve tools for data analysis
– Transfer related technologies to the
private sector
– Address the ethical, legal, and social
issues that may arise from project
bibliography
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http://www.youtube.com/
http://www.wikipedia.org/
http://www.bionetonline.org/
http://www.dnai.org/
http://www.science-class.net/
http://www.pbs.org/
http://www.amnh.org/ology/?channel=genetics
http://www.fossilmuseum.net/
http://library.thinkquest.org/
http://www.buzzle.com/
http://learn.genetics.utah.edu/
http://ghr.nlm.nih.gov/
http://www.genetichealth.com/
http://www.biology-online.org/
http://science.howstuffworks.com/
http://www.actionbioscience.org/
http://nature.ca/genome/03/a/03a_10_e.cfm
Thank y u!