Genetics 101

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 dnaA DNA molecule is very long,when stretched out end to end.To fit inside a small cellit’s developed this knack to bend.

The DNA twists ‘round and ‘roundlike 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 loopsthat a ruler would measure as short.

Journey into dnaWe almost see the DNA strandas 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

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

Natural selection Produces adaptations Biodiversity arises by

surviving evolution


Development of antibiotic resistance in microorganisms

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

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


2nd Generation


3rd Generation

3:1


Parent plants

2nd Generation

3rd Generation


DOMINANT RECESSIVE


Parent plants

2nd Generation

3rd Generation

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 arrangementdiscovered 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)

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-classification

Breeding plants and animals for particular genetic traits (desirable characteristics)

Inbreeding depression Reduced genetic diversity

Weird Genetics-selective breeding

The Liger is the result of breeding a female Tiger to a male Lion.

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 Genetics-genetic engineering

Selective change of genetic material by man Technique of removing, modifying or adding

genes to a DNA molecule

Weird Genetics-so what is GE?

Scientists successfully genetically engineered a rat to grow a human ear on its back.

ANDi (DNA inserted spelled backwards): The first genetically modified monkey

Advantages:– Pest resistance– Herbicide tolerance– Disease resistance– Cold tolerance– Drought tolerance– Salinity tolerance– Nutrition– Medicine

Weird Genetics-gm food for thought

Bright face of genetically modified corn plant: pest-infected non-GM (left) and pest-free GM plant (right) planted side-by-side in a field trial. (photo: Dr. Yu Jialin, China Agricultural University)

Disadvantages:• Environmental hazards

o Unintended harm to other organismso Reduced effectiveness of pesticides

• Human health riskso Unknown effects on human health

• Economic concernso Corporate monopolyo Dependence on GM companieso Monoculture

Weird Genetics-gm food for thought

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 Genetics-design-a-baby?

Weird Genetics-the genetic menu

MENUTODAY’S SPECIAL• TENNIS CHAMPION $19,000 (LIMITED OFFER!)

APPETISERS• EYE COLOUR BROWN $10,000

BLUE $10,500BLACK $9,500

• HAIR COLOUR BLACK $9,000WHITE $10,000RED $10,500GREEN $12,000 (MUST TRY!)


MENUSIDE ORDERS• SKIN TONE $9,50O• WEIGHT/HEIGHT $11,000

ENTREES• BEAUTY $20,000• INTELLIGENCE $23,000• GENDER $19,500

MAIN COURSE• MUSIC PRODIGY $25,000


MENUMAIN COURSE• GREAT ARTIST $25,000 • NOBEL PRIZE-WINNING SCIENTIST $26,000• GENIUS PHILOSOPHER $26,000• NEXT PRESIDENT OF AMERICA $40,000

DESSERT• WORLD-CLASS SPORTSMAN $25,000• CANCER-FREE BABY $35.000

FOR FULL BABY MAKEOVER $1,500,000TERMS AND CONDITIONS APPLY

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

Environmental influence? Discrimination? Imbalance between rich and poor? Loss of humanity? Is it right to experiment on babies? Other moral complications?

Weird Genetics-terms and conditions?

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• 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

http://www.youtube.com/

http://www.wikipedia.org/

http://www.bionetonline.org/

http://www.dnai.org/

Thank y u!

Genetics 101

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