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Why do we learn this topic?

• State the unit of inheritance;• State the location of genes;• Describe the structure of DNA;• Describe the manifestation of a trait of an organism from the basic unit of inheritance;

• Explain the importance of genetics to mankind;

• Describe the application & abuse of knowledge in genetics;

• Argue on the need for ethics & morals in the application of genetics

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GENES & CHROMOSOMESGENE•A unit of inheritance that controls a specific trait.

•A functional segment of DNA located at a particular place on the chromosomes.

•Subunits of DNA are called nucleotides.

•Consist of three units :•A pentose sugar•A phosphate group•A nitrogenous base

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PENTOSE SUGAR

NITROGENOUS BASE

PHOSPHATE GROUP

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•Nucleotides can combine by condensation reactions to form a long polynucleotide chain.

•1953, James Watson & Francis Crick proposed that the DNA molecule consists of two polynucleotide chains running in opposite directions.

•Two polynucleotide chains are held together by hydrogen bonds that form between the protruding bases ladder-like structure

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• The polynucleotide chains in the DNA molecule are not straight double helix.

• Nitrogenous bases in DNA :– A (adenine), T (thymine), C (cytosine) & G (guanine).

– A always bond with T, & G with C by hydrogen bond.

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THE MANIFESTATION OF A TRAIT OF AN ORGANISM

• Gene occupies a specific position gene locus on a chromosome.

• Gene = a DNA segment = a particular sequence of nucleotides code for the synthesis of a specific polypeptide chain @ protein in an organism.

• Most chemicals in an organism are manufactured with the aid of enzymes (proteins).

• DNA can determine the traits of an organism.

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• Have wide implications to mankind.

• Genetic research has concentrated mainly on two fields:–Selective breeding–Biotechnology & genetic engineering

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SELECTIVE BREEDING

• To produce offspring that give DESIRABLE characteristics such as:– Increased crop yields– Products with higher nutritional value– Greater resistance to pathogens– Resistant to insecticides or pesticides– Shorter maturity time, more offspring can

be produced– Better adapted to local environmental

conditions.

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SELECTIVE BREEDING OF OIL PALM PLANTSDURA PISIFERA

GOOD FEATURE•Buah tidak mudah gugur sblm masak

BAD FEATURES•Thick shell•Less content of olein

GOOD FEATURE•Thin shell•High content of olein

BAD FEATURES•Buah mudah gugur sblm masak

TENERAGOOD FEATURES

• Thin shell•High content of olein

•Buah tidak mudah gugur

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DNA FINGERPRINTING

• A technique used to distinguish between individuals of the same species using only samples of their DNA.

• Only 5% of genes code for proteins, 95% are non-coding microsatellites.

• Two unrelated individuals different number of microsatellites at a given locus, except identical twins.

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PROCEDUREDNA extract from sample

(blood cells, semen @ hair)

DNA is cut into fragments by DNA restricted enzymes

The DNA fragments are separated by electrophoresis

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DNA FINGERPRINTINGDNA is heated to separate the double

strands. The copy is transferred to nylon membrane. Radioactive probes are

applied

An X-ray film is placed on the nylon membrane.

A characteristic pattern of the DNA fragments (DNA fingerprinting) is

produced

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HUMAN GENOME PROJECT• An organism’s complete

set of genes made up of DNA nucleotide bases.

• The Human Genome Project (HGP) was started in 1998.

• Formerly founded by US in 1990, later it became an international effort involving geneticist from UK, France, China, Japan, & Germany.

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HUMAN GENOME PROJECT

•The human genome consists of 30,000 genes.

•April 2003, 99% of the gene-containing regions of the genome have been map

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Benefits of HGP•Understanding the mechanism of a

genetic disease & eventually conquering it.

•Helps geneticist predict which individuals have an increased susceptibility to disorders (cancer, heart disease, diabetes) results from complex interaction between genes & the environment

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POTENTIAL STEM CELL RESEARCH

• STEM CELL = relatively undifferentiated cells that can develop into different types of cells in the human body.

• Stem cells mitosis differentiate specialised cells (erythrocyte, muscle or neurone)

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TYPES OF HUMAN STEM CELLS

• Adult stem cells small numbers in tissues or organ– Found in specific areas remain non-dividing

until activated by disease / tissue injury.– Found in bone marrow, blood vessel, skin,

skeletal muscle & liver.

• Embryonic stem cells inner cell mass of the blastocyst.– Can develop into all tissues except gametes.– Greater developmental potential.– Genetically identical to the host avoided

rejection.

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Advantages of sc research

• Specific cells / parts of the body can be grown from stem cells. To treat diseases such as diabetes, Parkinson’s disease, Alzheimer’s disease & some forms of cancer.

• Can be used instead of humans to test the wide range of new drugs, some of which may have toxic side effects.

• Developmental embryonic stages can be studied using stem cells from embryos.

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Disadvantages of sc research

•Adult stem cells do not differentiate easily

•Some scientist prefer to use stem cells extracted from embryos.

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GENETIC ENGINEERING • The modification of the

characteristics of an organism by manipulating its DNA.

• A DNA molecule from an organism is cut into fragments using specific enzymes inserted into cells of another organism

• Possible to transfer fragments of DNA from one organism to another.

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APPLICATION OF GENETIC ENGINEERING

• Gene Therapy– The insertion of genes into an individual’s

cells / tissues to treat a hereditary disease.

– To correct faulty genes

– Being developed for single gene disorders sickle-cell anaemia, muscular dystrophy, Huntington’s disease & cystic fibrosis.

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APPLICATION OF GENETIC ENGINEERING

• Genetically Modified Organisms (GMO)– Plants, animals @ microorganisms with

genetic codes that have been altered, subtracted @ added

– Example: the transfer of a gene for luciferase (enzyme allows fireflies to glow) into a tobacco plant) glow in the dark.

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GENETICALLY MODIFIED FOODS (GMF)

• Tomato yang biasanya mudah rosak dan kulit berkedut dengan cepat telah diubahsuai secara genetik pada tahun 1994 dan telah dipasarkan.

• Di Amerika, gen kaktus telah dipindahkan ke dlm kromosom gandum.

• Gen drpd ikan Flounder yg dpt hidup dibawah 0oC dlm lautan Artik dipindahkan ke dlm kromosom tumbuhan.

• Di Malaysia (1997), kacang soya telah diubahsuai genetiknya supaya tahan racun herba.

• Tumbuhan lain yg juga telah diubahsuai secara genetik dan telah dijual dipasaran adalah kacang soya,kubis bunga, jagung gandum dsb.

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PRODUCTION OF MEDICINE• Genetically modified form of insulin by

Escherichia coli.• Insulin gene removed from human DNA

inserted into bacteria reproduce more human insulin

• Keadaan tumbesaran fetus yg sedang membesar boleh dikesan.Beberapa penyakit keturunan (Thalassaemia,Hungtington,Cystic fibrosys dsb) boleh dikesan pada peringkat awal melalui kejuruteraan genetik

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Abuse of knowledge in genetics• GM products may take months @ years

before the harmful side effects show up.• May become harmful production of

allergen.• Transplant gene may activate oncogenes

in humans & cause cancer.• Food may contain an animal gene

objectionable to vegetarians.• Etc.

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Ethics & Morals in the Application of Genetic

• Should cloning of humans be allowed?

• Do consumers have a choice of eating natural food of GMF?

• What are the pros & cons of rapid advances in genetics.

• Etc.

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Sindrom Turner

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Sindrom Turner

1 drpd 2500 org

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Sindrom Klinefelter

1 drpd 500 @ 1 drpd 1000 org

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Sindrom Down

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