DNA and BIOTECHNOLOGY

- DNA is the molecule that stores genetic information.

- It is a chain (polymer) of smaller molecules (monomers) called

NUCLEOTIDES.

- Each nucleotide is formed by a sugar (deoxyribose), a nitrogenous

base (A, T, C, G), and phosphoric acid.

- There are four different types of nucleotides, depending on the base.

- DNA is a DOUBLE HELIX of two nucleotide chains.

- The two chains are linked thanks to the bonds

formed between the bases:

A is always paired to T we say they are

G is always paired to C COMPLEMENTARY

James Watson and Francis Crick discovered the double helix

structure of the DNA in 1953, and won the Noble Prize in 1962.

Genetic information is stored in the SEQUENCE OF NUCLEOTIDES

of the DNA (that is, their order in the chain)

DNA REPLICATION: making two exact copies of a DNA molecule

1.- The helix uncoils and the two strands separate.

2.- The free nucleotides in the nucleus pair with the nucleotides of

each chain, according to the complementary rules (A-T, G-C).

3.- The new nucleotides join to form the new strands.

4.- In the end, two identical molecules of DNA are obtained: each

of them has an old strand and a newly-formed strand. That is why

we say that DNA replication is semi-conservative.

REMEMBER:- Genes are fragments of DNA that have the information needed to produce a

protein. Genes are sequences of bases (ATTGCCTAG...) and they form a

person's genotype.

- Proteins are the molecules that do the different jobs in the cells. They are

made of 20 different types of amino-acids joined in chains. Two proteins are

different depending on the composition and order of their amino-acids

(sequence of amino-acids) They are responsible of a person's phenotype.

- So, the sequence of bases of DNA will be used as a template to build

proteins (sequence of amino-acids).

How is genetic information used in the cell?:

GENES AND PROTEINS: TRANSCRIPTION AND TRANSLATION

Transcription: the genetic information stored in the DNA is copied to a

RNA molecule called mRNA (messenger RNA). This goes out of the

nucleus into the cytoplasm.

RNA is a single-strand molecule of polinucleotides. It has ribose instead of

deoxy-ribose, and U instead of T.

Translation: the genetic information that the RNA carries (in the

sequence of bases) is read in the cytoplasm by the ribosomes, which use it

as a template to synthesise proteins.

A group of 3 nucleotides (CODON or TRIPLET) codifies an amino-acid

Ala

GENETIC CODE:

- A 3 letters (codon) code.

- UNIVERSAL: shared by

all living beings.

- DEGENERATE: one

amino-acid is codified by

more than one codon (=

the genetic code is

redundant)

- 3 stop codons mark the

end of protein synthesis.

MUTATIONS are changes in the DNA: These changes happen RANDOMLY and naturally, although there are some

MUTAGENIC AGENTS or MUTAGENS that increase their frequency:

- RADIATIONS (X-rays, gamma-rays, UV-rays)

- some chemicals like mustard gas and many chemicals in tobacco

- pollutants in the environment

Mutations in somatic cells

cause alterations, diseases

(cancer...) but ONLY MUTATIONS IN GERMINAL CELLS (GAMETES) MAY BE TRANSMITTED TO THE NEXT GENERATION (INHERITED)

Most mutations are harmful, or even deletereal for the individuals that carry them.

But some may be beneficial and give them an advantage to survive and reproduce.

Mutations increase genetic diversity, which allows the EVOLUTION of species.

Point mutations (change in a

single base):

- insertion

- deletion

- substitution

TYPES OF MUTATIONS:

Silent mutations don't change the sequence

of amino-acids in the protein. This is possible

thanks to the degeneracy of the genetic code.

AN EXAMPLE OF MUTATION: SICKLE CELL ANAEMIAA mutation in the gene of haemoglobin produces an abnormal protein that

makes red blood cells stiff and sickle-shaped instead of flexible and disc-

shaped. This sickle cells can block the bloodflow in the capilaries.

Mutations can also happen with fragments of chromosomes. Or

even whole chromosomes or whole sets of chromosomes

Humans have 23 pairs of chromosomes, while

all the other apes have 24. Human

chromosome 2 is thought to have resulted from

the fusion of two ancestral chromosomes.

What is Biotechnology?Biotechnology is the use of living organisms or

molecules obtained from them to develop products

that are useful for the people, the industry or the

environment.

BIOTECHNOLOGY

RED BIOTECHNOLOGY:Applied to HEALTHCARE

e.g. treating diseases,

designing organisms to

produce antibiotics

gene therapy, etcBLUE BIOTECHNOLOGY:Applied to MARINE and

FRESHWATER ORGANISMS

e.g. increasing food supplies,

controlling proliferation, etc

GREEN BIOTECHNOLOGY:Applied to AGRICULTURE

e.g. transgenic plants resistant to

pests and diseases, with increased

nutritional value, and other

improvements

WHITE BIOTECHNOLOGY:Applied to INDUSTRIAL

PROCESSES

e.g. producing enzymes and

other chemicals

And others:

BIOINFORMATICS, etc

BIOTECHNOLOGY IN HISTORY:- For ten thousand years fermentation has been used

to produce wine, beer and bread.

- Selective breeding of animals such as horses and

dogs has been going on for centuries.

- Selective breeding of essential foods such as rice,

corn and wheat have created thousands of local

varieties with improved yield compared to their wild

ancestors.

Nowadays, biotechnology uses GENETIC ENGINEERING techniques to transfer

genes from one organism to another, in order to improve its properties or produce useful products. Genetic engineering has some important advantages:

- Genetic engineering allows us to transfer only the precise isolated gene we are interested in, and not

the whole genome.

- Also, it allows us to transfer genes between

organisms of different species.

The gene that is transferred from one organism to the

other is called a TRANSGENE. The organism that are

obtained with this technique are GENETICALLY MODIFIED ORGANISMS (GMO), and the DNA that

contains fragments of different origins is

RECOMBINANT DNA.

Cloning a Gene: isolating a gene and producing many copies of it in another organism.A plasmid from a bacterium can be used to clone a gene of interest from another

organism

After cloning it in a host cell,

multiple copies of a gene of interest

can be harvested.

The cloned genes are useful for

basic research, and their proteins

can be applied to many uses.

- Pest resistance in plants.

- Cleaning up toxic waste.

- Proteins that dissolve blood clots.

- Human growth hormone (HGH).

APPLICATIONS OF BIOTECHNOLOGY:1.- DRUG PRODUCTION- ANTIBIOTICS

- HUMAN INSULIN

- GROWTH FACTOR

- COAGULATION FACTOR VIII

- VACCINES (Hepatitis A, B)

2.- GENE THERAPY

3.- BIOSENSORS:Analytical devices that give us information about our organism with a

non-invasive procedure.

The enzymatic oxidation of glucose produces

hydrogen peroxide, which in turn generates

electrons by electrode reaction. The current

density is used as a measure of glucose in

the sample.

4.- AGRICULTURE AND FOOD PRODUCTION:

Genetic Engineering allows us to introduce one or a few

known genes into a plant, giving it the desired qualities

that traditionally we would obtain by random crossing.

Through these techniques we can obtain new crops (ie. rice, cotton, corn, soy,

tobacco, tomatoes, sugar beet) with new features such as:

- plague or herbicide resistances

- higher tolerance to adverse conditions (droughts,

temperatures, salinity)

- faster growth, higher efficiency

- new industrial applications: biodegradable

plastics, bioplastics – plastics made of

vegetables-, edible vaccines; Euro notes are made

of transgenic cotton.

Bt corn incorporates a gene of a soil bacterium called Bacillus thuringiensis and

so it is able to produce a protein “Bt toxin” that kills Lepidoptera larvae, in particular,

European corn borer.

Growers use Bt corn as an alternative to spraying insecticides for control of this

plague.

Biotechnology may be applied to any of the steps in the food production chain:

- improvements in the foods: golden rice (genetically modified to contain beta-

carotene, a source of vitamin A that may prevent blindness caused by malnutrition)

- new products with new scents and additives

- enriched foods (in vitamins, fibre...)

- detection of pathogens

- detection of alimentary frauds

- Transgenic animals are more difficult

to develop than plants.

- To obtain GM animals, we inject the

desired genes in the ovule, so alll the

cells in the animal will inherit it.

- We can produce drugs (ie. Factor IX

in sheep milk) or animal models to

study human diseases.

.

5.- BIOTECHNOLOGY IN VETERINARY

- We can also clone a whole animal by injecting the nucleus of a cell from an

individual in the previously enucleated zygote of another. Dolly the sheep was the

first animal that was clonned in this way (1996-2003)

6.- ENVIRONMENTAL BIOTECHNOLOGY- treatment of waste waters

- degrading the hydrocarbons in black tides /oil spills

- removal of heavy metals (As, Pb, Hg) from the soil

BIOFUELS- fuels obtained from living beings or organic matter that help

reduce the use of fossil fuels

- BIODIESEL: from oily seeds. It is used mixed with normal diesel.

- BIOETANOL: an alcohol obtained from the fermentation of sugars

(sugar cane, sugar beet, corn...)

- BIOGAS: mixture of methane and carbon dioxide obtained from

the bacterial decomposition of organic wastes.

SOCIAL/ETHICAL ASPECTS

- EFFECTS ON GENETIC BIODIVERSITY- POSSIBLE GENE TRANSFER FROM TRANSGENIC TO WILD

PLANTS

- EFFECTS ON HUMAN HEALTH ??

What Do YOU Think?