12th Class Biology Chapter 9 Biotechnology Short Questions Answer

Genetically engineered becteria have been used to clean up environmental pollutants increase the fertility of soil and kill insect pests.

There are natural enzymes of bacteria which they use for their own protection against viruses.They are called restriction enzymes because thy restricy the growth of enzyme.

Transgenic animals are cloned in order to obtain the product in large quantity.

DNA polymerase used is temperature-insensitive extracted from the bacterium thermus aquaticus which lives in hot springs.Commonly this enzyme is also known as Taq polymerase.

Techniques have been developed to insert genes into the eggs of animals.It is possible to micro inject foreign genes into eggs by hand but another method uses vortex mixing.The eggs are placed in an agitator with DNA and silicon-carbide needles,and the needles make tiny holes through which the DNA can enter.When these eggs are fertilized the resulting offsprings are transgenic animals.

Antithrobin III for preventing blood clot during surgery is currently being produced by a gerd of goats and clinical trials have begun.

There are two main metnods used for gene therapy: i) Ex-vivo ii)in-vivo

After enucleated eggs have been injected with 2n nuclei of adult cells they can be coaxed to begin development.The offspring have the genotype and phenotype of the adult that donated the nuclei therefore the adult has been cloned.

In 1997 scientists at the Roslin Insitute in Scotland produced a cloned sheep called Dolly.

Recombinant DNA technology is used when a very large quantity of a gene is required.The polymerase chain reaction is used to create a lesser number of copies within a laboratory test tube.

Genes can be isolated from the chromosomes by cutting the chromosomes on the flanking sites of the gene using special enzmes known as restriction endonucleases.

The gene of choice can also be synthesized in the laboratory from massenger RNA using reverse transcriptase.This DNA molecule is called complementary DNA.

Bacteria produces a variety of such restriction enzymes which cut the DNA at very specitic sites characterized by specific sequence of four to six nucleotides arranged symmetrically in the reverse order.Such sequences are known as palindromic sequences.

The single stranded but complementary ends of the two DNA molecules are called sticky ends because they can bind by complementary base pairing.

A vector is the means by which recombinant DNA is introduced into a host cell.One common type of vector is a plasmid.

Plasmids are natural extra chromosomal circular DNA molecules which carry genes for antibiotic resistance and fertility etc.One of the plasmids discovered earlier PSC 101 has antibiotic resistance gene for tetracycline whereas PSR 322 has antibiotic resistance genes for tetracycline as well as ampicillin.

The gene of interest is then joined with the sticky ends produced after cutting the plasmid with the help of another special enzyme known as DNA ligase.This enzyme seals the foreign piece of DNA into the vector.

When the two different pieces of DNA have been joined together it is known as recombinant DNA or chimaeric DNA.

A clone can be a large number of molecules or cell or organisms that are identical to an original specimen.

A genome is a full set of genes of an individual.A genomic library is a collection of bacterial or bacteriophage clones each clone containing a particular segment of DNA from the source cell.

A probe is a single stranded nucleotide sequence that will hybridize into a certain piece of DNA.

The PCR is used to create millions of copies of a single gene or any specific piece of DNA quickly in a test tube.Kary B.Mullis developed the polymerasew chain reaction in 1983.

PCR takes its name from DNA polymerase the enzyme that carries out DNA replication in a cell.It is considered a chain reaction because DNA polymerase will carry out replication over and over again.until there are millions of copies of the desired DNA.

DNA Finger printing is a method of identification that compares fragments of deoxyribonucleic acid DNA.

It is the process by which the fragments of DNA can be separated according to their lengths and the result is a number of bands that are so close together that they appear as a smear.However the use of probes for genetic markers produces a distinctive pattern that can be recorded on X-ray film.

In DNA or gene sequencing scientists create many copies of a single-stranded DNA fragment that will be used to synthesize a new DNA strand.Then these will be used to determine sequence of nucleotides.

1) Snager method 2) Maxam-Gilbert method

In this method dideoxy ribonucleoside are used to terminate into DNA synthesis at different sites.

In this method DNA threads are chemically cut into pieces of different sizes.

In order to separate DNA pieces of different sizes on gel dideoxy method is used.

It includes plant chloroplasts and animal mitochondria large numbers of bacteria many of the yeasts a nematode worm Drosophila the model plant Arabidopsis the mouse and human.

The human genome project is massive effort to map the human chromosomes.The genes along the length of each type of chromosome are sequenced and then base pairs are found.

The products produced by genetically engineered organisms are called biotechnology products.Today bacteria plants and animals are genetically engineered to produce biotechnology products.

Organisms that have had a foreign gene inserted into them are called transgenic organisms.

Bioreactors are large vats in which bacteria reproduce when recombinant DNA technology is used to produce them.

Biotechnology products produced by bacteria such as insulin human growth hormone tissue plasminogen activator haemophilia factor VIII,and hepatitis B vaccine are now in the market.

The transgenic organisms used to prevent airborne chemical pollutants from being released into the air are said to be biofilters.For example use of such bacteria in industry.

The plant cells that have had the cell wall removed are called protoplasts.

i) Resistant to pests and herbicides. ii)Improvement of dietary contents.

i) Bovine growth hormone. ii) Producing larger animals.

Gene therapy is the insertion of genetic material into human cells for the treatment of a disorder.

In ex-vivo gene therapy normal gene is give to certain cells of the patient outside the body of the patient and then these cells are returned to the patient.

Bone marrow stem cells are removed from the blood and infected with a retrovirus that carries a normal gene for the enzyme then the cells are returned to the patient.

In in-vivo gene patients are directly given normal genes in one way or the other.

It is a condition that develops when liver cells lack a receptor for removing cholesterol from the blood.The high levels of blood cholesterol make the patient subject to fatal heartl attacks at a young age.

Cystic fibrosis patients lack a gene that codes for trans-memrane carrier of the chloride ion.Patients often die due to numerous infections of the respiratory tract.

In clinical trials researchers have given genes to cancer patient that either make healthy cells more tolerant of chemotherapy or make tumours more vulnerable to it.Once the bone marrow stem cells were protected it was possible to increase the level of chemotherapy to kill the cancer cells.

The balloon catheter is coated with a plasmid that contains a gene for vascular endothelial growth factor.The expression of the gene which promotes the proliferation of blood vessels to bypass the obstructed area has been observed in at least one patient.

Tissue culture is the growth of a tissue in an artificial liquid culture medium.

Plant cells are totipotent which means that each cell has the full genetic potential of the organism and terefore a single cell could become a complete plant.

The name of the enzyme is reverse transcriptase.

It is an enzyme that binds to specific short sequences of four to six nucleotides of DNA and cuts the DNA at or near this point. Such enzymes are produced by certain bacteria in response to invasion by bacteriophage. They destroy the virus by cutting up its DNA.

These are the sequences of base pairs of the nucleotides repeated at many different places throughout the chromosomes.

Vectors are the carrier molecules which are used to introduce the recombinant DNA into the host cells, in genetic engineering.

The plasmids are extra chromosomal circular DNA molecules found in bacteria which are common vectors being used in recombinant DNA technology. They themselves carry genes for antibiotic resistance and fertility etc.

pSC 101 has antibiotic resistance gene for tetracycline whereas pBR 322 has antibiotic resistance genes for tetracycline as well as ampicillin.

The restriction enzyme cuts open the plasmid ring for the preparation of recombinant DNA during genetic engineering.

The DNA ligase serves to attach desired genes to the sticky ends (open ends) of the plasmid ring, thus closing it again.

The vector along with the attached foreign genes is known as recombinant DNA and the technique for such attachment is called as recombinant DNA technology.

It is Chimeric DNA.

The DNA of the bacteriophages (lambda phage) can also be used as a vector.

The total number of different genes found within the cell of an individual is called its genome (or genetic material or hereditary material).

The genomic library is a collection of bacterial of bacteriophage clones, each of which contains a particular segment of DNA from the donor cell.

Totipotency is the capacity of an isolated cell to form a complete plant because it has the full genetic potential of the organism.

A German botanist, Gottleib Haber land said in 1902 that the plant cells are totipotent.

A botanist, F.C. Steward grew a complete carrot plant from a tiny piece of phloem in 1958.

It is the cytokinin.

The protoplast is the plant cell without cell wall.

It is the system of growing single cells or small clumps of cells in a liquid growth medium that is kept agitated by means of bubbling, shaking of stirring so that the cells do not settle out.

These are respectively the quinine and digitoxin.

The crossing of different varieties (or even species) to produce plants with desirable traits is called hybridization.

The Lucifer in is a protein-like substance found in the luminous organs of certain animals like firefly Luciferase is the enzyme that contributes to light production from the Lucifer in.

It is a condition of having excessive cholesterol in the blood in certain families that is caused when liver cells lack a receptor for removing cholesterol from the blood.

A small portion of the liver is surgically excised (cut) and is infected with a retrovirus containing a normal gene for the receptor needed to remove cholesterol from the blood.

Cystic fibrosis is a fatal genetic disease that is characterized by secretion of thick mucus that blocks passages in the lungs, liver and pancreas.

The plastic surgery of blood vessels is known as angioplasty.

The examples of ex-vivo gene therapies in man are the severe combined immunodeficiency syndrome, hypercholesterolemia, cystic fibrosis, cancer and coronary artery angioplasty whereas those of in-vivo therapies are hemophilia, diabetes, Parkinson’s disease and AIDS.

It can be cured by grafting dopamine-producing cells directly into the patients brain.

Tissue culture is the growth of a tissue in an artificial liquid growth medium.

The desirable genes can be isolated from the chromosome or synthesized chemically or made from messenger RNA.