Biology Chapter 12 Biotechnology And Its Applications

2. Production of genetically modified plants and animals.

(ii) The milk was enriched with human alpha-lactalbumin.

(ii) Aspergilus niger a fungus.

1. Providing the best catalyst in the form of improved organism usually a microbe or pure enzyme.

2. Creating optimal conditions through engineering for a catalyst to act, and

3. Downstream processing technologies to purify the protein/organic compound.

(1) Their genes are altered by manipulation.

(2) They have incresed resistance to pests and can tolerate abiotic stresses more efficiently.

(3) They have high nutritional value.

(4) They may produce biological products which help in curing diseases.

(i) Therapeutics (ii) Genetically modified crops

(iii) Molecular diagnostics (iv) Processed food items.

(v) Bioremediation (vi) Gene therapy.

(vii) Vaccine production.

2. Cloned gene can be used to detect antibodies or antigens in infections. Like in ELISA which is based on antibody-antigen interaction.

Steps of ELISA

1. A micro titer plate is coated with antigen.

2. Primary antibody specific to antigen for diagnosis  is added to the plate. The antibody interacts with the antigen. then the plate is washed to remove any extra free antibody.

3. Secondary antibody which has a tag  is then added  to the well. The secondary antibody attaches to the primary antibody. The plate  is washed to remove free secondary antibody.

4.Chromagen is added which produces color and aids in detection.

1. Human insulin.

2. Vaccines .

Synthesis of insulin in humans-:
i. Insulin is synthesised as an inactive form pro-insulin which contains an extra stretch called the C peptide. 
ii.This pro-insulin is cleaved.
iii. C-peptide is removed and
iv. The two chains A and B  are joined by disulfide bridges  to form mature insulin.

  Fig.-  Proinsulin which contain C-peptide is cleaved and C-peptide is removed and the Two chains A and B are joined to by disulfide bridges to form insulin.

E.coli can be used to produce human insulin in the following way.
1. Gene encoding for the production of insulin in humans is isolated. Like the gene for two insulin chain A and B are isolated.
2. The desired genes are introduced in plasmids of  two E.coli.
3. Since the plasmid is self replicating the introduced gene is expressed and the two chains A and B are formed separately. 
4. These chains are extracted
5. They are joined by creating disulfide bonds to form insulin.

1. They are highly specific, relatively rapid and much simpler.

2. They fascilitate detection because they have a tagged radioactive molecule.

3. They help in detecting even a single mutation in gene.

(a) Recombinant therapeutics are very effective and more potent.
(b) The recombinant therapeutics are safe and  do not induce unwanted immunological responses like similar products of non-human origin.

About 30 recombinant therapeutics have been approved world over.

12 of them are being marketed in India.

2. Economic- The transgenic crops have a high yield  and vaccines produced by genetic engineering can prove economical and highly useful.

3. Environmental - Genetically engineered microbes are used to clear oil spills and also increase the fertility of soil.

(b) Animals as organ donors for human. Organ transplantation from animal to humans is called as xenotransplantation. Usually baboons are used for transplantation as they are closely related to humans and chances of rejection are less.

(ii) Humulin. It is the human insulin made using  E.coli and recombinant DNA technology 

(iii) Biofortified foods. They are food rich in nutritional values produced using genetic engineering.

Example. Transgenic bacteria like E.coli which produces insulin. This bacteria is genetically manipulated by introducing two DNA sequences corresponding to A and B chains of human insulin in plasmids of E. coli to produce insulin chains. Chains A and B produced separately are extracted and  combined by disulfide bonds to form human insulin.

Orally active protein pharmaceuticals are biologically active protein or peptides  administered orally for the treatment of various diseases.
Orally active proteins pharmaceuticals  are made by encapsulating the protein or peptide in liposomes or formulations. The encapsulation fascilitates their delivery.
The major problem encountered with orally active protein is that they are degraded by the proteases present in the stomach and thus their effect is nullified. 

(b) Biopatent. is a patent right granted for a invention in the field of biology by a Government to an inventor to prevent others to make commercial use of their invention. 

(c) Bioethics. Bioethics is the study of ethical issues that come up  with the advances in the field  of  biology

(d) Biopiracy. Exploitation of  biological resource  by others without proper permission and without providing compensation from the people or country concerned.

(e) Genetically Modified Food. The food produce by genetically modified crops is called genetically modified food (GM food). 

(i) Transgenic animals are designed to allow the study the regulation and functioning of gene.

(ii) Transgenic animals are designed to understand  the development of diseases and their detection.

(iii) Transgenic animals are used to produce useful  biological compounds .

(iv) Transgenic animals are used to test the safety of vaccines.

1.The transgeniv animals that are used as model are only produced to solve the purpose and usually suffer alot.

2. Crossing species or recombinant species is unnatural, immoral.

3. Transgenic animals can have unpredicatable results when such organisms are introduced into the ecosystem.

4. The use of non human gene in humans and human cloning is socially unacceptable.

Gene Therapy. It is defined as the introduction of a normal functional gene into cells which contain the defective gene with the objective of correcting a gene defect that has been diagnosed in a child/embryo.

For example - Treatment of ADA deficiency by gene therapy. Adenosine deaminase is an enzyme crucial for funtioning of immune system. Gene therapy has been used to cure the deficiency of ADA enzyme
1. By growing the lymphocyte from blood cells of patient in culture outside the body.
2. A funtional ADA gene is introduced in the cultured lymphocyte using retrovirus.
3.The transformed lymphocytes are then returned to the patient.  
4. Thus the cells now contain funtional gene for the enzyme and deficiency is cured.

1. The specific genes  from the parasite are introduced into the plant using Agrobacterium as the vector.

2. The introduced gene produces both sense/coding RNA and antisense RNA .

3. The two RNA being complementary anneal and become double stranded RNA.

4. This ds RNA initiates RNAi and silences the mRNA of the nematode. 

5. As a result, the parasite cannot live in the transgenic host and the transgenic plant is protected from the pest.

(ii) It also ensure the safety of introducing GM-organism for public services.

C.

D.

B.

A.

B.

B.

D.

C.

D.

D.

A.

D.

C.

C.

C.

Plant cells are considered suitable for the gene guns to introduce an alien DNA.

Agrobacterium is a pathogen that affects several dicots and delivers a piece of DNA known as ‘T-DNA’ to transform normal cells to tumor cells. This potential of Agrobacterium has been used to transfer desired gene into the plant. The desired gene is inserted in the T-DNA region and the bacterium is allowed to infect the plant. In this way, the desired changes are made in the plant.

Sticky ends are produced by restriction enzymes. These enzymes cut the strand of DNA a little away from the centre of the palindrome sites but between the same two bases on the opposite strands. This leaves single-stranded portions at the ends. These overhanging stretches are called 'sticky ends'. 

RNA Interference (RNAi) is a gene-silencing process that is used for cellular defense in all eukaryotic organisms. RNAi has been used to control the nematode Meloidegyne incognitia that affects the roots of tobacco plants in the following way:

 Using Agrobacterium vectors, nematode specific genes were introduced in the host plant. The genes were introduced in such a way that it produced both sense and anti-sense RNA in the host cells. The two RNA’s being complementary to each other form a double-stranded RNA dsRNA that initiates RNA interference and silences mRNA that is it inhibits mRNA expression. The nematode is not able to survive in the host which expresses specific interfering RNA and thus the plant is protected from the nematode.

Biopiracy is the use of bio-resources by multinational companies and other organisations without proper authorisation from the countries and people concerned without compensatory payment.

Preparation of Human Insulin Using Recombinant DNA Technology

DNA fingerprinting is the modern scientific method used for the identification of kinship. Variable Number of Tandem Repeats (VNTR) are satellite DNAs that show high degree of polymorphism. They are used as probes in DNA fingerprinting.

Procedure of DNA Fingerprinting:

i. Firstly, DNA from the individual and closest relative is isolated and cut with restriction endonucleases.

ii. Fragments are separated according to their size and molecular weight through gel electrophoresis of both the individual and the relative.

iii. Fragments separated through electrophoresis gel are blotted (immobilised) on a synthetic membrane such as nylon or nitrocellulose.

iv. Immobilised fragments are hybridized with a VNTR probe.

v. Hybridised DNA fragments can be detected by autoradiography. The autoradiograph of the individual and the relative is compared.

VNTRs vary in size, ranging from 0.1 to 20 kb. Hence, in the autoradiogram, a band of different sizes will be obtained. These bands are characteristics of an individual. They are different in each individual, except in the case of identical twins. The presence of similarities, between the individual and the relative helps to determine the kinship.

Hence the body of the individual can be handed over to their relatives.

(i) PCR - Polymerase Chain Reaction. It is used to amplify the gene of interest.

(ii) ELISA - Enzyme linked Immuno-sorbent Assay. It is widely used as diagnostic test for AIDS.

The difference between the mode of action of endonuclease and exonuclease is that Exonuclease removes nucleotides from the ends of the DNA whereas Endonuclease makes cut at specific positions within the DNA.

(b) Restriction endonuclease functions by inspecting the entire length of the DNA sequence. When it finds the specific recognition sites it binds to the DNA molecule and cuts both the strands at specific palindromic sites in their sugar-phosphate backbone.

e.g. Eco R1 cuts the DNA at following pallindromic sequences.

               |

        5' G A A       T T C   3'

        3' C T T       A A G 5'

                                   |  

(a) Transgenic animals are so called because they have their DNA manipulated and thus they possess and express foreign gene.

(b) Role of transgenic animals in :

(i) Vaccine safety

Transgenic mice are being developed and used to test the safety of the vaccine before they are used on humans.

 (ii) Biological products

(a) DNA ligase is an enzyme which is used to join two DNA fragments.

Stanley Cohen and Herbert Boyer conducted one of the first genetic engineering experiments. They invented the technique of DNA cloning. Cohen developed a method of removing plasmids from the cell and then reinserting them in other cells. Combining this process with that of DNA splicing enabled Boyer and Cohen to recombine segments of DNA in desired configurations and insert the DNA in bacterial cells, which could then act as manufacturing plants for specific proteins. Stanley Cohen and Herbert Boyer accomplished this in 1972.

The Bt toxin is encoded by the cry gene. The cry I AC and cry II Ab control cotton bollworms, while the cry I-Ab controls corn borer. Bt gene produces Bt toxin. This toxin provides resistance to plants against lepidopteron, coleopterans and dipterans pests.

An example is Bt cotton, in which the gene from the bacterium that encodes for the toxin is incorporated. The activated Bt toxin binds to the surface of the midgut epithelium of the insects and causes swelling and cell lysis, which eventually leads to the death of the insects.

(a) This representation is of a normal person because in a normal person the mRNA contains the codon GAG at 6^th position which codes for glutamic acid .

(b) In a sufferer, the codon GAG is replaced by GUG at the 6^th position in the mRNA. Hence, during translation of the defective mRNA, Glutamic acid is replaced by Valine.

(c) The disease represented by the defect in the given gene is sickle-cell anaemia which is an autosomal recessive trait. This disease is transmitted to the progeny when both the parents are carriers for the disease (heterozygous). Since it is an autosomal recessive trait both males and females are equally at risk to develop the disease.

The Restriction sites mentioned in the figure are Hind III, EcoR I, BamH I, Sal I, Pvu II, Pst I, Cla I (any two can be considered)

Antibiotic resistant genes: amp^R and tet^R

Gene therapy can be used to correct hereditary diseases. It involves delivery of a normal gene into the individual or embryo to take over the function of and compensate for the non-functional gene.

The first clinical gene therapy was given in 1990 to a 4-year old girl with adenosine deaminase (ADA) deficiency. In this disease, the gene coding for enzyme ADA gets deleted leading to deficiency of ADA and problems in immune system. Gene therapy for ADA deficiency includes isolation of lymphocytes from patient’s blood, culturing them in-vitro, introduction of functional ADA cDNA and returning the cells to the patient’s body.

Satellite DNA consists of highly repetitive and generally non-coding DNA. It is very significant in DNA fingerprinting for the following reasons:

i. It shows high degree of polymorphism which forms the basis of DNA fingerprinting

ii. Different tissues in the body show the same degree of polymorphism and thus are useful as an identification tool in the forensic application.

iii. They are inheritable from parents to offsprings and  can be used for paternity testing.

American Company Eli Lilly used the knowledge of r-DNA technology to produce human insulin in the following way.

C-peptide is the extra stretch of polypeptide which makes the insulin inactive (proinsulin).

(a) Transgenic animals can be used for the production biological products which are otherwise expensive to make. For example Rosie the transgenic cow produced human protein enriched milk. The milk contained human alpha-lactalbumin and thus was nutritionally more balanced for human babies than natural cow milk.
(b)Transgenic animals are made that carry genes which make them more sensitive to toxic substances than non-transgenic animals. They are then exposed to the toxic substances and the effects studied. Toxicity testing in such animals will allow us to obtain results in less time.

Plant breeding and improvement of crops is well supported by the governments and private companies. The major steps involved in the process are –
1. Collection of variability
2. Evaluation and selection of parents
3. Cross hybridisation among the selected parents
4. Selection and testing of superior recombinants
5. Testing, release and commercialisation of new cultivars

1. Collection of variability -Genetic variability is the primary requirement of breeding program, the wild character of plants is collected, preserved and characteristics for exploring natural genes called as germplasm collection.

2. Evaluation and selection of parents -The collected germplasm is then screened for the desirable character, followed by their multiplication and preparing for hybridization to obtain pure line.

3. Cross hybridisation among the selected parents
- Different characters are combined with two different parents e.g high quality protein gene is combined with disease resistant gene and developed a new cross hybrid.
4. Selection and testing of superior recombinants -The best combination is selected among the progeny; selection should be done very crucially with help of scientific community. The plant obtained in this step is superior to both parental plants. The plants are self-pollinated to obtain uniform generation, where character remains intact in the progeny.
5. Testing, release and commercialisation of new cultivars - Newly selected plant are evaluated (disease resistance, quality) by growing in research field and recognize management, irrigation requirement, followed by cultivation of the crop for 3 seasons under different climate. Then the plant is evaluated with present crop and defined useful or not.

(a) ADA (Adenosine deaminase) is an enzyme crucial for immune system. Its deficiency is caused due to the deletion of the gene coding for adenosine deaminase. Immune system is affected by ADA deficiency in humans.

Animals that have had their DNA manipulated to possess and express an extra (foreign) gene are known as transgenic animals.
For example - Transgenic cow like Rosie. 

 Enzyme replacement therapy
In enzyme replacement therapy functional ADA is given to the patient by injection
1) Lymphocyte from the blood of the patient are given in a culture outside the body
2) A functional ADA cDNA ( using a retroviral vector ) is introduced into the lymphocyte , which are Returned to the patient.
3) These cells are not immortal , the plant require them periodic infusion. 4) If the gene isolate from marrow cells producing ADA is introduced into the cells at early embryonic stage, it could be permanent cure.

TWO DISADVANTAGES OF THIS PROCEDURE
i.These cells do not always remain alive.
ii. Patient required periodic infusion of genetically engineered lymphocyte.

(A) It is necessary to make cell competent in order to enhance the efficiency of cell to take up foreign DNA easily.
When the cell is treated with a specific solution of divalent cation calcium. It increases the efficiency of the cell to take up the foreign DNA through the pores in the cell wall.
(B) Biolistics and Gene gun is one of the methods to transfer the foreign DNA into the host.
In this method the suitable plant cells are bombarded with high-velocity micro-particles 
of gold & tungsten coated with DNA. 

A genetically modified organism (GMO) is a living organism whose genes have been altered by biotechnological manipulation. 

i. GMO are free from the diseases, resistant to pest or insects and thus reduce the dependency on chemical fertilisers or pesticides.
ii. GMO crops are more tolerant to abiotic stress, which can be in the form of cold, drought, heat or salt.
iii. The crops have a high yield and high nutritional value.
iv. It reduces post-harvest losses.
v. It increases the efficiency of mineral usage by plants and prevents early exhaustion of soil. 

The introduction of DNA using the Agrobacterium vectors into the host plant produced both sense and anti-sense RNA in the host cells. The RNAi (RNA interference method was initiated as the two RNA's were complementary to each other and formed double-stranded RNA. The dsRNA silenced the specific mRNAof the nematode and thus the parasite could not survive in the transgenic host plant. The plant was therefore protected from the parasite. 

Agrobacterium tumafaciens is known as a natural genetic engineer of a plant because it has the natural ability to integrates its plasmid genes into the plant genomes. It can deliver a piece of T-DNA in the plant genome. 

Rosie was a transgenic cow. It was considered different from a normal cow as it produced human protein enriched milk. The milk contained 'human alpha-lactalbumin' and was nutritionally a more balanced product for human babies than the normal cow milk. 

Biodiversity is very instrumental in development of agriculture –
1. It helps in the conservation and promotes farming of all wild and native variety of plants.
2. Agricultural biodiversity is the base of our agricultural food chain, development and safeguard of live-stocks etc. For ensuring food security to all peoples.
3. It promotes sustainable management of agricultural resources. 

1. Shoot tips or meristem of the plant
2. The virus free healthy sugarcane plants are obtained through the Meristem culture of the diseased plants. The meristematic tissues are free from viruses and are used as an explant for micropropagation.

Steps in Meristem Culture

i. The shoot tip explants are grown in a nutrient medium in either a test tube a Petri dish under aseptic conditions.
ii. The nutrient medium consists of a carbon source, inorganic salts, vitamins, amino acids and growth regulators like auxin and cytokinin in proper define ratio.
iii. The plantlets obtained are transferred to the nurseries and then sent to the fields.
3. Micropropagation is the technology used for the crop improvement. 

The application of Glomus to agricultural field increases the farm output by increasing the nutrient availability to the crops. Glomus develops symbiotic association with the roots of plants, called mycorrhiza. It absorbs phosphorus from the soil and passes it to the plants it associates with. In return, it derives sugars from the host plant cells for its survival.
Thus, it acts as a biofertiliser. This association has other advantages also, like
(i) Resistance to root borne pathogens
(ii) Tolerance to salinity and drought
(iii) Increase in plant growth and development

To obtain a foreign-gene product, following steps should be undertaken:
(i) Identification of DNA with desirable genes.
(ii) Introduction of the identified DNA into suitable host to form recombinant DNA (rDNA).
(iii) Maintenance of introduced DNA in particular host and gene cloning.
(iv) Transfer of the DNA (gene transfer) to its progeny.
(v) Selection of the recombinants from non-recombinants.
(vi) Expression of gene of interest by culturing recombinant cells.
(vii) Culturing of cells in bioreactors for large scale production of desired gene product.

Bt cotton plants are the transgenic plants that express a Bacillus thuringiensis gene called cry gene. This gene, encodes for protein crystals having insecticidal properties against insects of group Lepidoptera, Diptera and Coleoptera. Inside the bacterium, these proteins remain inactive and does not harm the bacteria. However, these inactive crystals can get activated in the alkaline pH of the gut of insects upon ingestion. After activation, these crystals can bind to the receptors present on the membranes of gut epithelial cells. Due to this binding, the membrane swells and pores are created on them. These pores lead to bursting of cell. Hence, soon the lepidopteran die due to starvation.

Cry genes codes for a toxin which is poisonous to some insects thus giving resistant to the plants. They are present in bacterium Bacillus thuriengiensis.

* Insulin contains two short polypeptide chains: chain A and chain B linked together by disulphide bridges.
* In mammals insulin is synthesised as a pro-hormone. It contains an extra stretch called C-peptide.
* C-peptide is absent in the mature insulin and is removed during maturation into insulin.
* Production of insulin by rDNA techniques was achieved by an American company, Eli Lilly in 1983. It prepared two DNA sequences corresponding to A and B, chains of human insulin and introduced them in plasmids of E. coli for production. The A and B chains produced were separated, extracted and combined, by creating disulfide bonds to form human insulin.

The proinsulin is cleaved to remove extra stretch called the C-peptide to form mature insulin having only A-chain and B-chain joined by a disulphide bond.

A.

Zinc finger analysis

Zinc finger is a small structural motif that is characterised by the co-ordination of one or more Zn ions in order t stabilise the folds. 

C.

Root

The nematode inects the roots of the tobacco plant and result in root know disease.

D.

Vitamin A

Golden rice is a variety of rice produced through genetic engineering to biosynthesize -carotene, a precursor of vitamin-A, in the edible parts of rice. 

D.

controls multiple traits in an individual

Pleiotropic gene is a gene that controls multiple traits is an individual. It is also called polyphenic gene, e.g., phenylketonuria causing multiple adverse effects due to the mutation in a single gene coding for enzyme phenylalanine hydroxylase.

A.

1960's

Green revolution is the rapid increase in agricultural production (especially wheat and rice) during 1960-70. It has been achieved through introduction of high yielding varieties, increased irrigation facilities, fertilizer application, pesticides and agriculture management, Dr. MS Swaminathan is known as Fathe of Green Revolution in India.

A.

Both sense and anti-sense RNA

Antisense RNA can be produced by inverting a cDNA copy of an mRNA with respect to the promoter in an expression vector. This yields a full length complementary copy of mRNA sequence. Antisense RNA molecule are thought to interact with mRNA molecule by base pairing to form double stranded RNA.

D.

adenosine deaminase deficiency

Gene therapy is the treatment of disease by the transfer and extension of genetic material in the patient's cell in order to restore normal cellular functions. The first clinical gene therapy was given for treating adenosine deaminase deficiency.

A.

alkaline pH of the insect gut

The Bt toxin is an inactive protoxin, which is activated due to the alkaline pH in the insect gut. 
Bt toxin dissolve in high pH of insect gut and become active. The toxins then attack the gut cells of the insect, punching holes in the lining. 
(i) Insect eats Bt crystals and spores. 
(ii) The toxin binds to specific receptors in the gut and the insects stops eating. 
(iii) The crystals cause the gut wall to break down allowing spores and normal gut bacteria to enter the body. 
(iv) The insect dies as spores and gut bacteria proliferate in the body.

D.

herbicides

Glyphosate (N-phosphonomethyl glycine) is systemic broad spectrum herbicide used to kill weeds especially broad leaves and grasses. It is used to engineer new crop for having herbicides tolerance (resistant).

D.

Statements (I) and (II)

Transgenic Rosiae is actually Cow. It is first transgenic cow produced in 1997.
Restriction enzymes cut the DNA at a specific site. The separation of DNA is performed by gel electrophoresis

D.

high yield and resistance to bolloworms

Bacillus thuringiensis forms crystals containing a toxic insecticidal protein. Bt toxin protein exists as an inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut, which solubilises the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores the cause cell swelling and lysis and eventually cause the death of the insect. Specific Bt toxin genes were isolated from B. thruingiensis and incorporated into the several plants such as cotton. The toxin is coded by the gene name cry. There is a number of them, eg, the proteins encoded by the genes cry IAc a cry II Ab control the cotton bollworms, that of cry IAB control corn borers.

D.

Paceilomyces Lilacinus

Paexcilomyces Lilacinus is proved effective for biological control of nematodal  disease in plants. it is easily produced in vitro, Rhizosphere competent, attack the eggs of several nematodes species and treatment of plant matter, eg, seed tuber, can be effective.

D.

Application of iron and magnesium to promote synthesis of chlorophyll

If a pulse crop possesses premature yellowing of leaves and decrease in yield and application of magnesium and iron to promote synthesis of chlorophyll may become most beneficial to overcome the problem and to obtain maximum seed yield.
Magnesium is an important part of ring structure of chlorophyll molecule and its deficiency causes chlorosis and premature leaf abscission.
In iron deficiency also, the leaves become chlorotic because iron is required for the synthesis of some of the chlorophyll protein complexes in the chloroplast.

A.

Escherichia coli and Agrobacterium tumefaciens

Escherichia coli and Agrobacterium tumefaciens are the microbes found to be very useful in genetic engineering. 
E. coli is a motile, gram negative, rod shaped bacterium which is a normal inhabitant of human colon. It is most extensively used in bacterial genetics and molecular biology.
Agrobacterium tumefaciens is a soil bacterium. It has Ti plasmid (Tumour inducing plasmid) and it can be used for the transfer of a desired gene in dicot plants.

D.

Modified scale

The female cone of Pinus is formed by the aggregation of megasporophylls, which bear ovules. Each megasporophyll consists of a lower bract scale and a larger upper ovuliterous scale.

A.

Transfer of some genes from one bacteria to another bacteria through virus

Transduction involves the picking up of DNA by bacteriophage from one bacterial cell and carrying it to another where the DNA fragment may get incorporated into the bacterial host's genome.

D.

Gene flow does not occur between the populations of a species

Gene flow means the spread of genes through the population as affected by movements of individuals and other propagules, e.g., spores seeds, etc.

B.

Neurospora crassa

One gene- one enzyme theory was given by Beadle and Tatum in 1958, while they were working on red mould or Neurospora crassa (Ascomycetes fungus), which is also called Drosophila of plant kingdom.

A.

mitochondrial genome

Mitochondria are the eukaryotic cell organelles. These originate from pre-existing mitochondria only. Also known as semi autonomous organelles because they consists of  a circular, double stranded DNA molecule, RNA and 70 S type of ribosome. The genes, located outside of nucleus (i.e., within the cytoplasm) also governes some traits and are referred as plasmogenes or cytoplasmic genes. Cytoplasmic male sterility (i.e., dominance of female cytoplasmic genes over male) is due to plasmogenes located in mitochondrial DNA (mtDNA).

C.

bio- insecticidal plants

Bioinsecticides are those biological agents, which are used to control harmful insects. A bacterium, Bacillus thuringiensis is used for this purpose. Spores of this bacterium produce the insecticidal cry-protein. Therefore, spores, of this bacterium kill larvae of certain insects. The commercial preparations of B. thuringiensis contain a mixture of spores, cry-protein and an inert carrier.

D.

Restriction enzymes - Genetic engineering

Restriction enzyme recognises specific nucleotide sequences in DNA and then makes a double-stranded cleavage of DNA molecule. Restriction enzymes are called genetic scissors as they slice off genes and is recently being used in gene therapy technique. They are key tool of genetic engineering. Central dogma is related with protein synthesis. Okazaki fragments are found during DNA synthesis and RNA polymerase is used in synthesis of RNA.

C.

can cut DNA at specific base sequence

Restriction enzyme are also known as molecular knifes or molecular scissors. They are isolated from bacteria. They recognize specific base sequence in DNA and cleave both strands of it.

C.

wheat and rye

The Triticale is the first man made cereal. It is formed by a cross between wheat (Triticum) and rye (Secale cerale) followed by allopolyploidy (multiplication of non- homologous chromosomes).

Triticum sp $\times$ Secale cerale 

$\downarrow$

Diploid

                     $\downarrow$ Allopolyploidy

Triticale

A.

Agrobacterium

The bacterium-Agrobacterium acts as a vehicle for transfer of DNA or genes from one organism to another organism because it infects all dicot plants.