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PART I (1 Mark Each)

1. Answer the following questions:

a. Cutting and joining of DNA are part of recombinant DNA technology.

b. Taq polymerase is a thermostable enzyme.

c. Klenow fragment is the modified enzyme of DNA polymerase I from E. coli.

d. DNA fingerprinting identifies differences in short tandem repeats (STRs) or minisatellites.

e. Creation of mutant proteins with novel properties is called protein engineering.

f. The efficiency of a drug is not dependent on storage conditions.

g. Agrobacterium tumefaciens causes crown gall disease.

h. The first transgenic plant generated was tobacco.

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PART II (1.5 Marks Each)

a. What is ultrasonication?

Ultrasonication is a process where high-frequency sound waves (ultrasound) are used to disrupt cells, tissues, or materials. It helps in breaking cell walls, releasing intracellular contents, or dispersing particles in a liquid.

b. Define reverse transcription.

Reverse transcription is the process of synthesizing complementary DNA (cDNA) from an RNA template using the enzyme reverse transcriptase.

c. What is genome mapping?

Genome mapping is a technique used to identify and record the locations of genes and other genetic markers within an organism's genome. It helps in understanding gene functions and linkage.

d. What is a cDNA library?

A cDNA library is a collection of complementary DNA (cDNA) fragments synthesized from mRNA templates of an organism. It represents expressed genes.

e. Define electroporation.

Electroporation is a technique in which electrical pulses are applied to cells, creating temporary pores in their membranes, allowing the uptake of DNA or other molecules.

f. What is a primer?

A primer is a short single-stranded DNA or RNA sequence that binds to a complementary region on the template strand, providing a starting point for DNA synthesis.

g. Which is a chimeric protein?

A chimeric protein is a hybrid protein formed by combining domains from two or more different proteins, often used in research or therapy.

h. What is an episome?

An episome is a genetic element that can replicate independently of the host chromosome or integrate into it, like plasmids in bacteria.

i. Define random mutagenesis.

Random mutagenesis is a technique where mutations are introduced randomly into a DNA sequence to study gene functions or create proteins with improved properties.

j. Define gene targeting.

Gene targeting is a genetic technique where a specific gene is modified or replaced to study its function or introduce desired changes.

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PART III (75 Words Each)

a. Reverse Transcription:

Reverse transcription is the synthesis of complementary DNA (cDNA) from an RNA template using reverse transcriptase. This process is critical for analyzing RNA molecules, creating cDNA libraries, and conducting RT-PCR. For example, in retroviruses like HIV, reverse transcription is a natural step in their replication cycle. In research, it helps scientists understand gene expression patterns and study RNA viruses.

b. Cloning Vector:

A cloning vector is a DNA molecule used to carry foreign DNA into a host cell for replication and expression. Common vectors include plasmids, bacteriophages, and artificial chromosomes. They contain essential features like a replication origin, multiple cloning sites, and selectable markers. Cloning vectors are widely used in molecular biology for gene cloning, protein expression, and genome editing studies.

c. cDNA Libraries:

A cDNA library represents the collection of complementary DNA (cDNA) synthesized from the mRNA of an organism. It reflects only the expressed genes of the organism at a specific time. Researchers use cDNA libraries to study gene expression, identify coding sequences, and produce recombinant proteins.

d. Genome Mapping:

Genome mapping determines the positions of genes and other functional elements on chromosomes. There are two types: genetic mapping (based on recombination frequency) and physical mapping (based on DNA sequence). Genome mapping aids in studying genetic diseases, identifying markers for traits, and understanding gene functions.

e. Immune Modulators and Vaccines:

Immune modulators are substances that enhance or suppress the immune response. Vaccines are immune modulators that stimulate the immune system to produce specific antibodies against pathogens. For example, mRNA vaccines like Pfizer's COVID-19 vaccine prime the immune system for protection.

f. Gene Shuffling:

Gene shuffling involves recombining gene segments to create new genes with improved or altered properties. This technique mimics natural recombination and is widely used in protein engineering to enhance enzyme activity or stability.

g. Primer Extension:

Primer extension is a technique where a primer anneals to a DNA or RNA template and is extended by a DNA polymerase to synthesize a complementary strand. It is commonly used for mapping transcription start sites or determining RNA lengths.

h. Electroporation:

Electroporation creates temporary pores in cell membranes using an electric field, allowing molecules like DNA, RNA, or drugs to enter the cell. It is commonly used in gene transfer and genetic engineering.

i. Episomal Expression Vector:

An episomal expression vector is a plasmid that remains extra-chromosomal within a host cell, replicating independently of the genome. It is used to express foreign genes in mammalian cells.

j. Artificial Chromosome:

Artificial chromosomes are synthetic DNA constructs that replicate and segregate like natural chromosomes. Examples include bacterial artificial chromosomes (BACs) and yeast artificial chromosomes (YACs). They are used in cloning large DNA fragments.

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PART IV (500 Words Each):

4. Describe the principle and applications of PCR.

Polymerase Chain Reaction (PCR) is a revolutionary technique in molecular biology that amplifies specific DNA sequences exponentially. The principle of PCR is based on three main steps: denaturation, annealing, and extension.

1. Denaturation: The double-stranded DNA is heated to 94-98°C to break hydrogen bonds, resulting in two single strands.

2. Annealing: The reaction is cooled to 50-65°C, allowing primers to bind to their complementary sequences on the template DNA.

3. Extension: The temperature is raised to 72°C, where Taq polymerase synthesizes new DNA strands by adding nucleotides complementary to the template strand.

This cycle repeats approximately 25-40 times, leading to the exponential amplification of the target DNA sequence. The key components of PCR include template DNA, primers, thermostable DNA polymerase (Taq), dNTPs, and a buffer solution.

Applications:

Medical Diagnostics: PCR is used to detect genetic mutations, identify pathogens like Mycobacterium tuberculosis or SARS-CoV-2, and diagnose hereditary disorders.

Forensic Science: It amplifies DNA from crime scene evidence, enabling identification through DNA fingerprinting.

Molecular Research: Researchers use PCR for cloning genes, studying gene expression, and conducting mutational analyses.

Food Safety: It detects foodborne pathogens like Salmonella or GMOs in food products.

Evolutionary Studies: PCR helps amplify ancient DNA from fossils to study evolutionary relationships.

In summary, PCR is a versatile, robust, and indispensable tool in modern biology, revolutionizing diagnostics, research, and biotechnology.

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5. Discuss the applications of genetic engineering in animals.

Genetic engineering involves altering the genome of organisms using recombinant DNA technology. In animals, genetic engineering has revolutionized agriculture, medicine, and research.

1. Agriculture:

Genetic engineering improves livestock traits such as growth, disease resistance, and productivity. For instance, genetically modified cows produce higher milk yields, and pigs are engineered for enhanced growth rates.

2. Medicine:

Biopharmaceuticals: Transgenic animals like goats and cows are used to produce therapeutic proteins in milk, such as antithrombin for blood clot prevention.

Xenotransplantation: Pigs are genetically engineered to reduce immunological rejection in organ transplants for humans.

Disease Models: Mice are engineered to carry human genes, enabling the study of diseases like cancer, Alzheimer’s, and diabetes.

3. Research:

Transgenic animals are used to study gene functions and regulatory pathways. Knockout mice, where specific genes are silenced, help in understanding the roles of those genes.

4. Environmental Benefits:

Engineered animals like Enviropigs are designed to reduce environmental pollution by digesting phosphorus more efficiently.

In conclusion, genetic engineering in animals offers immense potential to address challenges in health, agriculture, and research. However, ethical concerns regarding welfare and safety require careful consideration.

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6. Describe the PCR-based methods of site-directed mutagenesis.

Site-directed mutagenesis (SDM) is a technique used to introduce specific mutations into DNA sequences to study gene functions or create proteins with novel properties. PCR-based methods have simplified and improved SDM by making it faster and more precise.

1. Principle:

In PCR-based SDM, primers containing the desired mutation are designed to anneal to the target DNA sequence. These primers, during PCR, introduce the mutation into the amplified product.

2. Steps:

Primer Design: Mutant primers with mismatches corresponding to the desired mutation are synthesized.

PCR Amplification: Mutant primers are used to amplify the DNA template, incorporating the mutation into the product.

DpnI Digestion: The parental template DNA is digested using DpnI, an enzyme that targets methylated DNA, leaving only the mutant plasmid.

Transformation: The mutant DNA is introduced into host cells for expression.

Applications:

Protein Engineering: SDM is used to enhance enzyme activity, stability, or substrate specificity.

Functional Studies: Researchers introduce mutations to study gene functions and interactions.

Therapeutic Development: It helps create modified proteins or antibodies for therapeutic applications.

PCR-based SDM has become an essential tool in modern biotechnology, enabling precise genetic modifications efficiently.

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7. Describe the process of using Agrobacterium for gene transfer to plant cells.

Agrobacterium tumefaciens is a soil bacterium that naturally transfers DNA into plant cells, making it a powerful tool in genetic engineering.

1. Mechanism:

Agrobacterium contains a Ti plasmid (tumor-inducing plasmid) that carries T-DNA, the segment integrated into the plant genome.

When Agrobacterium infects a plant wound site, it transfers T-DNA into plant cells via a Type IV secretion system.

2. Genetic Engineering:

Scientists modify the Ti plasmid by replacing tumor-inducing genes with genes of interest.

Selectable markers (e.g., antibiotic resistance) are added to identify transformed cells.

The engineered Agrobacterium infects plant tissues, and transformed cells are selected and regenerated into whole plants.

Applications:

Crop Improvement: Traits like insect resistance (Bt cotton) and herbicide tolerance (Roundup Ready soybeans) are introduced.

Pharmaceuticals: Plants are engineered to produce therapeutic proteins and vaccines.

Stress Tolerance: Genes for drought, salt, and heat tolerance are introduced to enhance crop resilience.

In summary, Agrobacterium

-mediated gene transfer is a cornerstone of plant biotechnology, enabling sustainable agricultural and pharmaceutical advancements.