9. Biotechnology : Principles and Processes

Class 12 Biology Chapter 9 Biotechnology : Principles and Processes

Chapter 9. Biotechnology : Principles and Processes

Class 12 Biology Chapter 9. Biotechnology : Principles and Processes Exercise Questions and Answers :

1. Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (use the internet).

Answer : The Recombinant proteins are widely used in medical practice as therapeutics.

Given 10 examples of recombinant proteins and where they are used:

(i) Insulin: Recombinant insulin is used to treat diabetes by regulating blood sugar levels in patients with insulin deficiency.

(ii) Erythropoietin (EPO): Used to treat anemia, EPO stimulates the production of red blood .

(iii) Factor VIII: Used in hemophilia A treatment to aid blood clotting.

(iv) Factor IX: Used in hemophilia B treatment to aid blood clotting.

(v) Interferon-alpha: Used to treat viral infections and some cancers.

(vi) Tissue Plasminogen Activator (tPA): Used to dissolve blood clots in stroke and heart attack patients.

(vii) Parathyroid Hormone (Teriparatide): Used in the treatment of osteoporosis.

(viii) Follitropin Alfa: Used in assisted reproductive technologies to stimulate ovarian follicle development.

(ix) Glucagon-Like Peptide-1 (GLP-1) Agonists (e.g., Exenatide, Liraglutide): Used in the treatment of type two diabetes.

(x) Pegfilgrastim: A long-acting form of G-CSF used to prevent neutropenia in cancer patients undergoing chemotherapy.

2. Make a chart (with diagrammatic representation) showing a restriction enzyme, the substrate DNA on which it acts, the site at which it cuts DNA and the product it produces.

Answer : The diagrammatic representation of recombinant DNA by action of restriction endonuclease enzyme - EcoRI :

3. From what you have learnt, can you tell whether enzymes are bigger or DNA is bigger in molecular size? How did you know?

Answer : DNA molecules are larger in molecular size compared to enzymes. DNA serves as genetic information storage and has a long, double-stranded structure composed of nucleotide base pairs. Enzymes, on the other hand, are proteins that catalyze biochemical reactions, and their sizes vary but are generally smaller than DNA due to their amino acid composition and folded structures.

4. What would be the molar concentration of human DNA in a human cell? Consult your teacher.

Answer : The human diploid genome consists of 46 chromosomes.

Each chromosome is made up of a single molecule of DNA.

The molar mass of DNA is 660 grams per mole (g/mol).

Since there are 46 chromosomes in a human cell, you have 46 copies of DNA.

Number of moles of DNA = (Number of chromosomes) x (Molar mass of DNA)

Number of moles of DNA = 46 x (660 g/mol)

Number of moles of DNA ≈ 30,360 g/mol

Now, assuming a typical human cell has a volume of approximately 1 picoliter ( liters) .

Molar Concentration

So, the molar concentration of human DNA in a human cell is .

5. Do eukaryotic cells have restriction endonucleases? Justify your answer.

Answer : No, eukaryotic cells do not have restriction endonucleases. These enzymes are primarily found in prokaryotic cells as part of their defense mechanisms against foreign DNA like bacteriophages. Eukaryotic cells have different mechanisms to protect against foreign DNA, such as the immune system and DNA repair pathways. Eukaryotic DNA is also modified differently, and it is compartmentalized within the nucleus, reducing the need for restriction enzymes.

6. Besides better aeration and mixing properties, what other advantages do stirred tank bioreactors have over shake flasks?

Answer : In addition to better aeration and mixing properties, stirred tank bioreactors offer the advantage of continuous culture, allowing for the maintenance of cells in their most active growth phase. This continuous culture system results in a larger biomass, leading to higher yields of the desired protein or product. Unlike small-volume shake flasks, bioreactors, with capacities ranging from 100 to 1000 liters, enable the production of significant quantities of products. They provide optimal growth conditions, including temperature, pH, substrate, salts, vitamins, and oxygen, to achieve the desired product efficiently. The integrated systems in bioreactors, such as agitation, oxygen delivery, foam control, temperature control, pH control, and sampling ports, facilitate precise process control and monitoring.

7. Collect 5 examples of palindromic DNA sequences by consulting your teacher. Better try to create a palindromic sequence by following base-pair rules.

Answer : There are five examples of palindromic DNA sequences, which read the same forwards and backwards when considering the base-pairing rules of DNA:

(i) 5' – GATC –3'

This is a simple palindromic sequence that reads the same on both strands: GATC on one strand and CTAG on the complementary strand.

(ii) 5'– GGCC – 3'

This sequence is palindromic because the base pairs on one strand match those on the complementary strand: GGCC on one strand and GGCC on the other.

(iii) 5' –AAGCTT – 3'

This sequence is palindromic and longer. It reads the same in both directions: AAGCTT on one strand and TTCGAA on the complementary strand.

(iv) 5' – TACGTCA –3'

This sequence is palindromic, reading the same in both directions: TACGTCA on one strand and TGACGTA on the complementary strand.

(v) 5' – AGTGCATGCT –3'

This is a longer palindromic sequence that reads the same forwards and backwards: AGTGCATGCT on one strand and TGCACTACGA on the complementary strand.

These palindromic sequences are important in molecular biology and genetics, as they play a role in DNA replication, recognition sites for restriction enzymes, and various genetic regulatory elements.

8. Can you recall meiosis and indicate at what stage a recombinant DNA is made?

Answer : Meiosis is a cell division process that reduces the chromosome number by half, resulting in four haploid cells. Recombinant DNA is generated during meiosis in the Prophase I stage when homologous chromosomes exchange genetic material through a process called crossing-over. This creates genetic diversity by mixing and matching genes from the maternal and paternal chromosomes, leading to the formation of recombinant DNA sequences in the resulting gametes.

9. Can you think and answer how a reporter enzyme can be used to monitor transformation of host cells by foreign DNA in addition to a selectable marker?

Answer : A reporter enzyme can be used in addition to a selectable marker to monitor transformation in host cells by foreign DNA. In this setup, the reporter gene is linked to the foreign DNA along with the selectable marker. When transformation is successful, the host cells not only gain resistance to the selective agent (e.g., ampicillin) but also produce the reporter enzyme. This enzyme can be easily detected, confirming both successful transformation and the presence of foreign DNA in the host cells.

10. Describe briefly the following :

(a) Origin of replication

(b) Bioreactors

Answer : (a) Origin of Replication: The origin of replication is a specific DNA sequence in a chromosome or plasmid where DNA replication begins. It serves as the starting point for DNA synthesis during cell division or replication in microorganisms. At the origin of replication, enzymes unwind the DNA double helix, allowing replication machinery to access and duplicate the DNA.

(b) Bioreactors: Bioreactors are controlled environments used in biotechnology and microbiology for the cultivation of microorganisms or cells to produce biological products. They provide optimal conditions for cell growth, including temperature, pH, oxygen levels, and nutrient supply. Bioreactors are essential tools for various applications, such as fermentation, bioprocessing, and the production of biopharmaceuticals.

(c) Downstream processing : Downstream processing is a crucial stage in the production of biotechnological products. After the biosynthetic phase, the product undergoes a series of processes for separation and purification, collectively known as downstream processing. This stage also involves product formulation with appropriate preservatives. Clinical trials may be required, especially for drugs. Strict quality control testing is essential for each product, but the specific processes and tests vary depending on the type of product being produced.

11. Explain briefly :

(a) PCR

(b) Restriction enzymes and DNA

Answer : (a) PCR (Polymerase Chain Reaction): PCR is a laboratory technique used to amplify a specific segment of DNA. It involves cycles of heating and cooling to denature, anneal, and extend DNA strands. PCR is widely used in molecular biology for tasks such as DNA sequencing, genetic testing, and cloning, as it can rapidly produce millions of copies of a target DNA sequence.

(b) Restriction Enzymes and DNA: Restriction enzymes, also known as restriction endonucleases, are proteins that recognize specific DNA sequences and cleave the DNA at or near those sequences. They are a natural defense mechanism in bacteria against foreign DNA, like bacteriophages. These enzymes are crucial tools in molecular biology for DNA manipulation, such as cutting DNA for cloning or DNA fingerprinting.

(c) Chitinase: Chitinase is an enzyme that breaks down chitin, a complex carbohydrate found in the cell walls of fungi, exoskeletons of arthropods, and some other organisms. Chitinase is produced by various organisms, including bacteria, fungi, and plants. It plays a role in recycling chitin-containing materials and can also be used in biotechnological applications, such as pest control and fungal disease management.

12. Discuss with your teacher and find out how to distinguish between

(a) Plasmid DNA and Chromosomal DNA

(b) RNA and DNA

Answer : (a) The distinguish between Plasmid DNA and Chromosomal DNA :

Characteristic	Plasmid DNA	Chromosomal DNA
Location	Typically found in the cytoplasm of bacterial cells, separate from the chromosomal DNA.	Located within the cell's nucleus in eukaryotes or the nucleoid region in prokaryotes.
Size	Smaller in size, usually a few kilobase pairs (kb) to a few hundred kb.	Larger in size, ranging from megabase pairs (Mb) to gigabase pairs (Gb) in eukaryotes.
Copy Number	Multiple copies per cell, often many plasmids within a single cell.	Usually exists as a single copy or a few copies per cell.
Genetic Content	Contains non-essential genes, often associated with specific functions like antibiotic resistance or metabolic pathways.	Contains essential genes for the cell's normal functions and survival.
Inheritance	Not always passed on to daughter cells during cell division, can be lost if not actively selected for.	Passed on to daughter cells during cell division, essential for cell viability.

(b) The distinguish between RNA and DNA :

Characteristic	RNA	DNA
Sugar	Ribose	Deoxyribose
Bases	A, U, G, C	A, T, G, C
Double or Single Strand	Usually single-stranded	Double-stranded
Function	Primarily involved in protein synthesis (mRNA, tRNA, rRNA), gene regulation (miRNA), and other cellular processes.	Carries genetic information, stores and transmits instructions for protein synthesis and cellular functions.

Characteristic	Exonuclease	Endonuclease
Type of Enzyme	Cleaves nucleotides from the ends of a DNA or RNA strand.	Cleaves nucleotides within the middle of a DNA or RNA strand.
Location	Can be found in various cellular compartments and organisms.	Found in cells and organisms where DNA repair, recombination, and other processes occur.
Function	Involved in processes like DNA repair, degradation of nucleic acids, and processing of DNA ends.	Essential for repairing damaged DNA, cutting DNA at specific sites (e.g., restriction enzymes), and playing roles in recombination and replication