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Biotechnology and its Applications - Biotechnology: Principles and Processes

Grade 12ICSEBiology

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Biotechnology is defined as the use of living organisms or their components to produce products and processes useful to humans. It involves two core techniques: Genetic Engineering (altering chemistry of DNA/RNA) and Bioprocess Engineering (maintaining sterile conditions for growth of desired microbes).

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Restriction Endonucleases: Known as 'molecular scissors,' these enzymes cut DNA at specific palindromic sequences. For example, EcoRIEcoRI recognizes the sequence 5′−GAATTC−3′5' - GAATTC - 3'. They produce 'sticky ends' which facilitate the action of DNA ligase.

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Gel Electrophoresis: A technique used to separate DNA fragments based on size. Since DNA is negatively charged due to phosphate groups, it moves towards the positive electrode (anode). Smaller fragments move faster and farther than larger ones through the agaroseagarose gel matrix.

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Cloning Vectors: DNA molecules used as vehicles to carry foreign DNA into a host cell. Key features include an Origin of replication (oriori), Selectable markers (e.g., ampRamp^R, tetRtet^R genes), and Cloning sites.

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Polymerase Chain Reaction (PCR): A technique for in vitroin\ vitro amplification of a specific DNA segment. It involves three steps: Denaturation at ≈94∘C\approx 94^\circ C, Annealing at ≈54∘C\approx 54^\circ C, and Extension at 72∘C72^\circ C using a thermostable enzyme, TaqTaq polymerase.

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Downstream Processing: The series of processes including separation and purification of the biosynthetic product before it is formulated and marketed.

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Bioreactors: Large vessels (100−1000100 - 1000 liters) used for the large-scale production of recombinant proteins under controlled conditions like temperature, pHpH, and oxygen concentration.

📐Formulae

Number of DNA copies after n PCR cycles=2n\text{Number of DNA copies after } n \text{ PCR cycles} = 2^n

Velocity of DNA fragment (v)∝1log(Molecular Weight)\text{Velocity of DNA fragment (v)} \propto \frac{1}{\text{log(Molecular Weight)}}

Recombinant DNA (rDNA)=Vector DNA+Foreign DNA fragment\text{Recombinant DNA (rDNA)} = \text{Vector DNA} + \text{Foreign DNA fragment}

💡Examples

Problem 1:

Calculate the total number of DNA molecules produced after 3030 cycles of a PCR reaction starting with a single double-stranded DNA template.

Solution:

Using the formula 2n2^n where n=30n = 30: Copies=230≈1.07×109\text{Copies} = 2^{30} \approx 1.07 \times 10^9

Explanation:

In each cycle of PCR, the number of target DNA molecules doubles. After 3030 cycles, approximately 11 billion copies are generated.

Problem 2:

Identify the complementary strand and the palindromic sequence for the following DNA segment: 5′−GAATTC−3′5' - GAATTC - 3'.

Solution:

The complementary strand is 3′−CTTAAG−5′3' - CTTAAG - 5'. Written in 5′→3′5' \rightarrow 3' direction, it is 5′−GAATTC−3′5' - GAATTC - 3'.

Explanation:

A palindromic sequence in DNA is a sequence of base pairs that reads the same on the two strands when orientation (5′→3′5' \rightarrow 3') is kept the same.

Problem 3:

During agarose gel electrophoresis, in which direction will a DNA fragment move and why?

Solution:

DNA fragments move towards the positive electrode (anode) because DNA molecules carry a net negative charge.

Explanation:

The phosphate groups (PO43−PO_4^{3-}) in the DNA backbone impart a negative charge to the molecule. In an electric field, these molecules migrate towards the oppositely charged anode (++).

Biotechnology: Principles and Processes Revision - Class 12 Biology ICSE