Essential (Indispensable) Amino Acids

Essential amino acids, also known as indispensable amino acids, are those amino acids that cannot be synthesized by the human body in sufficient amounts. Therefore, they must be obtained from dietary sources such as milk, eggs, meat, legumes, nuts, and cereals.

These amino acids are crucial for normal growth, development, tissue repair, muscle formation, and overall health. A deficiency of any essential amino acid can lead to poor growth, weakness, impaired immunity, and metabolic disorders.

                AMINO ACIDS

                     |

        --------------------------------

        |                                          |

   Essential                         Nonessential

 (From diet)                   (Body makes itself)

        |

  -------------------------------------------

  Arg  Val  His  Ile  Leu  Lys  Met  Phe  Thr  Trp

List of Essential Amino Acids in Humans (10):

·         Arginine

·         Valine

·         Histidine

·         Isoleucine

·         Leucine

·         Lysine

·         Methionine

·         Phenylalanine

·         Threonine

·         Tryptophan

Why are they important?

Essential amino acids play key roles in:
✔ Protein synthesis and muscle growth
✔ Tissue repair and wound healing
✔ Hormone and enzyme production
✔ Brain function and neurotransmission
✔ Immune system support

Easy Memory Trick (for exams)

“AVHILL MPT”
(Arginine–Valine–Histidine–Isoleucine–Leucine–Lysine–Methionine–Phenylalanine–Threonine–Tryptophan)

Exam Notes — Nonessential (Dispensable) Amino Acids

Definition (Very Important)

Nonessential amino acids are those amino acids that can be synthesized by the human body, so they do not need to be taken regularly from the diet.

The body can synthesize 10 nonessential amino acids through normal metabolic pathways.

Key Points for Exams

✔ Also called Dispensable amino acids
✔ Required for protein synthesis, metabolism, and tissue repair
✔ Although “nonessential,” they are biologically very important
✔ Their synthesis depends on availability of precursors and vitamins

List of 10 Nonessential Amino Acids (Must Remember)

Sl. No.	Amino Acid
1	Glycine
2	Alanine
3	Serine
4	Cysteine
5	Aspartate
6	Asparagine
7	Glutamate
8	Glutamine
9	Tyrosine
10	Proline

Memory Trick:
“G A S C A G G T P”
(Glycine–Alanine–Serine–Cysteine–Aspartate–Asparagine–Glutamate–Glutamine–Tyrosine–Proline)

Functions (Exam-Oriented)

Nonessential amino acids help in:

• ✔ Building body proteins
• ✔ Repair of tissues
• ✔ Enzyme and hormone production
• ✔ Energy metabolism
• ✔ Neurotransmission (especially Glutamate, Glycine)

Simple Diagram

AMINO ACIDS

|

--------------------------------

|                                            |

Essential                            Nonessential

          (From diet)                       (Body makes itself)

                                                     |

                                                        ---------------------------------

                                                     | | | | | | | | | |

                                                    Gly Ala Ser Cys Asp Asn

                                                        Glu Gln Tyr Pro

Caption you can write under the diagram:
“Figure: Classification of amino acids into essential and nonessential types.”

One-line Exam Answer (Very Useful)

Nonessential amino acids are those which the body can synthesize on its own and therefore are not required to be supplied regularly through diet (e.g., Glycine, Alanine, Serine, Cysteine, Aspartate, Asparagine, Glutamate, Glutamine, Tyrosine, Proline).

 

 

 

Recombinant DNA Technology: Revolution in Modern Biotechnology

Recombinant DNA Technology: Revolution in Modern Biotechnology

Introduction

Recombinant DNA (rDNA) technology is one of the most powerful and transformative tools in modern biotechnology. It allows scientists to combine DNA from different organisms to create new genetic combinations that do not exist in nature. This technology has revolutionized medicine, agriculture, industry, and research by enabling the production of valuable proteins, improved crops, and disease-resistant organisms.

In simple words, recombinant DNA technology is like “genetic engineering,” where useful genes are inserted into another organism to give it new and beneficial properties.

Discovery of Recombinant DNA Technology

The foundation of recombinant DNA technology was laid in the early 1970s by scientists Stanley Cohen and Herbert Boyer. They successfully transferred a gene from one bacterium into another using plasmids (small circular DNA molecules).

This breakthrough experiment marked the birth of genetic engineering and opened the doors to modern biotechnology. Since then, rDNA technology has grown rapidly and become a core tool in biological research.

Goals and Objectives of rDNA Technology

The main objectives of recombinant DNA technology include:

• Producing useful proteins like insulin and vaccines
• Improving crop quality and resistance
• Understanding gene function
• Treating genetic diseases
• Creating industrial enzymes

Basic Steps of Recombinant DNA Technology

The process of rDNA technology involves the following key steps:

1. Isolation of Desired Gene

A useful gene is identified and cut from the donor organism using restriction enzymes (molecular scissors).

2. Selection of Vector

A plasmid or viral DNA is chosen as a carrier (vector) to transport the gene into a host cell.

3. Cutting and Joining

Both the gene of interest and the vector are cut using the same restriction enzyme and then joined using DNA ligase.

4. Transformation

The recombinant plasmid is inserted into a host organism, usually bacteria like E. coli.

5. Multiplication and Expression

The host cell multiplies and starts producing the desired protein.

Key Enzymes Used in rDNA Technology

Some important enzymes include:

• Restriction enzymes – cut DNA at specific sites
• DNA ligase – joins DNA fragments
• DNA polymerase – copies DNA
• Reverse transcriptase – makes DNA from RNA

Applications of Recombinant DNA Technology

1. Medical Applications

• Production of human insulin for diabetes
• Growth hormones
• Blood clotting factors
• Vaccines
• Gene therapy for genetic disorders

2. Agricultural Applications

• Development of pest-resistant crops
• Herbicide-resistant plants
• Drought-tolerant varieties
• Improved nutritional value of food

Example: Golden rice enriched with Vitamin A.

3. Industrial Biotechnology

• Production of enzymes for detergents
• Biofuels
• Bioplastics
• Waste treatment

4. Environmental Uses

• Bioremediation of polluted soil and water
• Degradation of toxic chemicals

5. Fun and Novel Applications

• Fluorescent fishes like GloFish
• Glow-in-the-dark organisms used in research

Advantages of rDNA Technology

• Increases food production
• Helps cure diseases
• Reduces chemical pesticide use
• Produces life-saving medicines
• Improves quality of life

Limitations and Ethical Concerns

Despite its benefits, rDNA technology raises concerns such as:

• Environmental risks
• Ethical issues
• Genetic contamination
• Biosafety problems

Therefore, strict regulations are required.

Conclusion

Recombinant DNA technology is a cornerstone of modern biotechnology. It has transformed healthcare, agriculture, and industry. With responsible use and proper regulation, this technology can greatly benefit humanity in the future.

 

CSIR NET Interactive Quiz — Recombinant DNA Technology

Time Left: 10:00

Instruction: Attempt all questions before time runs out.

1) DNA ligase joins DNA fragments.
DNA polymerase
RNA polymerase
DNA ligase
Restriction enzyme

2) Restriction enzymes recognize:
Random sequence
Palindromic sequence
mRNA
tRNA

3) Most common vector is:
Chromosome
Plasmid
Ribosome
Histone

4) Best host in rDNA is:
Bacillus
E. coli
Yeast
Fungus

5) DNA cutting enzyme:
Ligase
Restriction enzyme
Helicase
Polymerase

6) Sticky ends produced by:
Blunt cut
EcoRI
Polymerase
Ligase

7) DNA from RNA made by:
Reverse transcriptase
Ligase
Helicase
Endonuclease

8) Selectable marker helps to:
Kill bacteria
Select transformants
Break DNA
Identify host

9) Common selectable marker:
Antibiotic resistance gene
Insulin gene
Histone
rRNA

10) Golden rice enriched with:
Vitamin A
Vitamin C
Iron
Protein

Basic Functions of a Fermenter

• It should provide a controlled environment of optimum biomass yields.
• It should permit aseptic fermentation for a number of days reliably and dependably, and meet the requirements of containment regulations Containment involves prevention of escape of viable cells from a fermenter or a downstream processing equipment into the environment.
• It should provide adequate mixing and aeration for optimum growth and production, Without damaging the microorganisms.
• The power consumption should be minimum,
• It should provide easy and dependable temperature control.
• Facility for sampling should be provided.
• It should have a system for monitoring and regulating pH of the fermentation broth.
• Evaporation losses should be as low as possible.
• It should require a minimum of labour in maintenance, cleaning, Operating and harvesting operations.
• It should be suitable for a range of fermentation processes. But this range may often be restricted by containment regulations.
• It should have smooth production internal surfaces, and joints should be welded wherever possible.
• The pilot scale and production stage fermenters should have similar geometry to facilitate scale-up.
• It should be contrasted using the cheapest materials that afford satisfactory results.
• There should be adequate service provisions for individual plants.

Ti-Plasmid

Introduction

 Agrobacterium tumefaciens is a rod shaped, gram negative Bacteria, soil born motile bacterium. This bacterium infects the parts of the plant which are in contact with soil. The genus Agrobacterium inclides four species of bacteria. They are A.tumefaciens, A.radiobacter, A.rubi, A.rhizogens. They  are pathogenic in nature and cause cancerous growth in the infected plant tissues. They infect the plants and cause tumberous growth in the infected portion. The induction of tumerous growth is due to the presence of a large sized plasmid named Ti Plasmid. Accourding to Zaenen et al. (1974) almost all the strain of A.tumefaciens contain Ti plasmid.

Agrobacterium is a bacterium which is used to produce transgenic plants because it contain tow kinds of vectors which are used in the transfer of genes of one plant to the genome of another plant:-

 1. Ti plasmid, 

 2. Ri plasmid,

                                                              Structure  

T-DNA carry genes for phytohormones, AND opine

Auxin:- The main function of auixn is to help plant grow. Auxin stimulates plant cell to elongate, and the apical meristem of a plant is one of the main places where auxin is produced.

Cytokinin:- Increased cell division by stimulating the process of mitosis. Increased formation of shoot and buds, as well as development of fruits and seeds.

Opin:- Nutritional source for agrobacteria and fall into different chemical grouping such as nopaline, Octopine, Mannopine, agrocinopine etc.

Fig:- Crown gall disease

Vir genes:-

Vir Gene / Protein	Function / Role
Vir A	Kinase protein present in the bacterial membrane; acts as a receptor for phenolic compounds released by wounded plant cells
Vir A & Vir G	Constitutively expressed; together sense and respond to phenolic compounds from wounded plants
Vir G	Acts as a transcriptional activator; activates expression of other vir genes
Vir E / Vir E2	Protects T-DNA from nucleases; targets T-DNA to plant cell; acts as SSB (single-stranded binding protein)
Vir C	Stimulates T-DNA transfer; promotes high-efficiency T-strand synthesis
Vir D (overall)	Responsible for virulence activity of the bacterium
Vir D1	Topoisomerase-like protein; helps VirD2 recognize and cleave the 25 bp Left Border (LB) sequence
Vir D2	Endonuclease; cuts T-DNA at Right Border (RB); helps in integration of T-DNA into host genome
Vir D1 (additional role)	Prevents exonuclease attack at the 5′ end of T-DNA; important for phosphodiester bond cleavage
Vir B / Vir D4	ATP-dependent protein complex; forms Type IV secretion system spanning inner and outer bacterial membranes for T-DNA transfer
Vir D2 / Vir E2	Contain Nuclear Localization Signals (NLS) for transport of T-DNA into plant nucleus
Vir F	Expressed in plant cell cytosol; interacts with VBF1 protein (involved in uncoating T-DNA complex)

 

Fig:- Ti Plasmid Used in Recombinant DNA technology

                                                               Advantage

• Occure naturally in Bacteria.
• Have different restriction sites.
• Replication completely independent of Bacteria.
• Genes are easily inserted into plasmids.
• Easily transformed into bacteria.
  
  
  
  
  

Vir Genes MCQ Quiz

1. VirA protein functions mainly as:

Transcription factor Kinase receptor for phenolic compounds Endonuclease SSB protein

2. VirG protein acts as:

Receptor protein DNA ligase Transcriptional activator ATPase

3. Which Vir protein protects T-DNA from nucleases?

VirC VirB VirE2 VirA

4. VirC gene is involved in:

T-strand synthesis enhancement Nuclear localization Phenolic recognition Protein degradation

5. Which Vir protein cleaves T-DNA at Right Border?

VirD1 VirD2 VirE2 VirF

6. VirD1 mainly assists VirD2 by acting as:

Endonuclease Topoisomerase Helicase Polymerase

7. VirB and VirD4 together form:

Ribosome complex Type IV secretion system DNA replication fork Spliceosome

8. Nuclear localization signals are present in:

VirA and VirG VirC only VirD2 and VirE2 VirB proteins

9. VirF protein functions inside:

Bacterial cytoplasm Plant cell cytosol Bacterial membrane Plant nucleus

10. Vir genes are activated in response to:

UV radiation Antibiotics Phenolic compounds from wounded plants Heat shock