The Molecular Word Processor: The Next Step Beyond CRISPR

CRISPR is a powerful gene-editing tool that works like molecular scissors. It can cut DNA and help scientists edit genes. But CRISPR has one problem: it makes a full cut in the DNA, and sometimes the cell repairs this cut in the wrong way. This can lead to mistakes.

Because of this, scientists have created newer and safer gene-editing tools. These new tools work like a “Molecular Word Processor” instead of scissors. They can edit DNA without making big cuts. This makes gene editing more accurate and less risky.

CRISPR-Cas9: The Molecular Scissors

CRISPR-Cas9 was the first major gene-editing tool.

How it works:

• A guide RNA finds the place in the DNA that needs editing.
• The Cas9 enzyme cuts both strands of the DNA.
• The cell repairs the cut, but sometimes the repair is messy or wrong.

This method is powerful but not always safe because it creates a double-strand break.

Base Editing: The Molecular Pencil

Base Editing was the next improvement. It does not cut the whole DNA. Instead, it changes just one letter of the DNA.

How it works:

• A modified Cas9 makes a small nick in one DNA strand.
• An enzyme changes one DNA base to another (like C to T or A to G).

Why it matters:
Many diseases are caused by a single wrong DNA letter. Base editing can fix these “DNA typos” safely.

Prime Editing: The Molecular Word Processor

Prime Editing is the most advanced tool so far. It works like the “Find and Replace” feature in a computer.

It can:

• Change any DNA letter
• Insert small DNA sequences
• Delete small DNA sequences
   all without making a dangerous double-strand cut.

Prime Editing uses three parts:

1. Nickase Cas9 – cuts only one DNA strand
2. Reverse Transcriptase – writes the new DNA
3. pegRNA – guides the editor and provides the corrected DNA sequence

Steps:

1. The pegRNA guides the editor to the target.
2. Nickase Cas9 cuts one strand.
3. The Reverse Transcriptase writes the new DNA.
4. The cell replaces the old DNA with the new, corrected version.

This method is clean, safe, and very accurate.

Why Prime Editing Is Important

Prime Editing can do:

• Substitutions (change one base)
• Insertions (add small pieces)
• Deletions (remove small pieces)

It can fix around 89% of known genetic mutations.
And it does this without making a full cut in the DNA.

Future Tools: Transposons and TIGR

Scientists are working on even newer systems:

1. Transposon-based editors
   These may help insert large pieces of DNA, like whole genes.
2. TIGR systems
   These are very small proteins that may edit any part of the genome easily.

These tools could make gene editing even more powerful and flexible.

Prime Editing and Sickle Cell Disease

Sickle Cell Disease happens because of one small mistake in the HBB gene.

• Healthy DNA: GAG
• Sickle DNA: GTG

This single-letter change causes red blood cells to become sickle-shaped.

Prime Editing can correct GTG back to GAG by changing just one base.

Why it is better than CRISPR-Cas9:

• CRISPR makes a full cut; Prime Editing makes only a small nick
• Prime Editing is more accurate
• Prime Editing causes fewer mistakes

How treatment works:

1. Doctors collect the patient’s blood stem cells.
2. They edit the cells using Prime Editing.
3. The corrected cells are placed back into the patient.
4. These cells can make healthy red blood cells for life.

This could be a permanent cure.

The Future of Gene Editing

CRISPR started the revolution.
Base Editing made it cleaner.
Prime Editing made it precise.

Soon, gene editing may cure diseases, help in drug discovery, and prevent genetic problems before they occur.

We are entering a future where DNA can be edited as easily as editing words in a document.

Table: Major Fields of Biotechnology and Their Key Applications

Biotech Field	Key Focus	Important Applications	Examples
Medical Biotechnology	Developing therapies & diagnostics	Vaccine development, gene therapy, disease diagnostics	mRNA vaccines, CRISPR-based therapies
Agricultural Biotechnology	Crop improvement & protection	High-yield crops, pest-resistant plants, stress-tolerant varieties	Bt Cotton, Golden Rice
Industrial Biotechnology	Large-scale bio-processing	Enzyme production, biofuels, bioplastics	Bioethanol, biodegradable plastics
Environmental Biotechnology	Pollution control using microbes	Wastewater treatment, bioremediation, bio-filtering	Oil spill clean-up, heavy metal removal
Food Biotechnology	Food quality & preservation	Fermentation, probiotic foods, nutritional enhancement	Yogurt, cheese, fortified foods
Marine Biotechnology	Exploring marine organisms	Novel enzymes, pharmaceuticals, bioactive compounds	Anticancer compounds from algae
Microbial Biotechnology	Using microbes for innovation	Antibiotics, enzyme production, fermentation industries	Penicillin, lactase enzyme

 

Advanced Biotechnology Quiz

15 MCQs for CSIR-NET / GATE / DBT-JRF practice. Choose one answer for each question, then click Submit.

Q1. In Sanger sequencing, which molecule acts as a chain terminator causing termination of DNA synthesis?

A. dATP B. ddNTP (dideoxynucleotide) C. rNTP D. DNA ligase

Q2. Which of the following is FALSE about quantitative PCR (qPCR) using SYBR Green dye?

A. SYBR Green binds to double-stranded DNA. B. SYBR Green can differentiate between specific and non-specific products. C. Melt curve analysis helps identify primer-dimers. D. SYBR Green fluorescence increases proportionally with product amount.

Q3. In enzyme kinetics, which plot is used to determine Vmax and Km by linearization?

A. Michaelis-Menten plot (v vs [S]) B. Lineweaver-Burk plot (1/v vs 1/[S]) C. Scatchard plot D. Hill plot

Q4. Which method is most suitable for isolating high-molecular-weight genomic DNA free from RNA contamination?

A. Boiling lysis without RNase B. CTAB extraction followed by RNase treatment C. Phenol-only extraction D. Direct PCR from colony

Q5. In plant tissue culture, which plant growth regulator combination is commonly used to induce callus formation?

A. High cytokinin, low auxin B. High auxin, low cytokinin C. No hormones D. Gibberellin alone

Q6. Which technique is used to measure genome-wide DNA methylation at single-base resolution?

A. ChIP-seq B. ATAC-seq C. Bisulfite sequencing D. RNA-seq

Q7. In next-generation sequencing, 'paired-end' reads are useful because they:

A. Reduce sequencing error rate to zero B. Provide sequence information from both ends of a DNA fragment, helping with alignment across repeats C. Double the read length automatically D. Only used in Sanger sequencing

Q8. Which statement about Agrobacterium tumefaciens-mediated transformation is CORRECT?

A. It is effective only in monocots and not dicots B. It transfers T-DNA from the Ti plasmid into the plant genome C. It uses electroporation to enter plant cells D. It inserts RNA directly into the nucleus

Q9. Which of the following best describes a 'silent mutation' at the codon level?

A. Changes an amino acid to a stop codon B. Changes the DNA sequence but not the encoded amino acid C. Always causes a frameshift D. Deletes an exon

Q10. In fermentation, which parameter is most directly used to estimate microbial biomass in real time?

A. Optical density (OD) at 600 nm B. pH measurement C. Glucose concentration D. CO2 sensor only

Q11. Which DNA repair pathway is primarily active during non-dividing (G0/G1) cells and is error-prone?

A. Homologous recombination (HR) B. Base excision repair (BER) C. Non-homologous end joining (NHEJ) D. Mismatch repair (MMR)

Q12. Which viral vector is most commonly used for stable integration into dividing mammalian cells for gene therapy?

A. Adeno-associated virus (AAV) B. Adenovirus C. Retrovirus / Lentivirus D. Bacteriophage

Q13. Which technique separates proteins based on isoelectric point and molecular weight sequentially?

A. SDS-PAGE B. 2D gel electrophoresis C. Western blot D. Size-exclusion chromatography

Q14. In population genetics, which effect describes loss of genetic variation when a new population is founded by a small number of individuals?

A. Bottleneck effect B. Founder effect C. Gene flow D. Stabilizing selection

Q15. Which reagent is commonly used as a reducing agent to break disulfide bonds during SDS-PAGE sample preparation?

A. SDS B. β-mercaptoethanol (or DTT) C. EDTA D. Triton X-100

Tip: This quiz is for practice. For exam-style preparation, attempt without notes and time yourself for 20 minutes.

Kerala Brain‑Eating Amoeba — Simple Guide & Precautions

KB

Kerala Brain‑Eating Amoeba — Simple Guide

Short, clear advice about Naegleria fowleri, symptoms, and easy precautions.

What is it?

Naegleria fowleri is a tiny amoeba found in warm freshwater. It can enter the body through the nose and cause a rare brain infection called PAM. Infections are very rare but serious.

Found in: Warm lakes, rivers, ponds, hot springs, and poorly maintained pools.

Symptoms (watch closely)

• Severe headache and high fever
• Nausea, vomiting, stiff neck
• Light sensitivity, confusion, seizures

If symptoms appear within 1–14 days after freshwater exposure, get emergency care and tell doctors about the water contact.

Quick Precautions — Easy Steps

1. Avoid warm, stagnant water

Skip shallow, warm ponds and unchlorinated pools.

2. Keep water out of your nose

Use a nose clip or avoid submerging your head.

3. Use safe water for nasal rinsing

Only boiled (cooled) or distilled water for neti pots.

4. Prefer chlorinated pools

Public pools with good maintenance are safer.

Compact Flowchart

A small visual guide you can save or share.

Remember

The infection is very rare. Simple steps like not letting water go up your nose and using safe water for nasal cleaning reduce risk a lot. Stay calm and be careful.

This page is for awareness only and not medical advice. For emergencies, contact local health services.

50-Question Biochemistry Quiz Try to Solve it............

50-Question Biochemistry Quiz

Answer all questions below and submit to see final results and download scorecard PDF.

Made for study & practice — edit questions freely.

Biotechnology PCR MCQ Quiz Series

🧬 Biotechnology PCR MCQ Quiz Series

Welcome to the CSIR-NET/GATE Level Quiz Series on Polymerase Chain Reaction (PCR).
Attempt quizzes step by step and test your preparation.

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🔥 Best of luck with your CSIR NET / GATE exam preparation!
Attempt all quizzes to strengthen your PCR knowledge.

Polymerase Chain Reaction (PCR) Quiz – Part 5 (Advanced Variants & Troubleshooting)

Attempt all 10 questions. Click Submit to check your score and correct answers.

41. Which PCR variant is BEST suited for quantifying mRNA expression levels?

a) Nested PCR
b) RT-qPCR
c) Digital PCR
d) Hot-start PCR

42. A PCR reaction shows multiple nonspecific bands. Which adjustment is MOST helpful?

a) Lowering annealing temperature
b) Increasing primer concentration
c) Increasing annealing temperature
d) Decreasing Mg²⁺ concentration

43. Which PCR method is MOST suitable for detecting rare alleles in a heterogeneous population?

a) Touchdown PCR
b) Digital PCR
c) Multiplex PCR
d) Gradient PCR

44. In case of primer-dimer formation, which modification is MOST effective?

a) Reduce template concentration
b) Increase extension time
c) Redesign primers
d) Add more Mg²⁺ ions

45. Which PCR variant is MOST useful for detecting viral load in patients?

a) Nested PCR
b) RT-qPCR
c) Digital PCR
d) Hot-start PCR

46. Which of the following is a common cause of PCR failure?

a) Incorrect primer design
b) Absence of Mg²⁺ ions
c) Poor template quality
d) All of the above

47. Which modification in PCR helps to reduce contamination issues?

a) Hot-start PCR
b) Nested PCR
c) Use of uracil-DNA glycosylase (UDG)
d) Touchdown PCR

48. Which PCR technique is MOST used for single-cell analysis?

a) Digital PCR
b) Multiplex PCR
c) RT-PCR
d) Gradient PCR

49. Which step would you modify to increase yield without affecting specificity?

a) Increase cycle number
b) Decrease extension time
c) Reduce primer length
d) Increase annealing temperature

50. Which advanced PCR technique allows absolute quantification without reference standards?

a) qPCR
b) Digital PCR
c) RT-PCR
d) Hot-start PCR

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Polymerase Chain Reaction (PCR) Quiz – Part 4: Numerical & Analytical Questions

Attempt all 10 questions. Click Submit to check your score and correct answers.

31. Which factor MOST affects PCR specificity?

a) dNTP concentration
b) Annealing temperature
c) Polymerase concentration
d) Buffer pH

32. Hot-start PCR prevents:

a) Primer degradation
b) Nonspecific amplification
c) Template denaturation
d) Enzyme inactivation

33. Which additive is often used to improve PCR amplification of GC-rich templates?

a) Glycerol
b) DMSO
c) NaCl
d) EDTA

34. Which enzyme is commonly used for high-fidelity PCR?

a) Taq polymerase
b) Pfu polymerase
c) Reverse transcriptase
d) DNA ligase

35. Which PCR type is BEST suited for identifying rare mutations in a sample?

a) Nested PCR
b) qPCR
c) Digital PCR
d) Multiplex PCR

36. Which PCR technique allows amplification without thermal cycling?

a) LAMP (Loop-mediated isothermal amplification)
b) Touchdown PCR
c) Nested PCR
d) Hot-start PCR

37. Which application commonly uses reverse transcriptase PCR?

a) Gene expression studies
b) DNA fingerprinting
c) Protein purification
d) Plasmid cloning

38. Which PCR method allows simultaneous detection of multiple pathogens?

a) Nested PCR
b) Multiplex PCR
c) Hot-start PCR
d) Digital PCR

39. Which step in PCR is MOST heat-sensitive?

a) Denaturation
b) Annealing
c) Extension
d) Template storage

40. Which variant of PCR is widely used in next-generation sequencing (NGS) library preparation?

a) qPCR
b) Bridge PCR
c) Nested PCR
d) Allele-specific PCR

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