NEET Biology — Advanced + Cheatsheet

Biotechnology

Recombinant DNA technology:
  Restriction enzymes: "molecular scissors" cut DNA at specific sequences
    EcoRI cuts at GAATTC (palindromic sequence)
    Creates "sticky ends" for ligation
  DNA ligase: joins cut ends
  Vectors: plasmids (bacterial), bacteriophages, cosmids, BAC, YAC
  Host: E. coli (most common), Bacillus, yeast

PCR (Polymerase Chain Reaction):
  Amplifies specific DNA segment
  Steps: Denaturation (94°C) → Annealing (55°C) → Extension (72°C)
  Enzyme: Taq polymerase (thermostable, from Thermus aquaticus)
  Uses: disease diagnosis, forensics, paternity testing, cloning

Gel electrophoresis: separates DNA by size (smaller = moves further)
Southern blotting: DNA detection; Northern: RNA; Western: protein

Applications:
  Insulin production: human insulin gene in E. coli (Humulin)
  Golden Rice: β-carotene synthesis genes from daffodil
  Bt toxin crops: Bacillus thuringiensis toxin gene in cotton/brinjal
  Gene therapy: ADA deficiency (first clinical trial)

NEET Biology Cheatsheet

IMPORTANT SCIENTISTS:
  Robert Hooke: discovered cell (1665, cork cells)
  Schleiden & Schwann: cell theory (1838-39)
  Virchow: "Omnis cellula e cellula" (cells from cells, 1855)
  Watson & Crick: DNA double helix (1953)
  Mendel: genetics experiments on peas (1865)
  Darwin: Theory of evolution by natural selection
  Meselson & Stahl: semi-conservative DNA replication
  Hershey & Chase: DNA is genetic material (phage experiment)

MUST-KNOW NUMBERS:
  Human chromosomes: 46 (23 pairs); Gametes: 23
  Human RBC count: 5 million/mm³ (male), 4.5 million (female)
  Normal blood pH: 7.4 (slightly alkaline)
  Heartbeats: 72/min; Breathing: 15-18/min
  Body temperature: 37°C (98.6°F)
  Nephrons per kidney: ~1 million
  Neurons: ~100 billion in human brain

PHOTOSYNTHESIS QUICK:
  PSII = P680 = water splitting, O₂ released
  PSI = P700 = NADPH formation
  Cyclic photophosphorylation: only PSI, only ATP (no NADPH, no O₂)
  Non-cyclic: both PS, ATP + NADPH + O₂

COMMON MCQ TRICKS:
  "Powerhouse of cell" = Mitochondria
  "Suicide bag" = Lysosome (only in animal cells)
  "Kitchen of cell" = Chloroplast
  "Traffic police" = Golgi apparatus
  Universal donor blood group for blood = O negative
  Universal recipient = AB positive