Introduction

The cell is the basic structural and functional unit of life. Understanding cell structure, organelles, and functions is crucial for NEET Biology. Questions in NEET often cover prokaryotic vs eukaryotic cells, cell organelles, cell cycle, and cell division.

Cells are the building blocks of all organisms, ranging from unicellular organisms (Amoeba, Bacteria) to multicellular organisms (Humans, Plants).

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1. Discovery of Cell

• Robert Hooke (1665): Observed cork cells → coined the term “cell”

• Anton van Leeuwenhoek: First observed living cells → Protozoa, Bacteria

• Cell Theory:

  1. All living organisms are composed of cells.

  2. Cell is the structural and functional unit of life.

  3. All cells arise from pre-existing cells.

NEET Tip: Cell theory is a high-yield point for MCQs.

2. Types of Cells

a. Prokaryotic Cells

• No true nucleus; DNA in nucleoid

• No membrane-bound organelles

• Cell wall made of peptidoglycan

• Examples: Bacteria, Cyanobacteria

• NEET Shortcut: “Pro = Primitive, No nucleus”

b. Eukaryotic Cells

• True nucleus with nuclear membrane

• Membrane-bound organelles

• Examples: Plant cells, Animal cells, Fungi, Protists

• NEET Tip: Euk = Elaborate, complex, organelles present

3. Cell Organelles and Functions

H4 bold headings format for NEET-friendly content:

a. Nucleus

• Control center of the cell

• Contains DNA and nucleolus

• Functions: DNA storage, RNA synthesis, cell division

b. Mitochondria

• “Powerhouse of the cell”

• Site of cellular respiration and ATP production

• Double membrane; inner membrane folded into cristae

c. Endoplasmic Reticulum (ER)

• Rough ER: Ribosomes attached → Protein synthesis

• Smooth ER: Lipid synthesis, detoxification

d. Golgi Apparatus

• Modifies, sorts, and packages proteins

• Forms lysosomes and secretory vesicles

e. Ribosomes

• Protein synthesis

• Free → cytoplasmic proteins, Bound → secretory proteins

f. Lysosomes

• Contain digestive enzymes

• Functions: Digestion, autophagy

g. Peroxisomes

• Contain oxidases, catalase

• Functions: Breakdown of fatty acids, detoxification

h. Chloroplasts (Plant Cells Only)

• Site of photosynthesis

• Contain chlorophyll and thylakoid membranes

i. Vacuoles

• Storage of water, food, and wastes

• Large central vacuole in plant cells → turgor pressure

j. Cytoskeleton

• Microtubules, microfilaments, intermediate filaments

• Functions: Cell shape, intracellular transport, movement

4. Cell Membrane and Transport

• Cell membrane / Plasma membrane: Semi-permeable barrier

• Structure: Fluid mosaic model → phospholipid bilayer + proteins

• Transport Mechanisms:

  • Passive: Diffusion, Osmosis, Facilitated diffusion

  • Active: Active transport (requires ATP)

  • Bulk transport: Endocytosis, Exocytosis

NEET Tips:

• Osmosis → Water movement

• Endocytosis → Phagocytosis (solid), Pinocytosis (liquid)

5. Cell Cycle and Division

a. Cell Cycle:

• G1 → S → G2 → Mitosis → Cytokinesis

• NEET Tip: S phase → DNA replication

b. Mitosis:

• Produces 2 genetically identical daughter cells

• Stages: Prophase → Metaphase → Anaphase → Telophase

c. Meiosis:

• Produces 4 genetically distinct gametes

• Stages: Meiosis I → Meiosis II

• Important for sexual reproduction

NEET Formula:

• Diploid (2n) → Meiosis → Haploid (n) gametes

6. Structural Organisation in Prokaryotic vs Eukaryotic Cells

NEET Tip:

• MCQs often ask differences in ribosome size, DNA type, organelles

7. NEET Formulas / Memory Aids

1. Levels of cell structure: Cell → Organelle → Macromolecule → Atom

2. Mitochondria → ATP = Energy production

3. Ribosome → Protein synthesis

4. Chloroplast → Photosynthesis → Glucose production

5. Cell cycle: G1 + S + G2 + Mitosis → 2 daughter cells

6. Meiosis → 2n → n gametes

Mnemonic for Organelles:
“Never Make Elephants Go Running Like Crazy Very Calmly” → Nucleus, Mitochondria, ER, Golgi, Ribosome, Lysosome, Chloroplast, Vacuole, Cytoskeleton

8. NEET Exam Tips

• Draw diagrams of plant and animal cells with organelles labeled.

• Remember prokaryotic vs eukaryotic differences.

• Focus on cell cycle stages and types of cell division.

• Use tables and mnemonics to memorize organelle functions and key formulas.

Conclusion

The cell is the fundamental unit of life, and mastering cell structure, organelles, transport, and cell division is crucial for NEET Biology.

With this StudentBro.in guide, students can efficiently revise cell formulas, organelle functions, and division mechanisms, saving time and improving accuracy during exams.

Remember: Linking structure → function → example is the key to mastering “Cell: The Unit of Life” for NEET.