Numerical values and concepts related to cell structure and function for JEE and CBSE board exams:

1. Cell Size:

• Typical plant cell size: 10-100 µm (micrometers)
• Typical animal cell size: 10-30 µm (micrometers)
• Red Blood Cell (Erythrocyte) size: Approximately 7-8 µm in diameter

2. Organelle Dimensions:

• Mitochondria: Length 0.5-1 µm, Diameter 0.2-0.5 µm
• Chloroplasts: Length 5-10 µm, Width 2-4 µm
• Nucleus: Diameter 5-10 µm
• Ribosomes: Diameter 15-20 nm (Prokaryotic) and 20-25 nm (Eukaryotic)

3. Membrane Potential:

• Typical resting membrane potential of a cell: -70 mV to -90 mV

4. Surface Area to Volume Ratio:

For a spherical cell with radius “r”:

• Surface Area = 4πr^2
• Volume = (4/3)πr^3
• Surface Area to Volume Ratio = (3/r)

5. Diffusion and Osmosis:

• Diffusion: Movement of molecules from higher to lower concentration
• Osmosis: Movement of water molecules across a selectively permeable membrane from a hypotonic solution (lower solute concentration) to a hypertonic solution (higher solute concentration).

Terms To Remember

• Water Potential (Ψ): Measure of the tendency of water to move from one region to another based on solute concentration.
• Tonicity: Describes the effect of the extracellular environment on a cell’s water balance.

6. Active Transport:

• Sodium-Potassium Pump: Transports 3 Na+ ions out of the cell and 2 K+ ions into the cell, maintaining concentration gradients.
• Proton Pump: Transports hydrogen ions (H+) across the thylakoid membrane during photosynthesis, creating a proton gradient.

7. Protein Structure:

• Van der Waals Forces: Weak forces that contribute to the stabilization of protein structures.
• Peptide Bonds: Covalent bonds formed between amino acids during protein synthesis.
• Polypeptide Chain: Linear sequence of amino acids linked by peptide bonds.
• Primary Structure: Sequence of amino acids.
• Secondary Structure: Regular patterns of amino acid folding, including α-helices and β-pleated sheets.
• Tertiary Structure: Three-dimensional structure of a single polypeptide chain.
• Quaternary Structure: Arrangement of multiple polypeptide chains into a functional protein.

8. Enzyme Kinetics:

• Enzyme-Substrate Complex: Temporary molecular complex formed between an enzyme and its substrate.
• Km: Michaelis-Menten constant, represents the substrate concentration at which the enzyme reaction rate is half of its maximum velocity (Vmax).
• Vmax: Maximum reaction rate achieved by an enzyme at saturating substrate concentration.

9. Nucleic Acids:

• Nucleotide: Basic building block of nucleic acids, composed of a nitrogenous base, a pentose sugar, and a phosphate group.
• Double Helix: Structural model of DNA proposed by Watson and Crick, consisting of two strands twisted around each other in a spiral shape.
• Base Pairing: Specific hydrogen bonding between complementary nitrogenous bases (adenine with thymine and guanine with cytosine) maintains the stability of the double helix.

10. Gene Expression:

• Transcription: Process of copying the genetic information from DNA to messenger RNA (mRNA) molecules.
• Translation: Process of converting the genetic code in mRNA into a sequence of amino acids in proteins.
• Genetic Code: Set of three-nucleotide sequences (codons) that specify which amino acid will be incorporated into a protein.
• Central Dogma of Molecular Biology: Describes the two-step process of transcription and translation, which allows the information in genes to direct protein synthesis.