Cell Structure And Function-Biomolecules

1. Carbohydrates Reference: NCERT Biology Class 11, Chapter 14, Plant Physiology

• Monosaccharides:

• Glucose: most abundant monosaccharide, energy source, component of disaccharides and polysaccharides

• Fructose: sweet taste, found in fruits, honey

• Galactose: component of lactose, galactolipids

• Disaccharides:

• Sucrose: common sugar, obtained from sugarcane and sugar beet

• Lactose: sugar found in milk, broken down by lactase enzyme

• Maltose: product of starch digestion, found in germinating seeds

• Polysaccharides:

• Starch: storage polysaccharide in plants, glucose polymer, amylose and amylopectin components

• Cellulose: structural polysaccharide in plants, glucose polymer, strong and insoluble

• Glycogen: storage polysaccharide in animals, glucose polymer, readily available energy source

Glycolysis:

• Overview of glycolysis: series of ten enzymatic reactions, converts glucose to two molecules of pyruvate
• Role: first stage of cellular respiration, generates ATP, NADH, pyruvate

2. Proteins Reference: NCERT Biology Class 11, Chapter 15, The Living World; Class 12, Chapter 14, Biomolecules

• Amino acids:

• Building blocks of proteins
• 20 different types, classified based on side chain properties
• Peptide bond formation: covalent bond between amino acids

• Protein structure:

• Primary structure: sequence of amino acids
• Secondary structure: alpha-helix and beta-pleated sheet
• Tertiary structure: three-dimensional arrangement of polypeptide chain
• Quaternary structure: multiple polypeptide chains organized together

• Enzymes:

• Specialized proteins that catalyze biochemical reactions
• Mechanism: lower activation energy of reactions by providing an alternative pathway
• Factors affecting activity: temperature, pH, substrate concentration, enzyme concentration

3. Lipids Reference: NCERT Biology Class 11, Chapter 15, The Living World

• Classification:

• Oils, fats, waxes, phospholipids, and steroids
• Saturated and unsaturated fatty acids: based on double bonds between carbon atoms

• Triglycerides:

• Most abundant lipids, storage form of fatty acids
• Composed of glycerol and three fatty acids
• Breakdown: releases energy during cellular respiration

• Phospholipids:

• Major component of cell membranes

• Consist of glycerol, two fatty acids, and a phosphate group
• Amphipathic nature: hydrophilic head and hydrophobic tails

• Cholesterol:

• Waxy steroid, essential component of animal cell membranes
• Regulates membrane fluidity and permeability

Membrane structure and function:

• Fluid mosaic model: mosaic of phospholipids, proteins, and cholesterol
• Membrane transport: passive diffusion, facilitated diffusion, active transport, endocytosis, exocytosis

4. Nucleic Acids Reference: NCERT Biology Class 12, Chapter 6, Molecular Basis of Inheritance; Chapter 7, Gene Expression

• Nucleotides:

• Basic units of nucleic acids
• Consists of a nitrogenous base, a pentose sugar, and a phosphate group

• DNA (Deoxyribonucleic Acid):

• Double helix structure, genetic material
• Replication: exact copying of DNA prior to cell division
• Transcription: synthesis of RNA using DNA as a template
• Translation: synthesis of proteins based on RNA sequence

• RNA (Ribonucleic Acid):

• Single-stranded, three types (mRNA, tRNA, rRNA)
• Transcription: synthesized by RNA polymerase using DNA as a template
• mRNA: carries genetic information from DNA to ribosomes
• tRNA: brings specific amino acids to ribosome during protein synthesis
• rRNA: structural component of ribosomes

5. Cell Signaling Reference: NCERT Biology Class 12, Chapter 22, Chemical Coordination and Integration

• Overview:

• Process of communication between cells
• Involves chemical messengers (signaling molecules) and receptors

• Types of signaling molecules:

• Endocrine: released into the bloodstream, acts on distant target cells
• Paracrine: acts on nearby target cells
• Autocrine: acts on the same cell that releases it

• G protein-coupled receptors (GPCRs):

• Most common type of cell surface receptors
• Transduce extracellular signals into intracellular responses

• Second messengers:

• Molecules that transmit signals within the cell
• cAMP, Ca2+, and IP3 are examples of second messengers

6. Cell Metabolism Reference: NCERT Biology Class 11, Chapter 14, Plant Physiology; Chapter 15, The Living World; Class 12, Chapter 9, Breathing and Exchange of Gases; Chapter 10, Body Fluids and Circulation

Overview:

• Sum of all chemical reactions that occur within a cell

Glycolysis:

• Occurs in cytoplasm
• Breaks down glucose into two molecules of pyruvate
• Releases energy in the form of ATP

Citric acid cycle (Krebs cycle):

• Occurs in mitochondria
• Further breakdown of pyruvate
• Generates ATP, NADH, FADH2

Oxidative phosphorylation:

• Final stage of cellular respiration
• Occurs in the inner mitochondrial membrane
• Utilizes energy from NADH and FADH2 to generate ATP

Electron transport chain:

• Series of protein complexes in the inner mitochondrial membrane
• Transfers electrons from NADH and FADH2 to oxygen
• Generates ATP through chemiosmosis

7. Cell Cycle Reference: NCERT Biology Class 12, Chapter 10, Cell Cycle and Cell Division

Overview:

• Sequence of events that occur in a cell leading to its division and duplication

Phases:

• Interphase: longest phase, includes DNA replication
• Prophase: chromatin condenses, spindle fibers form
• Metaphase: chromosomes align at the cell’s equator
• Anaphase: chromatids separate and move to opposite poles
• Telophase: nuclear membrane reforms, spindle fibers disappear
• Cytokinesis: division of cytoplasm, forming two daughter cells

Regulation:

• Cyclins and cyclin-dependent kinases (CDKs) control progression through the cell cycle
• Checkpoints ensure accurate progression and prevent errors

8. Biotechnology Reference: NCERT Biology Class 12, Chapter 12, Biotechnology and its Applications

Overview:

• Application of biological organisms, systems, or processes for technological advancements

Basic techniques:

• Tissue culture, fermentation, gene cloning, Polymerase Chain Reaction (PCR)

Recombinant DNA technology:

• Combines DNA from different sources to create a new DNA molecule
• Applications: insulin production, gene therapy, genetic engineering

Remember:

• Refer to the NCERT Biology textbooks (11th and 12th classes) for detailed information on each subtopic.
• Focus on understanding the concepts and mechanisms rather than memorizing isolated facts.