CBSE Class 11 Biotechnology

1. Biotechnology: An Overview

Biotechnology: an overview

Coming soon

2. Molecules of Life

Biomolecules: building blocks · Macromolecules: structure and function

• Biomolecules – A cell is mostly water, plus four big families of carbon compounds: proteins, carbohydrates, lipids and nucleic acids. Grinding tissue in acid separates small molecules (acid-soluble pool) from big ones – proteins, polysaccharides and nucleic acids (acid-insoluble pool). Proteins are chains of amino acids folded into four levels of structure. Polysaccharides are chains of sugars; lipids are fatty acids on glycerol; nucleic acids are chains of nucleotides. Enzymes are protein catalysts that bind a substrate at the active site, lower the activation energy, and are affected by temperature, pH, substrate level and inhibitors.
• Enzymes – Enzymes are proteins that act as biological catalysts: they speed up reactions in cells without being used up. Each enzyme has an active site that fits only one kind of substrate (specificity). Enzymes work by lowering the activation energy. They work best at an optimum temperature and pH; too much heat or the wrong pH changes the active site's shape and denatures them.

3. Genetics and Molecular Biology

Concepts of genetics · Genes and genomes: structure and function

Coming soon

4. Cells and Organisms

The basic unit of life · Cell growth and development

• Cell Cycle and Cell Division – A cell grows, copies its DNA and splits in a fixed order called the cell cycle: interphase (G1, S, G2) and M phase. In S phase the DNA doubles (2C → 4C) but the chromosome number stays the same. Mitosis (prophase, metaphase, anaphase, telophase) and cytokinesis give two cells identical to the parent – it is an equational division used for growth and repair. Meiosis has two divisions; in meiosis I homologous chromosomes pair, cross over and separate, halving the chromosome number (2n → n). It makes four haploid cells for gametes and creates variation.