CBSE Class 12 Biotechnology
Chapters: 2
1. Protein and Gene Manipulation
Recombinant DNA technology · Protein structure and engineering · Genomics, proteomics and bioinformatics
- Biotechnology: Principles and Processes (Recombinant DNA Technology) – Genetic engineering means changing the genes of a living thing on purpose. We cut the gene we want with restriction enzymes (molecular scissors), paste it into a carrier DNA called a vector using DNA ligase (molecular glue), put it into a host cell, pick out the cells that took it, and grow them in big tanks (bioreactors) to collect the product. PCR makes millions of copies of a gene, and gel electrophoresis sorts DNA pieces by size.
- Protein Engineering: Designing Better Proteins – Proteins are chains of amino acids that fold into a precise 3D shape, and the shape decides what the protein does. Natural proteins are not always suited to human use: an enzyme may stop working when hot, or a hormone may act too slowly. Protein engineering designs and makes changed (or completely new) proteins. Because proteins are made from the instructions in genes, it works backwards: start from the function we want, predict the structure that would give it, work out the amino-acid sequence, then change or synthesise the DNA (gene) that codes for it. The changed gene is put into cells such as bacteria or yeast, which produce the new protein for testing. Two main strategies are rational design (planned changes such as site-directed mutagenesis) and directed evolution (many random changes followed by selection). Genetic engineering moves existing genes to make natural proteins; protein engineering creates proteins that do not exist in nature, so it is sometimes called second-generation genetic engineering.
- Bioinformatics: Computers in Biology – Bioinformatics uses computers to store, search and compare biological data. Lab results go into spreadsheets; DNA and protein sequences go into online databases; alignment tools compare sequences to find matches, differences (like SNPs) and relatives; image software measures what a microscope camera sees. Data about people must be kept private and used fairly.
2. Cell Culture and Genetic Manipulation
Microbial cell culture · Plant cell culture · Animal cell culture
- Microbial Culture: How to Grow Microbes in a Lab – To study a microbe, we grow lots of it from a few cells. This is a culture. First we kill every germ on tools and food (sterilisation). Then we give the microbes food in a dish (a culture medium). We spread a few cells with a hot-then-cooled wire loop (streaking) and keep the dish warm. Each cell becomes a dot we can see, called a colony. In a flask, the number of cells grows in four phases: lag, log, stationary and death.
- Plant Tissue Culture: Growing Many Plants From a Tiny Piece – Plant tissue culture means growing plant cells, tissues or organs on a clean jelly food in a closed glass jar. A tiny piece of the plant (the explant) is cleaned and placed on a medium with sugar, salts, vitamins and plant hormones. Its cells divide into a soft lump called callus. The hormone mix decides whether shoots or roots grow. Each new shoot can be cut and grown again, so one piece gives thousands of identical plants. This is micropropagation.
- Animal Cell Culture: Growing Animal Cells Outside the Body – Animal cell culture means growing animal or human cells outside the body, in a clean flask with a liquid food called the medium. The cells are kept warm at 37 °C with 5% carbon dioxide. They stick to the flask, divide and fill the floor. Then we split them into new flasks. Cultured cells are used to make vaccines, antibodies and medicines, to test drugs, and to grow skin for burns. Stem cells, which can turn into many kinds of cells, are grown the same way.