Download Class 9 Cbse/Icse science chapter 5 The fundamental unit of life and more Cheat Sheet Biology in PDF only on Docsity! Cell Class 9 Cell- Is the basic fundamental unit of life. present in all living beings. Unicellular-Have a single cell Multicellular- Have many cells Prokaryotic cell Eukarytotic cell Nuclear region is not defined and nuclear membrane is absent Nuclear region is well defined and surrounded by a nuclear membrane Single chromosome More than one chromosome Membrane bound cell organelles absent Membrane bound cell organelles present Diffusion: Process of molecules from a high concentration area to an area of low concentration is diffusion. Cell wall: Cell wall is made of cellulose. It is somewhat hard but permeable to most of the substances. Cell wall is available in plant cells and in cells of bacteria and fungi. Plasma membrane: Plasma membrane is a semi-permeable membrane. It is composed of bilayer of lipid and protein. composed of numerous tubes. It extends from the plasma membrane to the nuclear membrane. There are two kinds of endoplasmic reticulum, viz. smooth ER and rough ER. Rough ER has ribosomes on its surface which give it the rough appearance. Function of ER: It serves as the transport channel in the cell. Substances are transported from cell membrane to cytoplasm and to nucleus and vice-versa. ER also serves the role of packaging many substances in the cell. Plant cell Golgi Complex: Golgi Complex was discovered by Camillo Golgi. It is composed of many sac-like structures which are stacked one above another. Functions of Golgi Complex: Golgi complex is responsible for packaging of various substances in the cell. Lysosome: Lysosome are small sac-like structures and they are derived from Golgi complex. Lysosome contains digestive enzymes. Functions of lysosome: The enzymes in the lysosome digest foreign particles and thus destroy them. Sometimes, the lysosome may burst open and its content ends up digesting the contents of the cell. The cell gets killed in the process. Due to this, lysosome is also called the ‘suicide bag of the cell’. Ribosome: These are tiny dot like structures interspersed in the cytoplasm and also on the surface of Rough ER. Ribosome is responsible for protein synthesis. Plastids: These are somewhat similar to mitochondria; in appearance. Plastids are found in plant cells. They are of two types, chromoplast and leucoplast. Colourful plastids are called chromomplast and colourless plastids are called leucoplast. Chloroplast is green in colour and is found in green parts of plants. Plastids too have their own DNA and ribosome. Functions of Plastids: Leucoplasts are responsible for storing food; such as Mitosis & Meiosis Mitosis is a process where a single cell divides into two identical daughter cells (cell division). Meiosis is a process where a single cell divides twice to produce four cells containing half the original amount of genetic information. How to remember Mitosis - two i's = two identical cells. Meiosis - e and s = egg and sperm = mother and father's chromosomes.
