These MP Board Class 11th Biology Notes for Chapter 8 Cell: The Unit of Life help students to get a brief overview of all the concepts.
MP Board Class 11th Biology Notes Chapter 8 Cell: The Unit of Life
→ The blue-green algae resembles bacteria in many details but most of them form multicellular colonies.
→ The smallest cells observed so far are of Pleuropneumonia like organism (PPLO) namely Mycoplasma gallisepticum.
→ Mature nerve cells never divide but may reach length of 90 cm.
→ In our body many red blood cells and outer cells of the epidermis of the skin are destroyed daily.
→ The Ostrich egg cell is considered as the largest cell, its diameter is about 175 mm.
→ Liver cells and muscle cells retain mitotic ability, but rarely divide.
→ Multicellular organisms are adapted for longer life span.
→ Tissue culture is a technique by which cells are cultured on an artificial culture medium. The technique was developed by White (1932).
→ Embryo developed outside the cell other than zygote is called embryoids.
→ Term ‘cell’ was used for the first time by Robert Hooke.
→ Rudolf Virchow states that cells are originated from pre-existing ones.
→ Viruses do not have cellular structure hence they are acellular bodies.
→ Centriole and ribosomes are non-membranous organelles.
→ Plant cell contains cell wall of cellulose which is absent in animal cells.
→ Prokaryotic cell: A cell which has an incipient nucleus and lacks membrane-bound organelles, is called as prokaryotic cell.
→ Eukaryotic cell: A cell which has a well defined nucleus and membrane-bound organelles, is called as eukaryotic cell.
→ Mesosomes : Mesosomes are extensions of plasma membrane into the cell in the form of vesicles, tubules and lamellae, usually in prokaryotic cells.
→ Lysozyme : It is an enzyme present in body secretions like tear, saliva and sweat; it lyses the cell wall of bacteria.
→ Transmembrane proteins : The membrane proteins which extend through the phospholipid bimolecular layer as a single helix are called transmembrane proteins.
→ Plasmodesmata : The cytoplasmic bridges in the primary cell wall between adjacent cells are called plasmodesmata.
→ Symplasm : The cytoplasm (living matter) present in the plasmodesmata and cells is called symplasm.
→ Apoplasm : The non-living substances present in the intercellular spaces (outside the cell) constitute apoplasm.
→ Pits : The unthickened areas in the secondary cell wall are called pits.
→ Tonoplast: The single semipermeable membrane boundary of vacuoles in plant cells is called tonoplast.
→ Dictyosomes : In plant cells, the Golgi apparatus is present in the form of unconnected units, called dictyosomes.
→ GERL (Golgi-Endoplasmic Reticulum-Lysosome): It is a region of golgi bodies, which is thought to be involved in the formation of lysosomes and the secretory granules.
→ Diffusion : It is the phenomenon of movement of ions, atoms or molecules of any substance (gas, liquid or solid) from a region of higher concentration to a region of lower concentration, until equilibrium is reached.
→ Osmosis : It is the phenomenon of movement of solvent/water molecules from a region of higher concentration or weaker solution to a region of lower concentration or stronger solution through a semi-permeable membrane, until equilibrium is reached.
→ Endocytosis : It is a process of active cellular intake of such materials (in bulk) that cannot pass through the unbroken plasma membrane.
→ Exocytosis : It is a process of active cellular extrusion/expulsion of such materials (in bulk) which cannot pass through the unbroken plasma membrane.
→ Pinocytosis : It is the process of active cellular intake of droplets of fluid along with submicroscopic particles.
→ Phagocytosis : It is the process of active cellular intake (ingestion) of solid particles.
→ Osmotic pressure: The hydrostatic pressure which balances and prevents any osmotic entry of water into the concerned solution, is called osmotic pressure.
→ Electrical gradient: The difference of electrical charges between two sides of a membrane is called as electrical gradient.