字幕表 動画を再生する 英語字幕をプリント A building is made up of thousands and thousands of bricks likewise, our body is made up of thousands and thousands of cells What is a cell? Cell is a basic structural and functional unit of life. It is the smallest unit of life and is often called, the building block of life the cell was discovered by Robert hooke in 1665 he examined (under coarse, compound microscope) very thin slices of cork and saw a multitude of tiny pores that he remarked looked like the walled compartments and named them cells Matthias Jakob Schleiden and Theodore Schwann proposed cell theory in 1839 which states that all plants and animals are made up of cells and cell is the basic unit of life. unicellular organisms they are formed of one cell example amoeba, paramecium etc multicellular organisms they are formed of many cells examples we human beings etc take a look at the structure of an animal cell and now the structure of a plant cell let's talk about the components of a cell, cell membrane it is the outermost elastic covering of the cell it is made up of lipids and proteins it protects the cell from injury and allows osmosis it is selectively permeable and allows endocytosis membrane has carrier proteins for active transport cell wall it is a rigid semi elastic protective and permeable covering present outside the cell membrane only in plant cells it is made up of cellulose , hemicellulose and pectin . it gives strength to plants and prevents cell from bursting. nucleus it is made up of four parts nuclear membrane nucleoplasm nucleolus and chromatin material it controls all cell functions and brings about cell differentiation DNA of chromosome transfers the hereditary characters from parents to off springs cytoplasm it is a Jelly like semi fluid substance it is present between cell membrane and nucleus various cell organelles are present in it cell organelles these are tiny sub-cellular structures specialized to perform specific functions and hence are very important as they Carry out important functions the various cell organelles and their functions are endoplasmic recticulum, Golgi apparatus they are membrane-bound vesicles arranged parallel to each other in tiny sacs called cisternae, it helps in formation of cell wall, cell membrane and lysosomes complex sugars may be made from simple sugars in golgi apparatus Lysosomes they are smaller vesicles covered by single membrane and contain digestive enzymes they are known as a suicide bags of the cell. they destroy foreign particles and remove dead and wornout cells Mitochondria these are rod shaped covered by double membrane it is the site for respiration it provides the energy in the form of adenosine triphosphate for various chemical activities hence it is called the power house of the cell plastids these are present only in plant cells and are of two types: leucoplast and chromoplast green coloured plastids called chloroplast contain chlorophyll and are important for photosynthesis chromoplast give colour to flowers and fruits leucoplast store starch, oil and proteins , ribosomes this is a structure of a ribosome vacuole animal cells have small sized Vacuoles while plant cells have very large vacuoles they are covered by single membrane called tonoplast Turgidity and rigidity of plant cell is due to cells sap. thank you.
B2 中上級 細胞、細胞の構造と機能 - CBSE NCERTサイエンス (Cells, Cell Structure and Functions - CBSE NCERT Science) 181 28 Study English に公開 2021 年 01 月 14 日 シェア シェア 保存 報告 動画の中の単語