Organelles PDF

SLO: 4.2.1+ 4.2.2 Organelles 9th Cell Wall Plasma Membrane Extracellular space Outside of the cell Cytosol Inside of the cell Mitochondria Nucleus Ribosome Endoplasmic Reticulum Golgi Apparatus Lysosomes Lysosomes Structure: single-membrane bou...

SLO: 4.2.1+ 4.2.2 Organelles 9th Cell Wall Plasma Membrane Extracellular space Outside of the cell Cytosol Inside of the cell Mitochondria Nucleus Ribosome Endoplasmic Reticulum Golgi Apparatus Lysosomes Lysosomes Structure: single-membrane bound organelles. Sphere-shaped sacs. Composition: Lysosomes contain strong digestive enzymes/ hydrolytic enzymes.  Function: 1. Hydrolytic enzymes can break down (digestion) of food. During its function, a lysosome fuses with the vacuole that contains the targeted material and its enzymes break down the material. 2. Lysosomes can also digest waste materials produced due to various metabolic activities of the cell. 3. Destruction of pathogens including bacteria and viruses. 4. Digestion of organelles that lost their ability to work within cell. 5. Lysosomes also involve in restoration of cell membrane. 6. Autolysis: lysosomes can destroy cell membrane with its digestive enzymes causing lysis of the cell called autolysis. Thus lysosomes are called as suicidal bags. Autolysis occur when cell gets old or damage. Centrioles Vacuole Structure: fluid filled single-membrane bound organelles. Membrane of vacuole called the tonoplast, which regulate the movement of substances in and out. Vacuole is filled with a solution of water, ions, sugars and other substances called cell sap. Cells have many small vacuoles in their cytoplasm. However, when a plant cells matures its small vacuoles absorb water and fuse to form a single large vacuole in centre. Cell in this state becomes turgid. Composition: Vacuoles are made up of water, organic and inorganic molecules. The contents of vacuoles vary depending on the cell type and its function, but vacuole can store: proteins, amino acids, enzymes, and nucleic acids. Mineral salts: such as Na+, K+, and Cl−. Organic acids. sugars, such as glucose and fructose.  Functions: 1. Vacuole stores salts, minerals, pigments and proteins in cell sap. Large no. of lipids are also stored on vacuoles. 2. Many cells take in materials from outside in the form of food vacuole and then digest the material with the help of lysosomes. 3. Some unicellular organisms use contractile vacuole for the elimination of wastes from their bodies. 3. Turgor pressure in plants. Thus provide structural support to plant cell. 4. Homeostasis: Vacuoles help cells adapt to environmental changes by storing many inorganic and organic molecules. 5. Vacuoles help maintain cell acidity. Plastids  Plastids are also membrane-bound organelles that only occur in the cells of plants and photosynthetic protists (algae). They are of three type i.e chloroplasts, leucoplasts and chromoplasts. Chloroplast: Structure: Like mitochondria, chloroplast is also bound by a double membrane. The outer membrane is smooth while the inner membrane gives rise to sacs called thylakoids. The stack of thylakoids is called granum (plural = grana). Grana are the functional unit of chloroplast. The photosynthetic pigments including chlorophyll (the green pigment necessary for photosynthesis) and associated pigments are present in the thylakoids of grana. Light dependent reactions of photosynthesis occur in thylakoids. Grana float in the inner fluid of chloroplast i.e. stroma. Stroma is similar to the cytoplasm in cells in which all the organelles are embedded Stroma also contains various enzymes, DNA, ribosomes, and other substances. Stroma lamellae function by connecting the stacks of thylakoid sacs or grana. Light independent reactions of photosynthesis occur in stroma. Chloroplasts are the sites of photosynthesis in eukaryotes.  Composition They have their own DNA & Ribosomes. Mainly contain chlorophyll pigment, essential for photosynthesis. Also have proteins, lipids & carbohydrate, which makeup their membrane and internal structures. They also contain enzymes, and other molecules necessary for photosynthetic process. Functions: Convert light energy into chemical energy in the form of food (Photosynthesis). Provide green colour to leaves, stem and vegetable. Chromoplasts The second type of plastids in plant cells are chromoplasts. They contain pigments associated with bright colours and are present in the cells of flower petals and fruits.  Composition They have there own DNA and ribosomes. Contain (Carotenoids) pigment, which give fruits and flower their red , orange and yellow colors. Also have proteins, lipids and carbohydrates which make up their membrane. Function Involved in synthesis and storage of pigment. Give colors to flower petals and fruits. Help in pollination and dispersal of fruit. Leucoplasts Leucoplasts are the third type of plastids. Colorless plastid Non pigmented organelles Present in the cell of those parts where food is stored such as in fruits and seed. Structure Have with double membrane structure (outer and inner membrane) with an internal compartment contain vesicles in stroma. Composition Their membrane composed of lipids, proteins and carbohydrates. Stroma include enzymes necessary for synthesis & storage of substances such as starch, oils, and proteins. Functions: Involved in the synthesis and storage of starches, protein, and lipids. Conversion of nutrients: conversion of simple sugars amino acids into more complex molecules. THE END