CBSE Class 9 Answered
CHARACTERISTICS |
FUNCTIONS |
Plasma membrane |
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Very thin, flexible and delicate living semi-permeable membrane |
Acts as an effective barrier and regulates the entry of certain solutes and ions |
Cell wall |
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Freely permeable, mainly composed of cellulose |
Gives rigidity and shape to the plant cells and provides protection |
Cytoplasm |
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Contains a mixture of water and soluble organic and inorganic compounds and various cell organelles |
Seat of occurrence of glycolysis (production of pyruvic acid) |
Endoplasmic reticulum |
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May be smooth (SER) or rough (RER) |
Acts as a supportive framework of the cell |
Mitochondria |
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Double-walled, inner wall thrown into folds called cristae |
Seat of aerobic respiration and synthesises respiratory enzymes and energy-rich compounds |
Golgi apparatus (in animal cells) Dictyosomes (in plant cells) |
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Consists of a set of membrane-bounded, fluid-filled vesicles and vacuoles |
Synthesis of the plasma membrane, cell wall etc. and synthesis and secretion of enzymes and hormones |
Ribosomes |
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Single-walled, dense, spherical bodies composed mainly of RNA and proteins |
Synthesis of proteins |
Lysosomes |
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Contains 40 different types of enzymes |
Intracellular digestion |
Centrosomes |
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Contains one or two centrioles which are surrounded by radiating microtubules to form an aster shape |
Initiates and regulates cell division
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Plastids |
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Double membrane, proteinaceous matrix containing DNA and disc-like structures called thylakoids containing chlorophyll |
Chromoplasts: Impart colour to flowers and fruits Chloroplasts: Trap solar energy for photosynthesis Leucoplasts: Store starch |
Nucleus |
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Mostly spherical and dense, surrounded by nuclear membrane with pores |
Regulates cell cycle and cell functions |
Nucleolus |
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Round, one or more in number |
Participates in protein synthesis by forming and storing RNA |
Chromatin fibres |
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Network of thread-like structures which are made of DNA |
Chromosomes carry hereditary information or genes
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Vacuoles |
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Non-living structures
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Storage of water and other substances, food, pigments and waste products |
Granules |
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Small particles, crystals or droplets |
Starch (in plant cells), glycogen (in animal cells) and fat-containing granules serve as food for the cell |