CELL STRUCTURE & CELL

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    Organelles (little organ) tiny structures

    inside a cell that perform specific functions for

    a cell. Example: mitochondria, lysosome and

    chloroplast.

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    THE UNIQUENESS OF THE CELL

    A cell is unique:

    Specialisation Division of labour

    Coordination and integration

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    Living components of cell is called as

    PROTOPLASM (cytoplasm + nucleus)

    The cytoplasms contains ORGANELLES

    - Perform specific functions which enable the

    cell to function as a unit of life

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    NUCLEUS

    contains the genetic material

    regulates and controls the activities of the cell

    an organelle bounded by double (2)

    layers of nuclear membrane with poresand selectivelypermeable

    responsible forall cellular structure, chemical functions, growth and reproduction

    separates the genetic materials (chromatin)from cytoplasm

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    NUCLEOLUS

    spherical structure within the nucleus

    consists of DNA (deoxyribonucleic acid)

    and RNA (ribonucleic acid) and proteins

    visible when the cell is not dividing

    synthesis RNA which is needed to

    make ribosomes

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    NUCLEOPLASM

    fluid contained within the nucleus

    highly viscous solid

    made up of the chromatin and the nucleolus

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    CHROMOSOMES

    thread-like structures (consists of genetic

    material)

    appears as chromatin spread throughout the

    nucleus in the form of tiny granules

    chromatin condenses into chromosomes

    (during cell division)

    carry genetic information in its DNA

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    ENDOPLASMIC RETICULUM(ER)

    connected to the nuclear membrane

    synthesises proteins, steroids and lipids

    collects, stores and distributes protein, steroids andlipids

    exists as rough ER and smooth ER

    Rough ER: covered with ribosomes, flat sealed sacwhich continued from the nuclear membrane,transports protein, and have a large surface area for

    chemical reactions. Smooth ER: does not have ribosomes, transports lipids

    and presents in large amounts of cells.

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    PLASMA MEMBRANE

    cell membrane

    thin membrane surround the cytoplasm of a

    cell

    selectively permeable / semi permeable

    a protective and selective outer barrier

    consistsof phospholipids and protein molecules

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    GOLGI APPARATUS

    bound sacs

    processes, packages and transport moleculessynthesised in the cell

    forms lysosomes

    transports and stores lipids

    synthesis of carbohydrate from hormone

    changes protein into glycoprotein

    excretes waste products out of the cell

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    CYTOPLASM

    aqueous solution (except nucleus)

    stores water, enzymes, nutrient, salts and

    dissolved gases

    provided support, shape and protects the cell

    organelles

    medium for metabolic reactions

    provides substances

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    LYSOSOME (ac)

    sac-like organelle with one membrane

    digest proteins, lipids and carbohydrates

    removes undigested materials releases enzymes to digest external materials

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    CENTRIOLE (ac)

    are paired cylindrical organelles

    nine tubes with three tubules each

    produces spindle during cell division (mitosisand meiosis)

    migrate to the opposite poles of the cell

    (during cell division will be discussed in

    Chapter 5 Cell Division)

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    CELL WALL (ac)

    rigid and tough cellulose layer surrounding the

    plasma membrane (cell membrane)

    protects and supports the cell

    maintains the shape

    prevents the cell from busting (excessive

    intake of water)

    allows substances to move freely through the

    cell wall

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    CHLOROPLAST (pc)

    disc / lens-shaped organelle

    have two membranes: inner and outer

    membrane

    contains chlorophyll in the grana to trap

    sunlight energy

    carry out photosynthesis in the chlorophyll

    storage of food and pigments

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    CELL ORGANISATION

    Unicellular

    A single cell performs all thebasic life process. Example:Amoebasp.,Paramecium sp., Chlamydomonas, Bacteria

    and Euglena. MulticellularAn organism consists of more

    than one cell. Each group of cell specialized tocarry our life processes. Example: Homosapien (human), animals and plants. It has fivelevels of organisation

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    Cells: basic units of structure and function.Example: Red blood cells and xylem vessel cells.

    Tissues: made up of cells with similar in structure andfunction.Example: Epithelial tissues and vascular tissues.

    Organs: made up of tissues that perform a specificfunction.Example: Heart and flower.

    System: two of more organs that perform a specificfunction.Example: Digestive system and root system.

    Organisms: whole living thing that carry out all thebasic life processes.Example: Human and durian tree.

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    CELL ORGANISATION in Amoeba sp.

    Cell structure

    Amoeba sp.: plasma membrane, food vacuole,

    contractile vacuole, pseudopodium, nucleus,

    ectoplasma, endoplasm.

    Locomotion

    Amoeba sp.: Pseudopodium (false foot) helps

    it to move forward slowly and it is known

    asamoeboid movement.

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    Feeding

    Amoeba sp.: Omnivore. Eat bacteria, plantcells, algae and other microscopic organisms.

    Entrapment extend pseudopodium.

    Engulfment

    engulf tiny food (phagocytosis)

    with its pseudopodia.

    Digestion food enclosed in food vacuole

    Absorption

    enzyme digests the bacteria

    Egesting expel indigestible material.

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    Reproduction

    Amoeba sp.: two types of reproduction. Binary Fission nucleus divides (favourable

    condition) and then follows by division of

    cytoplasm. Two daughter cells are formed(mitotic division).

    Spore Formation spores form (bad

    condition) and germinate into new amoeba

    under favourable condition.

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    Osmoregulation

    Amoeba sp.: water moves into the cell by

    osmosis and prevention of bursting, it has a

    contractile vacuole.

    Respiration

    exchange gases throughout the whole cell

    membrane

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    Excretion

    waste products are ammonia and carbon

    dioxide by diffusion. Solid waste in

    paramecium is expelled through its anal pore.