Animal and Plant Cells - Organelles

Structure and Functions of Cell Organelles

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Nucleus

  • largest organelle with two membranes with fluid inbetween
  • nuclear envelope with pores - large enough for molecules to pass through.allows substances to move bewteen nucleus and cytoplasm
  • chromatin - when stained show as dark patches.consists of DNA and proteins.some of the proteins regulate cell's activity.has instructions for making protein. when cells divide chromatin condense into chromosomes.
  • nucleolus - dense spherical structure. houses cell's genetic material.makes RNA and ribosomes.pass through into cytoplasm and proteins assembed at them.
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Golgi Apparatus (GA)

  • stack of membrane bound,flattened sacs with vesicles at the edge of sacs
  • receives proteins from endoplasmic reticulum and modifies them. may add sugar to them. then GA packages the modified proteins into vesicles that can be transported.some secreted and some go to cell surface.
  • makes lysosomes
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Vesicles

  • small fluid filled sac in cytoplasm surrounded by membrane
  • transports substances in and out of cell and between organelles
  • some formed and golgi apparatus or ER, others formed at cell surface
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Endoplasmic Reticulum (ER)

  • consist of flattened membrane bound sacs - cisternae.
  • rough ER - studded with ribosomes.transports proteins made on the attached ribosomes.some may be secreted from cell.some placed on cell surface membrane.
  • smooth ER - synthesises and processes lipids
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Mitochondria

  • spherical or sausage shaped
  • two membranes seperated by fluid - outer and inner membrane.
  • inner membrane - highly folded forming cristae
  • central part of mitochondria - matrix - contains enzymes involved in respiration
  • site where ATP(universal energy carrier) is produced during respiration. almost all activities that need energy in cell are driven by energy released from ATP.
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Chloroplasts

  • found only in plant cells and some protoctists
  • small flattend structure
  • two membranes seperated by fluid
  • inner membane has network of flattened membrane sacs - thylakoids
  • stack of thylakoids - granum - linked together by lamellae
  • chorlophyll molecules present on thylakoid membrane and un intergranal membranes
  • site of photosynthesis
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Lysosomes

  • spherical sacs
  • single membrane
  • no clear internal structure
  • contain powerful digestive enzymes - break down materials
  • examples: white blood cell lysosomes break down invading microorganisms
  • acrosome(specialised lysosome) in head of sperm helps penetrate egg by breaking down the material surrounding it
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Ribosomes

  • tiny organelle
  • some in cytoplasm and some are bound to rough ER
  • consists of two subunits
  • site of protein synthesis
  • coded unfo from nucleus is used to make proteins from amino acids
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Centrioles

  • small hollow cylinders of protein fibes(microtubules)
  • take part in cell division
  • form spindle fibres which move chromosmes during nuclear division
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Cilia

  • small hair like structures found on surface membrane of some animal cells
  • cross section - have an outer membrane and ring of nine pairs of protein microtubles with a single pair in the middle
  • microtubles allow cilia to move. used to move substances along cell surface
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Flagellum

  • on eukaryotic cells
  • like cillia but longer
  • stick out from cell surface and surrounded by plasma membrane
  • two microtubles in the centre and nine pairs around the edge
  • microtubles contract to make flagellum move
  • propel cells forward
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Vacuole

  • contain water and solutes, pushes cytoplasm againest cell wall - turgid
  • plasma membrane surrounding vacuole
  • supports the plant and maintains cell stability
  • plant cells only
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Cell Wall

  • plant cells only
  • outside of plasma membrane
  • made of cellulose
  • supports cell so helps support the plant overall
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Plasma Membrane

  • found on the surface of animal cells and just inside cell wall of plant cells and prokaryotic cells
  • made of mainly lipids and proteins.
  • regulates movement of substances into and out of the cell
  • has receptor molecles on it which allow it to respond to chemicals like hormones
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Thank you for this - clear, concise and useful.

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