Organization of the Organism (1.6-1.7)

Cell Structure and Organization

  • %%All living organisms are made of cells%%
  • %%Cell%%: The basic structural unit of life
  • Although cells carry out different functions, animal and plant cells both have common features:   * Cell membrane   * Cytoplasm   * Nucleus   * Endoplasmic reticulum   * Mitochondria   * Ribosomes   * Golgi Body   * Lysosomes

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%%Plant cell%%%%Animal cell%%
Has a cell wallNo Cell wall
Chloroplasts is presentNo chloroplasts
Vacuoles occupy most spaceNo vacuole
Starch as carbohydrate storeGlycogen as carbohydrate store
AutotrophicHeterotrophic
No secretory vesiclesSecretory vesicles present
Regular shapeIrregular shape

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Functions of Cellular structures

  • Cell wall: makes up the outer most structure in the plant cell, is made of cellulose and is dead   * Fully permeable meaning that the cell wall allows substances in and out of the cell   * Gives the cell its shape and structure
  • Cell membrane: located in the inner cell wall of a plant cell and in the outermost structure in an animal cell   * Semi-permeable meaning that the cell membrane allows some/specific substances in and out of the cell
  • Cytoplasm: jelly like fluid inside the cell made of water and dissolves substances eg. glucose & salt   * Site of all metabolic (chemical) reactions
  • Nucleus: Contains genetic material of the cell in chromosomes which controls cell functions & the center of the cell   * Determines quality and quantity of proteins made by the cell
  • Chloroplasts: Site of photosynthesis and contains a green pigment (chlorophyll)   * Chlorophyl absorbs light energy and converts it into chemical energy by photosynthesis

    @@6H2O + 6CO2 → C6H12O6 + O6@@

  • Mitochondria: Made up of a double membrane: inner and outer   * Inner has many folding to increase the surface area for enzyme reactions   * Site of aerobic respiration and release energy   * Nicknamed the “Powerhouse” of the cell
  • Rough of Endoplasmic Reticulum (ER): Membranous outgrowth of outer nuclear membranes and has ribosomes attached to its surface   * Site of synthesis and transport of protein
  • Ribosome: The smallest cell of organelles present in the cytoplasm   * Either free or attached to rough ER   * Site of protein synthesis
  • Vacuole: While large and permanent, it is centrally located in a plant cell but is small and temporary in animal cells.   * Contains cell sap which is a solution of nutrients and salts   * Provides turgor pressure to the plant cell and helps maintain its shape
  • Vesicle: Sac like structures containing secretory substances eg. enzymes in the cytoplasm

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Specialized Cells

  • Large organisms are multicellular
  • Different types of cells have particular structures to help them carry out specific functions, and so they become %%specialized%%
Root Hair Cells
  • Absorb nutrients from soil by osmosis, absorbs minerals by active uptake/transport, and fixes the plant in the soil
  • Adaptations:   * Have finger like outgrowth to @@increase the surface area for more absorption@@   * Have extended vacuole and cytoplasm for @@easier absorption@@   * Have more mitochondria to provide energy for @@active uptake/transport@@

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Xylem Vessels
  • They are found in vascular bundles, transporting water and minerals from the roots to the stem and leaves
  • Provide mechanical support to the stem and leaves
  • Adaptations:   * Do not have a nucleus or cytoplasm to @@make space for bulk transport of water and minerals@@   * Cells are dead and hollow and connected from end to end to @@form a long continuous tube@@   * Cell wall is strengthened with lignin (hard substance) which @@gives mechanical support@@

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Specialized Animal Cells

Red Blood Cells
  • Transport oxygen from lungs to the rest of the body as well as transport CO2 from the body to the lungs
  • Adaptations:   * Have red pigment (hemoglobin) which @@binds with oxygen to allow transport@@   * Don’t have a nucleus because of its biconcave shape, but their shape enables the cells’ increased surface area to @@carry more oxygen@@   * Are spongy/flexible to squeeze into capillaries

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Ciliated Epithelial Cells
  • Goblet cells secrete mucus which @@trap the dust particles from the inhaled air@@
  • Cilia of the cells beat and push the trapped dust and air towards the throat (outside)

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Muscle Cells
  • Contracts and relaxes which brings about movement; structures can be brought closer
  • Adaptations:   * Made of myofibrils which have the ability to contract and relax   * Have protein fiber which can @@shorten the cell when energy is present@@

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Nerve Cells
  • Sensory Nerve Cell: conducts message from sense organ to the central nervous system
  • Motor Nerve Cell: carries message from central nervous system to the effector
  • Adaptations   * Have extensions and branches so that it @@communicates with other nerve cells and glands@@   * The Axon (extension of the cytoplasm away from cell body to carry impulse long distances) is covered with fatty sheath which @@insulates the cell and speeds up the nerve impulse@@

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Egg Cells
  • Female Gamete: responsible for reproduction in females
  • Adaptations:   * A lot of cytoplasm that contains a lot of nutrients for the @@growth of the early embryo@@   * Haploid nucleus contains @@genetic material for fertilizations@@   * Cell membrane @@modifies after fertilization so that only one sperm cell can penetrate@@

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Sperm Cells
  • Male Gamete: responsible for reproduction in males
  • Adaptations:   * Head contains haploid nucleus   * @@Acrosome in head contains digestive enzymes to breakdown jelly coat around egg cell so sperm can penetrate egg cell@@   * Many mitochondria to provide energy so sperm can ==travel long distances==   * Flagellum allows sperm to travel

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Levels of Organization

  • Cell: Basic structural and functional unit of life
  • Tissue: A group of identical cells which work together to perform a specific function
  • Organ: Many tissues which work together to perform a specific function
  • Organism: A group of organ systems which coordinate with each other to create an effective functioning of the body
  • %%Cell → Tissue→ Organ → Organ System → Organism%%

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Size of Specimens

  • Size of a structure or an organism
  • Magnification = Measured length / Actual length   * Magnification has no units so is represented as eg. x100   * The image size is usually given in centimeters (cm) or millimeters (mm) so make sure to @@convert both the actual size and image size units to be the same to get the correct magnification@@     * 1cm = 10mm     * 1mm = 1000μm (micrometer)

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