The Eukaryotic Animal Cell by sdfwerte

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									              AS BIOLOGY
       The ultrastructure of the cell
LEARNING OBJECTIVES
By the end of this section you should be able to:-
• Recognise the following organelles from a diagram of the
  eukaryotic animal and plant cell (rough and smooth endoplasmic
  reticulum, Golgi apparatus, mitochondria, ribosomes, lysosomes,
  chloroplasts, plasma (cell surface) membrane, nuclear envelope, centrioles,
  nucleus, nucleolus and cilia).
• Outline the functions of the following structures:-rough and
  smooth endoplasmic reticulum, Golgi apparatus, mitochondria, ribosomes,
  lysosomes, chloroplasts, plasma (cell surface) membrane, nuclear
  envelope, centrioles, nucleus, nucleolus and cilia.
            The Eukaryotic Cell
The Beginnings
•Robert Hooke was the first person to observe cells in 1665.
•He looked at thin slices of cork under a very simple microscope.
•The cork appeared as little boxes which he called cells.
•In 1883 MathiasSchleiden and Theodor Schwann proposed that all
plants and animals were composed of cells which were the basic
building blocks of life.
•In 1855 Rudolf Virchow stated that new cells arise from the
division of pre-existing cells and that chemical reactions needed for
life occurred inside the cell.
•All this work led to the formation of the cell theory (click to
complete exercise on cell theory)

•For more information click on link below
http://fig.cox.miami.edu/~cmallery/150/unity/cell.text.htm
             Eukaryotic Animal Cell
• Eukaryotic means “true nucleus”
• Eukaryotic cells have a nucleus which contains the
  DNA.
• Eukaryotic animal cells are surrounded by a cell
  membrane.
• Inside is the jelly like substance called cytoplasm.
• Contained in the cytoplasm is the nucleus and other
  organelles (copy the glossary file into your area and continue to add words and meanings)
• The other cell organelles include the endoplasmic
  reticulum,(rough & smooth) mitochondria, Golgi
  apparatus, ribosomes, lysosomes, centrioles, cilia,
  nucleolus.
        Endoplasmic Reticulum
           STRUCTURE                           FUNCTION
• Complex system of sheet like   •   Forms an extensive transport
  double membranes continuous        system
  with the nuclear membrane      •   Site of protein synthesis
• Fluid filled spaces/sacs           (Rough ER)
  between the membranes          •   Site of lipid, steroid and
  called CISTERNAE which             carbohydrate synthesis
  allow materials to be              (smooth ER)
  transported through cell       •   Stores and transports these
• Two types of ER –                  materials
   – smooth – has no ribosomes   •   SEE DIAGRAM
     attached (RER)
   – rough – has ribosomes
     attached (SER)
                         Mitochondria
              STRUCTURE
•   Relatively large organelle
                                                         FUNCTION
•   Rod/sausage shaped – 1um –
    5um
•   Have a double membrane                 •   Site of aerobic respiration (Krebs
                                               cycle & oxidative phosphorylation)
      – The outer controls the entry &
         exit of materials                 •   Responsible for the production of
                                               energy rich ATP molecules
      – Inner has many folds called
         cristae                           •   The numbers of mitochondria
                                               reflect the metabolic activity of the
•   Surface of each crista is covered          cell – so large numbers are found
    with stalked particles where ATP           in muscle and liver cells
    is made
                                           •   SEE DIAGRAM
•   Mitochondria are filled with a jelly
    like matrix
•   The matrix contains proteins,
    lipids, ribosomes and loops of
    DNA
•   Mitochondria can replicate
    themselves when the cell divides
                   Golgi apparatus
            STRUCTURE                              FUNCTION
•   Formed from small pieces of       •   Assembling glycoproteins
    rough ER which form small             (such as mucin) by combining
    vesicles which join to make a         carbohydrate and protein
    Golgi body                        •   Transporting and storing lipids
•   Chemicals made in the ER          •   Formation of lysosomes
    collect in the Golgi body where   •   Producing digestive enzymes
    they are modified
•   Small vesicles can then be        •   Secretes carbohydrates which
    „pinched‟ off the Golgi body          are used in the formation of
    carrying new chemicals away           plant cell walls and in insect
    which are secreted when the           cuticles
    vesicle reaches the cell          •   SEE DIAGRAM
    membrane
•   Some of the vesicles become           What have you learnt?
    lysosomes
                                          Click here to walk the plank
                       Ribosomes
STRUCTURE                            FUNCTION
• Small dense structures found       • Synthesize proteins
  in huge numbers.                   • Synthesize enzymes
• Can be attached to the rough
  ER of floating in the cytoplasm.   • SEE DIAGRAM
• Are about 20 – 25 nm in
  diameter in eukaryotic cells
  and slightly smaller in
  prokaryotic cells
• (80s type – prokaryotic)
• (70s type – eukaryotic)
• Made up from two sub units
                      Lysosomes
STRUCTURE                          FUNCTION
• Small vacuoles formed when       • Release enzymes which
  small pieces of Golgi body are     destroy worn out organelles
  pinched off                      • Digest material taken into the
• Contain hydrolytic enzymes         cell (eg white blood cells which
  which digest materials in the      have engulfed a bacterium) –
  cell                               phagocytosis
                                   • Release enzymes to the
                                     outside of the cell which digest
• SEE DIAGRAM                        material around the cell –
                                     exocytosis
                                   • Completely break down cells
                                     after they have died – autolysis
Plasma (cell surface) membrane
STRUCTURE                        FUNCTION
• This is the boundary between   • Controls movement of
  the cell cytoplasm & the         substances in & out of the cell
  environment                    • Forms a recognition site so
• Is partially permeable           that the body‟s immune system
• Made up 45% protein & 45%        can recognize its own cells
  phospholipids with the         • Acts as a receptor site for the
  remaining 10% cholesterol,       attachment of specific
  glycoprotein & glyolipids        hormones and
                                   neurotransmitters.

                                 • SEE DIAGRAM
                  Nucleus, Nucleolus &
STRUCTURE
                   Nuclear envelope
•   Largest organelle in the cell (10um         FUNCTION
    diameter)
•   Surrounded by a nuclear membrane
    / envelope                                  •   Acts as the control centre of the
                                                    cell through the production of
•   Double membrane – outer is                      mRNA and protein synthesis
    continuous with the ER
                                                •   Retains the genetic material in the
•   Nuclear pores in the membrane                   cell in the form of DNA /
    allow the passage of large                      chromosomes
    molecules in & out (eg
    messengerRNA)                               •   Manufactures ribosomal RNA
                                                    (rRNA) & ribosomes
•   Material inside the nucleus is called
    nucleoplasm – this contains                 •   Starts the process of cell division
    chromatin which makes up the DNA
    of the cell – in non-dividing cells it is   •   SEE DIAGRAM
    spread out and during cell division it
    condenses to form the
    chromosomes                                 •   What have you learnt?
•   A spherical structure called the            •   Click here to complete the
    nucleolus is found in the nucleus –             crossword
    this makes ribosomal RNA and
    assembles the ribosomes.
                         Cilia
STRUCTURE                     FUNCTION
• 3-10 um in length, 0.2um    • To move an entire
  in diameter                   organism (eg in
• Made of rings of 9 pairs      paramecium it propels it
  of microtubules               through the water)
• Have basal body             • To move material within
  embedded in cytoplasm         an organism ( eg cilia in
• Rest extends from basal       the lining of the
  body                          respiratory tract)
• Only a few types of cell
  possess cilia               • SEE DIAGRAM
• On cells which have cilia
  there are large numbers
              CENTRIOLES
         (not found in plant cells)
• Two short bundles of hollow cylinders (microtubules)
  positioned at right angles to each other
• Found just outside the nucleus in a clear area of
  cytoplasm called the centrosome
• Wall of each centriole is made of 9 triplets of tubes
  arranged at an angle
• During cell division they migrate to opposite poles to
  produce the spindle – which helps to move the
  chromosomes during cell division

• SEE DIAGRAM
                         Chloroplasts
•   Found inside photosynthetic tissues of plants (abundant in palisade
    mesophyll cells of leaves)
•   Flat discs 2-10 um in diameter & 1um thick
•   Have a double membrane called the chloroplast envelope
•   Inner membrane folded into a series of lamellae
•   Membrane controls the entry & exit of substances
•   Inside the membrane is a fluid – stroma – which contains the enzymes
    involved in photostnthesis
•   Small amounts of DNA and oil are found in the stroma
•   In stroma is a network of flattened sacs called thylakoids
•   Grana (granum = sing) are formed when many thylakoids are stacked
    together (like a pile of coins) (thylakoids also called lamella)
•   Chlorophyll molecules are attached to the thylakoids
•   Large starch grains are also present which act as a tempory store of
    charbohydrate made in photosynthesis
•   SEE DIAGRAM
•   Click here to label the eukaryotic animal cell
Click here to play cell organelles
          catch phrase

								
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