Anatomy of the Eukaryotic Cell

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Anatomy of the Eukaryotic Cell

• This lecture will be a brief review of eukaryotic
  structure and function. It is important that you
  have a clear understanding of these concepts so
  that you can move on to prokaryotic cellular
  structure and function.

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Structures external to cell wall

• Some eukaryotic cells have appendages for
  motility. Motility is important for the organism
  to acquire nutrients and get away from toxic or
  harmful things in the environment.
• Flagella on eukaryotic cells are few in number (1
  or ) and long.
• Flagellar movement is wavelike, like cracking a
  whip.
• Cilia are also used for motility.
• They are more numerous and much shorter than
  flagella (resemble hairs). They work like oars
  on a boat for move the cell from place to place.
• Fewer types of cells have cilia as compared to
  those that have flagella.

3
Structures External to Cell Wall Continued

• Glycocalyx outermost covering found on most
  cells.
• The glycocalyx is usually composed of sugars.
• It functions to strengthen the cell surface.
• It aids in adherence to other cells and surfaces.
• It is important in signal reception between cells
  and the environment.
• Generally the glycocalyx is categorized as either
  a capsule or a slime layer.
• Ex. The glycocalyx is like the sugar coating on a
  jawbreaker. Underneath that first colored sugar
  coating there are many other layers.

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Cell Wall

• Not all eukaryotes have a cell wall.
• Plants and most algae have a cell wall composed
  of cellulose. Other cell walls are composed of
  pectin, mannans and minerals.
• Fungi have cell walls composed of chitin.
• Chitin is the same component that makes up the
  exoskeleton of crustaceans and insects.
• The cell wall provides structure and shape to the
  cell. For example, plant cells look rectangular.
  It is the cell wall that holds the cell in that
  particular shape.

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Cell/Plasma Membraneaka. Cytoplasmic Membrane

• The cell membrane is a phospholipid bilayer.
  That means that each half of the membrane is
  composed of a phosphate group with 2 lipid chains
  attached to it. (See diagram on next page.) You
  can also find a diagram of a phophate group on
  page 44 of your textbook.
• Within the lipid bilayer there are proteins.
  These proteins are often used to transport
  nutrients into the cell and waste outside of the
  cell.
• The cell membrane also acts as a selectively
  permeable barrier for the transport of nutrients
  into and out of the cell.
• In addition it encloses the cells organelles.

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Structure of the Cell Memrane
Outside Cell
Phosphate Group
Lipid or fat chain
Important!
The phosphorus loves the protons from the oxygen.
It pulls the protons towards it and leaves the
electrons on the outer edge of the oxygen. This
creates a slight negative charge on the phosphate
group. Ultimately the cell membrane is
negatively charged.
Transport protein within cell membrane
R
O
-
P
O
O
Inside Cell
Phosphate group looks like this
O
R
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Structures inside cell membrane

• The cell membrane encloses the cytoplasm. The
  cytoplasm is composed of a large amount of water.
  It is a substance in which various cellular
  components are found.
• It contains the cells organelles.
• It contains microfilaments, a network of protein
  strands used by phagocytes to form pseudopods.
• It also contains microtubules, which are long,
  hollow tubes used for structure inside eukaryotic
  cells without a cell wall.
• Microtubules also transport substances from one
  part of cell to another.

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• In addition, the cytoplasm houses the organelles.
  Organelles are structures within the cell that
  have specific shapes and specialized functions.
• Organelles are found only eukaryotic cells.
• The nucleus is the organelle that contains DNA,
  the genetic material of the cell.
• The nucleus contains the nucleolus. It is the
  site for rRNA (ribosomal RNA) synthesis.
• The Endoplasmic Reticulum (ER) is the factory for
  protein and lipid synthesis.
• Rough ER has ribosomes attached to the outside.
  Its job is to synthesize protein, (specifically
  proteins headed for the cell membrane).
• Smooth ER has no ribosomes. Its function is to
  synthesize lipids.

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• There are also free ribosomes, meaning that they
  are not bound to the ER, in the cytoplasm. Free
  ribosomes synthesize protein used inside cell.
• The Golgi Complex (or Golgi Apparatus) is the
  post office for proteins. It packages and
  addresses the proteins for their final
  destination inside the cell.
• The Mitochondria is the power house of the
  cell. It is responsible for ATP synthesis.
• Aka. site of cellular respiration

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• Other types of organelles that some cells have
  are
• Lysosomes, which store digestive enzymes that are
  used by the cell to break down nutrients into
  units small enough to be utilized by the cell.
• Vacuoles, which are temporary storage for
  proteins, sugars, organic acids, and inorganic
  ions.
• Peroxisomes, which oxidize toxic substances into
  hydrogen peroxide. They also contain the enzyme
  catalase, that functions to safely decompose
  hydrogen peroxide into substances that are not
  harmful to the cell.
• Now complete the homework for Lecture 2. It is
  due on Friday, September 8 at midnight.