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• Idea – get them to do the slides for the
organelles!
CELL THEORY
 All living things are made up of one or more cells.
 The chemical reactions of a living organism take
place within cells.
 All cells are formed from pre-existing cells and
these cells contain the hereditary information.
 Cells vary in size, shape, function and life span
 The cell is the smallest organisational unit
Properties of cells
• Most cells have some common features:
Plasma membrane
• The cell membrane is a structure that forms the outer boundary
of the cell and allows only certain materials to move into and out
of the cell. Food, oxygen and water move into the cell through
the membrane. Waste products also leave through the
membrane. Cells that perform photosynthesis (plants and some
protists) take in carbon dioxide through the cell membrane
instead of oxygen.
• The cell membrane is like a gate because it allows only certain
materials to move in and out of the cell
Properties of cells
Properties of cells
• Most cells have some common features:
Cytoplasm
• Gel-like material inside the cell membrane and outside
the nucleus.
• Cytoplasm contains a large amount of water and many
chemicals and structures that carry out the life
processes in the cell. These structures that the
cytoplasm contains are called organelles.
• Cytoplasm is the jelly-like material inside the cell (but
unlike gelatin it does flow; cytoplasm constantly
moves or streams.
Properties of cells
• Most cells have some common features:
Nucleus
The largest organelle in the cytoplasm of a cell is usually the nucleus,
a structure that directs all the activities of the cell. The nucleus
contains genetic blueprints for the operations of the cell.
• The nucleus is a highly specialized organelle that serves as the information
and administrative center of the cell. This organelle has two major
functions. It stores the cell's hereditary material, or DNA, and it
coordinates the cell's activities, which include intermediary metabolism,
growth, protein synthesis, and reproduction (cell division).
Properties of cells
• Most cells have some common features:
Flagella or Cilia
• Many cells have extensions called flagella (whip-like processes) or cilia
• (small hair-like structures) that are used for movement either of the cell
itself or of the medium surrounding the cell.
Types of cells
• There are two types of cells
• Organisms are grouped according to what type of cell they have
• Prokaryotes - have cells with a ‘primitive’ nucleus and lack membranebound organelles. Prokaryote cells contain a single, circular DNA
chromosome. (unicellular or simple multicellular organisms - Bacteria,
cyanobacteria) (pic pg 23)
• Eukaryotes- have cells that are usually much larger and more complex
than prokaryote cells. They have a membrane-bound nucleus, and their
cytoplasm includes specialised membrane-bound structures called
organelles. Many of their cellular processes take place within these
membrane-bound subcellular compartments. (protists, fungi, plants &
animals
Cell Organelles
Overview
Mitochondrion
• Cells require a continuous supply of
energy.
• Organelles where:
– food molecules are broken down.
– energy is released.
• The energy is then stored in other
molecules that can power cell reactions
easily.
• Mitochondria (plural) – use when you
refer to more than one mitochondrion.
Nucleus
• Usually the largest organelle in the
cytoplasm of a cell.
• Directs all the activities of the cell.
• Contains genetic blueprints for the
operations of the cell.
Centrioles
•
•
•
•
Self-replicating organelles
Made up of nine bundles of microtubules
Found only in animal cells.
Help in organizing cell division.
Cell membrane
• Forms the outer boundary of the cell.
• Allows only certain materials to move into and out of
the cell.
• Food, oxygen and water move into the cell through
the membrane.
• Waste products also leave through the membrane.
• Cells that perform photosynthesis (plants and some
protists) take in carbon dioxide through the cell
membrane instead of oxygen.
Cell wall
• The cell wall is a rigid structure outside
the cell membrane that supports and
protects the cell (for plants, fungi, and
some protists and bacteria but NOT
animals).
• Animal cells DO NOT have a cell wall.
• The cell wall is made of tough cellulose
fibres and other materials made by the
cell.
• Note: fungal cell walls contain chitin
instead of cellulose.
Cytoplasm
• Gel-like material inside the cell membrane
and outside the nucleus.
• Cytoplasm is the jelly-like material inside
the cell (but unlike gelatin it does flow;
cytoplasm constantly moves or streams.
• Contains a large amount of water (cytosol)
and many chemicals and structures that
carry out the life processes in the cell.
• The structures that the cytoplasm
contains are called organelles.
Endoplasmic reticulum
• A folded membrane that moves materials around
in the cell.
• Extends from the nucleus to the cell membrane
and takes up quite a bit of space in some cells.
• Two different types: Smooth ER and Rough ER.
Rough ER has ribosomes attached to its outer
membrane, while Smooth ER does not.
Golgi bodies
• Golgi bodies package and move proteins
• In a business, products are made, packaged, and moved
to loading docks to be carried away.
• In cells, structures called Golgi Bodies are stacks of
membrane-covered sacs that package and move
proteins to the outside of the cell.
• When something is secreted, it is given off by the cell.
• Note: Golgi Bodies are sometimes referred to as Golgi
Apparatus.
Vesicle
• Vesicles transport proteins.
Chloroplasts
• Chloroplasts take in sunlight,
water and carbon dioxide to
make oxygen and sugar.
• This process is called
photosynthesis.
• A plant's chloroplasts
convert light energy into
chemical energy.
• Contain a green pigment
called chlorophyll. This is
what makes plants green.
Vacuole
• Acts as a temporary storage space for the
cell.
• Vacuoles store water, food, pigments,
waste or other materials.
• Vacuoles are large in plant cells and small
in animal cells.
• Vacuoles can also be found in fungi and
protists.
Lysosomes
• An active cell constantly produces waste
products.
• Contain chemicals (enzymes) that:
– digest wastes and worn-out cell parts
– break down food.
Ribosome
• One chemical that takes
part in nearly every cell
activity is protein.
• Proteins are needed for
chemical reactions that
take place in the
cytoplasm.
• Cells make their own
proteins on small
structures in the
cytoplasm called
ribosomes.
Cilia and Flagella
• For single-celled eukaryotes, cilia and flagella are
essential for the locomotion of individual
organisms.
• In multicellular organisms, cilia function to move
fluid or materials past an immobile cell as well as
moving a cell or group of cells.
– Cilia lining nasal passage
– Sperm
Microfilaments
• Solid rods made of globular proteins called actin and are common to
all eukaryotic cells.
• Long chains of the molecules are intertwined in a helix to form
individual microfilaments.
• Filaments are primarily structural in function and are an important
component of the cytoskeleton, along with microtubules.
• In association with myosin, microfilaments help to generate the forces
used in cellular contraction and basic cell movements.
• They enable a dividing cell to pinch off into two cells and are involved
in amoeboid movements of certain types of cells.
• They also enable the contractions of muscle cells.
Microtubules
• Straight, hollow cylinders are found
throughout the cytoplasm of all eukaryotic
cells (prokaryotes don't have them) and
perform a number of functions.
• Gives structure and shape to a cell,
• Serve as conveyor belts moving other
organelles through the cytoplasm
• Are the major components of cilia and
flagella, and participate in the formation of
spindle fibers during cell division (mitosis).
• These filaments are composed of linear
polymers of tubulin, which are globular
proteins, and can increase or decease in
length by adding or removing tubulin
proteins.
Plant cell
Animal cell
Copy down the characteristics of cells in the 5
kingdoms
pg 26
HW - Q 1- 8