The smallest structural unit of an organism that is capable of independent functioning, consisting o

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What is a cell?
The smallest structural unit of an organism that
is capable of independent functioning, consisting
of one or more nuclei or nucleoid, cytoplasm,
and various organelles, all surrounded by a
semipermeable cell membrane Remember that
fungi are multinucleate (more than one nucleus)
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Multinucleate
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Independent functioning whats that?
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Independent functioning whats that?

• Must be able to gain its food
• Must be able to remove its wastes
• Must be able to reproduce
• (either by itself, ASEXUALLY, or with
  another, SEXUALLY)

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How small is small?
1/10 mm or 100µm
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How small is small?
Members of Kingdom Monera (Bacteria) are
typically 1-5 µm in length If we took a 5 µm
bacteria cell and laid 200 of them end to end
they would stretch 1mm in distance Then there is
the nanobacteria Nanobacteria can be less lt50
nm (nanometres) How big is a nanometre?
one-billionth of a metre A pin-head is over a
million nm across
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The main parts of a cell
Genetic material / Nuclei All cells contain
genetic material in the form of DNA. In
prokaryotic cells the region containing the DNA
is the nucleoid. NOT NUCLEUS. The nucleoid is one
long, single molecule of double stranded,
helical, supercoiled DNA. In most bacteria, the
two ends of the double-stranded DNA covalently
bond together to form both a physical and
genetic circle. This is not contained within a
membrane. In eukaryotic cells the genetic
material is bound in a membrane. This structure
is called a nucleus. Cell membrane (or Plasma
membrane) The cell membrane separates the
internal cellular environment from the external
environment and regulates the entry and exit of
materials to and from the cell. The membrane is
semi-permeable. This means some molecules can
move freely through via osmosis or diffusion,
while other molecules have to be actively
transported across the membrane (ie energy is
used). All cells have a cell membrane, some also
have a cell wall.
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The main parts of a cell
Cytoplasm is a homogeneous, generally clear
jelly-like material that fills cells. The
cytoplasm consists of cytosol and the cellular
organelles, except the nucleus. The cytosol is
made up of water, salts and organic molecules and
many enzymes that catalyse reactions. The
cytoplasm plays an important role in a cell,
serving as a "molecular soup" in which the
organelles are suspended and held together by a
fatty membrane. It is found within the plasma
membrane of a cell and surrounds the nuclear
envelope and the cytoplasmic organelles.
Organelles one of several structures with
specialized functions, suspended in the cytoplasm
of a cell. Think of the human body as a cell.
Our organs (heart, lungs, kidneys) have
specialised roles, within the organism.
Organelles are similar. They perform specialised
roles within the cell to undertake cell function.
You should know several organelles and their
roles, particularly chloroplasts and mitochondria.
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Organelles (1) nucleolus (2) nucleus (3)
ribosome (4) vesicle,(5) rough endoplasmic
reticulum (ER), (6) Golgi apparatus, (7)
Cytoskeleton, (8) smooth ER, (9) mitochondria,
(10) vacuole, (11) cytoplasm, (12) lysosome, (13)
centrioles
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All living things are constructed from small
units called CELLS
Some of the more simple forms of life are
UNICELLULAR. These include Nearly all
Bacteria Protozoans Fungi
Animals, plants and some bacteria, protozoans and
fungi are MULTICELLULAR This means they are made
of two or more cells.
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There are two main types of cells Prokaryotic
Eukaryotic
The presence or absence of a nucleus defines
this Genetic material NOT contained in a
membrane-bound nucleus PROKARYOTIC Genetic
material contained in a membrane-bound nucleus
EUKARYOTIC
All Prokaryotic organisms are found in Kingdom
Monera All other Kingdoms (Protista, Fungi,
Plantae, Animalia) consist of Eukaryotic organisms
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Features of Kingdom Monera (Prokaryotae)

• Typically unicellular, rarely more
• Lack nucleus and organelles - their genetic
  information is not contained within a nucleus
• Cell walls made of carbohydrates and proteins
• Reproduce asexually (split in half)
• Small 1-5 µm (1/1000 5/1000 of a millimeter)
  though can be larger
• Inhabit nearly every conceivable habitat on Earth

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Cell Wall / Cell Membrane
All cells have a cell membrane. This controls the
movement of molecules from the internal cell
environment to the outside environment (and visa
versa) Bacteria, Fungi, Plants and Algal
Protists also have a cell wall. A cell wall is
on the outer of the cell and provides structural
support Cells interact though plasmodesmata,
which are inter-connecting channels of cytoplasm
that connect to the protoplasts (cell membrane,
cytoplasm, organelles) of adjacent cells across
the cell wall.
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Why dont we get MASSIVE cells?
SA V
Surface Area to Volume Ratio
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Osmosis movement of water through a
semipermeable membrane from a solution with a
low solute concentration to a solution with a
higher solute concentration until there is an
equal concentration of fluid on both sides of the
membrane Diffusion the random movement of
particles to reach equilibrium Active
Transport the use of energy to transport
material
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Dont forget to mention osmosis, diffusion and
active transport. These are the way cells gain
food and remove wastes and they are the key
reason cells are generally small (got to do with
SAV) So dont forget to mention them! Enjoy
your prac!