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Cells
The Basic Units of Life
Cell Structures
Cell Membrane
O Look: a thin line that surrounds
the whole cell
O Function: - barrier between
inside/outside
and what comes
in/out
- helps with
shape/form
Cell Wall
O Look: a rigid, frame-like covering that
surrounds the cells
O Function: - helps regulate pressure in the
cell (too much water in or out)
- also protects the cell
- only in plant cells
Cytoplasm
O Look: a liquid inside the cell, grainy look
O Function: - the “kitchen” of the cell
- contains nutrients cell needs to
maintain life processes
Nucleus
O Look: a fairly large, dark, circular structure
usually near the center of the cell
O Function: - a “command center”
- directs all cellular activity (i.e.: growth, movement)
Vacuoles
O Look: clear, liquid-filled space in various places
within the cytoplasm
O Function: - a “storage room” for nutrients, waste, etc…
- many in animal cells, plant cells 1 big one
P.C.
A.C.
Chloroplasts
O Look: medium sized, green circular shaped
structures, typically around edges of cell
O Function: - solar panel of the cell & found on green
parts (i.e.: leaves)
- perform photosynthesis & only plant cells
Animal Cell
Plant Cell
Organelles
O Most cellular life cannot be seen with a light
microscope
O Problem solved with electron microscope
Organelles
O Organelles: specialized structures that carry
out specific functions
O Cells work just like mini factories in that they
have specialized areas to accomplish
specific tasks
Organelles
O Mitochondria: - “powerhouse” of the cell
- chemical reactions occur
here converting energy cell
receives to form it can use
Uni vs. Multi Cellular
O Smallest known organism is the
mycoplasma which is magnified 18000x to
be viewed
O This is a
single cell
organism
(as are most
bacteria)
Uni vs. Multi Cellular
O Largest known animal is the blue whale, it
can be 30m long
O It is a
multicellular
organism
(as most
plants/
animals are)
UniCellular
O Not all unicellular organisms are simple
O See: Diatoms
Amoeba
O Common unicellular organism
O Lives in water
O Moves using tiny foot-like projections
(pseudopods)
O Uses them to eat too
- engulfs food creating a vacuole then
digests it into cytoplasm
Paramecium
O Another Common unicellular organism
O This has tiny hairs all around it
O Called cilia
O They use it to move (like tiny oars) and to eat
(sweeps food down into oral grooves where
eaten)
Substance Movement
O Every second of every day your cells are moving
things (waste, energy, nutrient, etc…)
O This is vital for survival
O Cells have a structure that permits vital exchange
of substances  cell membrane
O Process is typically via diffusion
Diffusion & Osmosis
O Diffusion is key for plant roots
O Moving and distributing evenly from areas of
higher concentrations to lower concentration
Diffusion
O So what is it?
O High Concentration to Low Concentration
O An “evening out” process
O Occurs until concentrations are the same everywhere
O How?
O Selectively permeable membrane
O That is to say it allows certain things in (i.e.: oxygen) while
holding what it needs in (i.e.: no cytoplasm leaking out)
O For example: mitochondria need oxygen to function and
diffuses into the cells as needed because the concentration is
higher outside of the cell compared to inside
Osmosis
O Is essentially the same as diffusion but speaking
specifically about water in cells
O Diffusion of water particles through a selectively
permeable membrane
O Water from higher concentration to lower concentration
O Why?
O Water in cells need to stay relatively consistent for proper
cell health and function
Cells Reproduce
O Unicellular organisms grow and develop
O Differences?
O When they reach their max they divide into
two identical organisms
O This is how your cells reproduce as well
O It is how your body replaces the roughly
50000 skin cells it loses each day or repairs
skin when you get scraped or cut
Specialized Cells
O Our bodies are made up of trillions of cells …
many are specialized
O Example:
O Red blood cells carry oxygen, lose nucleus so
they cannot self-reproduce when they mature
and are pliable to fit small spaces
O To reproduce they need other organs/tissues
in the body
O This case blood needs marrow (found in most
bones) to make new cells
Cell Categories
Connective Tissue
Nervous Tissue
Epithelial Tissue
Muscle Tissue
Plant Cell Categories
O Plants are similar in that they have 3 cell categories
O 1) Photosynthesis/Storage
O 2) Protective
O 3) Transport
O No organ systems exist in plants though however they
need the substances produces/provided by the other
cell categories to survive
O Good way to identify them? Look at leaf, stem and
root cells
So ..!
O Here is a question to see if you were paying
attention!
O Is a red blood cell more specialized than an
amoeba or is it the other way around?
O Discuss…
Goodbye Topic 2