Cell Structure and
Function I
Cell Theory
• 1. All living things are made of cells.
• 3. New cells are produced from existing
cells
• 2. Cells are the basic unit of structure
and function in living things.
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Cell Exploration
• Light Microscopes
– Living organisms can be
seen
– Light limits the
resolution
so extremely small
things
like
proteins and viruses
cannot be observed
Cell Exploration
• High resolution video
technology
– Allows scientists to see time
elapsed movies of cells as the
grow, divide and develop.
– http://www.cellsalive.com/mitosis.
htm
Cell
Exploration
• Transmission
Electron
Microscopes
(TEMs)
– Can see more detain and extremely small
structures
– Beams of electrons must pass through
ultra-thin sliced samples therefore no
living things can be seen
Cell Exploration
• Scanning Electron
Microscope (SEMs)
– Beams of electrons
scanned over the
surface of a specimen
– Produces a 3D image
– Samples must be
chemically
preserved
and removed of all
water so no living
Prokaryotes vs.
Eukaryotes
• Prokaryotes
(bacteria)
have no nucleus
and very few
organelles. DNA is
not contained
• Eukaryotes
(protists, fungi,
plants and animals)
larger,more
complex,DNA is
inside the nucleus
Plant Cells Vs. Animal
Cells
• Both plant and animal cells
contain a variety of
organelles. Some
structures are specific to
either plant cells or animal
cells only.
– Only plant cells contain:
• Cell wall
• Chloroplasts
• Large central vacuoles
– Only animal cells contain:
• Centrioles
Smooth ER vs. Rough ER
• Rough ER - ribosomes on the ER
make proteins, the ER modifies the
proteins
• Smooth ER - makes lipids
Mitochondria
vs.
Chloroplasts
• Mitochondria make
energy from chemicals
(food molecules)
• Chloroplasts make
energy
from light
through
photosynthesis
Cytoskeleton
• Network of
protein
filaments
• Maintains
shape
• Involved in
cell
movement
Prokaryotes
DNA is
free
floating
Cell membrane
Contain DNA
Eukaryotes
Nucleus
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Vacuoles
Mitochondria
Cytoskeleton
Cell Structure and
Function II
Cell Wall
• Provides support and
protection for plant
cell walls
• Made of porous cellulose
so it does not regulate
what enters and leaves
Cell Membrane
• Regulates what enters and leaves
the cell and provides support and
protection
• Structure – lipid bilayer with
embedded proteins
Diffusion through Cell Boundaries
• Particles move from an area
of high concentration to an
area of lower concentration
• No energy is required
Osmosis
• Diffusion of water through a selectively
permeable membrane
Is this really Osmosis???
Isotonic
"ISO" means the same
• Concentration of
solutes (salts) is
the same inside
and outside of cell.
• Water flows in and
out in equal
amounts
• No effect on cell
Hypertonic
“Hyper” means more
• Concentration of solutes is
more outside the cell than
inside
• Water flows out of cell
• The cell shrivels and may die.
• This is why it is dangerous to
drink sea water
• This is also why "salting
fields" was a common tactic
during war, it would kill the
crops in the field, thus
causing food shortages.
Hypotonic
"HYPO" means less
• Concentration of
solutes is less outside
the cell than in.
• Water flows in
• The cell swell with
water and becomes
“turgid”
Active Transport
• Carried our by protein pumps found
in the membrane
• Energy is required
Facilitated Diffusion
• Molecules move through protein
channels.
• No energy required
Endocytosis
• Cell takes material into cell by infolding of the cell
membrane
• Phagocytosis – eating – cell engulfs large particles
• Pinocytosis – drinking – cell takes in liquid
• www.endocyte.com/ animation/animation.htm
Exocytosis
• Cell releases large
amounts of material
Cell Specialization
• The cells in multicellular organisms can develop in
different ways to perform different tasks.
Levels of
Biological
Organization
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Organism
Organ system
Organ
Tissue
Cell
Organelle
DNA
Atoms