Download Cell Functions

Important Actions of the Cell
Homeostasis
Process of maintaining a cell’s environment
Keeping everything in balance
Selective Permeability
Cell allows only certain things across membrane at certain
times
It’s selective
Movement of Materials Across Cellular
Membrane
Simple Diffusion
Movement of particles across cellular membrane
Caused by the concentration a specific material on one side of
the membrane being higher or lower than the concentration on
the other side
Happens automatically
High concentration low concentration
o (Ex. calcium ions)
Facilitate Diffusion
Assisted movement of particles across a cellular membrane
Protein carriers move materials
High concentration low concentration
Osmosis
Water moving across cellular membrane
Happens by simple diffusion
High concentration low concentration
Do not want this to happen unchecked
o Or cell could explode (takes in too much water) or deflate
(looses too much water)
Osmotic pressure – pressure required to stop the flow
Active Transport
Forced movement of particles across a cellular membrane
Low concentration high concentration
Requires a lot of energy
 Allows cell to take in substances that are in low concentrations in
the environment around the cell

And allows cell to concentrate different substances within itself
How the cell takes in and remove particles
Done by using vesicles (small membrane bound sacs)
Allow large quantities of materials across the membrane
Endocytosis
o Cells take in materials using vesicles
Phagocytosis
o Cell takes in solid material
Pinocytosis
o Cell takes in liquids
Exocystosis
o Cells remove materials using vesicles
Fluid Types (based on how the cells react)
Isotonic
No change in the cell
Same amount of water and ions flowing into and out of the
cell
o
*ions* atoms that have an electrical charge
Hypertonic
Cells shrink and shrivel
Lower water concentration out of the
cell, higher conc. of ions
Hypotonic
Cell swells & can burst, cell fills with water
Higher concentration of water outside the cells, lower conc. of ions
Cell walls prevent bacteria, algae and plants cells from bursting or
shrinking too much (wilt), unless the cell wall is weakened.
Energy Reactions
Photosynthesis
Only in plants, algae, and some photosynthetic bacteria
Occurs in the plastids, most commonly chloroplasts
Take in sunlight and turn it into glucose (stored energy)
o 6CO2 + 6H 20  C6H12O 6 (glucose) + 6O2
½ of all atmospheric Oxygen comes from algae
and photosynthetic bacteria
rest comes from plants
Cellular Respiration (How the cell breathes & eats)
Break down nutrients to CO2 and water
Allows cell to take in different gases and release waste gases
Needs to occur in the presence of oxygen
Major energy activity (How cells get some of their energy)
o C6H12 O6 +6O2  6H2 0 + energy
(glucose)
Electron Transport Chain
o Uses part of the energy released in cellular respiration to
form ATP (Adenine Triphosphate)
high energy compounds
Use a bit of energy to make “super battery cells” used in
almost all cellular functions
The phosphate groups can be broken off to release huge
amounts of energy
Glycolysis
Process used to break down glucose (sugar)
Does not require oxygen, but it can occur in the presence or
absence of oxygen
Cell gets a relatively small amount of energy
Fermentation
Process used to break down glucose or other sugars
Cannot occur in the presence of oxygen
Cell gets a relatively small amount of energy
Many types of fermentation (depends on type of cell and what it
is breaking down)
o Usually give off gas (CO2)
o Some bacteria & cells create lactic acid
Cheese, yogurt, muscle pain
o Yeast (& a very few bacteria) can create ethyl alcohol

Beer, wine, bread, pickled foods (sauerkraut)