Cell Theory O Three Parts O All living things are made up of one or more cells O Cells are the basic...
-
Upload
everett-williamson -
Category
Documents
-
view
215 -
download
0
Transcript of Cell Theory O Three Parts O All living things are made up of one or more cells O Cells are the basic...
Cell TheoryO Three Parts
O All living things are made up of one or more cells
O Cells are the basic units of structure and function
O All cells arise from existing cells
Features of CellsO Cell Membrane:
O Cytoplasm:
Features of CellsO Cytoskeleton:
O Ribosomes:
Cell Membrane
Passive TransportO Movement across cell membrane
that requires no energy
O Mostly occurs through diffusionO Diffusion: movement from area of
high to low concentration
What does this mean?O Concentration gradient:
difference in amount of substance in a space
O Ex: sugar cube in water
DiffusionO Many molecules and ions diffuse in
and out of a cellO This is due to semi-permeable
membraneO Let’s some things in without energy,
some things need energy to get inO Ex: Food coloring in water
EquilibriumO All cells want to reach equilibrium
with concentrationsO Equilibrium: when concentration is
equal throughout the spaceO Ex: when sugar cube dissolves and
water is now equal parts water and sugar throughout
OsmosisO Diffusion of water through semi-
permeable membraneO Three types of solutions result from
osmosisO Hypertonic solutionO Hypotonic solutionO Isotonic solution
HypertonicO Water moves out of cellO Fluid outside the cell has a higher
concentration of dissolved particles than the cytoplasm
O Ex: salt water with egg inside
HypotonicO Water moves into the cellO Fluid outside of cell has lower
concentration of dissolved particles than cytoplasm
O Ex: Water with egg in it
IsotonicO No overall water movementO Fluid inside and outside of cell
appear to be similar in concentration and no water movement is needed
O Ex: When egg and water meet equilibrium
Ion ChannelsO Some substances cross the cell
membrane with help from transport proteins
O Ion channels allow important ions into the cell such as sodium, potassium, calcium and chloride
Facilitated DiffusionO Carrier Proteins bind to specific
substances to carry them across the cell membrane
O Facilitated diffusion moves substances down their concentration gradient without using the cell’s energy
Steps for Facilitated Diffusion
Step 1: a molecule outside the cell binds to a carrier protein on the cell membrane
Step 2: The carrier protein transports the molecule across the cell membrane
Step 3: The molecule is released from the carrier protein inside the cell
Active TransportO The transport of a substance across
the cell membrane against its concentration gradient
Sodium-Potassium Pump
O Transports three sodium ions out of a cell, and two potassium ions into the cell
O Energy needed for processO ATPO Important in animal cells
Sodium-Potassium Pump
Step 1: Three sodium ions inside the cell bind to the pump. A phosphate group from ATP also binds to the pump
Step 2: The pump changes shape, transporting the three sodium ions across the cell membrane. The sodium ions are released outside the cell
Step 3: Two potassium ions outside the cell bind to the pump. The potassium ions are transported across the cell membrane
Step 4: The phosphate group is released and the two potassium ions are released inside the cell.
VesiclesO Some substances are too large to
transport any of the above ways
O Proteins for example use vesicles to move across the cell membrane
EndocytosisO Movement of a substance into a cell
by a vesicle
ExocytosisO Movement of a substance to the
outside of a cell
Signal MoleculesO Binds to a receptor proteinO Can change activity of cell in three
ways:O Enables specific ions to cross the cell
membraneO Cases the formation of a second
messengerO Speeds up chemical reactions inside
cells