cell membrane, transport, enzymes, & energy · plasma/cell membrane the cell membrane is the...
TRANSCRIPT
Cell Membrane, Transport, Enzymes, & Energy
Unit 4 Review
The Cell
Membrane
helps maintain
Homeostasis
by regulating
transport of
materials in/out
of the cell.
Function of the Cell Membrane
The Cell Membrane is like the
of the cell because it controls what can come in and out of
the cell.
Security Guard
PLASMA/CELL MEMBRANE
The Cell Membrane
is the barrier between
the cytoplasm and the
ExtraCellular Fluid
(outside)
of the Animal Cell.
In Plant Cells (and
other types), it
separates the
cytoplasm from the
Cell Wall.
Cell Membrane Structure
Cholesterol adds structure and stability to the cell membrane. It makes up about 20% of the cell membrane.
Carbohydrate chains (glycolipids & glycoproteins) are always on the OUTSIDE of the membrane.
Phospholipids make up the majority of both layers of the cell membrane.
Phospholipids
Hydrophobic fatty acid tails = repel water
Hydrophilic phosphate heads = love water
Phospholipid Bilayer
This process is called Diffusion.
Solute
Solvent
The sugar molecules are
spreading out.
Molecules always move from HIGH concentration to
LOW concentration. It takes added ENERGY to move
from low concentration to high concentration.
Semipermeable means that it is selective about what
can enter or leave, kind of like a picky eater.
Molecules that easily diffuse across the membrane are
Hydrophobic (O2/CO2) or SMALL & Uncharged/Polar (H2O).
Sugars can NOT diffuse because of SIZE (too big). Ions can NOT diffuse
because of CHARGE (charged & large molecules can not get across).
Does the cell have to use energy for this? NO
This is called PASSIVE Transport.
This is called
moving WITH the
concentration
gradient (HIGH
to LOW).
The diffusion of WATER is
called OSMOSIS.
This means that H2O is moving from
where there is MORE H2O & LESS
solutes TO where there is LESS H2O &
MORE solutes.
Does the cell have to use energy for this? NO
This is called PASSIVE Transport.
Hypotonic Solution = Cell swells because H2O diffuses (osmosis) INTO the cell.
Animal cells may burst. Plant cells have increased turgor pressure but are protected by their cell walls.
Isotonic solution = SAME concentration as the cytoplasm of the cell. H2O diffuses (osmosis) IN & OUT
of the cell at the same rate. The cell stays the same size.
Hypertonic Solution = Cell shrinks because H2O diffuses (osmosis) OUT of the cell.
Facilitated Diffusion
Large or polar
molecules MUST
diffuse through a
Channel Protein
LOW Concentration
HIGH Concentration
Co
ncen
tration
Grad
ient
Does the cell have to use energy for this? NO
This is called PASSIVE Transport.
HIGH Concentration
LOW Concentration
Active Transport
LOW Concentration
HIGH Concentration
MUST USE
ENERGY
ACTIVE TRANSPORT
This is moving AGAINST the
concentration gradient
(LOW to HIGH)
Does the cell have to use
energy for this? YES
That is why it is called
ACTIVE Transport!
(ATP is the energy molecule)
ENERGY
The Na+/K+ Pump moves 3 Na+ ions out of the cell & 2 K+ ions into the cell
for every molecule of ATP. This ION PUMP controls Neuron function.
This is called the SODIUM (Na+)/POTASSIUM (K+) Pump
Active Transport!
Paramecia have a
Contractile Vacuole that
allows water to be pumped
OUT of the cell because
they live in a HYPOTONIC
environment. This takes
ENERGY but it allows them
to maintain
HOMEOSTASIS.
Contractile Vacuoles
Other Transport Mechanisms
Into
the
cell
Out of
the
cell
Import Export
Pinocytosis = takes in fluid
Phagocytosis = takes in food/large particles Receptor Mediated = will only
take in specific molecules
Types of Endocytosis
Vesicle from Golgi Apparatus
ENZYMES ENZYMES are
PROTEINS that are used in many chemicals
reactions.
They are necessary for living things because
they SPEED UP (accelerate) important chemical reactions by lowering the amount of ACTIVATION ENERGY
needed to start the reaction.
Enzymes & Substrates have to fit together
(complementary shapes) at the ACTIVE SITE
so they are very specific
Enzymes are reusable because they are not
permanently changed in the reaction.
Enzymes help weaken or form chemical bonds so that the reaction takes
less energy to occur.
Activation energy is like
the COST of the reaction
& the enzyme is like a
COUPON because it
lowers the cost.
Higher Cost (more energy required)
LOWER Cost (less energy required)
Reactants =
SUBSTRATES
Substrates bind to
the enzyme at the
ACTIVE SITE to
provide a place for
the reaction.
Enzyme-Substrate Complex
The Enzyme is NOT permanently
CHANGED in the reaction = Reusable
The Cell’s Energy Molecule = ATP
Adenine Ribose 2 Phosphate
groups
3rd Phosphate group
Adenosine
triphosphate
ATP = Adenosine Triphosphate
Chemical bonds
store ENERGY
ATP - P = ADP
RELEASES energy
This is called HYDROlysis
ADP ATP
ADP + P = ATP
STORES energy
Glucose gets broken down during
Cellular Respiration so that
energy can be stored in ATP.
This is called PHOSPHOrylation
produces
Is broken down during The products go through the
occurs in the occurs in the
produces
produces
32
TOTAL
36
Cellular Respiration Equation
C6H12O6 + 6O2 6CO2 + 6H2O + 36ATP