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1b) proteins in membranes - Coggle Diagram
1b) proteins in membranes
Cell membrane
The
boundary
that
separates
the internal living
contents
of a cell from its
external
surroundings.
It controls what
enters and leaves the cell
and by
separating
these two
environments
, it maintains
concentration gradients
.
Protein pores, pumps, and enzymes are embedded in membranes and are involved in this regulation.
The fluid bilayer/Phospholipids
Phospholispids
One end is
hydrophobic
(repelled by water), the other is
hydrophilic
(loves water).
The
hydrophobic tails
all in the
middle
and the
hydrophilic heads
on the
outside
.
This means they form a
bilayer
.
Phospholipids
are molecules which behave differently at each end.
Protein pores, pumps, and enzymes
Pores
Allows substances to move via diffusion in/out of cells
Some molecules are too big or too charged to move directly through the bilayer so the membrane has channel proteins that act as pores (still no energy needed)
Glucose is moved this way
Enzymes
Allows chemical reactions to take place
Pumps
Membrane proteins that move substances against the concentration gradient (active transport, so require energy) are essential for maintaining concentrations in compartments.
Compartmentalisation
Small compartments present larger surfaces on which reactions can take place
High concentrations of reactants increase the rate of a chemical reaction
Cells have different areas or compartments (organelles) for different functions.