CELL MEMBRANE proteins present in it. The types of
proteins that may be present in the cell
STRUCTURES OF CELL MEMBRANE membrane and the functions they carry
- cell membranes are lipid bilayers made out are as follows:
up mostly of phospholipids. The polar
head of a phospholipid interacts with
water molecules; the nonpolar fatty acids
tails do not. organize themselves as a
lipid bilayer sheet or bubble in a liquid
medium.
CELL MEMBRANE LIPIDS
#1. PHOSPHOLIPIDS
-major component of cell membranes. It
forms a lipid bilayer.
-HYDROPHILIC (attracted to water) HEAD
areas spontaneously arrange to face the
aqueous cytosol and he extracellular
fluid, HYDROPHOBIC (repelled by water)
TAIL areas face away from the cytosol and
extracellular fluid.
-lipid bilayer is semi-permeable, allowing
only certain molecules diffuse across the
membrane.
#2. CHOLESTEROL
- another lipid component of animal cell
membrane, not ound in plant celss
-these molecules are selectively
-attached to the lipid bilayer are other dispersed between membrane
molecules like cholesterol and proteins. phospholipids. From being too closely
-CHOLESTEROL MOLECULES prevent packed together.
plasma membrane from becoming too
fluid at higher temperature and too solid FLUIDITY OF MEMBRANES
at lower temperatures. -Unsaturated hydrocarbon tails (kinked)
-Cell membrane described as FLUID prevent packing, enhancing membrane
MOSAIC. “MOSAIC” attributed to the fluidity.
mixed composition of the cell membrane, -Saturated hydrocarbon tails pack
and “FLUID” came from the ability of the together, increasing membrane viscosity.
bilayer to drift sideways and spin around
their long axis. Phospholipids in a typical
membrane are not bonded to one
another.
-Cell Membrane can have different
characteristics depending on the #3. GLYCOLIPIDS
, - located on cell membrane surfaces and #3 TRANSPORT PROTEINS, such as
have a carbohydrate sugar chain attached channel and carrier proteins, transport
to them. molecules across cell membranes
- help the cell to recognize other cells of through facilitated diffusion.
the body. #4 GLYCOPROTEINS have a carbohydrate
chain attached to them. They are
embedded in the cell membrane and help
in cell-to-cell communications and
molecule transport across the
membrane.
#5 JUNCTION PROTEINS are involved in
forming several types of junctions
between animal cells
CELL MEMBRANE PROTEINS
2 TYPES OF PROTEINS:
A. PERIPHERAL MEMBRANE PROTEINS
are exterior to and connected to the
membrane by interactions with other
proteins.
B. INTEGRAL MEMBRANE PROTEINS are
inserted into the membrane and most
pass through the membrane. Functions of the Plasma Membrane
-Portions of these transmembrane #1 It protects the integrity of the interior
proteins are exposed on both sides of the of the cell by allowing certain substances
membrane. into the cell while keeping other
substances out.
#2 It also serves as a base of attachment
for the cytoskeleton in some organisms
and the cell wall in others. Thus, the cell
membrane also serves to help support
the cell and help maintain its shape.
#3 Another function of the membrane is
to regulate cell growth through the
balance of endocytosis
#1 STRUCTURAL PROTEINS help to give TYPES OF SUBSTANCES:
the cell support and shape. #1 Hydrophobic substances – this is
#2 Cell membrane RECEPTOR PROTEINS similar to the phospholipid center of the
help cells communicate with their membrane cab easily diffuse across
external environment using hormones membranes without consuming energy.
neurotransmitters, and other signaling #2 Polar molecules – which are
molecules. chemically incompatible with the center
proteins that may be present in the cell
STRUCTURES OF CELL MEMBRANE membrane and the functions they carry
- cell membranes are lipid bilayers made out are as follows:
up mostly of phospholipids. The polar
head of a phospholipid interacts with
water molecules; the nonpolar fatty acids
tails do not. organize themselves as a
lipid bilayer sheet or bubble in a liquid
medium.
CELL MEMBRANE LIPIDS
#1. PHOSPHOLIPIDS
-major component of cell membranes. It
forms a lipid bilayer.
-HYDROPHILIC (attracted to water) HEAD
areas spontaneously arrange to face the
aqueous cytosol and he extracellular
fluid, HYDROPHOBIC (repelled by water)
TAIL areas face away from the cytosol and
extracellular fluid.
-lipid bilayer is semi-permeable, allowing
only certain molecules diffuse across the
membrane.
#2. CHOLESTEROL
- another lipid component of animal cell
membrane, not ound in plant celss
-these molecules are selectively
-attached to the lipid bilayer are other dispersed between membrane
molecules like cholesterol and proteins. phospholipids. From being too closely
-CHOLESTEROL MOLECULES prevent packed together.
plasma membrane from becoming too
fluid at higher temperature and too solid FLUIDITY OF MEMBRANES
at lower temperatures. -Unsaturated hydrocarbon tails (kinked)
-Cell membrane described as FLUID prevent packing, enhancing membrane
MOSAIC. “MOSAIC” attributed to the fluidity.
mixed composition of the cell membrane, -Saturated hydrocarbon tails pack
and “FLUID” came from the ability of the together, increasing membrane viscosity.
bilayer to drift sideways and spin around
their long axis. Phospholipids in a typical
membrane are not bonded to one
another.
-Cell Membrane can have different
characteristics depending on the #3. GLYCOLIPIDS
, - located on cell membrane surfaces and #3 TRANSPORT PROTEINS, such as
have a carbohydrate sugar chain attached channel and carrier proteins, transport
to them. molecules across cell membranes
- help the cell to recognize other cells of through facilitated diffusion.
the body. #4 GLYCOPROTEINS have a carbohydrate
chain attached to them. They are
embedded in the cell membrane and help
in cell-to-cell communications and
molecule transport across the
membrane.
#5 JUNCTION PROTEINS are involved in
forming several types of junctions
between animal cells
CELL MEMBRANE PROTEINS
2 TYPES OF PROTEINS:
A. PERIPHERAL MEMBRANE PROTEINS
are exterior to and connected to the
membrane by interactions with other
proteins.
B. INTEGRAL MEMBRANE PROTEINS are
inserted into the membrane and most
pass through the membrane. Functions of the Plasma Membrane
-Portions of these transmembrane #1 It protects the integrity of the interior
proteins are exposed on both sides of the of the cell by allowing certain substances
membrane. into the cell while keeping other
substances out.
#2 It also serves as a base of attachment
for the cytoskeleton in some organisms
and the cell wall in others. Thus, the cell
membrane also serves to help support
the cell and help maintain its shape.
#3 Another function of the membrane is
to regulate cell growth through the
balance of endocytosis
#1 STRUCTURAL PROTEINS help to give TYPES OF SUBSTANCES:
the cell support and shape. #1 Hydrophobic substances – this is
#2 Cell membrane RECEPTOR PROTEINS similar to the phospholipid center of the
help cells communicate with their membrane cab easily diffuse across
external environment using hormones membranes without consuming energy.
neurotransmitters, and other signaling #2 Polar molecules – which are
molecules. chemically incompatible with the center
