Cell membrane Flashcards
Phospholipids
Separate the inside and outside of the cell, selectively permeable.
Cholesterol
Membrane fluidity (at low temperatures)
found in animal cell membranes to help stabilize the membrane.
High temp, what does cholesteral do
high temperatures they restrain the movement of the lipids
(reduce the fluidity)
low temp, what does cholesteral do
low temperatures they take up
space so the lipids can’t condense as much therefore stopping the gel formation
what does fluidity depend on?
The fluidity depends on the saturation of the fatty acids and the temperature.
a cooler temperature will cause the membrane to gel.
Integral proteins (basic)
Transport of specific ions and molecules across the membrane.
Embedded in the phospholipid bilayer; may or may not extend through both layers
both hydrophilic and hydrophobic regions
Peripheral proteins (basic)
Attachment site for carbohydrates or other molecules. Associated with cell signalling and communication.
Many peripheral proteins exist on the surface of cell membranes to carry out enzymatic action on a specific substrate.
Others are hormone receptors and surface antigens
Cell Signaling: Some act as receptors or enzymes that help transmit signals inside the cell.
Structural Support: They help maintain the cell’s shape and connect to the cytoskeleton.
Attachment Sites: They help cells adhere to other cells or extracellular structures.
Transport Assistance: Some assist integral proteins in moving substances across the membrane
Carbohydrates
Attached to proteins or lipids. Associated with cell recognition and communication, immunity, and signalling.
Generally loosely attached to the membrane
peripheral proteins, more readily removed than are the integral proteins.
One of the main roles is to direct and maintain both the intracellular cytoskeleton and components of the extracellular matrix.
peripheral proteins
Make up a major transport system that moves molecules and ions through the polar phospholipid bilayer.
integral protein
role of membrane proteins
set of proteins determine its function
transport
enzymic activity
triggering signals
attachment and recognition
transport
a specific compound may be able to cross a membrane by way of a hydrophilic
protein channel. Alternatively, shape shifting may allow some membrane
proteins to shuttle molecules from one side of a membrane to the other.
enzymic activity
some membrane proteins like those associated with respiration and photosynthesis are enzymes
triggering signals
Membrane proteins may bind to specific chemicals, such as hormones. Binding to these chemicals triggers changes on the inner surface of the membrane, starting a cascade of events within the cell.
Attachment and recognition
oteins that are exposed to both the internal and external membrane surfaces act as attachment points for a range of cytoskeleton elements, as well as components involved in cell–cell recognition, and bond to the extracellular matrix. For example, surface proteins can recognize elements of disease-causing microbes that may try to invade cells, triggering an immune response.
