the cell surface membrane Flashcards
what cells have cell surface membranes?
all
what are the 3 main roles of cell surface membranes?
- separates the internal cell environment from the external environment
- forms compartments in cells
- control the exchange of materials
are membranes partially or fully permeable?
partially
what is the name of the model used to show the structure of a membrane?
the fluid mosaic model
why is it called the fluid mosaic model?
fluid because phospholipids and proteins can move around, mosaic as the proteins produce a scattered pattern
how many contents does the membrane have?
4
what are the 4 contents of the membrane?
- phospholipids
- cholesterol
- glycoproteins and glycolipids
- transport proteins
what are phospholipids?
the basic structure of a membrane (phospholipid bilayer)
describe the structure of a phospholipid
the head faces externally and is hydrophilic whereas the tail faces internally and is hydrophobic
what is the role of cholesterol in the membrane?
increases fluidity
how does cholesterol increase fluidity?
at low temperatures it stops the phospholipids from packing together too closely
what are glycoproteins and glycolipids?
lipids and proteins attached to carbohydrates
what is the role of a glycoprotein?
to signal/communicate
give an example of a glycoprotein
a receptor for insulin
what is the role of a glycolipid?
maintain cell stability
give and example of a glycolipid
an antigen
what substances cannot pass through membranes?
polar molecules, large molecules or ions
how do polar molecules or ions pass through membranes?
using transport proteins
give the 2 names of the transport proteins
channel and carrier
how do channel proteins work?
act as a passageway
how do carrier proteins work?
change shape to fit a specific substance to transport it
