Structure/Function of Plasma Membranes Flashcards
Basic function of the plasma membrane
Define the borders of the cell and keep it functional
What is selective permeability?
The membrane allows some materials to enter freely and leave the cell, while other materials cannot move freely, but require the use of a specialized structure
Three functions of a cell’s plasma membrane
defines the cell, outlines its borders, determines the nature of its interactions with the environment
The plasma membrane must be very
flexible
complex, integral proteins
receptors
example of a receptor being hijacked by a viral offender
HIV, human immunodeficiency virus
components of plasma structure
phospholipids, proteins, cholesterol and
carbohydrates
a phospholipid is a molecule consisting of
glycerol, two fatty-acids, and a phosphate-linked head group
in a typical human cell, protein accounts for
50% of the composition by mass, lipids 40%, and carbs about 10%
These extend from the outward-facing portion of the plasma membrane
Carbohydrates attached to lipids and proteins
The concentration of lipids and proteins
Varies among different cell membranes
Myelin is ____________
an outgrowth of the membrane of specialized cells that
insulates the axons of peripheral nerves
Myelin contains only
18 percent proteins and 76 percent lipid
Glycolipids vs glycoproteins
Carbohydrates are only on the exterior surface of the plasma membrane and are attached to proteins; are attached to lipids
Hydrophilic; hydrophobic; amphiphilic
Water-loving; water-hating; dual-loving
Hydrophobic molecules tend to be; tend to form a
non-polar; ball or cluster when placed in water
Phospholipids form an excellent
two-layer cell membrane that separates the internal components from the external
The head of a phosphate group has a
polar character or negative charge
What is an amphiphilic molecule
the head can form hydrogen bonds, but the tail cannot; positively or negatively charged area and an uncharged(non-polar)area
In an aqueous solution, phospholipids tend to arrange themselves in
polar heads facing outward and hydrophobic tails facing inward
Second major component of plasma membranes
Proteins
Third major component of plasma membranes
Carbohydrates
Briefly summarize the role of carbohydrate molecules within the plasma membrane
Always found on the exterior, attaching to proteins or lipids. Consist of 2-60 monosaccharide units and can be either straight or branched. Form specialized sites on the cell surface that allow it to be recognized by other cells. Gives the cell a recognition function important to the immune system, allowing it to differentiate between foreign and home(“self”)cells.
Carbohydrate components of glycoproteins and glycolipids are referred to as, which is ______
Glycocalyx; highly hydrophilic
