1.4 Introduction To Cell Membranes Flashcards
What are the two functions of the cell membrane?
Forms a selective barrier
Receives signals from outside the cell and communicates these to the nucleus
What is the cell membrane composed of?
2
A double lipid layer
Proteins - found within and attached to the membrane
What is a plasma membrane a barrier towards?
2
Ions
Water-soluble compounds
What are the two types of proteins found in a cell membrane?
Integral proteins
Peripheral proteins
Where are integral proteins found in a cell membrane?
They are found within the cell membrane
Where are peripheral proteins found in a cell membrane?
They are found bound to the inner or outer surface of the membrane
List the four functions of the plasma membrane
4
Physical isolation
Regulates exchange with environment
Monitors the environment
structural support
How does the plasma membrane provided physical isolation?
By acting as a barrier
How does the plasma membrane regulate exchange with the environment?
(3)
It allows ions and nutrients to enter
It eliminates wastes
It releases cellular products
How does the plasma membrane monitor the environment?
2
By monitoring the extracellular fluid composition
By monitoring chemical signals (hormones)
Describe the relationship between cell membrane proteins and hormones.
Cell membrane proteins bind to hormones
How does the plasma membrane provide structural support?
Anchors cells and tissues (cell to cell attachments)
What is the one difference between a plasma membrane and a cell membrane?
A cell membrane is only found enclosing cells while plasma membranes can be found enclosing organelles
Describe the structure of the double lipid layer in a cell membrane.
(3)
Double layer of phospholipid molecules
Hydrophilic heads point toward watery environment, both sides of the membrane
Hydrophobic fatty-acid tails - inside the membrane
Where are the hydrophilic heads of a plasma membrane located?
They are on either side of the membrane, facing the extracellular fluid and the intercellular fluid
