3.3 Cell Membrane Flashcards
What is the cell membrane responsible for? What is it made out of?
Separates cytoplasm from cell’s surroundings. It is composed of phospholipids.
What is a phospholipid?
a lipid containing a phosphate group in its molecule
What makes phospholipids soluble?
Phosphorous
The phosphate “head” is made of what and are/aren’t attracted to what?
The phosphate head is made of polar covalent bonds and is hydrophilic; attracted to water.
The phosphate “tails” are made of what and are/aren’t attracted to what?
The phosphate tails are made of two fatty acids and are hydrophobic; unattracted to water.
What is a phospholipid bilayer? Where do they form?
A double layer of phospholipids which form in water, forming a majority of a cell’s membrane
What does it mean when someone says the phospholipid bilayer has “selective permeability”?
Selective permeability means that some, but not all, substances can go through the bilayer.
What does the bilayer often let into the cell?
Lipids and small, nonpolar molecules such as O2 and CO2
What does the bilayer often reject from getting into the cell?
Ions and polar molecules; such as glucose.
What is the term “fluid mosaic” used to describe? What does it describe?
A term used to describe the movement in the bilayer. It describes how molecules drift laterally (left to right) within the bilayer.
What do steroid molecules do?
Maintain the membrane’s fluidity as temperature fluctuates. Ex: Cholesterol in animal cell’s membrane.
What are transport proteins? What are they responsible for?
Proteins embedded in the phospholipid bilayer. Responsible for creating passageways through which ions, glucose, and other polar substances pass in or out the cell.
What are recognition proteins?
Proteins which help label the body’s cells and help the immune system recognize it’s own cells.
What are adhesion proteins?
Proteins which enable cells to stick to one another
What are receptor proteins? What is their function?
Proteins which bind to outside molecules. Their function is to trigger an internal response such as releasing hormonal effects.
