88 Flashcards
(20 cards)
What is a living cell?
A living cell is a self-reproducing system of molecules held inside a container, which is the plasma membrane.
What is the plasma membrane?
The plasma membrane, also called the cell membrane, separates the interior of the cell from the outside environment.
What are the components of the plasma membrane?
The plasma membrane consists of a lipid bilayer that is semipermeable, along with proteins, carbohydrates, and cholesterol.
What is the function of the plasma membrane?
The plasma membrane regulates the transport of materials entering and exiting the cell.
What is the lipid bilayer?
The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules.
What is the role of the lipid bilayer?
The lipid bilayer keeps ions, proteins, and other molecules where they are needed and prevents them from diffusing into areas where they should not be.
What are amphipathic molecules?
Amphipathic molecules have both hydrophilic (water-loving) heads and hydrophobic (water-fearing) tails.
What are the most abundant lipids in cell membranes?
The most abundant lipids in cell membranes are phospholipids.
What is the function of membrane proteins?
Membrane proteins transport nutrients, metabolites, and ions across the lipid bilayer and serve other functions such as anchoring the membrane and acting as receptors.
What percentage of plasma membrane mass do proteins constitute?
Proteins constitute about 50% of the mass of most plasma membranes.
What are the types of membrane proteins?
Membrane proteins can be transmembrane proteins, anchored to the cytosolic surface, attached by covalent bonds to lipids, or bound indirectly to the membrane.
What is endocytosis?
Endocytosis is the process by which substances are engulfed into the cell.
What are the two principal forms of endocytosis?
The two principal forms of endocytosis are pinocytosis (cell drinking) and phagocytosis (cell eating).
What is exocytosis?
Exocytosis is the process by which cells expel materials enclosed in a vesicle out of the cell.
What are the functions of exocytosis?
Exocytosis functions in secretion of substances, waste elimination, and inserting membrane proteins and lipids into the cell membrane.
What are the two main types of exocytosis?
The two main types of exocytosis are regulated exocytosis and constitutive (non-regulated) exocytosis.
What is the process of regulated exocytosis?
Regulated exocytosis is a selective and stimulus-dependent process mainly involved in the release of signaling molecules.
What is the process of constitutive exocytosis?
Constitutive exocytosis is a continuous and non-selective process that delivers materials to the cell membrane or extracellular space.
What are the steps of exocytosis?
- A vesicle containing the material to be expelled moves toward the cell membrane. 2. The vesicle membrane fuses with the cell membrane. 3. The contents of the vesicle are expelled outside the cell.
What are examples of materials transported via exocytosis?
Examples include digestive enzymes, hormones, and waste products.
