Ch 3: Cell Biology- Plasma Membrane/ Transport Mechanisms Flashcards
Name 3 functions of the plasma membrane
• Separates the intracellular fluid (IF) from the extracellular
• Also known as the cell membrane
• Also encloses and supports cell contents
• Attaches cells to extracellular environment or to other cells
• Aids in communication
• Determines what moves into and out of cells
Define the words fluid and mosaic of fluid mosaic model of the plasma membrane
• Fluid = dynamic and constantly changing
• Mosaic = made of many tiny parts all working together
Composed of:
• Lipids
• Mostly phospholipids but also cholesterol and glycolipids
• Proteins
• Carbohydrates (part of glycocalyx)
What are the two components of membrane lipids?
- Phospholipids
- Cholesterol
________ interspersed among phospholipids. The amount determines the fluid nature of the membrane
Cholesterol
__________: bilayer. Polar heads facing water in exterior of the cell (hydrophilic); nonpolar tails faci interior of the membrane (hydrophobic).
Phospholipids
Fluid nature provides/ allows these 3 things
• Distribution of molecules within the membrane.
•
Phospholipids automatically reassembled if membrane is damaged.
•
Membranes can fuse with each other.
What are the two components of membrane proteins?
•Intergral membrane proteins
•Peripheral membrane proteins
Which type of membrane protein can form channels through the membrane?
Integral
________membrane proteins are attached to ________ proteins at either the inner surfaces of the lipid bilayer.
Peripheral; integral
Name the 3D shape or chemical characteristics that affect membrane protein functions
Markers, attachment sites, channels, receptors, enzymes, or carriers.
Glycoproteins or glycolipids are examples of
Marker molecules
What is the function of marker molecules?
Allow cells to identity one another or other molecules.
• Immunity.
• Recognition of oocyte by sperm cell.
• Intercellular communication.
• Glycocalyx - “sugar covering”
_______attach cells to other cells while _______ attach to extra cellular molecule
Cadherin; Integrins (integral proteins)
What are the 3 types of cell junctions and their general property
•Tight junctions - impermeable junctions
•Desmosomes - anchoring junctions (think like zippers)
•Gap junctions - cell connections with hollow cylinders
—-materials pass through cylinders from one cell to next
_________ binds cells together
Cell junctions
What cell junction anchors and works like a zipper?
Desmosomes
Cell junction with hollow cylinders
Gap junction
What protein includes channel proteins, carrier proteins and ATP-powered pumps?
Transport proteins
Hydrophilic region faces inward; charge determines molecules that can pass through is a characteristic of what?
Transport proteins
________ proteins- integral membrane proteins that form tiny channels through membrane
Channel
Leak Ion channels are always open and are responsible for the ________ of the plasma membrane ions at rest
Permeability
_______(type of channel protein) can be open or closed by certain stimuli
Gated ion channel
Small molecules binding to proteins or glycoproteins is a characteristic of what type of channel protein?
Ligand-gated ion channel
What must happen for a voltage-gated ion channel to open?
Charge change across the plasma membrane