Chapter 2 - Cells and Organelles Flashcards
cell membranes contain three main things:
phospholipids, proteins, cholesterol
Membrane proteins come in two types:
integral (transmembrane) and peripheral
True or false: peripheral membrane proteins extend throughout the entire bilayer
False - only on the periphery, generally hydrophilic
Transmembrane protein function
- transport proteins
2. receptor proteins
transport proteins
move large, polar molecules across the cell membrane since they cannot freely diffuse by themselves
examples of peripheral membrane proteins
adhesion proteins, cellular recognition proteins, receptor proteins
adhesion protein function
attach adjacent cells to other things (like other cells) and they also act as anchors for the cytoskeleton
cellular recognition proteins
peripheral membrane proteins that help cells recognize each other; usuallyt interact with receptor protein; attach to glycoproteins
receptor proteins
receive chemical signals from the extracellular environment that do not need to be transmitted inside the cell
agonist
ligands that bind to a receptor and activate its response
antagonist
ligands that bind to a receptor and prevent it from activating
what kind of molecules can travel directly across the phospholipid bilayer?
small, uncharged nonpolar molecules. ex co2 and o2
simple diffusion
flow of substances down their concentration gradient, does not consume energy. does not use proteins to help particles across membrane
what kind of molecules cannot travel directly across the bilayer?
large hydrophilic molecules
facilitated transport
describes how large, hydrophilic molecules travel across the bilayer through transmembrane proteins (usually uniport, moving in 1 direction)
symport
transmembrane protein that helps several molecules moving in 1 direction
antiport
several molecules moving in opposite directions
symport and antiport are examples of :
secondary active transport
channel proteins
face extra and intracellular of the cell at the same time, usually allow the passage of many small, polar molecules and ions
carrier proteins
change their shape to facilitate the movement of molecules through the protein