KINE 2P09 Lecture 2a - Cell Membranes and Movement Across Membranes (copy)

Membrane purpose (5)

Regulates substances passing in and out, detects chemical messengers, links cells together via junctions, anchors cells and signals transduction/ communication

Phopsholipids

Major membrane lipid

Membranes have what kind of bilayer?

A phospholipid bilayer

______ regions are at the surface, ________ regions are towards the middle

polar, nonpolar

Hydrophilic head

Likes water, negatively charged, has the phosphate

Hydrophobic tails

Two fatty acid chains, dislike water

Amphipathic

Contains both hydrophobic and hydrophilic regions

Integral membrane protiens

Amphipathic; closely associated with lipids; can move laterally; also known as transmembrane proteins

Peripheral membrane proteins

Not amphipathic; located in membrane surface; bind to polar regions

Proteins serve as…

Channels, carrier molecules, docking proteins, membrane bound enzymes, receptors, cell adhesion molecules (anchors)

In membranes, cholesterol provides…

Fluidity and stability

In membranes, glycoproteins provide…

Self recognition

Desmosomes

A region between two adjacent cells where the membranes are bound together but separated by a very small space

In desmosomes, accumulations of plaque are anchoring points for what?

Cadherins

Tight junctions

No extracellular space between cells that regulate material passage

Gap junctions

Connects the cytostome of neighbouring cells

Connexins

Proteins that join in gap junctions

Connexins are important in the sprad of what?

Ions like K+ and Na+ essential for neurons and the heart