Lecture 7 - Plasma Membrane

Question 1

What is a cell?

Answer 1

 A cell is the basic structural and functional unit of life

Question 2

Extracellular materials

Answer 2

Substances found outside of cells

These include:
Extracellular fluids (Blood plasma, interstitial fluid)
Cellular secretions (Substances that aid in digestion and aid in lubrication)
Extracellular matrix- jellylike substances of proteins that help hold cells together


Question 3

What is the Plasma membrane?

Answer 3

AKA cell membrane

Acts as active barrier
Separates intracellular fluid from extra cellular fluid
Controls what enters and leaves cells

Question 4

Membrane function

Answer 4

Membrane provides mechanical barrier with selective permeability that can also maintain an electrochemical gradient for functions like a nerve signaling/muscle contraction

Involved in cell to cell communication an attachment

Question 5

Integral proteins

Answer 5

Span entire width of membrane
Involved with transport as channels or carriers

Question 6

Peripheral proteins

Answer 6

Attached to integral or phospholipids
May function as enzymes or in mechanical functions of cell

Question 7

What are the six membrane proteins?
and which class (integral or peripheral)

Please read answer

Answer 7

Ion channel (integral) - Forms poor for specific ion to pass through
Carrier (integral) - Transport specific substance across by changing shape
Receptor (integral) - recognize the specific ligand and send‘s message
Enzyme (integral/peripheral) - Catalyzes reactions inside/outside cell
Linker (integral/peripheral) - Links to cells together/anchors filaments
Cell Identity maker (glycoprotein) - Helps immune system determine a cells are self or non self

Question 8

G-protein receptors

Answer 8

Indirectly cause cellular changes by activating G protein
Done very quickly

Question 9

Ligand

Answer 9

Specific molecule that binds to and activates receptor

Question 10

Glycocalyx

Answer 10

Consists of sugar sticking out of the cell surface
Marker for cell recognition and for immune system to recognize self vs. Non self

Question 11

Cell adhesion molecules

Answer 11

CAMs
Thousands of sticky glycoprotein

CAMs function to:
Anchor cells to extracellular matrix
Assist in movement in cells past each other
Attract immune cells to injured/infected area
Stimulate synthesis/Degradation of junctions
Transmit signals to direct cell migration (Proliferation, specialization)


Question 12

Cell junctions

Answer 12

Tight junctions: Integral proteins that joint adjacent cells to prevent molecules from passing through extracellular spaces

Desmosomes: Scattered attachments that reduce chance of tearing apart when tissue is stressed

Gap junctions: hollow cylinders of protein between cells, allow some small molecules to pass between adjacent cells, conduct action proteins

Question 13

What is the Cell Membranes permeability? (Selective, impermeable,permeable)

Answer 13

Cell membrane = selectively permeable ; only certain things can pass through

Usually permeable to small, non-polar and uncharged molecules and impermeable to large, polar and charged molecules