The Plasma Membrane

Question 1

Cytology

Answer 1

The study of cells

Question 2

Cell size

Answer 2

Measured in micrometers (mcm or μm)
Side note: 1 μm is one thousandths of a mm

Question 3

Plasma Membrane

Answer 3

Barrier that separates inside & outside the cell

Question 4

Nucleus

Answer 4

Largest structure, where genetic material (DNA) is stored

Question 5

Plasma membrane Functions

Answer 5

• keeps cytosol inside
• keeps Interstitial fluid Outside
• selectively regulates movement of material in and out.

Question 6

What does the plasma membrane let in?

Answer 6

Water, glucose and oxygen

Question 7

Phospholipids

Answer 7

MAIN lipid of the membrane; forms bi later

Question 8

Cholesterol

Answer 8

Stabilizes membrane during temp. change; keeps membrane “fluid”

Question 9

Glycolipids

Answer 9

Part of the glycocalyx (“sugar coating”); cellular ID marker
Extra note: “Glyco” = sugar

Question 10

Transport proteins

Answer 10

Allow certain substances to cross the membrane & move in or out the cell.

Question 11

Microvilli

Answer 11

Increases the surface area of the plasma membrane. For absorption of nutrients/water
On intestinal cells/ kidney cells

Question 12

Cilia

Answer 12

Moves material across the cell surface; sweep back and forth motion; like windshield wipers.
On respiratory tract cells and oviduct cells (fallopian tubes)- sweeps eggs around in the uterus

Question 13

Flagellum

Answer 13

Moves in a whip like motion; like a tadpole tail
- propels the cell through its environment
- on sperm cells

Question 14

Tights junction

Answer 14

Like a zipper or ziplock seal
Holds cells tightly together
Prevents leakage

Question 15

Where are tight junctions located at?

Answer 15

On stomach cells, intestine cells, blood vessel cells and bladder cells

Question 16

Desmosome

Answer 16

Like buttons or snaps b/tw 2 cells
Adds strength to tissue that are pushed or pulled on a lot.
Prevents neighboring cells from pulling apart.

Question 17

Where are Desmosomes located ?

Answer 17

On skin cells

Question 18

Gap junction

Answer 18

Like tunnels or connector pipes
-provides a direct passage for material to flow from cytolsol of one cell into the neighboring cells
- allows flows of ions/electrical signals
-

Question 19

Where are gap junctions found ?

Answer 19

On heart cells

Question 20

Passive Transport

Answer 20

Doesn’t require energy input
- generally moves substances w/their natural flow

Question 21

Active Transport

Answer 21

REQUIRES energy input
- generally moves substances against their natural flow

Question 22

Concentration Gradient

Answer 22

Difference in amount of a substance from one area to another
-Drives diffusion

Question 23

Diffusion

Answer 23

Movement of solute molecules from an area of higher solute concentration to an area of lower concentration.

Question 24

Passive transport: Facilitated Diffusion

Answer 24

Moves small charged or Polar solutes through the Plasma membrane

Question 25

Facilitated Diffusion requires what type of transport ?

Answer 25

Transport Proteins; Channels or carriers Channels: move ions Carrier: move glucose

Question 26

Simples Diffusion

Answer 26

Moves small non polar solutes straight through the Plasma membrane - no transport protein required

Question 27

What solutes does simple diffusion move?

Answer 27

Small lipids(fatty acids) Respiratory gasses such as O2 (oxygen gas), CO2 (carbon dioxide), Hint for remembrance: “Breathing is simple”

Question 28

Leak channel

Answer 28

Always open to allow ions to flow through

Question 29

Gates channels

Answer 29

Usually kept closed but can open temporarily in response to a certain stimulus (“a key”)

Question 30

Osmosis

Answer 30

Movement of solvent (water) across a selectively permeable membrane from a solution w/ lower solute concentration to a higher solute concentration.

Question 31

Tonicity

Answer 31

The ability of a fluid to cause water to move by osmosis

Question 32

Isotonic solution

Answer 32

Solute concentration is equal outside the cell and inside the cell—> water won’t move

Question 33

Hypotonic Solution

Answer 33

Solute concentration is lower outside of the cell than inside—> water will enter the cell (can swell up an burst “hemolysis”) Hint for remembrance: “Hypo hippo” makes the cell big like a hippo.

Question 34

Hypertonic solution

Answer 34

Solute concentration is higher outside the cell than inside—> water will leave the cell (cell shrivels) Hint: “Hyper sucks” Sucks the water out of the cell

Question 35

Why can’t we drink salt water??

Answer 35

Seawater is hypertonic. Our cells will shrivel.

Question 36

Why can drinking too much water in a short period of time kill you?

Answer 36

Pure water is hypotonic to our cells. Too much pure water will cause water to enter cells . Our cells will swell.

Question 37

Active Transport

Answer 37

Always requires energy input, b/c: Primary and secondary active transport, always move substance against their concentration gradient.

Question 38

Bulk/vesicular transport

Answer 38

Move substances too large for transport proteins. Uses vesicles and ATP energy Two types of vesicle, transport endocytosis and exocytosis

Question 39

Primary active transport

Answer 39

Sodium potassium pump= constantly working (uses up to 30% of cells ATP) to maintain proper concentration gradient (homeostasis) and every cell in the body

Question 40

How many sodium ions and potassium ions does the sodium potassium pump out and in?

Answer 40

Pumps, three sodium ions out of cell and pumps two potassium ions into cell

Question 41

Resting membrane potential

Answer 41

Sodium potassium pump contributes to charge gradient across cell. - (RMP) -Measured as voltage -80 mV in average cell Critical for cells that respond to electrical stimulation .

Question 42

Calcium ion pump:

Answer 42

Pumps calcium ions out of the RBCs (red blood cells) in neurons.

Question 43

Secondary active transport

Answer 43

Uses kinetic energy of one substance, moving down its concentration gradient to provide energy for a second substance to move up (against) it concentration gradient.

Question 44

Endocytosis

Answer 44

Moves, large material INTO cells

Question 45

Two types of endocytosis

Answer 45

Phagocytosis: “cell eating” only certain immune system cells can do this ,they eat bacteria ,dead cells or cell fragments. Pinocytosis: “cell drinking” all cells do this. Cells drink interstitial fluid, and it dissolves solutes.

Question 46

Exocytosis

Answer 46

Moves large material OUT of the cell. Reverse process of endocytosis