Cell Membrane Transport

Question 1

Cell membranes are ___ b/c the phospholipids move around and behaved like a liquid, and ___ b/c there are numerous different types of proteins and carbs. associated with it

Answer 1

fluid; mosaic

Question 2

Phospholipids have a ___ head and a ___ tail

Answer 2

hydrophilic; hydrophobic

Question 3

The membrane is ___

Answer 3

nonpolar

Question 4

Anything that is ___ will NOT cross the membrane very easily b/c they are large

Answer 4

polar

Question 5

Transport across membrane that does NOT require energy; high to low concentration

EX. punch a hole in a bag of sand and the sand will leave b/c there is more on the inside than the outside

Answer 5

passive

Question 6

transport across membrane that DOES require energy; low to high concentration

EX. if you have 10 glucose molecules on the inside of the cell and 3 on the outside, glucose will move OUT of the cell passively, w/o energy, but glucose will only move into the cell if energy is used

Answer 6

active

Question 7

Areas with more molecules (solute) are areas of high __ and high energy

Answer 7

concentration

Question 8

Difference in charge b/w inside and outside of cell

EX. -70 mV inside = 70 mV more negative than the outside

Answer 8

membrane potential

Question 9

There is ALWAYS more __+ outside the cell that inside

Answer 9

Na+

Question 10

There is ALWAYS more __+ inside the cell than outside

Answer 10

K+

Question 11

Charged molecules can’t cross w/o help of other ___ b/c ions have a charge and membrane itself does NOT

Answer 11

proteins

Question 12

Measure of the factors that determined which direction ions move across membrane

Answer 12

driving force

Question 13

___ force is a concentration gradient

Answer 13

chemical

Question 14

In chemical force, there is always more potassium (K+) inside the cell than outside, so the chemical force wants to move K+ ___ of the cell

Answer 14

outside

Question 15

In chemical force, there is always more sodium (Na+) outside of the cell than inside, so the chemical force always wants to push Na+ ___ of the cell

Answer 15

inside

Question 16

No matter what, the chemical driving force never ___

Answer 16

changes

Question 17

Since Na+ and K+ are both positive ions, each will be attracted to ___-___ areas and be repelled by ___-____ areas

**like charges repel, and opposite charges attract

Answer 17

negatively-charged; positively-charged

Question 18

If the membrane potential is negative, the electrical driving force will try to bring ___ and ___ into cell

Answer 18

Na+; K+

Question 19

If membrane potential is positive, the electrical driving force will try to push ___ and ___ out of the cell

Answer 19

Na+; K+

Question 20

Resting membrane potential for most cells

Answer 20

-70 mV

Question 21

Sum total of the chemical and electrical force acting on an ion

Answer 21

electrochemical driving force

Question 22

When electrical force is now larger than the chemical force

Answer 22

equilibrium potential

Question 23

Equilibrium potential for Na+ is +55 mV. Na+ will go into the cell most of the time, but for Na+ to leave the cell, the inside would have to be really ___, more than +55 mV

Answer 23

positive

Question 24

Equilibrium potential for K+ is -94 mV. K+ will leave the cell. For K+ to enter the cell, the inside of the cell must be really ___, more ___ than -94 mV

Answer 24

negative

Question 25

The membrane potential, at ANY time, will always be approaching equilibrium potential of the MOST permeable ___

Answer 25

ion

Question 26

Membrane potential tells use that at rest, the membrane potential is -70mV. What does this tell us?

Answer 26

that there is more K+ leaving the cell at rest than there is Na+ entering