Chap 4 pT 3

Question 1

Tonicity

Answer 1

Relative concentration of solutes (compared to cell)

Question 2

Isotonic

Answer 2

cytosol and solution have same solute concentration E.g., saline with a concentration of 0.9% NaCl is commonly in IV solutions
No net movement of water

Question 3

Hypotonic

Answer 3

solution has a lower concentration of solutes (and higher concentration of water) than the cytosol
Water enters the cell

Question 4

Lysis

Answer 4

rupturing of cells occurs if enough osmotic pressure

Question 5

Hypertonic

Answer 5

Solution with a higher concentration of solutes (and lower concentration of water) than the cytosol
Water leaves the cell

Question 6

Crenation

Answer 6

cell shrinks

Question 7

Active Process: active transport (and vesicular transport)

Answer 7

Movement of a solute against its concentration gradient

Question 8

Active Transport

Answer 8

Maintains gradient between cell and interstitial fluid

Question 9

Active Transport

Answer 9

Source of energy determines whether movement is primary or secondary

Question 10

Primary Active Transport (energy directly from breakdown of ATP)
Phosphorylation

Answer 10

Phosphate group added to protein
Changes protein’s shape

Question 11

Ion Pumps

Answer 11

Protein pumps that move ions across cell membrane
Maintains internal concentrations of ions
E.g., proton pumps from Chapter 3—electron transport system
Ca2+ pumps in plasma membrane of erythrocytes
E.g., Sodium-Potassium Pumps

Question 12

Secondary Active Transport 1

Answer 12

Moves substance against concentration gradient via energy from movement of second substance down its gradient

Question 13

Secondary Active Transport 2

Answer 13

Kinetic energy providing “power” to pump other substance
Na+ moves down concentration gradient
Dependent on Na+/K+ pumps to generate gradient of Na+

Question 14

2 types of Active Transport (1)

Answer 14

Symport
Same direction

Question 15

2 types of Active Transport (2)

Answer 15

Antiport
Opposite direction

Question 16

Vesicular Transport (“bulk transport”)

Answer 16

Involves energy input to transport large substances across the plasma membrane by a vesicle
Membrane-bounded sac filled with material

Question 17

Exocytosis

Answer 17

substances secreted from cell in vesicles

Question 18

Endocytosis

Answer 18

substances taken into cells in vesicles from external environment

Question 19

Macromolecules

Answer 19

too large to be moved across membrane is packed in vesicles

Question 20

Vesicle and plasma membrane fuse

Answer 20

Requires ATP

Question 21

Contents released to outside of cell following fusion

Answer 21

-E.g., release of neurotransmitters from nerve cells

Question 22

Endocytosis: Cellular uptake of large substances from external environment
Functions

Answer 22

Uptake of materials for digestion
Retrieval of membrane parts after exocytosis
Regulation of membrane protein composition

Question 23

Steps of endocytosis (Reverse of exocytosis)

Answer 23

Substances packaged into a vesicle formed at cell surface
Invagination—small area of membrane folds inward, forming a pocket
Pocket deepens and pinches off when lipid bilayer fuses
Requires expenditure of energy

Question 24

Steps of endocytosis (reverse of exocytosis) pT 2:

Answer 24

New intracellular vesicle with material that was formerly outside the cell

Question 25

Phagocytosis “Cellular eating”

Answer 25

A cell engulfs a large particle external to cell
(only a few cells do this Immune )
Forms large extensions to surround particle, enclosing it in a membrane sac
Contents of sac digested after fusing with lysosome

Question 26

Pinocytosis “cellular drinking”

Answer 26

Internalization of droplets of interstitial fluid with dissolved solutes
Multiple, small vesicles formed
Performed by most cells

Question 27

Resting membrane potential

Answer 27

Cells establish and maintain electrochemical gradient
Essential for muscle and nerve cell function

Question 28

Membrane Potential

Answer 28

potential energy of charge difference across membrane

Question 29

Resting membrane potential (RMP)

Answer 29

membrane potential when a cell is at rest (as opposed to “excited”)
Unequal distribution of ions across cell membrane
Unequal relative amounts of positive and negative charges
More positive on outside than inside of cell—RMP is negative!

Question 30

Na+ and K+

Answer 30

diffuse across membrane through leak channels

Question 31

What does Na+ / K+ pump maintain

Answer 31

K+ and Na + gradients despite diffusion
–uses ATP energy to do so

Question 32

Direct cellular contact important for immune system

Answer 32

Need to destroy unhealthy and foreign cells
Distinguishes normal cells from unwanted cells
Unhealthy and foreign cells express different glycocalyx pattern than normal cellsSubsequently destroyed

Question 33

Sperm and oocyte

Answer 33

Egg with unique glycocalyx
Allows for recognition by sperm during fertilization

Question 34

Cellular regrowth following injury

Answer 34

Damaged tissue replaced by cell division in epidermis
Cellular contact prevents overgrowth

Question 35

Ligands

Answer 35

Molecules that bind with receptor molecules
Neurotransmitters and hormones Controls growth, reproduction, and other cellular processes

Question 36

Channel Linked receptors

Answer 36

Permit passage of ions into or out of cells
Occurs in response to neurotransmitters
Help initiate electrical changes to RMP in muscle and nerve cells

Question 37

Enzymatic Receptors

Answer 37

Activated to phosphorylate other enzymes within the cell
Provides mechanism for altering enzymatic activity (off or on)