5.1-5.9

Question 1

What is the fluid mosaic model?

Answer 1

Membrane’s structure; fluid phospholipid bilayer.

Question 2

What is a quality of all cellular/plasma membranes

Answer 2

selective permeability (lets some substances cross more easily than others)

Question 3

What is the outer layer of the cell membrane called?

Answer 3

Extracellular side

Question 4

What is the inner layer of the cell membrane called?

Answer 4

Cytoplasmic side

Question 5

What molecules can diffuse the lipid bilayer?

Answer 5

Small, nonpolar molecules (like CO2, O2)

Question 6

What keeps a membrane fluid?

Answer 6

Kinks in the unsaturated tails of some phospholipids and the presence of cholesterol (in animal cells) keep phospholipids from packing too tightly.

Question 7

What is the function of a junction protein?

Answer 7

Membrane proteins that can “attach” adjacent cells.

Question 8

What is the function of a glycoprotein?

Answer 8

Protein that recognizes neighboring cell (with attached sugars)

Question 9

What is the function of an active transport protein?

Answer 9

Transport proteins allow specific ions or molecules to enter or exit the cell.

Question 10

What is the function of a channel protein?

Answer 10

Allow in certain molecules through faciliated diffusion

Question 11

What is the function of a receptor protein?

Answer 11

Signaling molecules bind to receptor proteins, which relay the message by activating other molecules inside the cell.

Question 12

What is the function of an attachment protein?

Answer 12

proteins that attach to the extracellular matrix and cytoskeleton and help support the membrane and can coordinate external and internal changes.

Question 13

What is the final type of protein found in cell membranes (mentioned in the book).

Answer 13

Enzymes. React inside of the cell.

Question 14

Identify the six different types of functions of proteins in a plasma membrane.

Answer 14

Attachment to the cytoskeleton and ECM, signal reception and relay, enzymatic activity, cell-cell recognition, intercellular joining, and transport.

Question 15

Why are phospholipids important in evolution?

Answer 15

They naturally form a bilayer with water in the center. This plasma membrane was essential to the development of cells.

Question 16

In the origin of a cell, why would the formation of a simple lipid bilayer membrane not be sufficient? What else would have to be a part of such membrane?

Answer 16

They would need embedded proteins that could regulate the movement of substances into and out of the cell.

Question 17

Diffusion is a result of____

Answer 17

thermal energy; imbalanced concentrations

Question 18

Define diffusion

Answer 18

the tendency for particles of any substance to spread out into the available space.

Question 19

What will there always be in diffusion?

Answer 19

net positive movement to the area with a lower concentration

Question 20

What is equilibrium, in diffusion

Answer 20

Equal distribution

Question 21

Concentration gradient?

Answer 21

the process of particles, which are sometimes called solutes, moving through a solution or gas from an area with a higher number of particles to an area with a lower number of particles

Question 22

Passive transport

Answer 22

where molecules do not have to work to diffuse themselves.

Question 23

Why is diffusion across a membrane called passive transport?

Answer 23

The cell does not expand energy to spread it,

Question 24

Osmosis

Answer 24

the diffusion of water over a selectively permeable membrane. Water will move so there is an equal concentration of solute across two membranes.

Question 25

Why are free water molecules important in osmosis?

Answer 25

They can move concentration gradients. Their polarity is bonds them to the solute-- but if there is not enough solute, they move.

Question 26

Which would move to which: 0.5% sucrose solution and a 2% sucrose solution

Answer 26

0.5 __> 2.

Question 27

Define tonicity

Answer 27

the ability of a surrounding solution to cause a cell to gain or lose water.

Question 28

What happens when you submerge a cell in a solution with the same tonicity as it? (isotonic)

Answer 28

The volume remains constant; H20 is constantly leaving or entering, but at equal rates.

Question 29

Define hypotonic

Answer 29

Lower solute concentration, gives water.

Question 30

Define hypertonic

Answer 30

Higher solute concentration, takes water.

Question 31

What is the control of water concentration called?

Answer 31

osmoregulation. Ex. A trout lives in a very hypotonic environment. It's kidneys work to remove excess water.

Question 32

What is the name for an isotonic plant cell?

Answer 32

flaccid, as opposed to turgid or shriveled.

Question 33

What regulates water concentration in plant cells?

Answer 33

Turgor pressure, turgid. Prevents too much water from entering

Question 34

What is plasmolysis?

Answer 34

When an organism is placed in a hypertonic environment and its cells lose water and shrivel. This causes plants to wilt and die.

Question 35

What is facilitated diffusion.

Answer 35

A type of passive transport in which polar molecules and ions enter/exit through a channel in a cell membrane.

Question 36

What molecules does facilitated diffusion bring across?

Answer 36

Ions and hydrophilic molecules. Ex. sugars, amino acids, water.

Question 37

How does facilitated diffusion work?

Answer 37

A transport protein forms a channel that allows molecules and atoms to come through and lower the outer concentration gradient..

Question 38

What is aquaporin?

Answer 38

A transport protein that allows for water to flow in and out of a cell.

Question 39

How do transport proteins contribute to a membrane's selective permeability?

Answer 39

Because they are specific for the solutes they transport, the numbers and kinds of transport proteins affect a membrane's permeability to various solutes.

Question 40

Why are aquaporins important in kidney cells?

Answer 40

Kidney cells must reabsorb a large amount of water when producing urine.

Question 41

Define active transport

Answer 41

a process in which a cell expends energy to move a solute against its concentration gradient. Needs ATP or other energy storing molecule.

Question 42

In the potassium sodium pump, inside has which?

Answer 42

Inside has potassium (K+) outside has sodium (Na+)

Question 43

What the distribution of sodium and potassium important for?

Answer 43

Nerve signaling.

Question 44

Remember to look at the sodium-potassium pump process!

Question 45

Define exocytosis

Answer 45

The process of exporting bulky materials such as proteins or polysaccharides.

Question 46

Describe exocytosis.

Answer 46

A transport vessel filled with macromolecules comes from the golgi apparatus and fuses with the plasma membrane, and spits out its contents.

Question 47

Give an example of exocytosis

Answer 47

The pancreas makes insulin. it is secreted into extracellular fluid by exocytosis, integrating itself into the bloodstream.

Question 48

Define endocytosis

Answer 48

An process in which a cell takes in large molecules. (Endo=inside)

Question 49

What are the two types of endocytosis?

Answer 49

Phagocytosis and receptor-mediated endocytosis. (pinocytosis)

Question 50

Describe the process of phagocytosis.

Answer 50

A cell engulfs a certain molecule with extensions called pseudopodia (singular: pseudopodium), and then encloses it in a sac, called a vacuole. The vacuole fuses with a lysosome, whose hydrolytic enzymes digest the contents of the vacuole. Also called "cellular eating"

Question 51

Give an example of phagocytosis.

Answer 51

Protists (like amobea) take in food this way. White blood cells deal with invading bacteria.

Question 52

Describe the process of receptor-mediated endocytosis.

Answer 52

The receptor proteins embedded in the cellular membrane (covered by a layer of coat proteins, which indent where the receptor proteins are). These receptors pick up certain molecules from extracellular fluid. Once connected, the coat pinches closed and takes the molecule in.

Question 53

Give an example of R-M endocytosis

Answer 53

Cholesterol from the blood is taken using this. In the blood, cholesterol is within molecules called low-density lipoproteins (LDLs), which can bind to receptor proteins.

Question 54

As a cell grows, its plasma membrane expands. Does this involve endocytosis or exocytosis? Explain.

Answer 54

Exocytosis: When a transport vesicle fuses with the plasma membrane, its contents are released and the vesicle membrane adds to the plasma membrane.