Membranes

Question 1

What are cell membranes formed from?

Answer 1

A phospholipid bilayer

Question 2

What does the molecule have?

Answer 2

A head and tail

Question 3

The head is hydrophilic which means it is what?

Answer 3

Water loving (phosphate part)

Question 4

The tail is hydrophobic which means what?

Answer 4

Water fearing (lipid part)

Question 5

The inside and outside of a cell is mostly water, so the phospholipid molecule take on what?

Answer 5

A specific orientation

Question 6

What else does the membrane contain that spans the whole cross-section?

Answer 6

Proteins; transmembrane proteins

Question 7

The membrane is what?

Answer 7

Not static, the molecules are not fixed in place

Question 8

Because the molecules are not static, they are allowed to do what?

Answer 8

Freely slide and drift around and past one another

Question 9

What does the cell membrane follow?

Answer 9

The fluid mosaic model

Question 10

What is facilitated diffusion?

Answer 10

A type of passive transport

Question 11

What is facilitated diffusion used for?

Answer 11

The movement of large molecules across the membrane with the help of transmembrane proteins

Question 12

What are the two types of transmembrane proteins?

Answer 12

Carrier proteins and channel proteins

Question 13

What are carrier proteins?

Answer 13

Act as a lock where a molecule is the key, only one type of molecule can work, the molecule fits in a shape specific region of the proteins which induces a conformational shift in the proteins, this transports the molecule across the membrane (no energy required)

Question 14

What are channel proteins?

Answer 14

Essentially a tunnel that let ions and water through, stuff substance specific

Question 15

What is active transport?

Answer 15

The opposite of passive transport

Question 16

Where do molecules move in active transport?

Answer 16

From an area of low concentration to an area of high concentration

Question 17

The movement of active transport is?

Answer 17

Against the concentration gradient

Question 18

Is energy required for active transport?

Answer 18

Yes, ATP

Question 19

What kind of molecules simply do active transport?

Answer 19

Small molecules (pumps)

Question 20

Large molecules are transported across the membrane in what?

Answer 20

Vesicles (formed from the cell membrane pinching in or by the Golgi)

Question 21

What is exocytosis for?

Answer 21

Secretion and waste removal; a vesicle moves toward the cell membrane, fuses with it and releases its contents

Question 22

What is endocytosis for?

Answer 22

To move large substances into the cell; solids by phagocytosis (eating) and liquids by pinocytosis (drinking)

Question 23

What is the function of the membrane?

Answer 23

Regulating the movement of substances into and out of a cell

Question 24

What are cells?

Answer 24

Semi-permeable; some substances can move in + out while others cannot

Question 25

What can slip directly between the phospholipid molecules?

Answer 25

Small molecules

Question 26

Large molecules and water must use what to cross the membrane?

Answer 26

Transmembrane proteins

Question 27

What is Brownian motion?

Answer 27

Particles are in constant random motion

Question 28

What is the concentration gradient?

Answer 28

The difference in concentration between two areas

Question 29

What is equilibrium?

Answer 29

When two areas have equal concentrations

Question 30

What is passive transport?

Answer 30

When molecules move across the membrane from an area of high concentration to low concentration

Question 31

What type of movement on the concentration gradient is passive transport?

Answer 31

Down the concentration gradient; doesn't require energy

Question 32

T or F; The way one type of substance undergoes passive transport is independent of other substances

Answer 32

True

Question 33

What is diffusion?

Answer 33

Basic passive transport

Question 34

What is osmosis?

Answer 34

A special term for the passive transport of water; through specialized transmembrane proteins called aquaporins

Question 35

What are related terms?

Answer 35

Used to describe the relationship between the concentration of two areas

Question 36

What does hypotonic mean?

Answer 36

An area with less concentration

Question 37

What does isotonic mean?

Answer 37

When two areas have equal concentrations

Question 38

What does hypertonic mean?

Answer 38

An area with greater concentration

Question 39

What tends to happen to hypertonic areas?

Answer 39

They tend to gain water

Question 40

What tends to happen to hypotonic areas?

Answer 40

They tend to lose water

Question 41

What happens at equilibrium?

Answer 41

Molecular movement continues, it just means that the rates forward and back are equal

Question 42

What can happen to cells in the extreme?

Answer 42

A cell could shrivel or burst