Biological Membranes

Question 1

What is a glycoproteins?

Answer 1

Protein with a chain of carbohydrate molecules attached

Question 2

What is a glycolipid?

Answer 2

Lipid/phospholipid with a chain of carbohydrate molecules attached

Question 3

What is the plasma membrane?

Answer 3

Cell surface membrane

Question 4

What does permeability refer to?

Answer 4

The ability to let substances pass through

Question 5

What can pass through a partially permeable membrane?

Answer 5

Very small molecules can diffuse through
Some substances dissolve in the lipid layer and pass through
Other substances pass through special protein channels or are carried by carrier proteins

Question 6

What is the fluid mosaic model?

Answer 6

Theory of cell membrane structure with proteins embedded in a sea of phospholipids

Question 7

Roles of membranes at the surface of cells

Answer 7

Separates components from its external environment
Regulates transport in and out
May contain enzymes involved in specific metabolic pathways
Has antigens
May release chemicals
Receptors for cell signalling
May b the site of chemical reactions

Question 8

Roles of membranes within cells

Answer 8

Large surface area for some reactions

Question 9

Cholesterols job in surface membranes?

Answer 9

Regulates fluidity
Mechanical stability
Resist the effects of temperature change

Question 10

What is the glycocalyx

Answer 10

Carbohydrate chains outside of the membrane are very hydrophilic and attract water with dissolved solutes, helping the cell interact with its watery environment and obtain dissolved substances

Question 11

What is diffusion?

Answer 11

Movement of molecules from an area of high concentration of that molecule to an area of low concentration; it may or may not be across a membrane; it does not involve metabolic energy

Question 12

What is facilitated diffusion?

Answer 12

Movement of molecules from an area of high concentration of that molecule to an area of low concentration, across a partially permeable membrane via protein channels or carriers; it does not involve metabolic energy

Question 13

What are processes described as passive?

Answer 13

Only use kinetic energy and not ATP

Question 14

What is it called when there is no diffusion gradient?

Answer 14

Equilibrium

Question 15

5 factors that effect simple diffusion?

Answer 15

Temperature 
Diffusion distance 
Surface area
Size of diffusion molecules 
Concentration gradient

Question 16

What molecules need facilitated diffusion?

Answer 16

Small molecules with polarity

Question 17

How do small polar molecules get through the cell membrane?

Answer 17

Diffuse through water filled protein channels embedded in membrane

Question 18

What does cholesterol do the the permeability?

Answer 18

Reduce permeability to small water soluble molecules

Question 19

How does glucose get through the cell membrane?

Answer 19

Bind with transmembrane carrier protein which allow them to pass though

Question 20

What is osmosis?

Answer 20

Passage of water molecules down their water potential gradient, across a partially permeable membrane

Question 21

What is water potential?

Answer 21

Measure of the tendency of water molecules to diffuse from one region to another

Question 22

What are aquaporins?

Answer 22

Protein channels which allow water to cross the membrane more rapidly

Question 23

What is water measured in?

Answer 23

Kilo pascals

Question 24

What is it called when water enters animal cells causing them to swell and burst?

Answer 24

Cytolysis

Question 25

What is it called when plant cells swell?

Answer 25

Become turgid

Question 26

What is it called when water leaves animal cells

Answer 26

Crenated

Question 27

What is it called when water leaves Plant cells

Answer 27

Plasmolysis. Described as flaccid

Question 28

What is active transport?

Answer 28

The movement of substances against their concentration gradient across a cell membrane, using ATP and protein carriers

Question 29

What is endocytosis?

Answer 29

Bulk transport of molecules, too large to pass through a cell membrane even via channel or carrier protein, into a cell

Question 30

What is endocytosis?

Answer 30

Bulk transport of molecules, too large to pass through a cell membrane even bio channel or carrier protein, out of the cell

Question 31

What provides the energy for active transport?

Answer 31

Energy provided by the hydrolysis of ATP

Question 32

Describe carrier proteins roles

Answer 32

They have specific sites that combine reversibly with only certain solute molecules or ions Also have region that binds to and allows hydrolysis of ATP Energy helps the carrier protein change its conformation and in doing so carries ions across the membrane

Question 33

What is bulk transport?

Answer 33

A process that requires ATP and allows substances which are too big to pass through the membrane pass through

Question 34

What is endocytosis?

Answer 34

How large molecules may be brought into the cell | Segment of the plasma membrane surrounds and encloses the particle and brings it in, in a vesicle

Question 35

What word refers to the intake of solid matter?

Answer 35

Phagocytosis

Question 36

What word refers to the intake of liquids?

Answer 36

Pinoendocytosis

Question 37

Why is energy needed in endocytosis?

Answer 37

To form a vesicle and move them using molecular motor proteins along the cytoskeleton

Question 38

What is endocytosis?

Answer 38

How large molecules may be exported out of cells. Don't pass through plasma membrane. Vesicle fuses instead

Question 39

Why does exocytosis require ATP?

Answer 39

Fuse the vesicle and move the vesicle. A molecule of ATP is hydrolysed for every step that a motor protein takes along the cytoskeleton thread, as it drags cargo

Question 40

What affect does temperature dropping have on cells

Answer 40

Saturated fatty acid become compressed Many unsaturated fatty acids making up cell membrane, become compressed the kinks in their tails push adjacent phospholipids molecules away Maintains fluidity Proportions of saturated and unsaturated determine membranes fluidity at low temperatures Cholesterol buffers the effect of lowered temperature to prevent reduction in membrane fluidity Prevent phospholipids packing together

Question 41

What affect does temperature increasing have on cells

Answer 41

Increase fluidity Permeability increases Effects embedded proteins rate of reaction May affect unfolding during phagocytosis Change the ability of cell signalling Cholesterol buffers to some extent

Question 42

What does high temperature to proteins?

Answer 42

Cause atoms within molecules to vibrate and this breaks ionic and hydrogen bonds that holds the structure Tertiary structure changes therefore they denature