2.5 Biological Membranes

Question 1

What are the roles of membranes within cells and at the surface of cells?

Answer 1

1. Sites of chemical reactions
2. Sites of cell communication
3. Partially permeable barriers

Question 2

which organelles have double membranes?

Answer 2

1. Mitochondria
2. Chloroplasts
3. Nucleus

Question 3

What is the Tonoplast?

Answer 3

Vacuole membrane

Question 4

Definition of membrane?

Answer 4

Membranes are partially permeable barriers between the cell and its environment, between organelles and the cytoplasm, and within organelles

Question 5

What is cell communication?

Answer 5

cell signalling is the process by which cells communicate with each other

Question 6

Why is cell signalling important?

Answer 6

its very important as it allows multicellular organisms to control and coordinate their bodies and to respond to their environments

Question 7

what is the charge of a phosphate group?

Answer 7

it is polar
slightly negative

Question 8

why does a membrane have a mosaic pattern?

Answer 8

proteins are scattered throughout the membrane which makes it look like a mosaic

Question 9

what is the movement of a phospholipid in a membrane like?

Answer 9

mainly move sideways through their own layers

Question 10

what is a glycoprotein?

Answer 10

a carbohydrate chain attached to a protein molecule

Question 11

what is glycocalyx?

Answer 11

very hydrophilic molecules on the outside of the membrane which attract water with dissolved solutes

Question 12

what is useful about glycocalyx?

Answer 12

they help the cell interact with its watery environmentand obtain dissolved substances

Question 13

what is a glycolipid?

Answer 13

a carbohydrate chain attached to a lipid

Question 14

what is a glycoprotein?

Answer 14

a carbohydrate chain attached to a protein

Question 15

what in the makeup of a membrane affects its fluidity?

Answer 15

cholesterol

Question 16

is membrane fluidity reversible?

Answer 16

yes, up to a certain point

Question 17

what does active transport require?

Answer 17

ATP
metabolic energy

Question 18

when an ion is trying to go through a carrier protein by active transport, what happens?

Answer 18

-the ion thats going to be transported binds to receptors on the carrier protein

-ATP binds to carrier protein and is hydrolysed into ADP and phosphate

-the phosphate and carrier protein binding causes the carrier protein to change shape

-this opens it up to the inside of the cell and ion is released into the cell

-phopshate released from the carrier protein and rejoins with the ADP to form ATP. the carrier protein returns to its original shape

Question 19

which factors affect simple diffusion?

Answer 19

temperature and concentration

Question 20

which factors affect membrane diffusion?

Answer 20

surface area
thickness of membrane

Question 21

what is facilitated diffusion?

Answer 21

protein channels and carrier proteins

Question 22

what kind of energy is used in diffusion?

Answer 22

kinetic energy

Question 23

why is diffusion passive?

Answer 23

only requires kinetic energy