Structure of membranes

Question 1

Where are membranes found around?

Answer 1

Prokaryotic cells, animal and plant cells, organelles e.g. nucleus and vesicles

Question 2

What is endocytosis?

Answer 2

Ingestion into a cell

Question 3

What is exocytosis?

Answer 3

Secretion from a cell

Question 4

What are functions of membranes at the surface of a cell?

Answer 4

Keep cell contents together and seperate from other cells, communication between cells by protein receptors for hormones and other signalling molecules, allows body to determine foreign and self via antigen detection, control the movement of substances in and out of cells, cell attachment and increase surface area of the cell

Question 5

What are functions of membranes within the cell?

Answer 5

Isolate the nucleus, separate organelles components from cell, prevent disruption of reactions and pathways, allow the attachment of ribosomes, allow internal transport inside of the cell, holds components of metabolic pathways in place and increase the surface area

Question 6

What is the effect of structures of a phospholipid?

Answer 6

The phospholipids polar head will dissolve and form a bilayer which is hydrophobic, and its interactions exclude water and this creates a lateral movement in the fluid

Question 7

What allows proteins to stay intact?

Answer 7

Movement of membranes molecules

Question 8

How thick is a phospholipid?

Answer 8

7-10nm

Question 9

How do phospholipids appear under a microscope?

Answer 9

As a thin line

Question 10

What are the 3 main formations of phospholipids?

Answer 10

Micelle, bilayer or liposome

Question 11

What are components of the membrane?

Answer 11

Glycoproteins and glycolipids, phospholipids in bilayer, cell adhesion proteins, cholesterol, peripheral proteins, receptor proteins and pore proteins

Question 12

What are glycoproteins and glycolipids?

Answer 12

They are carbohydrate or sugar side chains added to proteins and lipids

Question 13

What is the use of glycoproteins and glycolipids?

Answer 13

They are important in cell and antigen identification

Question 14

What is the purpose of phospholipids in the bilayer?

Answer 14

They are imperative to water-soluble molecules

Question 15

What do cell adhesion proteins do?

Answer 15

They attach cells firmly to eachother

Question 16

What does cholesterol do at low temperatures?

Answer 16

It prevents crystallisation of the membrane?

Question 17

What does cholesterol do at high temperatures?

Answer 17

It prevents excess fluidity

Question 18

What are peripheral proteins used for?

Answer 18

They are involved in intracellular signalling caused by binding of extracellular messengers

Question 19

What are pore proteins used for?

Answer 19

To allow polar molecules to pass through membrane through active or passive transport

Question 20

What are receptor proteins for?

Answer 20

They have a specific shape which binds with molecules of a complementary shape and sets of reactions in a cell which responds to the signal