Parts Of Membrane

Question 1

Function of membrane

Answer 1

• Control passage of molecule in/out of cell

- forms boundaries between organelles and the cytoplasm

Question 2

What are 5 components of cell membranes

Answer 2

• phosolipids
• glycoproteins
• cholesterol
• proteins
• glycolipids

Question 3

Functions of phosolipids

Answer 3

• allow lipid-soluble substances in/out of the cell
• prevent water soluble substances leaving/entering the cel
• make the membrane flexible and self sealing

Question 4

Describe the structure of a phosolipid

Answer 4

• hydrophobic tail

- hydrophilic head

Question 5

Describe the hydrophilic head in the Phosolipid biller

Answer 5

• point outside of the cell membrane

- attracted by water both sides

Question 6

Describe the hydrophobic tail i the phosolipid bilayer

Answer 6

• both layers points inside to the cell membrane

- repelled by water on both sides

Question 7

Where are proteins found

Answer 7

Completely span the membrane or sit in or on one of surfaces of the bilayer

Question 8

What is a protein channel

Answer 8

Form water filled tubes that allow water soluble ions to diffuse across the membrane

Question 9

What is a carrier protein

Answer 9

Bind to ions/molecules like glucose and amino acids the change shape in order to move these molecules cross the membrane

Question 10

Function of proteins

Answer 10

• provide structural support
• acts as a channel transporting water-soluble substances across the membrane
• allows active transport across membrane through carrier proteins
• helps cells adhere together
• acts as a receptor
• forms cell surface receptors for identifying cells

Question 11

What does extrinsic mean

Answer 11

Protein lying on the surface of the bilayer

Question 12

Example Intrinsic proteins

Answer 12

Channel protein and carrier protein

Question 13

Functions of cholesterol

Answer 13

• add strengths to the membrane
• reduce movement of other molecules
• make membrane less fluid at high temp
• prevents leakage of water and dissolved water

Question 14

How does cholesterol prevent the leakage of water

Answer 14

Because cholesterol molecules are hydrophobic

Question 15

How does cholesterol reduce the movement of other molecules

Answer 15

By pulling together fatty acid tails of phosolipid molecules which limits movement without the membrane becoming rigid

Question 16

What is a glycolipid

Answer 16

Lipid covalently bonded to a carbohydrate

Question 17

Functions of glycolipids

Answer 17

• Acts as recognition sites
• help cells attach to each other forming tissues
• helps maintain stability of membrane

Question 18

What are glycoproteins

Answer 18

Extrinsic protein covalently bonded to a carbohydrate

Question 19

Function of glycoproteins

Answer 19

• Recognition sites
• help cells to attach to one anther forming tissues
• allows cells to recognise one another

Question 20

What is the fluid mosaic model of Plasma membrane

Answer 20

arrangement of all the molecules in a plasma membrane

Question 21

What it mean by fluid in the fluid mosaic model

Answer 21

• Molecules can moves relative to each other

- Gives membrane a flexible structure that is constantly changing shape

Question 22

What does it mean by mosaic in the fluid mosaic model

Answer 22

• proteins embedded in the phosolipid bilayer

- vary. Shape size and pattern

Question 23

Molecules that can move out of plasma membrane

Answer 23

• small,non-polar molecules

- lipid soluble

Question 24

O2 and co2 are examples of

Answer 24

Small non polar molecules which can pass through the membrane

Question 25

What molecules can’t pass through the membrane

Answer 25

• not lipid soluble
• too large
• of same charge
• they are polar

Question 26

Why can’t polar molecule pass through membrane

Answer 26

They have the same electrical charge and can’t pass through Phosolipid bilayer and they are repelled