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Flashcards in Membranes Deck (55)
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1

What makes up a membrane?

Phospholipids and proteins make up the phospholipid bilayer

2

How wide are membranes?

7nm

3

What are membranes seen as on an electron microscope?

Two dark bands

4

What are the four functions of membranes?

1. Selectively permeable barrier
2. Taking up nutrients
3. Secreting chemicals
4.Cell to cell recognition (to avoid pathogens)

5

Is the phosphate group on a phospholipid hydrophilic or hydrophobic?

Hydrophilic

6

Is the fatty acid on a phospholipid hydrophilic or hydrophobic?

Hydrophobic

7

What is the function of the phospholipid bilayer?

Acts as a barrier to large polar molecules

8

What is the diagram of the plasma membrane called?

The fluid mosaic model

9

What is the function of the phospholipids in the plasma membrane?

Creates the bilayer

10

What is the function of the glycoproteins in the plasma membrane?

Used for cell to cell recognition

11

What is the function of the glycolipids in the plasma membrane?

Used for cell to cell recognition

12

What is the function of carbohydrates in the plasma membrane?

Used for cell to cell recognition

13

What is the function of cholesterol in the plasma membrane?

Makes the membrane stable and fluid

14

What is the function of extrinsic proteins in the plasma membrane?

Likely to be enzymes or structural material in the cytoskeleton

15

What is the function of channel forming proteins in the plasma membrane?

Hydrophilic pores that allows polar molecules through the membrane

16

What is the function of the phospholipid bilayer?

Creates a selectively permeable membrane

17

What is the function of channel proteins?

Allow polar molecules across the membrane

18

What is the function of carrier proteins?

Used in active transport and facilitated diffusion

19

What is the function of receptor proteins?

For hormones, a specific 3D shape complementary to molecules such as hormones

20

What are the four roles of internal membranes?

1. Separate components from cytoplasm for specialisation
2.Holds metabolic pathways in place. Chemical reactions take place on membranes
3.Ribosomes are attached to membranes (SER)
4. Control of movement of substances

21

Define diffusion?

The movement of molecules or ions from a region of high concentration to a region of low concentration down a concentration gradient

22

What type of molecules can be moved by diffusion? (2)

.Small non-polar molecules
.Large lipid soluble molecules

23

Does diffusion require ATP?

No

24

Does diffusion require specific proteins?

No

25

What are two requirements for diffusion to occur?

1. A concentration gradient
2.Molecules have kinetic energy

26

Give three named examples of molecules that can move by diffusion across a membrane?

O2, CO2, H2O

27

What six factors affect the rate of diffusion?

1. Temperature
2. Concentration Gradient
3. Surface Area
4. Diffusion Distance
5. Size of Molecules
6. Lipid solubility

28

How does temperature affect the rate of diffusion?

Increasing temperature increases kinetic energy and this the rate of diffusion

29

How does concentration gradient affect the rate of diffusion?

Having more molecules on one side of the membrane than the other increases diffusion rate (increasing concentration gradient)

30

How does surface area affect the rate of diffusion?

The greater the surface area, the greater the rate of diffusion