2.5- Biological membranes Flashcards Preview

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Flashcards in 2.5- Biological membranes Deck (52)
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1

What is the role of membranes? (name 3)

-To act as a partially a partially and sometimes selectively permeable membrane between cells and their environments
- Site of Chemical reactions
- Sites of cell communication and signalling

2

What is the function of phospholipids in a cell membrane

Phospholipids form the bilayer and are the main component of the surface area

3

What Is the function of Cholesterol in a cell mambrane?

It regulates membrane fluidity and flexibility

4

What is the function of proteins in cell membranes?

carrying out chemical reactions or regulating cross membrane transport

5

What are the 2 types of proteins in cell membranes?

Integral- span the entire membrane
Peripheral- embedded in half of a membrane

6

What is the function of glycoproteins and glycolipids in cell membranes?

can be antigens or receptor molecules
can bind with extracellular signalling molecules such as hormones

7

An increased temperature leads to the membrane increasing its.................

Fluidity and permeability

8

Why does an increased temperature increase fluidity and permeability? (Phospholipids)

Phospholipids aquire more energy so they move around more

9

Why does an increased temperature increase fluidity and permeability? (Fatty acids)

fatty acids become less compressed

10

Why does an increased temperature increase fluidity and permeability? (Proteins)

proteins can denature at high temperatures reducing their ability to control transport across membranes

11

Which 3 factors can affect membrane permebility?

Increased temperature
Changes in PH - affect the function of proteins in the membrane
Organic solvents such as ethanol can damage a membrane by dissolving lipids held through it

12

Can you draw the fluid Mosic model?

Hmmmmmmmmm

13

What is the definition of diffusion?

The movement of molecules from a region of high concentration to a region of low concentration until the concentrations of the 2 regions are equal.

14

What 3 factors does the rate of diffusion depend on?

Surface area of cell
thickness of membrane
Temperature

15

i am a small non polar molecule. can i diffuse through a membrane?

yes, i can diffuse quickly

16

I am a small polar molecule. can i diffuse across a membrane?

yes, although it will be slower

17

I am an ion. Can i diffuse across a cell membrane?

Noooo, i have to be transported by other methods

18

I am a large polar molecule. Can i diffuse across a cell membrane??

nope, i have to be transported by other methods

19

Give 3 examples of molecules which can diffuse through a membrane.

Oxygen
CO2
Steroids
Fat soluble vitamins

20

What is the definition of osmosis?

the diffusion of water molecules from a region of high concentration to low concentration across a partially permeable membrane

21

Is osmosis a form of active transport

No, osmosis is a specialised form of diffusion.

22

What molecules can facilitated diffusion transport that normal diffusion cant?

large and polar molecuses

23

Give 4 examples of molecules that are transported by facilitated diffusion.

glucose
fructose
ions
urea

24

is facilitated diffusion an active process?

No, it is passive

25

What is needed for facilitated diffusion to occur?

Carrier proteins or Channel proteins

26

What are the 3 steps for facilitated diffusion through a carrier protein?

-Molecule binds with carrier proteins molecules on cell surface
-Protein changes shape and transports molecule through
-Molecule detaches and protein reverts to its original shape

27

What does the rate of facilitated diffusion depend on?

-Concentration gradient
-Number of channels or transporter proteins that are available

28

What are 3 passive processes which move molecules across membranes?

Diffusion
Facilitated diffusion
Osmosis

29

What are 3 active processes that are used to transport molecules across membranes?

Active transport
Endocytosis
Exocytosis

30

Why do active processes require energy?

They move molecules against their concentration gradient