Membranes

Question 1

How is a red blood cell’s membrane adapted to do its function?

Answer 1

Permeable to oxygen, carbon dioxide.
It is a biconcave disc to have a larger surface area for better permeability.
It is very flexible to go into small places.

Question 2

How is a phagocytes membrane adapted to do its function?

Answer 2

Needs to be able to engulf pathogens.
Flexible to be able to wrap around foreign bodies.
They have receptors to engulf foreign bodies,

Question 3

How is a muscle cell’s membrane adapted to do its function?

Answer 3

Permeable to oxygen, carbon dioxide, and glucose.
Can transmit electrical impulses to each other using special molecules. have receptors to know when to contract and relax. Have a lot of proteins.

Question 4

How is a shoot cell’s membrane adapted to do its function?

Answer 4

Has auxin receptors to know when to grow
Flexible so it can grow

Question 5

How is a neurone cell’s membrane adapted to do its function?

Answer 5

Can transmit electrical impulses to each other using special molecules.

Question 6

How is chloroplast membrane adapted to do its function?

Answer 6

Permeable to oxygen, carbon dioxide and glucose.
Chlorophyll and many thylakoids to increase surface area

Question 7

What are the general functions of membranes?

Answer 7

Separates the cells internal parts to its surroundings
Site of chemical reactions
Releases chemicals to signal to other cells
Partially permeable to regulate transport in and out of the cell
-Has antigens to recognise own body and foreign cells
Contains receptors that receive chemical signals, such as hormones and drugs
-Contain enzymes involved in specific metabolic pathways

Question 8

What makes up different parts of the membrane

Answer 8

Phospholipid bilayer (lipids with a phosphate group)
- Glycolipids (lipid with a carb molecule)
Proteins, glycoproteins (protein with a carb molecule)
Fluid because compartments can move across each other
Channel proteins - to allow substances through
Antigens to allow the cell to be recognised

Question 9

What is a phospholipid?

Answer 9

A molecule with a phosphate head and 2 fatty acids as tails

Question 10

What part of the phospholipid is hydrophilic and why?

Answer 10

The phosphate head is polar so it is hydrophilic

Question 11

What part of the phospholipid is hydrophobic and why?

Answer 11

The fatty acid tail is not polar so it is hydrophobic

Question 12

What are the 2 structures can phospholipids make in water and why does it become these shapes ?

Answer 12

It can make a complete circle with the hydrophobic tails in the centre and the hydrophilic heads on the outside called a micelle to protect the hydrophobic tails
It can make a double layered membrane with hydrophilic heads on the outside on both sides and the hydrophobic tails in between them.

Question 13

What is cholesterol’s function?

Answer 13

-It is important in regulating the membranes fluidity, the more cholesterols the less fluid or permeable the membrane because nothing can enter where the cholesterol it.
-It also keeps the cell stable at normal body temperature, without it cell membranes would burst open

Question 14

What is a carrier protein function?

Answer 14

It transports substances that can’t go through the membrane, such as sugars, ions and amino acids but are still needed in the cell

Question 15

What is a channel protein function?

Answer 15

It transports ions that can’t go through the membrane but are still needed in the cell

Question 16

What is an intrinsic protein?

Answer 16

These are proteins that span the entire width of the membrane

Question 17

What is an extrinsic protein?

Answer 17

Proteins that may be free on the membranes surface of attached to an intrinsic protein

Question 18

Why is the cell membrane inside of a mitochondria folded?

Answer 18

To increase SA for more chemical reactions

Question 19

What is a glycoprotein?

Answer 19

A carbohydrate chain attached to a protein in the cell membrane

Question 20

What is a glycoproteins function?

Answer 20

It is a receptor involved in cell recognition and and cells binding to make tissues
it also can be a receptor for hormones or an enzyme. It also can give off hormones

Question 21

What is a glycolipid?

Answer 21

A carbohydrate chain attached to a phospholipid in the cell membrane

Question 22

What is a glycolipids function?

Answer 22

It is a receptor involved in cell recognition and and cells binding to make tissues

Question 23

What is the function of extrinsic proteins on the inside the cell membrane?

Answer 23

They are used in cell signalling or chemical signalling

Question 24

What types of molecules can pass through the phospholipids through the bilayer?

Answer 24

Small non-polar molecules can pass though the bilayer easily
Small polar molecules can pass though the bilayer slowly

Question 25

What types of molecules can’t pass through the phospholipids through the bilayer?

Answer 25

Charged particles like ions are unlikely to pass through the bilayer, even if they are small

Question 26

What happens to the saturated fatty acids in the cell membrane if the temperature decreases?

Answer 26

Fatty acids become more condensed

Question 27

What happens to the unsaturated fatty acids in the cell membrane if the temperature decreases?

Answer 27

They compress and the kinks in the tails push the phospholipids away to maintain the cell membranes permeability.

Question 28

What does cholesterol do when the temperature decreases?

Answer 28

It buffers the effect of the lowered temperature to prevent a reduction in the membrane fluidity by preventing the phospholipids from packing together too closely.

Question 29

What does cholesterol do when the temperature increases?

Answer 29

They buffer the effect of the increasing heat as it reduces the cell membrane permeability.

Question 30

What happens to the phospholipids in the cell membrane if the temperature increases?

Answer 30

They have more kinetic energy do they start to move more and in random ways, increasing fluidity and permeability

Question 31

What happens to the intrinsic proteins in the cell membrane if the temperature increases?

Answer 31

The intrinsic proteins may shift their position, altering the rate of the reaction they catalyse and the active site may change and denature the protein

Question 32

What affects phagocytosis and how?

Answer 32

An increase in temperature may affect the infolding of the plasma membrane during phagocytosis

Question 33

What happens to proteins in the cell membrane if the temperature increases?

Answer 33

The high temperatures cause the ionic and hydrogen bonds in the protein to break the bonds holding its structure together, so it unfolds.

Question 34

What happens to proteins tertiary structure in the cell membrane if the temperature increases?

Answer 34

They can’t change back to their original structure so they are denatured.

Question 35

What happens to cytoskeleton if the temperature increases?

Answer 35

If both the intrinsic proteins and cytoskeleton threads become denatured then the plasma membrane will start to fall apart and make the cell membrane more permeable.

Question 36

What happens to the phospholipids in the cell membrane if the there is a solvent?

Answer 36

Organic solvents such as acetone and ethanol will damage the cell membranes because they dissolve lipids.