Lipids and membranes

Question 1

What are fatty acids?

Answer 1

Long chain carboxylic acids

Question 2

What can fatty acids be?

Answer 2

Saturated or unsaturated

Question 3

What is a fat?

Answer 3

An ester between fatty acids and glycerol

Question 4

What is an oil?

Answer 4

Fat made from unsaturated fatty acids

Question 5

What are the two types of Unsaturated fatty acids?

Answer 5

Cis

Trans

Question 6

How are lipids formed?

Answer 6

They are hydrolysed triglycerides

Question 7

What are lipids?

Answer 7

Long carbon chains attached to a polar head

Question 8

What is the simplest form of a lipid?

Answer 8

Salts of fatty acids (soap)

Question 9

What are micelles?

Answer 9

Droplets of lipids where the hydrophilic heads point outwards and the hydrophobic tails point inwards

Question 10

When do micelles form?

Answer 10

In water

Question 11

Where are lipids in the cell membrane often derived from?

Answer 11

Triglycerides

Question 12

What lipids form bilayers in water?

Answer 12

Phospholipids

Sphingolipids

Question 13

What is found on the cell membrane?

Answer 13

Various proteins and enzymes

Question 14

What lipids make up the cell membrane?

Answer 14

Phosphoglycerides
Sphingolipids
Sterols

Question 15

What determines the properties of the cell membrane?

Answer 15

The composition

Question 16

What effect do saturated lipids have on the cell membrane?

Answer 16

They form tightly packed bilayers with gel-like consistency

Question 17

What effect do unsaturated lipids have on the cell membrane?

Answer 17

Unsaturated lipids can not pack as close and the bilayer becomes more fluid

Question 18

Can cholesterol form micelles or bilayers?

Answer 18

No

Question 19

What does small amounts of cholesterol do?

Answer 19

Makes the bilayer more fluid

Question 20

What does large amounts of cholesterol do?

Answer 20

Anchors the lipid tails and makes parts of the membrane more gel-like

Question 21

Can the lipids move within the bilayer?

Answer 21

Yes

Question 22

How often does a lipid change place with it’s neighbour?

Answer 22

107 times/sec

Question 23

What distance do lipids tend to move over?

Answer 23

0.5 μm

Question 24

What does the cell membrane prevent?

Answer 24

Most molecules from freely passing through the membrane

Question 25

What does the cell membrane allow to pass through the membrane?

Answer 25

Small, uncharged polar molecules

Question 26

What two ways can transmembrane proteins be anchored?

Answer 26

α-helix | β-barrel

Question 27

What are β-barrel anchored transmembrane proteins?

Answer 27

The β-sheets form a barrel like structure of hydrophobic amino acids The hydrophobic side chains points to the outside of the barrel

Question 28

What are α-helix anchored transmembrane proteins?

Answer 28

α-helix of about 20 hydrophobic amino acids | The hydrophobic side chains points to the outside of the helix

Question 29

What are some examples of transmembrane proteins that transport molecules across the membrane?

Answer 29

Ion channels Aquaporins Glucose transporters Amino acid transporter

Question 30

What two things can transmembrane proteins do?

Answer 30

Transport molecules across the membrane | Relay signals across the cell membrane

Question 31

What are examples of transmembrane proteins that can relay signals across the cell membrane?

Answer 31

G protein-couples receptors | Protein kinases

Question 32

How can proteins be anchored to the membrane?

Answer 32

By lipids which attach to the protein

Question 33

What are glycolipids?

Answer 33

Lipids with carbohydrates attached

Question 34

Where are glycolipids found?

Answer 34

Only on the extracellular surface

Question 35

What do glycolipids do?

Answer 35

They are active in cell recognition They protect against harsh conditions They maintain electrical gradients

Question 36

What reactive oxygen species can oxygen form?

Answer 36

Hydroxyl radical: HO• | Hydroperoxide radical: HO-O•

Question 37

What are reactive oxygen species used for?

Answer 37

To degrade unwanted proteins and molecules

Question 38

How does lipid peroxidation occur?

Answer 38

Reactive oxygen species can react with unsaturated lipids in the cell membrane

Question 39

What prevents lipid peroxidation?

Answer 39

antioxidants | They trap the intermediates