Lipids and membranes

Question 1

What bonds does rotation occur in fatty acids?

Answer 1

SIngle bonds

Question 2

What bond does not allow for rotation?

Answer 2

Double bond

Question 3

What are examples of saturated steroisomerism?

Answer 3

Stearic acid

Question 4

What are examples of unsaturated steroisomerism

Answer 4

Elaidic acid (trans isomer)

Oleic acid (Cis isomer)

Question 5

How are trans-fatty acids caused?

Answer 5

Side reaction with the catalyst of the hydrogenation process

Question 6

What are ingested fatty acids stored as?

Answer 6

Triglycerides

Question 7

What is Olestra?

Answer 7

Sucrose esterified with long chain fatty acids

Question 8

Why does Olestra cause cramps, gas and loose bowels?

Answer 8

Unable to be absorbed or metabolised

Question 9

What is Saponification?

Answer 9

Hydrolysis of esters to form glycerol and soap

Question 10

What is Sodium palmate?

Answer 10

A sodium salt of fatty acids derived from palm oil

Question 11

What is Sodium oleate?

Answer 11

Soidum salt of fatty acids derived from olive oil

Question 12

What is the structure of Micelle?

Answer 12

• Hydrophillic head groups on outside
• Hydrophobic hydrocarbon chain on inside

Question 13

What is the structure of a bilayer membrane?

Answer 13

• Too long for micelle formation
• Head groups on outside
• Hydrocarbon chains on the inside

Question 14

What is the liposome structure?

Answer 14

• Aqueous environment inside and outside liposome

Question 15

What is Cholesterol a precursor to?

Answer 15

Steroid horomones in regulating gene expression

Question 16

What is Cholesterol in bile acids used for?

Answer 16

• Dissoicate to produce bile salts
• Biles is used to solubilse, digest and absorb fats

Question 17

What are the three phospholipids with different heads?

Answer 17

• Sphingolipids
• Phosphatidylcholine
• Phosphatidylethanolamine

Question 18

What is a component of mitochondrial membrane?

Answer 18

Cadiolipin

Question 19

What is preripheral proteins in membrane composition

Answer 19

Surface proteins with polar hydrophillic side chains
- Bind via covalent, non-covalent, ionic or hydrogen bonding interactions

Question 20

What is integral proteins in membrane composition?

Answer 20

• Extend through membrane, contain non polar hydrophobic sequence
• Transport proteins

Question 21

What is type 1 and 2 in integral proteins?

Answer 21

• Single transmembrane helix
• Amino terminus is on the outside
  for type 1 and the inside for type 2

Question 22

What is type 3 integral proteins in membrane?

Answer 22

• Mulitple transmembrane helices
• Single polypeptide

Question 23

What is type 4 in intergral proteins?

Answer 23

• Transmembrane helices
  of different peptides
  form a channel

Question 24

What is type 5 and 6 in integral protein?

Answer 24

• Peptide secured by lipid anchor
• Type 5 secured only by anchor, type
  6 also has a transmembrane helix

Question 25

What is Glycophorin?

Answer 25

Intergral prtoein found int he membrane of red blood cells

Question 26

Where can the positive charged amino acids side chains in glycophorin be found?

Answer 26

In the cytoplamsic region

Question 27

What are β barrels

Answer 27

- β barrel conformation stabilised by intrachain hydrogen bonding. - β barrel only need 7-9 residues to span a membrane. - Harder to detect β barrels from amino residue sequence alone.

Question 28

How is fluidity in fluid mosaic model affected?

Answer 28

- Temperature - Fatty acid saturation - Sterols

Question 29

What affect does temperature have on fluid mosaic model?

Answer 29

Temperature increase causes more disorder - more fluidity

Question 30

What affect does temperature have on fluid mosaic model?

Answer 30

Temperature increase causes more disorder - more fluidity

Question 31

What affect does fatty acid saturation have on fluid mosaic model

Answer 31

- Saturated fatty acids created rigid and ordered structure - Unsaturuated are kinked so it causes fluidity

Question 32

What affect does sterols have on fluid mosaic model?

Answer 32

- Pack unsaturated fatty acids into extended conformation causing less fluidity - Associate with saturated fatty acids causing more fluidity

Question 33

What do Sphingolipids and Cholesterol form in lipid distribution?

Answer 33

Microdomains

Question 34

What does Microdomains cause?

Answer 34

Less fluidity due to being thick and ordered

Question 35

What do Microdomains (rafts) do?

Answer 35

Rafts keep lipid molecules aggregated together and also certain proteins and transporters close together.

Question 36

What is Lateral diffusion?

Answer 36

Phospholipid moves throught he membrane, remaining on the same side of the bilayer

Question 37

What happens in catalysed transbilayer diffusion?

Answer 37

Phospholipid moves from extracellular site to cytosolic site

Question 38

What enzymes require energy

Answer 38

Flippase and floppase

Question 39

What enzyme does not require energy

Answer 39

Scramblase

Question 40

How is a cell marked for cell death?

Answer 40

Moving phosphatidylserine (a phospholipid) to the extracellular site marks a cell for cell death. - Must be found in high numbers on the extracellular site.

Question 41

What type of molecule can easily diffuse through the plasma membrane?

Answer 41

• Small, non-polar molecules • Water molecules (due to their small size)

Question 42

What are the 3 transport methods?

Answer 42

Passive diffusion, facilitated diffusion, Active transport

Question 43

What else are transporter proteins are known as?

Answer 43

Permeases

Question 44

What is Erythrocyte glucose transporter (GLUT1)

Answer 44

Uniporter protein - passive facilitated diffusion

Question 45

What is secondary active transprot?

Answer 45

X moves down concentration gradient and provides the energy for S to move against concentration gradient

Question 46

What is Na+–K+ ATPase pump?

Answer 46

Pump helps keep the Na+ and K+ ions at different concentrations inside and outside the cell. - Maintains the membrane potential