Lipids

Question 1

Name two classes of lipids.

Answer 1

Storage and membrane

Question 2

Name a primary function of membrane lipids.

Answer 2

They form boundaries around the cell and intracellular organelles

Question 3

True or false: membrane lipids are semi-permeable barriers.

Answer 3

True

Question 4

Membrane proteins are involved in ________ processes.

Answer 4

Signalling

Question 5

True or false: all membrane lipids contain carbohydrates.

Answer 5

False

Question 6

Membrane lipids may be amphipathic or ___________.

Answer 6

Amphiphilic

Question 7

How many polar, or hydrophilic, heads does a membrane lipid have?

Answer 7

One

Question 8

True or false: lipids may have one or two nonpolar, or hydrophobic, tails.

Answer 8

True

Question 9

The polar phosphorylated headgroup, the three-carbon glycerol backbone, and the two nonpolar, hydrocarbon fatty acid chains are components of which type of membrane lipid?

Answer 9

Glycerophospholipid

Question 10

The phosphorylated headgroup of a glycerophospholipid varies by membrane lipid, and is attached to the _____ of the lipid’s backbone.

Answer 10

C3

Question 11

Two fatty acid chains are attached to C1 and ____ of the membrane lipid’s backbone.

Answer 11

C2

Question 12

Name the simplest glycerophospholipid.

Answer 12

Phosphatidic acid

Question 13

Sphingolipids have a __________ backbone.

Answer 13

Sphingosine

Question 14

Sphingolipids have one fatty acid tail, but two __________ chains.

Answer 14

Hydrocarbon

Question 15

True or false: different sphingolipids can be formed by varying headgroups.

Answer 15

True

Question 16

What is the most abundant type of sphingolipid?

Answer 16

Sphingomyelin

Question 17

What is the simplest sphingolipid, with a hydrogen headgroup?

Answer 17

Ceramide

Question 18

Name the headgroups observed on sphingolipids.

Answer 18

Choline and ethanolamine

Question 19

Cerebrosides and gangliosides are also derived from sphingosine, and have one or more ______ residues in their headgroup

Answer 19

Sugar

Question 20

Galactocerebrosides have a single galactose residue and are predominately found in ________.

Answer 20

Neurons

Question 21

Most of the cholesterol in the body is ________ in origin

Answer 21

Dietary

Question 22

Cholesterol is insoluble in blood, so it is transported in the circulatory system, bound to one of a variety of ___________.

Answer 22

Lipoproteins

Question 23

True or false: water-soluble proteins can carry cholesterol in the blood.

Answer 23

True

Question 24

Name the main two types of cholesterol found in the body.

Answer 24

Low-density lipoprotein (LDL) and high-density lipoprotein (HDL)

Question 25

Large numbers of _____ __________ _________ molecules are associated with the presence of atheromatous disease within the arteries

Answer 25

Low-density lipoprotein

Question 26

Name the hard substance formed by inordinate levels of high-density lipoprotein, which can cause strokes and heart attacks.

Answer 26

Plaque

Question 27

High-density lipoprotein molecules transport cholesterol back to the _______ for excretion, and a large amount of high-density of lipoprotein is congruent with better outcome.

Answer 27

Liver

Question 28

True or false: cholesterol imbalances can be restored, in many cases, via diet and lifestyle changes.

Answer 28

True

Question 29

Fatty acids are _______ acids with hydrocarbon chains of 4-36 carbons

Answer 29

Carboxylic

Question 30

Saturated acids contain no double bonds, and the tail is __________.

Answer 30

Straight

Question 31

Unsaturated acids have one or more double bonds, and the tail is __________.

Answer 31

Twisted

Question 32

True or false: almost all naturally-occurring unsaturated fatty acids are in the trans configuration.

Answer 32

False

Question 33

What accounts for the poor solubility of fatty acids in water?

Answer 33

Nonpolar hydrocarbon chains

Question 34

When required, phospholipase-A cleaves arachidonic acid from the _________ backbone.

Answer 34

Glycerol

Question 35

Eicosanoids are used for ________ hormones, reproductive function, inflammation, pain, fever, etc.

Answer 35

Endocrine

Question 36

Name three forms of lipid aggregates.

Answer 36

Micelles, bilayers, and liposomes

Question 37

The following describes which type of lipid aggregate? 'Fatty acid salts, which contain only one fatty acid chain. Hydrophobic fatty acids are hidden in the interior. Hydrophilic headgroups interact with the surrounding water molecules, and the aggregates are usually very small, but the size varies by length of fatty acid chain.'

Answer 37

Micelles

Question 38

The charged head of a bilayer is aimed towards the _________ environment, and the tails point towards each other.

Answer 38

Aqueous

Question 39

When are stable, water-enclosing liposomes formed?

Answer 39

They are formed when a lipid bilayer folds back on itself to create a hollow sphere.

Question 40

Bilayers lead to the formation of _________ sheets.

Answer 40

Bilipid

Question 41

True or false: inner and outer leaflets are formed within a bilayer.

Answer 41

True

Question 42

True or false: bilayer leaflets are induced by proteins to self-assemble in aqueous conditions.

Answer 42

False

Question 43

Name a force which holds bilayer leaflets together.

Answer 43

van der Waals

Question 44

No _________ bonds exist between lipids.

Answer 44

Covalent

Question 45

Name two methods by which lipids may move in within the plane of either the outer or inner leaflet.

Answer 45

Lateral and rotational

Question 46

True or false: transverse movement between bilayer leaflets is readily achieved.

Answer 46

False

Question 47

Name the type of enzyme that allows for the movement of polar headgroups.

Answer 47

Flippase

Question 48

State three ways in which membrane fluidity can be altered.

Answer 48

Heating the lipid to a gel consistency, increasing the degree of unsaturation, and transition temperature

Question 49

What does the fluidity mosaic model display?

Answer 49

Membranes are free to diffuse laterally, but cannot move from one side of the bilayer to the other

Question 50

Integral membrane proteins are tightly bound to the membrane, through interactions with the __________ core of the bilayer.

Answer 50

Hydrophobic

Question 51

Most integral proteins have one or more regions of the _____________ chain that span the lipid bilayer, and interact noncovalently with the hydrophobic fatty acid chains.

Answer 51

Polypeptide

Question 52

True or false: lipids, integral proteins are amphipathic, having both hydrophobic and hydrophilic regions.

Answer 52

True

Question 53

How do peripheral membrane proteins bind to the lipid bilayer, compared to integral membrane proteins?

Answer 53

They are usually bound to the membrane by hydrogen bonding and ionic attraction. Some are attached to the bilayer via an embedded fatty acid. This anchors the protein to the membrane.

Question 54

Name two characteristics of the phospholipid bilayer.

Answer 54

Permeability to water, gases, and small, uncharged molecules, as well as impermeable to large molecules, such as amino acids.

Question 55

True or false: passive transport requires energy.

Answer 55

False

Question 56

Which type of transport does the following describe? 'Requires an input of metabolic energy, as molecules are being transported against their concentration gradient. This energy can be derived from either the hydrolysis of ATP, or by coupling the movement of the molecule to the movement of an ion down its concentration gradient. In the case of ATP-driven active transport, the energy is derived from the sodium-potassium-ATPase pump. A high internal concentration of potassium, and a low internal concentration of sodium is maintained.'

Answer 56

Active transport

Question 57

Name a type of transport used in the phospholipid bilayer.

Answer 57

Facilitated diffusion

Question 58

What is a uniporter, and what is its purpose?

Answer 58

Facilitated diffusion of a molecule is dependent on specific integral membrane proteins, called uniporters. The protein undergoes a conformational change, and the transporter is specific for one particular molecule, or a group of molecules.

Question 59

Symporters move molecules and ions in the ______ direction.

Answer 59

Same

Question 60

Antiporters move molecules and ions in the ______ direction.

Answer 60

Opposite

Question 61

What is the technical term for a signaling molecule?

Answer 61

Ligand

Question 62

What does the binding of a molecule to a ligand induce?

Answer 62

A conformational change in the receptor, which initiations a series of reactions, termed 'signal transduction', leading to a change in cellular function.

Question 63

Endogenous ligands are generally _________.

Answer 63

Hormones

Question 64

List three functions of membranes.

Answer 64

Structure, conduction of nerve impulses, and signal transduction

Question 65

Triacylglycerols are the scientific term for:

Answer 65

Storage lipids

Question 66

Simple triacylglycerols have _____ identical fatty acids; mixed triacylglycerols have two or three different fatty acid chains.

Answer 66

Three

Question 67

___________ store large amounts of triacylglycerols, in the form of fat droplets. They are used as energy stores, and as insulation.

Answer 67

Adipocytes

Question 68

True or false: triacylglycerols are nonpolar lipids.

Answer 68

True

Question 69

Triacylglycerols serve what purpose?

Answer 69

Fuel storage