Lecture 13/02.14.25

Question 1

Are lipids hydrophobic or hydrophillic?

Answer 1

Hydrophobic and sometimes polar or have charged groups

Question 2

What is the function of lipids?

Answer 2

They store energy, signaling, and form membrane structures

Question 3

What are some membrane structures that lipids form?

Answer 3

They form the partitions that divide cellular compartments from one another separate the cell from its surroundings

Question 4

Are lipids selective?

Answer 4

Yes. They have selective gates that control the passage of materials in specific directions

Question 5

How are lipids found?

Answer 5

They are found in complex soluble protein transporters or part of higher order assemblies

Question 5

Are lipids soluble?

Answer 5

No. This is because of their hydrocarbon feature which means that they are not free in solutions

Question 6

Do lipids form covalent bonds? Non covalent bonds?

Answer 6

Lipids do not form covalent bonds and instead form non covalent bonds.

Question 7

What makes up a lipid?

Answer 7

A polar hydrophilic head connected to large non polar and hydrophobic tail

Question 8

What other forms of bonding do lipids have?

Answer 8

They have van der waals interactions between the hydrocarbon regions of the molecules

Question 9

Are lipids amphipathic?

Answer 9

yes

Question 10

What is the simplest lipid?

Answer 10

A fatty acid

Question 11

What is the basic model of a lipid?

Answer 11

A hydrophilic carboxylate group is attached to one end of the hydrocarbon chain, which contains typically 12 to 24 carbons

Question 12

What is an example of a saturated fatty acid?

Answer 12

Stearic acid where the carbons of the tail are saturated with hydrogen atoms. Also, no double carbon bond

Question 13

What is an example of a unsaturated fatty acid?

Answer 13

Oleic acid found in animal fats where the double bonds are cis.

Question 14

What is true about unsaturated fatty acids and room temperature?

Answer 14

At room temperature, unsaturated fatty acids are a liquid state. For example, olive oil.

Question 15

What is true about saturated fatty acids and room temperature?

Answer 15

Saturated fatty acids at room temperature are at a solid level. Especially true if their hydrocarbon chain is long.

Question 16

Why is unsaturation important?

Answer 16

It keeps membrane fluid rather than solid. It helps keeps movement and confirmation changes of transmembrane proteins

Question 17

What explains the solid feature of saturated fatty acids?

Answer 17

Noncovalent bonds and van der waals interactions because they are packed together.

Question 18

What helps oils from spoilage and converting fat oils into firmer fats?

Answer 18

partial hydrogenation

Question 19

What are the long hydrocarbon chains used for?

Answer 19

They are efficient for energy storage due to having carbon in a reduced form that yield large oxidation

Question 20

What is the form that lipids take place in as storage?

Answer 20

triacylglycerols, tryglycerides or simply fats

Question 21

What is true about naturally occurring fatty acids and their carbons?

Answer 21

They have an even number of carbons

Question 22

What do tryacylglycerols have?

Answer 22

Mixed fats that contain different groups of faty acids

Question 23

What does estirification do?

Answer 23

It diminished the hydrophilic nature of glycerols which makes the water-insoluble

Question 24

What does fat storage provide to animals?

Answer 24

1. energy production for ATP 2. heat production 3. insulation for cold environments

Question 25

What are triacylglycerols composed of?

Answer 25

fatty acids and glycerol

Question 26

What is the common form of lipids?

Answer 26

They contain one polar head group and two hydrocarbon tails

Question 27

What happens when a head connects with a lipid with only one tail?

Answer 27

It will form micelles and take on a circular shape

Question 28

What happens when a head connect with a lipid with two tails?

Answer 28

it will form a cylindrical shape

Question 29

What is the most abundant lipid?

Answer 29

glycerophospholipids (phosphoglycerides) that are naturally occurring. They have phosphate heads that are polar.

Question 30

What are sphinogolipids?

Answer 30

A type of lipid that differed from glycerol and is replaced by an -NH2 group and a hydrocarbon group

Question 31

What are glycosphinolipids?

Answer 31

A type of lipid that contains saccharide groups. Also known as glycolipids

Question 32

What is the orientation of glycolipids?

Answer 32

They asymmetrical in the plasma membrane and are always facing the extracellular side

Question 33

What is cholesterol?

Answer 33

It is a type of lipid that is the precursor to steroids that are needed for hormones

Question 34

What is true about cholesterol and lower temperature?

Answer 34

It increases fluidity and prevents close packing of fatty acid structures

Question 35

What is true about cholesterol and high temperatures?

Answer 35

It acts as a fluidity buffer and keeps membrane rigid at temps higher than lipid melting point

Question 36

Is cholesterol amphipathic?

Answer 36

Yes but it is weak

Question 37

Why are there so many lipids?

Answer 37

Because they have different properties and some cells need specific lipid such as brain, nerves, etc.

Question 38

Where are glycolipids located?

Answer 38

They are always on the outer plasma membrane towards aqueous environment and maintained by flip flop proteins

Question 39

What is the lipid fluid mosaic model?

Answer 39

It is how proteins and lipids interact in a bilayer and mode laterally

Question 40

What are integral proteins?

Answer 40

Proteins buried within the membrane but are usually exposed on both faces. Present in bilayer

Question 41

What is a peripheral protein?

Answer 41

Proteins associated with H bonds or ionic interactions

Question 42

What are anchored proteins?

Answer 42

Covalently linked to fatty acid chains or glycolipids at surface

Question 42

What is the difussiion type for lipids?

Answer 42

They are usually lateral and rapid and rarely transverse

Question 42

What controls membrane fluidity?

Answer 42

It is controlled by fatty acid composition and their melting temperature(Tm).

Question 43

How are unsaturated fatty acids packed?

Answer 43

Disordered state and less tight packing

Question 44

How are saturated fatty acids packed?

Answer 44

Tight packing and ordered state

Question 45

What do membranes do when the temperature is changed?

Answer 45

They can adapt quickly by incorporating lipids with different properties. This is something that many hibernating animals do to their unsaturated fatty acids

Question 46

What can cholesterol do to packing?

Answer 46

It can disrupt tight packing because it functions as a regulator for membrane fluidity

Question 47

What maintains asymmetry in membranes?

Answer 47

it is maintained by rare flip flopping

Question 48

What is true about inner and outer membrane are where they face?

Answer 48

They differ because of lipid composition and in types of associated proteins

Question 49

What does flippase do?

Answer 49

It can move lipids between inner and outer membranes

Question 50

Where is transmembrane porin found?

Answer 50

It is found in most cell membrane and outer membrane of certain bacteria, mitochondria, and chloroplasts

Question 51

What does transmembrane porin do?

Answer 51

It makes membrane permeable to small, polar molecules

Question 52

What types of structures do transmembrane porin have?

Answer 52

They have water filled channels with amphipathic B barrel structure and hydrophobic residues are outside close to lipid bilayer

Question 53

What are the functions of membranes(plasma membranes)?

Answer 53

They transport substances in/out of cell(passive vs. active), ion transport and nerve cell conductance, cell signaling, maintain shape, and cell-to-cell interaction