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Biochemistry > Lipids > Flashcards

Lipids Flashcards

1
Q

What is a lipid?

A

water insoluble biomolecule that is highly soluble in organic solvents

membrane constituents

made up of fatty acids which provide the hydrophobic properties

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2
Q

How is the solubility of a fatty acid/lipid determined?

A

The longer the hydrocarbon tail the more insoluble the lipid/fatty acid.

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3
Q

What are fatty acids?

A

contain hydrocarbon chains of various lengths and degrees of unsaturation that terminate with carboxylic acid group

building blocks of phospholipids and glycolipids

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4
Q

Which regions of a phospholipid are hydrophobic/hydrophilic?

A

hydrocarbon tails - hydrophobic

polar heads (carboxylic acid group) - hydrophilic

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5
Q

Describe a triglyceride (TAG).

A

3 fatty acid molecules covalently bonded to a glycerol backbone

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6
Q

What are the 2 ways to number a fatty acid?

A

Start from the the carboxyl terminus with the number 1, and on down the chain

or

start with the methyl carbon at the distal end of the chain

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7
Q

Which configuration are the double bonds in most unsaturated fatty acids?

A

cis

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8
Q

Are fatty acids usually even or odd numbered carbon atoms?

A

even; usually ranging from 14-24

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9
Q

What length of carbon atoms is most common for fatty acids?

A

16-18

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10
Q

True or False, fatty acids are ionized at physiological pH?

Do we refer to them in their acid state or their carboxylate state?

A

True

carboxylate form

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11
Q

What determines the properties of fatty acids?

A

length of chain and degree of saturation

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12
Q

True or False, unsaturated fatty acids have a lower melting point than compared to saturated fatty acids.

A

True

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13
Q

True or False, the melting points of saturated fatty acids increases with the chain length.

A

True

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14
Q

List the essential fatty acids.

A

Linoleate, Linolenate, Arachidonate

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15
Q

How does an archaeon membrane lipid differ from a human membrane phospholipid?

A

Archaeon has saturated branched fatty acid chains (instead of nonbranched chains) which are linked to glycerol backbone via ether linkages (instead of ester linkages).

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16
Q

List the 3 major types of membrane lipids.

A

Phospholipids, glycolipids, cholesterol

17
Q

What are the 4 components of a phospholipid?

A
  • 1 or more fatty acids
    * Provides hydrophobic barrier
  • Platform where fatty acids attach
    * Glycerol = Phosphoglycerides
    * 2 fatty acid chains
    * Phosphorylated alcohol
    * Simplest = phosphatidate
    * Common alcohol moieties are: amino acid serine, ethanolamine, choline, glycerol, and inositol
    * 3 carbon alcohol
    * Sphingosine
    * Sphingomyelin; backbone linked to fatty acid via amide bond
  • Phosphate
  • Alcohol attached to phosphate
18
Q

What enables the interaction with the environment of a phospholid?

A

The hyrdophilic properties of the phosphate and alcohol groups

19
Q

What is the simplest phospholipid containing a glycerol backbone?

A

phosphatidate

20
Q

What is an example of a phospholipid containing a shingosine backbone?

A

shingomyelin

21
Q

What is the simplest glycolipid containing a shingosine backbone?

A

cerebroside

22
Q

What is a glycolipid?

A

derived from sphingosine;

differs from sphingomyelin:

    replaced -OH group with sugar  on amino alcohol
    group of sphingosine

oriented with sugar on the extracellular side of the membrane

23
Q

What is cholesterol?

A

steroid

4 fused saturated hydrocarbon rings

also classified as a sterol

24
Q

Why is cholesterol classified as a sterol?

A

because of its C3-OH group and its branched aliphatic side chain of 8-10 carbon atoms at C-17

25
Q

True or False, cholesterol is present in most eukaryotes and prokaryotes.

A

False: cholesterol is present in most eukaryotes, but not in most prokaryotes.

26
Q

What is the most abundant steroid in animals?

A

cholesterol

27
Q

True or False, cholesterol is a major component of a eukaryotic plasma membrane.

A

True

28
Q

How is cholesterol oriented to the fatty acid chains of the phospholipids?

A

parallel

29
Q

True or False, cholesterol is not the metabolic precursor of steroid hormones.

A

False: it is the precursor of steroid hormones

30
Q

What are the roles of lipids?

A
  • Fuel molecules
  • Highly concentrated energy stores
  • Signal molecules
  • Messengers in signal-transduction pathways
  • Components of membranes
31
Q

What are the functions of lipids?

A

> Energy storage

> Information transduction

Biochemistry (13 decks)

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