CHAPTER FIFTEEN: LIPIDS Flashcards

1
Q

What are LIPIDS?

What does the Greek word “lipid” mean?

A

A family of biomolecules that have the common property of being soluble in organic solvents but not in water.

Lipid (Greek)= fat, lard

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2
Q

What are the characteristics of these types of lipids?
* waxes, fats, oils and glycerophospholipids
* steroids
*

A
  • fatty acids: esters that can be hydrolyzed to give fatty acids and other products including an alcohol (tail)
  • steroids: the steroid nucleus of four fused carbon rings. Do not contain fatty acids and cannot be hydrolyzed.
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3
Q

What are the function of LIPIDS in the body?

A

they provide energy and protection and insulation for the organs

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4
Q

What is a FATTY ACID?

A

The simplest type of lipids and found as components in more complex lipids. Contains a long, unbranched carbon chain attached to a carboxylic acid group at one end.

The long chain makes them insoluble in water.

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5
Q

Naturally occurring fatty acids have an ____ (even or odd) number of carbon atoms, usually between ___ and ___.

A

Even; 10 and 20

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6
Q

What is a SATURATED FATTY ACID?

What is the difference between a MONOUNSATURATED and a POLYUNSATURATED FATTY ACID?

A

Saturated: the long carbon chain is like an alkane because there are only single carbon-carbon bonds.

Mono: one double bond (properties similar to alkene)

Poly: at least 2 C-C bonds

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7
Q

What are ESSENTIAL FATTY ACIDS?

A

The polyunsaturated fatty acids that must be obtained from the diet.

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8
Q

Most SATURATED fats are ______ at room temperature.

Most UNSATURATED fats are ______ at room temperature.

A

solids

liquid oils

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9
Q

What are PROSTAGLANDINS?

How are they formed?

What other name are they known by?

A

hormone-like substances produced in small amounts in most cells in the body.

Formed from arachidonic acid, the polyunsatured fatty acid with 20 carbon atoms.

Eicosanoids (Greek word for 20)

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10
Q

What is the difference between between PROSTAGLANDIN E and F?

A

E= soluble in ether

F= soluble in phosphate buffer, starts with an F in Swedish

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11
Q

The various kind of PROSTAGLANDINS differ by the substituents attached to the 5-carbon ring. What are the differences between:

  • PGE
  • PGF

The number of double bonds is shown as a subscript _____ or ______.

A

PGE= has a ketone group on carbon 9

PGF= has a hydroxyl group on carbon 9

1 or 2

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12
Q

PROSTAGLANDINS are broken down quickly , but have ________ physiological effects.

Name some of these.

A

potent

Raise/lower blood pressure, stimulate contraction and relaxation of smooth muscle, may cause inflammation and pain.

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13
Q

What is a WAX?

A

an ester of a saturated fatty acid and a long-chain alcohol, each containing from 14-30 carbon atoms.

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14
Q

What are TRIACYLGLYCEROLS?

They are also known as _______.

In a TRIACYLGLYCEROL, ____ hydroxyl groups on glycerol form ester bonds with the ________ groups of ____ fatty acids.

A

fatty acids are stored as fats and oils known as TRIACYLGLYCEROLS. They are trimesters of glycerol (a trihydroxy alcohol) and fatty acids.

TRIGLYCERIDES

3, carboxyl groups, 3

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15
Q

__________ are the major form of energy storage for animals.

A

TRIACYLGLYCEROLS

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16
Q

What is a FAT?

What is an OIL?

A

Fat= a TRIACYLGLYCEROL that is solid at room temperature and usually comes from animal sources.

Oil= a TRIACYLGLYCEROL that is usually a liquid at room temperature and is obtained from a plant source.

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17
Q

Which has a higher melting point and why?

  • Saturated fatty acids
  • Unsaturated fatty acids
A

Saturated because they pack together more tightly.

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18
Q

Animal fats usually contain more ______ fatty acids than do vegetable oils.

A

saturated

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19
Q

In the HYDROGENATION of an unsaturated fat, hydrogen is added to one or more carbon-carbon _______ bonds to form carbon-carbon _______ bonds.

A

double, single

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20
Q

What are LIPASES?

What are the products of hydrolysis of the ester bonds?

A

TRIACYLGLYCEROLS are hydrolyzed (split by water) in the presence of strong acids or digestive enzymes called LIPASES.

glycerol and 3 fatty acids.

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21
Q

What is SAPONIFICATION?

A

This occurs when a fat is heated with a strong base such as sodium hydroxide to give glycerol and the sodium salts of the fatty acids, which are soap.

22
Q

What are GLYCEROPHOSPHOLIPIDS and how are they different from TRIACYLGLYCEROLS?

A

A family of lipids similar to triacylglycerols, excepts that one hydroxyl group of glycerol is replaced by the ester of phosphoric acid and an amino alcohol, bonded through a phosphodiester bond.

23
Q

What are the three AMINO ALCOHOLS found in GLYCEROPHOSPHOLIPIDS?

In the body, at what pH are they ionized?

A

choline, serine, ethanoamine

7.4

24
Q

What are LECITHINS and CEPHALINS?

LECITHINS contain___________
CEPHALINS contain _____ and sometimes _______.

A

2 types of GLYCEROPHOSPHOLIPIDS that are particularly abundant in brain and nerve tissue, as well as egg yolks, wheat germ and yeast.

choline

ethanolamine, serine

25
Q

GLYCEROPHOSPHOLIPIDS- do they contain polar regions and/or non polar?

This allows them to interact with ______.

A

Both

both polar and nonpolar substances

26
Q

What important roles do GLYCEROPHOSPHOLIPIDS play in the body?

A

the most abundant lipids in cell membranes where they play an important role in cellular permeability.

Make up much of the myeline sheath that protects nerve cells.

27
Q

In general, what are GLYCEROPHOSPHOLIPIDS composed of?

A

a glycerol molecule in which:

  • 2 carbon atoms are attached to fatty acids
  • the 3rd carbon atom is attached by an ester bond to phosphate linked to an amino alcohol.
28
Q

What are STEROIDS?

A

Compounds containing the steroid nucleus, which costs of 3 cyclohexane rings and one cyclopentane ring fused together.

29
Q

What is the Steroid ABCD and numbering system?

A

See page 538;

The four rings in the steroid nucleus are designated ABCD, starting from the left.

The carbon atoms are numbered beginning with the carbons in ring A and, in steroids like cholesterol, ending with 2 methyl groups.

30
Q

What is one of the most important and abundant steroids in the body?

A

CHOLESTEROL

31
Q

Cholesterol is a STEROL because _____

A

…it contains an oxygen atom as a hydroxyl

(-OH) group on carbon 3.

32
Q

Like many steroids, CHOLESTEROL has methyl group (CH3) at carbons ____ and ____, a carbon chain at carbon ____, and a couple bond between carbons ____ and ___.

A

Like many steroids, CHOLESTEROL has methyl group (CH3) at carbons 10 and 13, a carbon chain at carbon 17, and a couple bond between carbons 5 and 6.

See page 538

33
Q

In the body, CHOLESTEROL is a component of what 3 things?

A

cellular membranes, myelin sheath, brain & nerve tissue.

34
Q

CHOLESTEROL is also found in the liver, bile salts and _______, where it forms Vitamin D.

A

skin

35
Q

In the adrenal gland, CHOLESTEROL is used to synthesize ________ hormones.

A

steroid

36
Q

CHOLESTEROL levels are considered elevated if the total plasma cholesterol level exceeds ____ mg/dL

A

200

37
Q

BILE SALTS are synthesized in the ______ from CHOLESTEROL and stored in the ________.

When secreted into the _________, they mix with the ___________ and act like soaps to _______.

They also help in the absorption of CHOLESTEROL into the intestinal _______.

A

liver; gall bladder

small intestine, water-insoluble fats/oils in our diet, break apart and emulsify large globules of fat.

mucosa

38
Q

What are GALLSTONES?

A

when large amounts of CHOLESTEROL accumulate in the gallbladder, cholesterol can precipitate out and form gallstones.

39
Q

What are LIPOPROTEINS?

Describe their shape, etc.

A

lipids are made more soluble by combining them with glycerophospholipids and proteins to form water-soluble complexes called LIPOPROTEINS.

They are spherical particles with an outer surface of polar proteins and glycerophospholipids that surround hundreds of nonpolar molecules of triacylglycerols and cholesterol esters.

40
Q

What are the prevalent form of cholesterol in the blood?

A

Cholesteryl esters

41
Q

Types of LIPOPROTEINS differ in _____, ______ and _____. They include:

  • CHYLOMICRONS
  • VLDL (very low destiny lipoprotein)
  • LDL (low-density lipoprotein)
  • HDL (high-density lipoprotein)

The density of the lipoproteins ________ as the % of protein in each type also ______.

A

Types of LIPOPROTEINS differ in density, lipid composition and function.

increases; increases

42
Q

What does each of these transport in the body?

  • CHYLOMICRONS and VLDLs
  • LDLs
A

CHYLOMICRONS and VLDLs: transport tricylglycerols, glycerophospholipids and cholesterol to the tissues for storage or to the muscles for energy.

LDLs transport cholesterol to tissues where it is used for the synthesis of cell membranes, steroid hormones and bile salts.

43
Q

When the level of LDL (BAD CHOLESTEROL) exceeds the amount of cholesterol needed by the tissues, what happens?

A

The LDLs deposit CHOLESTEROL in the arteries.

44
Q

Why are HDLs called GOOD CHOLESTEROL?

A

remove excess cholesterol from the tissues and carry it to the liver where it is converted to bile salts and eliminated.

45
Q

For adults, recommended levels for total cholesterol are less than ______ mg/dL, with LDL less than _____mg/dL and HDL higher than ________ mg/dL

A

200
130
40

46
Q

What are HORMONES?

A

Chemical messengers that serve as a kind of communication system from one part of the body to another.

47
Q

The STEROID HORMONES, which include the ______ hormones and the _______ hormones, are closely related in structure to cholesterol and depend on cholesterol for their synthesis.

A

sex; adrenocortical

48
Q

What do the male sex hormones TESTOSTERONE and ANDROSTERONE do?

A

Promote the growth of muscle and facial hair and the maturation of the male sex organs and of sperm.

49
Q

What do the ESTROGENS (a group of female sex hormones) do?

A

direct the development of female sexual characteristics- uterus increases in size, fat deposited in breasts, pelvis broadens.

50
Q

What does PROGESTERONE do?

A

prepares the uterus for the implantation of a fertilized egg.

51
Q

Where are the CORTICOSTEROIDS produced?

What does each one do?

  • ALDOSTERONE
  • CORTISONE
A

the adrenal glands

ALDOSTERONE, a mineralocorticoid, is responsible for electrolyte and water balance by the kidneys.

COSTISONE, a glucocorticoid, increases the blood glucose level and stimulates the synthesis of glycogen from amino acids in the liver

52
Q

Describe these mechanisms through which ions and molecules glow in and out of the cell:

  • DIFFUSION/PASSIVE TRANSPORT
  • FACILITATED TRANSPORT
  • ACTIVE TRANSPORT
A
  • DIFFUSION/PASSIVE TRANSPORT: migrate from higher to lower concentration
  • FACILITATED TRANSPORT: groups of integral proteins provide channels to transport ions and molecules more rapidly
  • ACTIVE TRANSPORT: to move an ion from a lower to higher concentration requires energy, which is accomplished by this process. A protein complex called a Na+/K+ pump is involved.