Lipids Flashcards

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1
Q

what are the 3 main roles of lipids? (S.E.M)

A
  • specific biological functions e.g. transmission of chemical signals into and within the cell.
  • Energy storage.
  • Membrane Structure.
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2
Q

What are the 6 classes of lipids based on their chemical structure? (F.A,T - PGST)

A

Fatty Acids, Triglyceride. phospholipid, glycolipid, sterols and terpenes.

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3
Q

What are Fatty Acids? give examples

A

long unbranched hydrocarbon chains w/ a carboxyl group at the end. e.g. myristic acid

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4
Q

Why are Fatty Acids highly reduced?

A

Bc they have lots of hydrogen atoms but few oxygen atoms so yield a lot of energy upon oxidation and are a more efficient form of energy storage.

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5
Q

What is the tail of a Fatty Acid?

A

long hydrocarbon chain

HYDROPHOBIC.

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6
Q

What is the head of a Fatty Acid?

A

CARBOXYL group

HYDROPHILIC.

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7
Q

Fatty Acids can be? (S.U.P)

A

Saturated
Unsaturated
Polyunsaturated

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8
Q

What does the Degree of unsaturation depend on?

A

the amount of hydrogen a compound can bind.

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9
Q

What is a saturated compound?

A

no double or triple bonds between carbons.

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10
Q

what is a unsaturated compound.

A

one or more double bonds between carbon atoms.

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11
Q

Saturated Fatty Acids?

A

Have long, straight chains that pack together well bc every carbon atom in the chain has the maximum number of hydrogen atoms attached to it.

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12
Q

Unsaturated Fatty Acids?

A

contain one or more double bonds, resulting in a bend or kink in the chain that prevents tight packing.

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13
Q

What are unsaturated Fatty Acids also known as and why?

A

Trans Fats

  • contain unsaturated fatty acids with a particular type of double bond that causes less of a bend in the fatty acid chain.
  • causes them to resemble saturated fatty acids both in their shape and in their ability to pack together more tightly than typical unsaturated fatty acids.
  • naturally present in small amounts of meat and dairy but trans fats are produced artificially during the commercial production of shortening and margarine.
  • Trans fats have been linked to changes in blood cholesterol that are associated with increased risk of heart disease.
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14
Q

Discuss the Double Bonds in Fatty Acids.

A
  • Almost always in cis- config.
  • Trans bonds considered to be carcinogenic.
  • Usually separated by methylene group.
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15
Q

What are Triglycerides composed of?

A

a glycerol molecule linked three fatty acids

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16
Q

How are Fatty Acids linked to glycerol and how is this formed?

A

Fatty acids are linked to glycerol by ester bonds, which are formed by
the removal of water (condensation reaction).

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17
Q

What is the main function of Triglycerides?

A

Energy Storage.

Animals: Adipocytes (fat cells)
-fat droplets fill the cell.
Large quantity in many seeds (energy for germinating)

18
Q

What are Triglycerides (triacylglycerol’s) containing mainly Saturated Fatty Acids structurally?

A

Are usually solid or semisolid at room temp and are called Fats.

19
Q

How are triglycerides (triacylglycerol’s) in plants?

A

In plants, most triacylglycerol’s are liquid at room temperature e.g. vegetable oil.

20
Q

How does the predominantly unsaturated fatty acid of oil effect it?

A

their hydrocarbon chains have kinks that prevent an orderly

packing of the molecules

21
Q

How are Fats more efficient?

A
  • They liberate more energy upon oxidation per unit wt.

- Fats are hydrophobic so don’t have associated water of hydration.

22
Q

Fat Function in body?

A

Insulation, protect internal organs

Adipocytes usually under skin
-seals, penguins, etc.

23
Q

What are Waxes? give examples

A

They are Esters of long chain Fatty acids with long chain alcohol.

e.g. Triacontanylpalmitate

24
Q

What is the function of Waxes?

W.H.E.P

A
  • Energy storage (plankton only)
  • H2O-repellant coatings
  • Wax layer on hair, feathers (esp. waterfowl)
  • Protective coating on fruit/berries/some leaves
25
Q

Industrial uses of waxes?

L.O.P

A

Production of ointments, lotions, polishes

26
Q

Why are phospholipids important in membrane structure?

A

due to their amphipathic nature.

(they are critical to the bilayer structure found in all membranes).

27
Q

What are Phospholipids classified as? (S.P.S)+ 3 Major membrane lipid types?

A
  • Phosphoglycerides (role: membrane structure)
  • Sphingolipids (role: membrane structure and signaling)
  • Sterols
28
Q

Phosphoglyceride structure? Phosoplipd

A
  • Has 2 conflicting polar forces.
  • Has a very POLAR HEAD and 2 long NON-POLAR chains which gives
    phosphoglycerides their
    characteristic amphipathic
    nature.
29
Q

What afftects membrane fluidity in membrane phospholipids?

A

The length and the degree of unsaturation of fatty acid

chains in membrane.

30
Q

Examples of phosphoglycerides?

A
  • Plasmalogens - Key components of the membranes of muscles and nerves
  • Phosphatidates - Lipid bilayers
  • Phosphatidylcholines – Lecithin’s in brain & nerve tissue. Sold as food supplement and medical uses
31
Q

What are glycolipids?

A

are lipids w/ a carbohydrate group instead of a

phosphate group.

32
Q

How do glycolipids get their amphipathic nature?

A

The carbohydrate groups, are hydrophilic.

33
Q

where do Glycolipids occur?

A

outer monolayer of the plasma membrane, and

are sites of biological recognition.

34
Q

What are Sphingolipids?

Give examples

A

are the 2nd major membrane lipid type:

  • w/ a Polar head & 3 non-polar tails but no glycerol
  • play a Role in signal transmission and cell recognition.

e. g. sphingomyelin
- Animal cell membrane, myelin sheath

35
Q

what are Sphingolipids composed of ?

A
  • 1 molecule of sphingosine (long chain amino alcohol)
  • 1 molecule of fatty acid
  • 1 polar head alcohol
  • 1 F.A.: usually saturated/monounsat. chain length: C16/C18/C22/C2
36
Q

What are Sterols (steriods)?

give examples

A
  • found only in Eukaryotic cells.
  • e.g. Cholesterol (amphipathic), is insoluble as its mainly hydrophobic
  • have a four-ringed hydrocarbon skeleton,
  • found and occurs in plasma membranes
37
Q

Why is cholesterol imporatnt?

A

Vital to animal cell membrane structure and function and is a
precursor to fat-soluble vitamins, bile acids [intestinal
detergents] and steroids [sex hormones]

38
Q

How does cholestrol travel through the blood stream?

A

As it cant travel alone it combines w/ protein transporting it to different parts of the body
When this happens, the cholesterol and protein form a lipoprotein together

39
Q

What LDL and HDL?

A
LDL = low-density lipoproteins, bad cholesterol, 70 - 130mg/dL, the lower the better
HDL = High density lipoprotien, good cholesterol, 40-60mg/dL the higher the better
40
Q

Why is high LDL bad?

A

When LDL cholesterol levels are high, cholesterol is deposited on the walls of arteries and forms a
hard substance called plaque.
Over time, plaque causes the arteries to become narrower, decreasing blood flow and causing
a condition called atherosclerosis or hardening of the arteries

41
Q

Cholesterol is the starting point for the synthesis of all the
steroid hormones which include the male and female sex
hormones, the glucocorticoids, and the mineralocorticoids
 The sex hormones include the oestrogens produced by the
ovaries of females, and testosterone by the testes of males
 The glucocorticoids (e.g. cortisol) are a family of hormones
that promote gluconeogenesis (synthesis of glucose) and
suppress inflammation reactions
 Mineralocorticoids such as aldosterone regulate ion balance
by promoting the reabsorption of sodium, chloride, and
bicarbonate ions in the kidney

A

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