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MC Biochem 1 > Chpt 12 Lipids > Flashcards

Chpt 12 Lipids Flashcards

1
Q

Lipids Definition

A

Defined on the basis of chemical properties, not chemical structure
-Heterogenous groups of water insoluble (hydrophobic)organic molecules that can be extracted from tissues by non polar solvents (Chloroform)

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2
Q

Fatty Acids

A

Long hydrocarbon chain of various lengths (C12-C24) and degree of saturation terminated with carboxylic acid group

Saturated-no double bonds
Unsaturated- contains double bonds (cis or trans)Fat

Alpha carbon-carbon 2
Beta Carbon- Carbon 3
Omega Carbon-Terminal Carbon

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3
Q

Fatty Acid Solubility

A

The longer the chain the less solube (solubility decreases)

-was less solube than carbohydrates

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4
Q

Nomenclature: Simplified System

A

of C: # of double bonds cis or trans Delta, Delta

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5
Q

Fatty Acids to Know

A

Fuck All Principle BioChem Lecture
PeoPole Should Only Listen ESSENTIALLY At Late Night

Formic Acid- 1 carbon
Acetic Acid-2 Carbons
Propionic acid- 3 Carbons
Butyric acid-4 carbons
Capric Acid- 10 C's
Lauric Acid- 12 C's

Palmitic acid 16:0
Palmit(ole)ic acid 16:1 cis 9

Stearic acid 18:0
Oleic Acid 18:1 cis 9
Linole(ic) 18:2 cisx2 9,12
Linole(nic) 18:3 cisx3 9,12,15
Arachidonic Acid 20:4 cisx4 5, 8, 11 ,14
Lignoceric acid 24:0
Nervonic Acid 24:1
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6
Q

Two essential Fatty Acids in humans

A

Linoleic Acid (Omega 6 FA)

  • 18:2 cis, cis (delta 9,12)
  • cis, cis-9,12 octadecadienoic acid
  • Precursor of arachidonic acid
  • Deficiency lead to making arachidonic acid essential

Linolenic Acid (Omega 3 FA)

  • 18:3 cis, cis (Detal 9, 12, 15)
  • cis, cis, cis-9,12,15-octandecatrienoic acid
  • Precursor for other omega 3 fatty acids
  • Deficiency leads to decreased vision, altered learning behavior
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7
Q

Functions of lipids

A

Cellmembranes:
Phospholipids, glycolipids, sterols

Energy Storage:

  • Triacylglycerol or fat
  • stores 2.5 x more energy than equal weight of carbohydrates

Cell Signaling:
steroid hormones

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8
Q

Phospholipids

A

or Phosphoglycerides
Amphipathic

contain a:

  • Glycerol
  • polar head group (phosphate)
  • two non polar tails (fatty acids)
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9
Q

Amphipathic

A

molecule with both hydrophobic and hydrophilic regions

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10
Q

Common Phospholipids

A

Head groups: Serine, ethanolamine, choline, inositol

Sphingoymylin

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11
Q

Sphingomylin

A
  • a non glycerol containing phospholipid

- contains sphigosine (modified serine)

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12
Q

Glycolipids

A

contain

  • substituted Serine (like sphingosine)
  • 2 fatty acids
  • Carbohydrate (ex glucose)
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13
Q

Triacylglycerol (fats)

A

Glycerol

-three fatty acids-> accumulates as fat droplets in cytoplasm

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14
Q

Cholesterol

A

Multi ring, non polar structure with a hydroxyl

  • component of cell membrane
  • precursor of steroid hormones
  • 27 carbons
  • four Rings A, B, C ,D called steroid nucleus

Substituted with

  • Hydroxyl group- may be substituted by addition of ester
  • two methyl groups
  • a branched 8 carbon side chain
  • one double bond
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15
Q

Micelle

A

Formed by ionized fatty acids

-steric constants prevent formation of micelle by phospholipids and glycolipids, which usually form vesicles

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16
Q

Phospholipid bilayer

A

(or vesicle)
Liposome (lipid vesicle) aqueous compartment surround by a phospholipid bilayer
-contains phospholipids, glycolipids, cholesterol

17
Q

Formation of Phospholipid bilayer

A

(or vesicles)
Phospholipids spontaneously form bilayers in aqueous environment
-Energy consideration-> hydrophobic interactions between fatty acid tails. Electrostate and hydrogen bonding between head group and water molecules.

1) Suspend liquid in aqueous solution
2) Sonicate
- agitating with high freq sound waves
3) Vesicles form
4) gel filtration- to seperate particles on size

18
Q

Phospholipid bilayer: Membrane proteins

A

Vary in percentage of proteins

Two types of proteins:
Trasmembrane (integral) proteins
-protein passes through both layers of the bilayer
-extraction requires detergent or organic solvent
-cross the membrane by hydrophobic alpha helixes
-some cross the membrane by hydrophobic beta sheets (BETA BARRELL)

Peripheral proteins

  • attached to one side of the membrane. Associations with polar head groups or membrane proteins
  • extraction requires increase in ionic strength or change in pH
19
Q

Bacteriorhodopsin

A

Aracheal protein

  • uses light energy to transport protons out of cell to create a proton gradient
  • seven alpha helixes span membrane
20
Q

Hydropathy Index

A
  • Hydrophobic alpha helixes can be identified by plotting the hydrophthy index
  • Plot sliding 20 amin acid average of free energy change
  • once it meets a critical/criterion level is transmembrane protein

Plotting hydropathy index is not able to detect BETA BARRELS

21
Q

Glycophorin

A

Red blood cell membrane protein

-single alpha helix spans membrane

22
Q

Porin

A

E. coli and Rhodobacter capuslatus

-allows movement of material across the membrane

23
Q

Peripheral proteins

A

Peripheral proteins are anchored to the membrane by:

  • lipid anchors
  • GPI anchors
  • sometimes Hydrophobic alpha helixes
24
Q

Solubility of membranes

A

Continium not all or non process

25
Q

Fluid Mosaic model of membrane

A

Membrane are 2D solutions oriented lipids and globular proteins (transmembrane and peripheral)
-“rigid” Fluid that separates two fluid filled compartments

Movement of phospholipids within bilayer:

  • Lateral is rapid
  • Transverse (flip flop) is VERY slow

Movements of proteins varies greatly:

  • Lateral movements: some proteins move as fast as lipids, others do not due to being anchored to cytoskeleton
  • transverse (flip flop)-does not happen for proteins- orientation of proteins is established at time of protein synthesis

Membrane Fluidity: Solid like vs fluid like
controlled by fatty acid composition and cholesterol content.
-fatty acids exist in rigid state or fluid state.
-changes of state changes abruptly at Tm: degrees of unsaturation and length of Fatty acid

Shorter fatty acids=Lower Tm
More double bonds=Lower Tm
Cholesterol-membrane antifreeze and coolant

Membranes are asymmetric
-membranes contain different lipids and protein components on the different surfaces (faces) of the membrane

MC Biochem 1 (30 decks)

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