Lipids Flashcards
are distinguished by their high solubility in non polar solvents and low solubility in H,O
Lipids
Lipids exist as ——- in nature - meaning it can be both hydrophilic and hydrophobic in nature
amphipathic
Lipids are (another) amphipathic molecules that can be:
Major components of biological membranes
Major form of stored energy in biological systems
Hormones
It define the basic unit of life (cell)
Membranes
lipids are largely reduced compounds; complete oxidation of lipids
generates —- – —– (ie. more than from sugars)
lots of energy
Lipids have 4 primary functions in living cells:
Fuel molecules
Signal molecules
Highly concentrated energy stores
Components of membranes
• Phospholipids
• Sphingholipids
• Cholesterol
Adipocytes
Fat storage cells
principal building blocks of complex lipids
Fatty acids
esters of fatty acids (heat sensitive)
Waxes
membrane precursors, energy storage
Triacylglycerols
membrane components
Glycerophospholipids
brain lipids, membrane components
Sphingolipids
cholesterol, bile salts, steroid hormones
Steroids
Building block of lipids
Fatty acid
Fatty acids are Composed of a ———– “head group” and ——— “tail”
carboxylic acid
a long hydrocarbon
tail generally contains an —- number of carbon atoms
Even
Hydrocarbon tail can be ——— or ———-
saturated or unsaturated
unsaturated hydrocarbon tails contain how many double bonds?
one or more double bonds
General Formula for Fatty Acids
COOH(CH2)nCH3 / CH3(CH2)nCOOH
CH3(CH2)10CO2H
Lauric Acid
CH3(CH2)12CO2H
Myristic Acid
CH3(CH2)14CO2H
Palmitic Acid
CH3(CH2)16CO2H
Stearic Acid
CH3(CH2)18CO2H
Arachidic Acid
16:0
Palmitic Acid
18:0
Stearic Acid
18:1 (∆⁹)
Oleic Acid
18:2 (∆⁹,¹²)
Linoleic acid
18:3 (∆⁹,¹²,¹5)
a-Linolenic Acid
20:4 (∆5,8,11,14)
Arachidonic Acid
2 Example of Essential Fatty Acids;must get these from plants
linoleic and a-linolenic fatty acids
high in polyunsaturated fats.
Good Fats
high in saturated fats.
Bad Fats
trans fatty acids; result from partial
hydrogenation of —— —–
Really Bad Fats
vegetable oils.
It has trans fatty acids.
Margarine
It has trans fatty acids.
Margarine
Transfatty acids are difficult to ——–; lead to increased ——— levels in the blood
Metabolized
Cholesterol
Energy storage in Lipids
Triacylglycerols (triglycerides)
1 Fatty Acid + Glycerol =
2 Fatty Acids + Glycerol =
3 Fatty Acids + Glycerol =
monoacylglycerol
diacylglycerol
triacylglycerol
a simple triacylglycerol)
Tristearin
A mixed triacylglycerol
Myristic
Palmitic
Stearic
A mixed triacylglycerol
Myristic
Palmitic
Stearic
Energy yield from burning: ~ ?? kj/gram as compared to ?? kJ/gram for carbohydrates (eg. sugars)
~ 37 kJ/gram,
~ 16 kJ/gram
are typically found in brain tissues (eg. brain lipids)
Based upon ——–, an amino alcohol
Sphingolipids
Sphingosine
Sphingosine is rare in —— and —_– while
sphingolipids are common
plants and animals while
In plant and animals
Simplest sphingolipids are
ceramides
Sphingosine + N-linked fatty acid =
Ceramide
are complex sphingolipids
Ganglioslides
Ceramide + 3 (or more) sugars including one sialic acid
Gangioslides
Membrane lipids(signalling)
Gangliosides
Built from same 5-carbon precursor as cholesterol
Terpenes and their derivatives
Terpenes are also called as
Isoprenoid
Steroids are basic skeleton consisting of four interconnected——— ; different structure than long chain FAs
These molecules bind to specific protein receptors, precipitating a
——– ——– ——–
carbon rings
signal transduction chain
Built from 5 carbon isoprene units and do not contain fatty acids
Terpenes
Terpenes are abundant in
Plants
Terpenes are Generally assembled by a ————- linkage of isoprene units
‘head to tail’
Diterpenes and larger terpenes arise from
Cyclization reactions
certain aromatic compounds with a wide range of functions also made of
Isprenyl C5 subunits
Many lipid classes, many lipid functions
Functions are obviously very diverse, fitting for such a large
family of molecules
structural
signaling
enzyme cofactors
(in membranes)
(steroids)
(vitamins)
all lipids have in common a ——– fatty acid chain,
hydrophobic
a glycerol backbone is linked to two FA molecules and one phosphate
Phospholipids
FA chain composed of an number of C atoms
even
Hydrophobic nature arises from —— —-
by C-H and C-C bonds present in chains
lack of dipoles formed
Numbering of C in FAs starts with
C2 and C3 often called
Methyl C at distal end of chain called
Position of double bond(s) also indicated by
carboxyl C
a and B
w-carbon atom
A
Many FAs in animal tissues are
Saturated
Most common FAs in animals and plants are
C16 and C18
most plant fats have at least
one C=C bond
Short chain length and unsaturation lower FA
Melting point
2 major places where FAs play a role in metabolism is when they are incorporated into either
—————— for energy storage, or
—————— for incorporation into membranes
triacylglycerols (triglycerides)
Phospholipids
Degradation converts storage fat
(triacylglycerol) into small 2-carbon, activated acetyl units that can be processed by the TCA cycle in a process called o. P
Oxidative Phosphorylation
To degrade FAs, the body must first get them out of “——–”
Lipids are stored as triacylglycerols in
Mammals are capable of storing large amount of lipids in specialized
cells called
storage
adipose tissue
adipocytes
lipids can store in a smaller volume
more energy
Complete oxidation of a lipid into acetyl-CoA 2-carbon units
yields - kcal/g, versus - kcal/g for carbohydrates
9 kcal/g
4 kcal/g
How many times does lipids as much energy as 1 g carbohydrate
6 g
Typical 70-kg man has energy stored as
• kcal in triacylglycerols
kcal in protein (muscle)
Kcal in glycogen
kcal in glucose
1 x 10^5
2.5 x 10⁴
600 kcal
40
Typical 70-kg man has energy stored as
• kcal in triacylglycerols
kcal in protein (muscle)
Kcal in glycogen
kcal in glucose
1 x 10^5
2.5 x 10⁴
600 kcal
Triacylglycerols are “— kg of body mass (~16% body fat)
11 kg
Carbohydrate stores alone allow maintenance of metabolism for ~ –; stored lipids allow survival for
~24 h
weeks
found in thylakoid membranes of chloroplasts
Galactolipids
(e.g. platelet activating factor, an important lipid signaling molecule
Ether glycerophospholipids
Animal sphingosine lipids can also contain sugars =
glycolipids
diphosphatidylglycerol (note two phosphatidyl and extra glycerol)
Cardiolipan
