Lipids Flashcards
what are the 3 main roles of lipids? (S.E.M)
- specific biological functions e.g. transmission of chemical signals into and within the cell.
- Energy storage.
- Membrane Structure.
What are the 6 classes of lipids based on their chemical structure? (F.A,T - PGST)
Fatty Acids, Triglyceride. phospholipid, glycolipid, sterols and terpenes.
What are Fatty Acids? give examples
long unbranched hydrocarbon chains w/ a carboxyl group at the end. e.g. myristic acid
Why are Fatty Acids highly reduced?
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.
What is the tail of a Fatty Acid?
long hydrocarbon chain
HYDROPHOBIC.
What is the head of a Fatty Acid?
CARBOXYL group
HYDROPHILIC.
Fatty Acids can be? (S.U.P)
Saturated
Unsaturated
Polyunsaturated
What does the Degree of unsaturation depend on?
the amount of hydrogen a compound can bind.
What is a saturated compound?
no double or triple bonds between carbons.
what is a unsaturated compound.
one or more double bonds between carbon atoms.
Saturated Fatty Acids?
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.
Unsaturated Fatty Acids?
contain one or more double bonds, resulting in a bend or kink in the chain that prevents tight packing.
What are unsaturated Fatty Acids also known as and why?
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.
Discuss the Double Bonds in Fatty Acids.
- Almost always in cis- config.
- Trans bonds considered to be carcinogenic.
- Usually separated by methylene group.
What are Triglycerides composed of?
a glycerol molecule linked three fatty acids
How are Fatty Acids linked to glycerol and how is this formed?
Fatty acids are linked to glycerol by ester bonds, which are formed by
the removal of water (condensation reaction).
What is the main function of Triglycerides?
Energy Storage.
Animals: Adipocytes (fat cells)
-fat droplets fill the cell.
Large quantity in many seeds (energy for germinating)
What are Triglycerides (triacylglycerol’s) containing mainly Saturated Fatty Acids structurally?
Are usually solid or semisolid at room temp and are called Fats.
How are triglycerides (triacylglycerol’s) in plants?
In plants, most triacylglycerol’s are liquid at room temperature e.g. vegetable oil.
How does the predominantly unsaturated fatty acid of oil effect it?
their hydrocarbon chains have kinks that prevent an orderly
packing of the molecules
How are Fats more efficient?
- They liberate more energy upon oxidation per unit wt.
- Fats are hydrophobic so don’t have associated water of hydration.
Fat Function in body?
Insulation, protect internal organs
Adipocytes usually under skin
-seals, penguins, etc.
What are Waxes? give examples
They are Esters of long chain Fatty acids with long chain alcohol.
e.g. Triacontanylpalmitate
What is the function of Waxes?
W.H.E.P
- Energy storage (plankton only)
- H2O-repellant coatings
- Wax layer on hair, feathers (esp. waterfowl)
- Protective coating on fruit/berries/some leaves
Industrial uses of waxes?
L.O.P
Production of ointments, lotions, polishes
Why are phospholipids important in membrane structure?
due to their amphipathic nature.
(they are critical to the bilayer structure found in all membranes).
What are Phospholipids classified as? (S.P.S)+ 3 Major membrane lipid types?
- Phosphoglycerides (role: membrane structure)
- Sphingolipids (role: membrane structure and signaling)
- Sterols
Phosphoglyceride structure? Phosoplipd
- Has 2 conflicting polar forces.
- Has a very POLAR HEAD and 2 long NON-POLAR chains which gives
phosphoglycerides their
characteristic amphipathic
nature.
What afftects membrane fluidity in membrane phospholipids?
The length and the degree of unsaturation of fatty acid
chains in membrane.
Examples of phosphoglycerides?
- 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
What are glycolipids?
are lipids w/ a carbohydrate group instead of a
phosphate group.
How do glycolipids get their amphipathic nature?
The carbohydrate groups, are hydrophilic.
where do Glycolipids occur?
outer monolayer of the plasma membrane, and
are sites of biological recognition.
What are Sphingolipids?
Give examples
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
what are Sphingolipids composed of ?
- 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
What are Sterols (steriods)?
give examples
- 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
Why is cholesterol imporatnt?
Vital to animal cell membrane structure and function and is a
precursor to fat-soluble vitamins, bile acids [intestinal
detergents] and steroids [sex hormones]
How does cholestrol travel through the blood stream?
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
What LDL and HDL?
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
Why is high LDL bad?
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
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
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