Lipids Flashcards
what are Lipids properties
- Large biomolecules
- Formed from carbon, hydrogen, oxygen and sometimes phosphorus
- Largely non-polar (mostly C-H and C-C bonds)
- Largely insoluble in water
- Soluble in non-polar solvents (e.g. hexane)
- Lipids are not polymers
- Hydrophobic interactions cause lipids to group together in water
give examples of lipids
- Fats
- Oil
- Waxes
- Phospholipids
- Steroids
what is the structure of lipids?
Two different subunits make a triglyceride (a type of lipid):
- Glycerol forms the backbone and has 3 side attachment sites for fatty acids
- 3 fatty acid side chains attach to the glycerol backbone to form a triglyceride
Formation of Triglycerides
• Dehydration synthesis (condensation reaction)
Triglyceride Digestion
- Triglycerides can be broken down by hydrolysis
- Digestion of triglycerides requires intestinal enzyme lipase and water
- Fatty acids are more easily absorbed and transported
glyceral,monoglyceride, diglyceride, fatty acids
what are the two classes of Fatty Acids
- Triglycerides are composed from a large variety of fatty acids added to glycerol
- Two classes of fatty acids form triglycerides:
- Saturated with single C-C bonds
- Unsaturated with numbers of double C=C bonds
give an example of a saturated fatty acid (SFA)
palmitate
give an example of • Unsaturated Fatty Acid (UFA)
Oleate
what are FFAs
give exaples of fats that cant be produced by the body.
- When not part of a triglyceride: free fatty acids (FFAs)
- Some FFAs are essential
- Cannot be synthesised in the body
- Omega-3 (-3) fatty acids (e.g. α-linolenic acid)
- Omega-6 (-6) fatty acids (e.g linoleic acid)
Dietary Fatty Acids
describe
SFAs and UFAs
- SFAs form compact, closely packed triglycerides, solid at room temperature
- UFAs form loosely packed triglycerides, liquid at room temperature
Steroids are lipids:
describe the structure and compounds involved in creating it
- Basic structure is four fused carbon rings with various side groups attached
- Lanosterol is the building block for other steroids
- Lanosterol is formed by the cyclization of squalene
give an examples of steroids
- Cholesterol
- Sex hormones
- Corticosteroids (produced in adrenal cortex)
- Vitamin D
examples of sex hormones
- Oestrogen
- Progesterone
- Testosterone
where are Corticosteroids found and give an example of this?
• Corticosteroids (produced in adrenal cortex)
Aldosterone (mineralocorticoid)
Cortisol (glucocorticoid)
whats the real name of vitamin D? give an example
• Vitamin D (cholecalciferol) – a secosteroid
what is a Phospholipids
• Some lipids have a phosphate group (PO42-) bonded to the glycerol in place of a fatty acid
what are the properties of phosphate group on phospholipids
- Polar
- Soluble in water (hydrophilic)
- Head
what are the properties of fatty acid groups on phospholipids
- Non-polar
- Insoluble in water (hydrophobic)
- Tail
describe the structure of Phosphatidylcholine
choline is attached to phosphate group on a phospholipid
what happens to phospholids in water?
form
Micelle(heads outside tails inside )creating sphere
liposome(same as the first one but hole in the middles) bilayer sheet(layer of phospholipids- only heads are exposed )
what does the cell membrane consist of?
protein channels globular proteins cholesterol glycolipid peripherial protein glycoprotein intergral protein filaments of cytoskeleton surface proteins Alpha-helix protein phospholipids
what are Glycolipids
- Lipid attached to an oligosaccharide
- Forms part of cell membrane and glycocalyx
- Determines ABO blood group
what are Lipoproteins
• Soluble complexes that transport lipids and are usually synthesized in the liver
in lipoproteins ,Spherical particles with central hydrophobic core are:
- Triglycerides
- Esterified cholesterol (cholesteryl ester)
- Small amounts of other lipids and fat soluble vitamins
In Lipoproteins, External hydrophilic layer:
- Phospholipids
- Cholesterol (OH functional group outermost)
- Apoproteins - stabilise structure and regulate enzymatic activity at the lipoprotein
what does the Chylomicrons do?
carry dietary fat to the liver
where are VLDL produced, composed of what, function is?
• VLDL produced in liver from synthesised TGs & CE (cholesterylester)and carry fat to tissues
what remove TGs
TGs gradually removed from circulating VLDL which becomes IDL then LDL
what is LDL and HDL?
- LDL is cholesterol rich (“bad cholesterol” leading to atheroma)
- HDL carries cholesterol to the liver (“good cholesterol” reducing atheroma
Atheroma and thrombosis
build up of cholesterol within the walls of the arteries which can lead to blood clot .
Lipoprotein Profile: list the density of lipoproteins asending order
HDL
LDL
TGs
total cholesterol
why are lipids high in energy and why is it a good energy storage
• Triglycerides and fatty acids have energy-rich C-H bonds available for chemical reactions within cells
- Triglycerides are largely nonpolar and relatively compact
- Stored as droplets in the cytoplasm of adipocyte cells in adipose tissue
whats white adipose tissue ?
- White adipose tissue cushions internal organs and acts as a shock absorber
- White adipose tissue gives insulation, protecting internal organs from temperature swings and reducing skin heat loss
whats brown adipose tissue
Brown adipose tissue is useful for generating body heat (brown adipocytes contain more numerous fat vacuoles and mitochondria)
whats the effects of Excess Adipose Tissue
- Atheroma, thrombosis, atherosclerosis, stenosis and aneurysms
- Exerts undue pressure on organs
- Sequestration of lipophilic substances
what is myelin formed from?
Phospholipids form the myelin insulation around nerve fibres
whats the importance of myelin
• Myelin increases speed of nervous impulses
what cells produce myelin and where does it produce it?
- Schwann cells produce myelin peripherally
* Oligodendrocytes produce myelin centrally
what are vitamins made of?
- Vitamins A D E K
* Fat soluble and some are lipid/steroid derived
list examples of vitamin: A D E K
- Vitamin A – retinol/retinoic acid/carotenoids
- Vitamin D – cholecalciferol and derivatives
- Vitamin E – tocopherol (antioxidant) found in oils
- Vitamin K – phylloquinone and menaquinone
what are Steroidal hormones and • Eicosanoids derived from ?
- Steroidal hormones derived from cholesterol
* Eicosanoids – derived from -3 and -6 fatty acids
give exampples of hormones
- Prostaglandins (inflammation and uterine contraction)
- Prostacyclins (vasodilators)
- Leukotrienes (asthma and allergy)
how does the lipids in your body help reduce Moisture loss
Lipid layers can inhibit evaporation of water
Skin moisture loss reduced by lipid layers
Lipid tear film reduces moisture loss from the corneal surface of the eye
describe the location of where white adipose tissue is found
In humans, adipose tissue is located beneath the skin (subcutaneous fat), around internal organs (visceral fat), in bone marrow (yellow bone marrow). Retroperitoneal
describe the location of where brown adipose tissue is found
brown fat makes up about 5% of the body mass and is located on the back, along the upper half of the spine and toward the shoulders. along the middle of the chest area too
Oligodendrocytes (CNS)
has a nucleus in the middle and there is 3 protruding parts of the cell that make coil.
Schwann cells (PNS)
a circular cell which coils around axon
describe how the epithelial cell reduces water loss (describe the basic composition of lipid tear film in the eye)
lipid layer
water layer
mucin layer (epithelial cell )
whats the difference between cis and trans lipids?
give examples
The difference between cis and trans is that the two H atoms are on the same side of the double bond (cis), compared to being on opposite sides (trans).
cis :oleate,α-linolenic acid
