Lipids Flashcards
Triglyceride=
1 glycerol
3 fatty acids (hydrophobic tails)
Ester bond
Triglyceride uses
-insulation
-energy store
-membranes
-energy source
-protection
-hormones
Fatty acids saturated
No double bonds between c-c
Straight
Fatty acids unsaturated
Double bonds between c=c
Kinky
Triglyceride properties
Energy storage
Insoluble in water-no effect on WP
Bundle as drops -Micelles
Phospholipids
2 fatty acids+ glycerol+ phosphate group (negatively charged=polar)=hydrophilic
3 polysaccharides?
starch, cellulose, glycogen
what kind of bonds are found in polysaccharides?
Glycosidic
Name the monomer that makes up starch
a-glucose
Name the two polysaccharide chains that make up starch
amylose and amylopectin
What does cellulose form when chains group together? Which bonds are involved in holding these together?
microfibrils/macrofibrils/fibres Hydrogen bonds
One similarity and one difference between starch and
glycogen
Similarity:
Both made of a-glucose
Both energy storage
Both insoluble/large/can’t diffuse out of cells
Difference: starch – plants, glycogen – animals; starch stains blue/black with iodine; branched and coiled chains in starch, only branched in glycogen
Properties of triglycerides
• Insolubleinwatersotheydon’taffectthe water potential of the cell and cause water to enter the cells by osmosis (which could cause them to swell)
• Triglyceridesalwaysbundletogetheras insoluble droplets in cells as the fatty acid tails are hydrophobic - the tails face inwards shielding themselves from water with glycerol heads on the outside
• Mainly used as energy storage molecules • The long hydrocarbon tails of the fatty
acids contain lots of chemical energy
• This means lipids contain about x2 as much energy as carbohydrates
Properties of phospholipids
• Makeupcellmembranes-phospholipid bilayer
• Controllingwhatenters/leavesthecell
• Phospholipidheadsarehydrophilic
• Thetailsarehydrophobic
• Formingadoublelayerwithheadsonthe outside
• Thecentreishydrophobic,meaningwater soluble substances cant easily pass through
One similarity and one difference between the structure phospholipids and triglycerides
Similarity:
Both made of glycerol Both contain fatty acids
Difference:
Phospholipids have 2 fatty acids and triglycerides here
Phospholipids have a phosphate group
Cellulose
Cellulose is made up of β 1-4 glucose molecules. Each alternate glucose molecule flips 180° to allow the bonding of the hydroxyl groups. This means that the CH2OH alcohol group of every other molecule is above the carbon ring, and the others are below.
Where is oh on alpha glucose
Bottom
Lipid digestion
• Bile salts emulsify lipids into micelles to increase surface area and solubility in water
• Lipids/triglycerides are hydrolysed by lipases to form fatty acids and monoglycerides
• Micelles contain bile salts and fatty acids/monoglycerides, making them soluble in water.
• Fatty acids/monoglycerides are released to cell/lining of the ileum.
• This maintains a higher concentration of fatty acids/monoglycerides outside the cell, so they are absorbed by simple diffusion.
• Triglycerides are reformed in cells and form chylomicrons.
• The chylomicron vesicles fuse with the cell membrane and are released by exocytosis.
Lipid digestion
• Bile salts emulsify lipids into micelles to increase surface area and solubility in water
• Lipids/triglycerides are hydrolysed by lipases to form fatty acids and monoglycerides
• • Micelles contain bile salts and fatty acids/monoglycerides, making them soluble in water.
• Fatty acids/monoglycerides are released to cell/lining of the ileum.
• This maintains a higher concentration of fatty acids/monoglycerides outside the cell, so they are absorbed by simple diffusion.
• Triglycerides are reformed in cells and form chylomicrons.
• The chylomicron vesicles fuse with the cell membrane and are released by exocytosis.
Lipid digestion
• Bile salts emulsify lipids into micelles to increase surface area and solubility in water
• Lipids/triglycerides are hydrolysed by lipases to form fatty acids and monoglycerides
• Micelles contain fatty acids, monoglycerides and bile salts
• They move through the ileum to the epithelium ce
Lipid absorption
• Micelles contain fatty acids, monoglycerides and bile salts. They make fatty acids soluble in water and move through the ileum releasing the monoglycerides and fatty acids
• Monoglycerides and fatty acids are non-polar so move through the membrane easily into epithelial cells by diffusion
• Monoglycerides and fatty acids are reformed into triglycerides in the ER
• In the golgi the triglycerides combine with lipoproteins and cholesterol to form chylomicron vesicles
• Chylomicrons move across the cell membrane by exocytosis and enter lymph vessels called lacteals
• They eventually move from the lymph to the blood where they are hydrolysed in the endothelium and diffuse into cells
