Case 1: sugar and fats Flashcards
What are the different types of sugar? (look at structures)
Different types of sugar are monosaccharide, which refers to a carbohydrate derivative possessing a single carbon chain, disaccharide which refers to molecules containing two monosaccharide units joined together and trisaccharide refers to molecules with 3 monosaccharide units joined together. The units are joined together through condensation. Oligosaccharides and polysaccharides refer to larger clusters of monosaccharide units.
What is the basic formula for sugars?
CnH2nOn
What is the Fischer projection?
Fisher projections show sugars in their open chain form. In a Fischer projection, the carbon atoms of a sugar molecule are connected vertically by solid lines, while carbon-oxygen and carbon-hydrogen bonds are shown horizontally.
What is D-sugar and L-sugar?
Location of hydroxyl group in second to last (e.g. 5th) Carbon determines whether it is an
L -Sugar (OH on the l eft) or D-Sugar (OH on the right)
What is the alfa glucose/beta glucose? (look at pictures)
The OH of C1 is written either above
( b-Glucose, cis ) or under ( a-Glucose,
trans ) the circle
What is the structure of fats?
Fat is made up of glycerol backbone and 3 long chain fatty acid tails due to a dehydration synthesis reaction.
Dehydration synthesis reaction: a reaction occurs with the loss of a water molecule.
During the dehydration reaction, one water molecule is removed for each fatty acid joined to the C of the glycerol backbone. The reaction between the glycerol backbone and the fatty acid chains creates ester bonds/ linkages.
Different types of fat
These terms refer to the structure of the hydrocarbon chains of the fatty acids.
In saturated fats, there are no double bonds between the carbon atoms. Whereas unsaturated fats have double bonds ñ the number of double bonds can vary.
- Monounsaturated = 1 double bond
- Polyunsaturated = multiple double bonds
What is trans-fat?
Trans unsaturated fats have a double bond, but due to the trans binding ( the H-atoms opposite of each other instead of next to one another) they are straight.
Nomenclature fats
Cn:x(n-y)
- n = chain length
- x = double bonds
- n-y = first double bound that occurs from the methyl end
What are the essential fatty acids?
The essential fatty acids must be supplied through the diet because the human body cannot synthesise these fatty acids. All essential fatty acids are polyunsaturated.
Two types of fatty acids: omega-6 (linoleic acid) and omega-3 fatty (linolenic acid) acids, depending on whether the first double bond occurs at the third or sixth carbon atom of the carbon chain.
Function sugars
→ Energy source
Sugars are processed into Glucose which acts as a
source of energy
→ Energy storage
Limited amount is stored in the liver and muscles as Glycogen , excess is turned into fat
→ Building macromolecules
Glucose is also converted to Ribose and Desoxyribose → crucial compounds of DNA,
RNA and ATP
Function fat
→ Energy storage
● Excess energy is stored in adipose (fatty) tissue as an energy reserve
● Fat is more dense with energy than Glycogen
● The storage of fat is able to expand almost indefinitely compared to Glycogen
→ Regulating and signalling
● Triglycerides regulate the body temperature and produce and regulate hormones
● Essential Omega-3 and Omega-6 lipids help regulate Cholesterol and blood clotting
● Used in cell membranes, insulate neurons and facilitate their signalling (myelin sheet)
→ Insulating
● Insulate body from extreme temperatures
Digestion of sugar
The digestion of sugars begins with chewing, also known as mastication, which crumbles the carbohydrate foods into smaller pieces. Amylase enzyme present in the saliva breaks the glycosidic bonds between the monomeric sugar units of disaccharides and polysaccharides, forming disaccharides and monosaccharides. Not all disaccharides and polysaccharides are broken down into monosaccharides. The unbroken carbohydrates reach the stomach into the mixture of chyme and then enter the small intestine, where there are 2 types of enzymes:
• Pancreatic amylase, which breaks down polysaccharides into disaccharides
• Glucosidases, which breaks down disaccharides into monosachharides
After all the poly- and disaccharides are broken down into monosachharides, the monosaccharides are then transported through the wall of the small intestine into the bloodstream and to the
liver.
Digestion of fats
- Lipids are broken into small components for absorption, the first step of the digestion of triacylglycerol’s and phospholipids begins in the mouth when it encounters saliva. The enzyme lingual lipase, along with phospholipid as an emulsifier, initiates the process of digestion.
- In the stomach, gastric lipase starts to break down triacylglycerols into diglycerides and fatty acids.
- emulsification of fats by bile (> liver: bile salts, lecithin + substances from cholesterol) + bile salts envelop the fatty acids and monoglycerides to form micelles which have a fatty acid core with a water-soluble exterior. This allows efficient transport to the intestinal microvillus.
- As pancreatic lipase enters the small intestine, it breaks down the fats into free fatty acids and monoglycerides
- Inside the intestinal cells, the monoglycerides and fatty acids reassemble themselves into triacylglycerols. Triacylglycerols, cholesterol, and phospholipids form lipoproteins when joined with a protein carrier.
What is a chlyomicron?
Chylomicron, which is a large lipoprotein that now enters the lymphatic system and will soon be released into the bloodstream via the jugular vein in the neck. Chylomicrons transport food fats perfectly through the body’s water-based environment
