Topic 5: Carbohydrates And Lipids Flashcards
Explain how monosaccharides are classified
Monosaccharides contain 3 to 7 carbons.
They usually end in “ose”.
Mono means one
They can be either aldehyde or ketane.
Aldehyde: carbon is double to oxygen and single bonded to H and R group.
Ketane: carbonyl attached to two carbons.
Classified As:
- number of carbons
- location of carbonyl groups
- Asymmetric Carbons
- for the 5 and 6 carbons are linear and ring forms
Why do we generally consider all 5 and 6 carbon monosaccharides to be ring structures?
Hexoses (5) and Pentoses(6) are mostly going to tend towards a ring structure in water.
Forms a ring with reaction between the carbon and carbonyl group and another carbon to build a bond.
Carbonyl group is not noticeable in the ring structure.
In water there are 2 different kinds of glucose.
Alpha glucose: OH bottom
Beta glucose: OH Top
Explain how monosaccharides relate to disaccharides and polysaccharides.
They are all forms of carbohydrates.
Monosaccharides are simple sugars.
When monosaccharides bond together and for a dehydration reaction a disaccharide is formed.
When this keeps occurring we get a long chain of monosaccharides linked by glycosidic bonds and we get a polysaccharide.
What are the polysaccharides that we learned about in this class? Indicate where they are found in nature and their function.
- Starch: when glucose is synthesized. Excess glucose is stored as starch. In plants, seeds, roots, stems. Can be both branched(amylose) or unbranched(amylopectin)
-Cellulose: present in the cell walls of plants. Made of repeated B 1-4 glycosidic bonds.
-Chitin: a polysaccharide that contains nitrogen. Made B1-4 glycosidic linkages. Forms exoskeletons on insects.
-Glycogen: is a form of stored glucose in humans. Found in liver and muscle cells. Branched polysaccharide.
All of these polysaccharides are made of glucose monomers, but not necessarily the same isomer. Explain how they differ structurally and how their structure leads to their function.
Starch: can be either branched or unbranched by alpha1-4 glycosidic linkages or alpha 1-6 glycosidic linkages formed by dehydration reactions. By this it’s easily broken down and serves as a great energy storage.
Cellulose: made of long chains of Beta 1-4 glycosidic linkages. Forms strong cable like structure make them strong and great for providing support to plant cells.
Glycogen: Branched polysaccharide contains a 1-4 and a 1-6 glycosidic linkages. Stores glycogen. When hydrolysis it’s also easy to break down and release glucose.
Chitin: the monosaccharides are linked together by B 1-4 glycosidic bonds. Contains nitrogen. This gives its strong exoskeleton to provide protection and strength.
What are triglycerides made of?
Triglycerides are made of three fatty acids and a glycerol
Describe the 3 types of triglycerides
-Saturated: are solid at room temperature. Contain no double bonds only single bonds in the hydrocarbon chain.
-Unsaturated: Liquids at room temperature. Contains one or more double bonds. They can be classified as cis(bend) or trans(linear).
- Trans Fat: they were man made through the hydrogenation process. Increase LDL!
How do the three triglycerides differ at a chemical level and how do these differences relate to human health.
Saturated: Are single hydrocarbon bonds in their chain. They have no double bonds. Increase both LDL and HDL levels.
Unsaturated: Contain double bonds. And increase HDL cholesterol. Cis is when the double bond is on the same plane causing a bend.
Trans is when the double bond is opposite sides leaving it linear.
They help lower cholesterol.
Trans Fats: One or more double bonds in the trans configuration. Leads to raising LDL bad cholesterol.
Describe the molecular structure of a single phospholipid. Describe how phospholipids arrange in water.
Phospholipids contain a glycerol, a phosphate attached to an R group and attached to two fatty acids. Fatty acids are unsaturated and saturated.
In water the hydrophilic heads attract to the water and the hydrophobic tails face away from water.
What are steroids? Why are they important to biology?
Steroids are lipids are composed of hydrocarbon rings and are components of the plasma membrane are known as signaling molecules.
Examples: Cholesterol, Estradiol, and Testosterone
