Carbohydrates and Lipids Flashcards
Monosaccharides can be classified according to what?
Their number of carbon atoms
What are 2 important trioses?
Glyceraldehyde + dihydroxyacetone
What are 2 important pentoses?
Ribose + deoxyribose
What are 3 important hexoses?
Glucose, fructose, galactose
What is an isomer?
Chemical structures which contain the same atoms but are bonded together to form different 3D arrangements
What is monosaccharide cyclisation?
Longer-chain monosaccharides (such as pentoses and hexoses) form cyclic molecules
How are disaccharides formed and what are some important examples?
When two monosaccharides join together and eliminate water to form a glycosidic bond.
Sucrose, lactose, maltose
What are starches?
Polymers of glucose which serve as storage carbohydrates in plants
Describe amylose in terms of its percentage make up of starch, types of glucose chains, and types of bonds.
25%
Linear glucose chains
a-1,4 glycosidic bonds
Describe amylopectin in terms of its percentage make up of starch, types of glucose chains, and types of bonds.
75%
Branched glucose chains
a-1,4 and a-1,6 glycosidic bonds
What is cellulose and why is it important in human digestion?
A linear polymer of glucose. Cellulose is not digestible by humans and forms dietary fibre.
What is glycogen, and why is its structure advantageous to its function?
An extensively branched polymer of glucose obtained from animal sources. Its high level of branching means it has a large number of free ends, facilitating its rapid breakdown into glucose.
What is dextrin?
A branched oligomer of glucose that comes from the breakdown product of starch and glycogen
What are the 4 main types of biologically important lipids?
Fatty acids
Triglycerides
Cholesterol
Cholesterol esters
Describe the structure of fatty acids.
Hydrocarbon chains with a carboxyl group at one end and a methyl group at the other
What can fatty acids join with to form triglycerides?
Glycerol
Fatty acids are classified using a system that includes what 3 pieces of information?
Number of carbon atoms
Number of double bonds
Position of the first double bond
What are phospholipids composed of?
A phosphate group attached to one or more fatty acid chains via glycerol or sphingosine
Where are ketone bodies produced and when, and why are they important?
They are formed by the liver during fasting, when they become important energy substrates for the brain
Name the 3 main ketone bodies.
Acetone
Acetoacetic acid
B-hydroxybutyric acid
List the 5 main functions of lipids in the body.
Fuels for cells
Energy storage
Transport between tissues
Structural components of cell membranes
Chemical messengers
How are lipids transported in the bloodstream?
As lipoproteins
Describe the structure of lipoproteins.
Hydrophobic core consisting of triglycerides and cholesterol esters
Hydrophilic surface consisting of apolipoproteins, free cholesterol, and phospholipids
Which enzyme releases fatty acids from chylomicrons and VLDLs into tissues?
Lipoprotein lipase
What is the function of chylomicrons?
Deliver dietary (exogenous) TAG to peripheral tissues
What is the function of VLDLs?
Deliver endogenous TAG to peripheral tissues
What is the function of LDLs?
Deliver cholesterol to peripheral tissues and liver
What is the function of HDLs?
Deliver cholesterol from peripheral tissues to liver for elimination
Describe chylomicrons in terms of their TAG and cholesterol content.
Highest TAG and lowest cholesterol
Describe VLDLs in terms of their TAG and cholesterol content.
High TAG and low cholesterol
Describe LDLs in terms of their TAG and cholesterol content.
Low TAG and highest cholesterol
Describe HDLs in terms of their TAG and cholesterol content.
Lowest TAG and high cholesterol
