Carbohydrates 1 Flashcards
What are Carbohydrates?
Aldehyde or ketone compounds with hydrocylngroups e.g.
Polyhydroxyl aldehydes
Polyhydroxyl ketones
Compounds that can be hydrolyzed to PHA or PHK
List the biological functions of Carbohydrates?
- Fuel source
- Energy storage
- Structural materials
- Intermediate metabolism
- Recognition
How do Carbohydrates contribute as a fuel source?
When oxidized, they are an important source of energy
How do Carbohydrates contribute to energy storage?
Starch in plants
Glycogen in liver and muscle of animals
Give examples where carbohydrates are used as structural material
- DNA and RNA,
- Cell walls of bacteria and plants
- Chitin in exoskeleton
Give an example of a carbohydrate that is an intermediate of metabolism
Sedoheptulose-7-P
How do carbohydrates play a role in recognition?
Glycoproteins and glyycolipids act as markers for cellular recognition, blood group determination, cell adhesion, cell migration, immune response, blood clotting
List the 4 classifications of Carbohydrates
Monosaccharides
Disaccharides
Oligosaccharides
Polysaccharides
Describe the characteristics of monosaccharides
Cannot be hydrolyzed into simple sugars
Describe the classification of disaccharides
Their hydrolysis yields 2 monosaccharides(sugars)
Describe the characteristics of oligosaccharides
Hydrolysis produces more than 2 but less than 10 monosaccharides
Describe the characteristics of polysaccharides
On hydrolysis produces many monosaccharide units
Give some examples of monosaccharides
Glucose, mannose, galactose, fructose and ribose
Give some examples of disaccharides
Sucrose, lactose, maltose, cellubiose and gentiobiose
Give some examples of oligosaccharides
Raffinose and stachyose
Give some examples of polysaccharides
Glycogen, starch and cellulose
Describe the formula of monosaccharides
- General formula: CnH2nOn where n ranges from 3 to 9
- formula may deviate( deoxyribose, sugar acids etc.) deoxyribose ( C5H9O4)
How are monosaccharides found?
Found as free sugars and as part of many biologically important molecules
What are the 3 criteria for the classification of monosaccharides ?
- Number of carbon atoms present in the molecules
- Whether the sugar contain an aldehyde or ketone
- The stereochemical configuration of the asymmetric carbon atom farthest from the carbonyl carbon
How are ketones named?
By inserting ‘ul’ to the name of the aldose
Erythrose-> erythrulose
Ribose-> ribulose
Xylose-> xylulose
Exception: ketohexoses -> fructose
What is the structural difference between ketones and aldosterone
Ketones has one less asymmetrical C than aldose
Why do all monosaccharides except DHA have optically active isomeric forms?
All monosaccharides except DHA contain one or more asymmetric C chiral center
A chiral/asymmetrical carbon atom is the source of optical isomerism
Describe the difference in the configurations in glyceraldehyde
- The form of glyceraldehyde that caused the rotation of plane polarized light to the right(dextrorotatory)was designated D
- the form that caused rotation to the left(levatorotary) was designated L
What configuration are most naturally occurring sugars?
D configuration