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How are carbohydrates produced?
Produced from CO2 and H2O via photosynthesis in plants
Whare are some functions of carbohydrates?
- Energy source and energy storage
- Structural component of cell walls and exoskeleton
- Informational molecules in cell-cell signaling
What is formed when carbohydrates are covalently linked with proteins?
Glycoproteins and proteglycans
How are glycoproteins and proteoglycans formed?
Formed when carbohydrates are covalently linked with proteins
What is the simplest carbohydrate?
What is an enantiomer?
When two molecules are mirror images of eachother
What are epimers?
two sugars that differ only in the configuration around one carbon atom
What is produced after the cyclization of monosaccharides?
Gives rise to structures that are hemiacetals for aldoses and hemiketals for ketoses
What compounds readily undergo imtramolecular cyclization?
Pentoses and hexoses
What changes occur in the cyclization of monosaccharides?
- The former carbonyl carbon becomes a new chiral center, called the anomeric carbon-giving rise to an anomeric pair
- The former carbonyl oxygen becomes a hydroxyl group; the position of this group determines if the anomber is alpha or beta
What is an alpha anomer?
If the hydroxyl group is on the opposite side (trans) of the ring as the CH2OH moiety
What is a beta anomer?
If the hydroxyl group is on the same side (cis) of the ring as the CH2OH moiety
What is mutarotation?
The conversion between alpha and beta anomers
What is a six-membered oxygen-containing ring known as?
What is a five-membered oxygen-containing ring known as?
How are pyranoses and furanoses usually frawn?
The anomeric carbon is usually drawn on the right side
What are the three structural representaions of monosaccharides?
- Fischer projection
- Haworth Projection
- Chair Confirmation
What is produced when monosaccharides oxidize?
A carboxylic acid
What do monosaccharides need to undergo oxidation?
How are disaccharides formed?
By condensation reaction between two alcohol groups
What are some chemial modifications of monosaccharides?
How are natural carbohydrates usually found?
Usually found as polymers
What are the 2 types of polysaccharides?
What are homopolysaccharides?
A polymer with the same monosaccharide repeated many times along the chain
What is a heteropolysaccharide?
A polysaccharide chain with many different types of monosaccharides
What is the main storage homo-polysaccharide in plants?
What is starch?
A mixture of two homo-polysaccharides of glucose
What is amylose?
An unbranched polyer of (alpha1-4 linked residues)
What is amylopectin?
A branched polymer (alpha1-4) linked resudes BUT the branch-points with (alpha1-6) linkers occur every 24-30 residues
What is the molecular weight of amylopectin?
up to 200 million
What is glycogen?
Main carbohydrate storage system in animal cells
Where is Glycogen often stored?
Liver is primary storage location (7% by weight)
What is cellulose?
A fibrous, water insoluble polymer of unbranched homopolysaccharide of glucose found in the cell wall of plants
What is cotton?
a neearly pure fibrous cellulose
What is the most abundant polysaccharide in nature?
Why is cellulose a difficult substrate to act on?
Its fibrous structure and water-insolubility
How can fungi, bacteria and protazoa use wood as a source of glucose?
Fungi, bacteria, and protazoa secrete cellulase, which breaks down cellulose
Why can most animals not used cellulose as a fuel source?
They lack the enzyme to hydrolyze linkages
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