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44 Cards in this Set
- Front
- Back
What is the generic formula of a carbohydrate? |
(CH2O)n, where n is greater than or equal to 3 |
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What are carbohydrates formed from?
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CO2 and H2O |
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What are the roles of carbohydrates? |
Energy in diet Mediating intercellular communication Structural support (e.g. cell walls) |
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How are carbohydrates classified? |
By length |
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What are monosaccharides? |
Simple sugars |
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What are the different types of small polymers of sugars? |
Disaccharides = two sugars bound together Trisaccharides = three sugars bound together Oligosaccharides = "several" sugars bound together |
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What are large polymers of sugars? |
Polysaccharides |
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What has five carbons? |
Pentose |
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What are six carbons? |
Hexose |
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What is the simplest aldose? |
Glyceraldehyde |
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What are the characteristics of monosaccharides? |
Described based on the number of carbon atoms in the molecules Made from aldehydes to form aldoses Made from ketones to form ketoses |
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What is the simplest ketose? |
Dihydroxyacetone |
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T or F: Most carbohydrates are chiral |
True |
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What is the definition of chiral? |
Have at least one chiral carbon = bound to four different groups |
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What does L stand for? |
Levorotatory |
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What does D stand for? |
Dextrorotatory |
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How do enantiomers behave? |
Although enantiomers behave identically in a strictly chemical sense, they are NOT biologically equivalent |
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How can biological systems be distinguished? |
As L or D |
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What are the rules for L and D notation? |
Draw aldehyde or ketone group at the top Identify lowest chiral center in the molecule Classify configuration based on OH group |
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How do you distinguish L and D notation? |
If OH is on the right = D If OH is on the left = L |
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What configuration do most sugars in nature have? |
D notation |
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What are epimers? |
Sugars that differ only by the configuration around one carbon atom |
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T or F: The same sugar can only be represented in one way |
False |
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Describe the cyclization of glucose |
Since the aldehyde group has rotational freedom about the C1 - C2 bond, anomers are possible Alpha-D-Glucose is most prevelant in biochemistry |
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In what two ways can carbohydrates be drawn? |
Haworth projections Fischer projections |
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What links the anomeric carbon with another group? |
Glycosidic bonds |
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Are cyclical sugars nonplanar? |
Yes |
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T or F: Monosaccharides can be derivatized in many different ways |
True |
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What is a key distinction between DNA and RNA? |
The 2'OH group is only found in RNA
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What does the enzyme ribonucleotide reductase catalyze? |
The removal of the 2'OH group |
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What is a popular sugar that is used as a sweetener in chewing gum, and has been shown to help prevent cavities? |
Xylitol |
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What is milk sugar? |
Lactose |
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What are the characteristics of the structure of lactose? |
Lactose has a beta(1-->4) glycosidic bond |
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What is the most abundant sugar in nature? |
Sucrose |
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Describe the structure of sucrose |
Has an alpha(1-->2) glycosidic bond |
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What is cellulose composed of? |
Glucose in beta(1-->4) linkages |
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What is formed by cellulose? |
Extended fibers that lend strength and rigidity to plant cell walls due to beta(1-->4) linkage |
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What two types of polymers is starch composed of? |
1. Amylose 2. Amylopectin |
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What is amylose? |
A linear and helical polymer of glucose with an alpha(1-->4) glycosidic bonds |
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What is amylopectin? |
A branched polymer of glucose with a beta(1-->6) glycosidic bonds |
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Describe starch (plants) and glucose (animals) functions |
Glucose polymers that store energy Glucose polymers are linked by alpha(1-->4) glycosidic bonds |
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What are the characteristics of glycogen? |
Found in animals, not plants Similar to amylopectin, but has a higher degree of branching Glucose is needed by the body --> quick removal of glucose monomers form multiple branch ends simultaneously Straight chains like amylose provide only one glucose molecule at a time --> slower to provide energy |
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What happens when bacteria polysaccharides form a biofilm? |
Bacteria produce extracellular polysaccharides that forma biofilm |
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What is a biofilm? |
A protective covering for bacteria to grow and thrive |