Ch.5 Exam Flashcards
What are the three common uses of carbohydrates?
- Energy as in sugars
- Storage as in starch and glycogen
- Structure as in peptidoglycan and cellulose
What is the general equation for carbohydrates? Write the equation for a carbohydrate where n=6, and another where n=3.
General equation: (CH2O)n
n=6 (CH2O)6
n=3 (CH2O)3
List the three categories of carbohydrates.
- Monosaccharides
- Disaccharides
- Polysaccharides
Define and explain monosaccharides.
- Simple sugars
- Monomers of larger carbohydrates
- Most common Ex: glucose (C6H12O6)
- Serve as the main fuel molecules for cellular work especially glucose
Ex: Glucose, Fructose, Galactose
Monosaccharide monomers are simple sugars that structurally vary in four primary ways. List those four primary ways.
- Location of the carbonyl group (C=O)
- Number of carbon atoms present
- Spatial arrangement of their atoms
- Linear and alternative ring forms
Where is the carbonyl group (C=O) located in an Aldose? In a Ketose?
- Aldose: found at the end of the monosaccharide
- Ketose: found in the middle of the monosaccharide
What is a monosaccharide with three carbon atoms present called? When it has five? Six?
- Three: Triose
- Five: Pentose
- Six: Hexose
(Not a question, just information!) Spatial arrangement of atoms in a monosaccharide is also key to how they differ structurally. This arises from a different arrangement of the hydroxyl groups.
Not the difference in the hydroxyl group between Glucose and Galactose from the notes.
(Not a question, just information!) The ring structures that sugars tend to form in aqueous solutions can vary. An example being the α and β-glucose monomers.
Name the type of covalent bond between two monosaccharides.
Glycosidic linkage
What is a disaccharide? List some examples.
- 2 monosaccharide monomers bound together
- Monomers can be identical or different
- Ex: Lactose, Maltose, Sucrose
Explain the difference between α (alpha) and β (beta) orientations in monosaccharides.
- Alpha and Beta refer to the contrasting orientations of the C-1 hydroxyls
- They are on opposite sides of the plane of the glucose rings
- alpha-1,4-glycosidic linkage and beta-1,4-glycosidic linkage
- Both linkages are between the C-1 and C-4 carbons
Name an example of a disaccharide with an α-1,4-glycosidic linkage, and one with a β-1,4- glycosidic linkage, from the notes.
-α-1,4-glycosidic linkage: Maltose
- β-1,4- glycosidic linkage: Lactose
What is a polysaccharide?
Carbohydrate polymers made u of many monosaccharides (held by glycosidic bonds)
Explain the five types of polysaccharides.
- Plants store sugar as starch (mixture of branched amylopectin, and unbranched amylose α-glucose polymer)
- Animals store sugar as glycogen (highly branched α-glucose polymer)
- Cellulose: a structural polymer found in plant cell walls (Polymer of β-glucose monomers
- Chitin: a structural polymer found in fungi cell walls, some algae, and many animal exoskeletons
- Compromised of N- acetylglucosamine (NAc) monomers
- Peptidoglycan: structural support for bacteria cell walls
- Backbones of alternating monosaccharides
Are α or β glycosidic linkages harder to break? Explain why.
- β-1,4 glycosidic linkages of structural carbohydrates are very difficult for animals to hydrolyze
- Few enzymes have an active site that interact and the β-1,4 glycosidic linkages geometry
