Ch.5 Exam Flashcards
(24 cards)
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
What is the active site of an enzyme?
The specific region of the enzyme that catalyzes reactions to occur
List the five functions of carbohydrates.
- Used in nucleotide assembly (Nucleic acids)
- Provide fibrous structural materials
- Indicate cell identity
- Store potential chemical energy
- Broken up as fuel molecules for cellular work
Define glycoproteins and their job. What are glycoproteins key molecules in?
- Proteins joined to carbohydrates by covalent bonds
- Key: Cell-cell recognition: Each cell in your body has glycoproteins on its surface to identify it as “self” (white blood cells won’t attack)
- Cell-cell signaling
Explain why carbohydrates and fats have more energy than CO2.
- Electrons in C—H bonds and C—C bonds are shared more evenly than in C—O bonds (due to electronegativity of oxygen)
- Monosaccharides are assimilated during photosynthesis CO2 + H2O + Sunlight —> (CH2O)n to O2
Write out the chemical reaction of photosynthesis.
CO2 + H2O + Sunlight —> (CH2O)n + O2
What catalyzes the hydrolysis of α-glycosidic linkages in glycogen?
Phosphorylase
What hydrolyzes α-glycosidic linkages in starch?
Amylase
Write out the chemical formula for the break down of carbohydrates/fats to create ATP.
CH2O + O2 + ADP —> CO2 + H2O + ATP
List the three types of cellular work ATP is used for in cells.
- Assimilate other macromolecules
- Transportation
- Catalyze chemical reactions
