30 Questions
What elements do carbohydrates mainly consist of?
Carbon, hydrogen, and oxygen
What is the common characteristic of carbohydrates in terms of their formula?
(CH2O)n
Which of the following is NOT a source of carbohydrates?
Steak
What class of biomolecules do carbohydrates constitute as the most abundant?
Carbohydrates
How are carbohydrates defined as per their chemical structure?
Aldehydes or ketones with at least two hydroxyl groups
Which of the following forms are the most common and abundant types of carbohydrates?
Sugars, fibers, and starches
What distinguishes aldoses from ketoses?
Aldoses have the carbonyl group at the end of the carbon chain, while ketoses have it at any other position.
What is the common characteristic of monosaccharides glucose and fructose?
They both have five hydroxyl groups
What is the role of D-Ribose in nucleic acids?
Component of RNA
What term is used to describe two sugars that differ only in the configuration of one carbon atom?
Epimers
What are hemiacetals and hemiketals derived from?
Aldehydes and ketones
What is the meaning of 'hemi' in hemiacetals and hemiketals?
Half
What is the product when an aldehyde reacts with an alcohol in a 1:1 ratio?
Hemiacetal
What is formed when a ketone reacts with an alcohol in a 1:1 ratio?
Hemiketal
What type of bond is produced when a second alcohol molecule substitutes the hemiacetal or hemiketal?
Acetal or ketal
What is the term used for isomeric forms of monosaccharides that differ in configuration around hemiacetal or hemiketal carbon atoms?
Anomers
Which carbon atom in a hemiacetal (or carbonyl) is referred to as the anomeric carbon?
Carbonyl carbon
What produces two stereoisomers, the alpha and beta anomers, when reacting in the formation of cyclic forms of D-glucose?
Reaction between the aldehyde group at C-1 and the hydroxyl group at C-5
What is the defining characteristic of polysaccharides?
Consist of more than 10 monosaccharide units
Which carbohydrate is an example of a multibranched polysaccharide of D-glucose?
Glycogen
How are amylose and amylopectin different?
Amylose has α(1→4) glycosidic bonds, while amylopectin has α(1→6) glycosidic bonds
How do we denote a sugar as a D-isomer?
If the hydroxyl group at the last chiral carbon lies towards the right side
What is the defining characteristic of monosaccharides?
Can either be aldehydes or ketones with two or more hydroxyl groups
Which glycosidic bonds are present in a straight chain polymer of D-glucose?
α(1→4) and β(1→4)
What are the four primary functions of carbohydrates in the body?
Provide energy, store energy, build macromolecules, spare protein and fat
What does the term 'saccharide' mean and where is it derived from?
It means 'sugar' and is derived from Greek
Which type of carbohydrate consists of short chains of monosaccharide units joined by glycosidic bonds?
Oligosaccharides
Which disaccharide is formed by the combination of D-glucose and D-fructose?
Sucrose
What is the most abundant type of oligosaccharide?
Maltose
In nature, what type of sugars are most common compared to L-amino acids?
D-sugars
Study Notes
Carbohydrates
- Carbohydrates are polyhydroxy aldehydes or ketones, consisting of carbon, hydrogen, and oxygen
- They are the most abundant biomolecules on earth
- Sources: wide array of food, including bread, beans, milk, popcorn, potatoes, cookies, spaghetti, soft-drinks, corn, and cherry pie
Classification of Carbohydrates
- Polysaccharides: consist of more than 10 monosaccharide units, examples include cellulose, starch, and glycogen
- Oligosaccharides: short chains of monosaccharide units joined by glycosidic bonds, examples include sucrose, lactose, and maltose
- Monosaccharides: single polyhydroxy aldehyde or ketone units, examples include D-glucose and fructose
D and L Isomers
- Fischer projection formulas are used to represent three-dimensional sugar structures on paper
- D-isomers have the hydroxyl group at the last chiral carbon towards the right side
- L-isomers have the hydroxyl group at the last chiral carbon towards the left side
Monosaccharides
- Examples of aldoses: glyceraldehyde, glucose, and galactose
- Examples of ketoses: dihydroxyacetone, fructose, and sorbose
- Can be classified as trioses, tetroses, pentoses, hexoses, etc. based on the number of carbon atoms
Functions of Carbohydrates
- Provide energy
- Store energy
- Build macromolecules
- Spare protein and fat for other uses
- Structural components
- Signal transduction and cell adhesion
- Flavor and sweeteners
- Eliminate waste materials and toxins from the body (dietary fiber)
Digestion and Absorption of Carbohydrates
- Carbohydrates are broken down into monosaccharides during digestion
- Absorbed into the bloodstream and transported to cells for energy production or storage
Test your knowledge on carbohydrates in this quiz covering Lecture 2-4 of the Introduction to Biochemistry & Biotechnology course. Topics include sugars, starches, celluloses, and their composition of carbon, hydrogen, and oxygen.
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