Types of Carbohydrates

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the term used to describe a carbon atom that has four different groups bonded to it?

Chiral carbon (correct)

Ketose carbon

Aldose carbon

Hexose carbon

What is the molecular formula of glucose?

C5H10O5

C6H12O6 (correct)

C4H8O4

C3H6O3

What is the term used to describe a pair of nonsuperimposable mirror images?

Anomers

Enantiomers (correct)

Isomers

Diastereomers

What is the name of the projection formula used to represent bonds in a Fischer projection?

Fischer projection Signup and view all the answers

What is the term used to describe the D and L isomers of glyceraldehyde?

Enantiomers Signup and view all the answers

What is the name of the cyclic form of glucose?

Hemiacetal Signup and view all the answers

What is the significance of the terms 'α' and 'β' in the context of glucose?

They refer to the anomers of glucose Signup and view all the answers

What is the term used to describe a sugar with five carbon atoms?

Pentose Signup and view all the answers

What is the term used to describe a sugar with six carbon atoms?

Hexose Signup and view all the answers

What is the name of the simplest carbohydrate that exhibits chirality?

Glyceraldehyde Signup and view all the answers

What is the major energy source for the body?

Glucose Signup and view all the answers

What percentage of daily calories does the USDA recommend come from carbohydrates?

45-65% Signup and view all the answers

What is the term for the bond that links two monosaccharides together?

Glycosidic bond Signup and view all the answers

What is the basic formula for monosaccharides?

(CH2O)n Signup and view all the answers

How many carbon atoms can a monosaccharide backbone have?

3-7 Signup and view all the answers

What is the term for a single sugar molecule?

Monosaccharide Signup and view all the answers

What is an example of a complex carbohydrate?

Starch Signup and view all the answers

How much energy is produced from one gram of digested carbohydrate?

4 kcal Signup and view all the answers

What is the term for chains of linked monosaccharide units?

Polysaccharides Signup and view all the answers

What is the process by which plants synthesize carbohydrates?

Photosynthesis Signup and view all the answers

What is the sweetest sugar?

Fructose Signup and view all the answers

Which sugar is the principal sugar found in mammalian milk?

Galactose Signup and view all the answers

What is the difference between ribose and deoxyribose?

The absence of an –OH group on C-2 Signup and view all the answers

What is the result of the reaction between Benedict's reagent and an aldose?

A red-orange precipitate forms Signup and view all the answers

What is the disaccharide formed by linking two D-glucose molecules?

Maltose Signup and view all the answers

What is the genetic disease that results from the absence of enzymes necessary to convert galactose to a phosphorylated glucose molecule?

Galactosemia Signup and view all the answers

What is the polysaccharide composed of α-linked glucose found in plants?

Starch Signup and view all the answers

What is the major structural polymer in plants?

Cellulose Signup and view all the answers

What is the repeating disaccharide of cellulose?

β-Cellobiose Signup and view all the answers

Why can ruminants (e.g., cows) eat grass?

The bacteria in their gut can digest cellulose Signup and view all the answers

What is the energy produced from one gram of digested carbohydrate?

4 kcal Signup and view all the answers

What is the backbone of a monosaccharide composed of?

Carbon, Hydrogen, Oxygen Signup and view all the answers

What is the term for a polysaccharide composed of α-linked glucose found in plants?

Starch Signup and view all the answers

What is the percentage of daily calories recommended by the USDA to come from carbohydrates?

45-65% Signup and view all the answers

What is the term for a single sugar molecule?

Monosaccharide Signup and view all the answers

What is the name given to sugars with six carbon atoms?

Hexose Signup and view all the answers

What is the type of bond that links two monosaccharides together?

Glycosidic bond Signup and view all the answers

What is the process by which plants synthesize carbohydrates?

Photosynthesis Signup and view all the answers

What determines the chirality of a molecule like glyceraldehyde?

A carbon atom with four different groups bonded to it Signup and view all the answers

What is the term given to the cyclic form of glucose?

Anomer Signup and view all the answers

What is the term for chains of linked monosaccharide units?

Polysaccharides Signup and view all the answers

What is the function of insulin and glucagon in the human body?

To regulate glucose concentration in the blood Signup and view all the answers

What is the number of carbon atoms in the backbone of a monosaccharide?

3-7 Signup and view all the answers

What is the molecular formula of glucose?

C6H12O6 Signup and view all the answers

What is the type of carbohydrate found in mammalian milk?

Lactose Signup and view all the answers

What is the term given to the bond that links two monosaccharides together?

Glycosidic bond Signup and view all the answers

What is the name of the simplest carbohydrate that exhibits chirality?

Glyceraldehyde Signup and view all the answers

What is the term used to describe the D and L isomers of glyceraldehyde?

Enantiomers Signup and view all the answers

What is the term used to describe a sugar with five carbon atoms?

Pentose Signup and view all the answers

What is the term used to describe a carbon atom that has four different groups bonded to it?

Chiral carbon Signup and view all the answers

What is the type of bond formed when an anomeric -OH group reacts with another -OH group on an alcohol or sugar?

Glycosidic bond Signup and view all the answers

Which of the following is NOT a reducing sugar?

Sucrose Signup and view all the answers

What is the name of the reagent used to test for reducing sugars?

Benedict's reagent Signup and view all the answers

What is the term for the process by which lactose is broken down into glucose and galactose?

Hydrolysis Signup and view all the answers

Which of the following is an example of a heteropolysaccharide?

Heparin Signup and view all the answers

What is the name of the disease resulting from the inability to convert galactose to a phosphorylated glucose molecule?

Galactosemia Signup and view all the answers

Which of the following is NOT a type of sugar?

Protein Signup and view all the answers

What is the term for the process by which monosaccharides are linked together?

Dehydration synthesis Signup and view all the answers

Which of the following is a characteristic of amylose?

Linear, with 1,4 glycosidic linkages Signup and view all the answers

What is the term for the carbohydrates found in plant cell walls?

Cellulose Signup and view all the answers

What is the main function of glucose in the body?

To act as a source of energy Signup and view all the answers

What is the general term for carbohydrates composed of three to seven carbon atoms?

Monosaccharides Signup and view all the answers

What is the name of the bond that links two monosaccharides together?

Glycosidic bond Signup and view all the answers

What percentage of daily calories does the USDA recommend come from carbohydrates?

45-65% Signup and view all the answers

What is the term for carbohydrates composed of multiple linked monosaccharides?

Polysaccharides Signup and view all the answers

What is the basic formula for monosaccharides?

(CH2O)n Signup and view all the answers

What is the term for a single sugar molecule?

Monosaccharide Signup and view all the answers

What is the energy produced from one gram of digested carbohydrate?

4 kcal Signup and view all the answers

What is the term for carbohydrates that are best for the diet?

Complex carbohydrates Signup and view all the answers

What is the process by which plants synthesize carbohydrates?

Photosynthesis Signup and view all the answers

What is the type of carbohydrate that has six carbon atoms in its main skeleton?

Hexose Signup and view all the answers

What is the term for a carbon atom with four different groups bonded to it?

Chiral carbon Signup and view all the answers

What is the name of the simplest carbohydrate that has a chiral carbon and exists as a pair of enantiomers?

Glyceraldehyde Signup and view all the answers

How do the two isomers of glucose differ from each other?

They have different locations of the –OH on the hemiacetal carbon Signup and view all the answers

What is the name of the projection formula used to represent bonds in a Fischer projection?

Fischer projection Signup and view all the answers

What is the name of the process by which glucose is regulated in the blood?

Insulin and glucagon regulation Signup and view all the answers

What is the term for a molecule that has nonsuperimposable mirror images?

Enantiomer Signup and view all the answers

What is the type of carbohydrate that has five carbon atoms in its main skeleton?

Pentose Signup and view all the answers

What is the term for the bond that forms between two monosaccharides?

Glycosidic bond Signup and view all the answers

What is the name of the cyclic form of glucose?

Cyclic hemiacetal Signup and view all the answers

What is the significance of the reaction between Benedict's reagent and an aldose?

To oxidize the aldehyde group of aldoses Signup and view all the answers

Which sugar can isomerize to form an aldose via an enediol reaction?

Fructose Signup and view all the answers

What is the linkage between the two glucose molecules in maltose?

α-1,4 glycosidic bond Signup and view all the answers

What is the function of lactase in the human body?

To break down lactose into glucose and galactose Signup and view all the answers

What is the structural difference between ribose and deoxyribose?

The absence of an –OH group on C-2 Signup and view all the answers

What is the term for a polymer of monosaccharides?

Polysaccharide Signup and view all the answers

Which sugar is commonly found in honey and corn syrup?

Fructose Signup and view all the answers

What is the term for the process by which glycogen is broken down into glucose?

Glycogenolysis Signup and view all the answers

What is the characteristic of the anomeric -OH group in disaccharides?

It can react with another -OH group on an alcohol or sugar Signup and view all the answers

Why is lactose intolerance a problem?

Because the enzyme lactase is necessary to break down lactose Signup and view all the answers

Study Notes

Carbohydrates

Carbohydrates are synthesized by photosynthesis in plants
Examples: grains, cereals, bread, sugar cane
Glucose is a major energy source, providing about 4 kcal of energy per gram

Monosaccharides

Monosaccharides are single sugar molecules, also called simple sugars
Composed of carbon, hydrogen, and oxygen, with the basic formula (CH2O)n, where n is an integer between 3 and 7
Examples: glucose (blood sugar), fructose (fruit sugar), and galactose
Classified based on functional groups and number of carbon atoms in the main skeleton
- Ketone carbonyl: ketose
- Aldehyde carbonyl: aldose
- Number of carbon atoms:
  - 3 carbons: triose
  - 4 carbons: tetrose
  - 5 carbons: pentose
  - 6 carbons: hexose

Enantiomers and Chirality

Enantiomers: nonsuperimposable mirror images
Chirality: a carbon atom with four different groups bonded to it is called a chiral carbon atom
Any molecule containing a chiral carbon can exist as a pair of enantiomers
Chirality in glyceraldehyde is conveyed by a chiral carbon
Larger biological molecules often have more than one chiral carbon

Biological Monosaccharides

Glucose is the most important sugar in the human body
Found in many foods, with common names including dextrose and blood sugar
Concentration in the blood is regulated by insulin and glucagon
Exists in a cyclic hemiacetal form under physiological conditions
Two isomers are formed, differing in the location of the -OH on the acetal carbon, C-1
An aldohexose with molecular formula C6H12O6
Cyclic form is shown as a Haworth projection

Disaccharides

Examples: sucrose, lactose, and maltose
Formed by linking two monosaccharides together
Linkage is called a glycosidic bond
Water is lost to form an acetal

Polysaccharides

Examples: starch, glycogen, and cellulose
Chains of linked monosaccharide units
Homopolysaccharides: composed of one type of monosaccharide
Heteropolysaccharides: made up of two or more different monosaccharides

Starch

Storage polymers of α-linked glucose found in plants
If the links are only 1,4 links, the polymer is linear = amylose
Comprises about 80% of plant starch
Both 1,4 and 1,6 links = amylopectin, highly branched with branches of approximately 20-25 glucose units

Glycogen

The major glucose storage carbohydrate in animals
A highly branched chain polymer like amylopectin
More frequent branching – 10 monomers
Stored in liver and muscle cells

Cellulose

The major structural polymer in plants
A linear homopolymer composed of β-D-glucose units linked β-1,4
The repeating disaccharide of cellulose is β-cellobiose
Animals lack the enzymes necessary to hydrolyze cellulose### Sugars
Fructose is also known as levulose or fruit sugar, and is found in honey, corn syrup, and fruits.
Fructose is the sweetest sugar and is a ketohexose.
Galactose is the principal sugar found in mammalian milk, and is an aldoheptose very similar to glucose.

Structure of Sugars

Glucose and galactose differ only in the orientation of one hydroxyl group.
Ribose is a five-carbon sugar and is an aldopentose, found in many biologically important molecules.
Deoxyribose is similar to ribose, but lacks a hydroxyl group on C-2.

Benedict's Reagent

Benedict's reagent is an alkaline Cu2+ solution that oxidizes the aldehyde groups of aldoses.
The reaction causes the blue color of the reagent to fade, and a red-orange precipitate forms as Cu2O.

Reducing Sugars

All monosaccharides and disaccharides except sucrose are reducing sugars.
Ketoses can isomerize to aldoses via an enediol reaction.

Biologically Important Disaccharides

Maltose is formed by linking two D-glucose molecules to give a 1,4 glycosidic linkage.
Lactose is formed by joining β-D-galactose to D-glucose to give a β-1,4-glycoside.
Sucrose is formed by linking α-D-glucose with β-D-fructose to give a 1,2 glycosidic linkage.

Polysaccharides

Homopolysaccharides are composed of one type of monosaccharide, while heteropolysaccharides are made up of two or more different monosaccharides.
Starch is a storage polymer of α-linked glucose found in plants, and can be linear (amylose) or branched (amylopectin).
Glycogen is a highly branched chain polymer similar to amylopectin, and is the major glucose storage carbohydrate in animals.
Cellulose is a linear homopolymer composed of β-D-glucose units linked β-1,4, and is the major structural polymer in plants.

Glycogen and Amylopectin Structures

Glycogen and amylopectin are α(1-4) chains with α(1-6) branches.

Cellulose

The repeating disaccharide of cellulose is β-cellobiose.
Animals lack the enzymes necessary to hydrolyze cellulose, but the bacteria in ruminants can digest cellulose.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge of carbohydrates, including their synthesis, types, and importance in our diet. Learn about monosaccharides, disaccharides, and daily calorie recommendations.