38 Questions
What is the primary function of liver glycogen?
To maintain blood glucose levels
What is the difference between glycogen and amylopectin?
Glycogen has more branching points, while amylopectin has fewer branching points
What is the ratio of glycogen in muscle to glycogen in liver?
3:1
What is the storage form of glucose in plants?
Starch
What type of bonds link glucose units in glycogen?
α-1,4 glycosidic bonds
What is the term often used to refer to glycogen?
Animal starch
What type of bond is formed at the branch points in glycogen?
Alpha-1,6 glycosidic bond
What is the primary function of cellulose in plants?
Structural support
What is the monomer unit of cellulose?
Beta glucose
What is the difference between alpha-1,4 and alpha-1,6 glycosidic bonds in glycogen?
The location of the bond in the glycogen molecule
What is the function of inulin in plants?
Energy storage
What is the difference between cellulose and chitin?
The location in the organism
What is the molecular structure of glycogen?
A branched chain of glucose molecules
What is the function of glycogen in animals?
Energy storage
What type of bonds are present in cellulose?
β-1,4-glycosidic bonds
What is the function of chitin in insects?
Protection and support
Why is cellulose indigestible to humans?
Because humans cannot break down β-1,4-glycosidic bonds
What is the monomer unit of chitin?
N-acetylglucosamine
What is the significance of microorganisms in the gut of ruminant animals?
They break down cellulose
What is the location of chitin in insects?
Exoskeleton
What type of glycosidic bonds are present in chitin?
β-1,4-glycosidic bonds
Where can the breakdown of cellulose occur in humans?
Large intestine
What is the characteristic of a reducing sugar?
Possessing a free anomeric carbon not involved in a glycosidic linkage
Which of the following disaccharides has no reducing properties?
Sucrose
What is the characteristic of an oligosaccharide?
A saccharide polymer containing a small number of simple sugars
Which of the following is an example of a polysaccharide?
Dextrin
What is the type of glycosidic bond found in maltose?
α- (1→4) glycosidic bond
What is the function of reducing sugars?
They reduce Benedicts solution and Fehlings solution
What is the characteristic of a non-reducing sugar?
It has no reducing properties
What is the significance of oligosaccharides in ABO blood type specificity?
They are responsible for the ABO blood type specificity
What is the characteristic feature of polysaccharides that distinguishes them from monosaccharides?
They are composed of more than 10 monosaccharide units
What is the term for polysaccharides composed of a single monosaccharide building block?
Homopolysaccharides
Which of the following polysaccharides is a structural element in the exoskeletons of insects?
Chitin
What is the approximate percentage of amylopectin in starch?
80-85%
What type of bonds are present between glucose units in amylopectin?
α-1,4 glycosidic bonds and α-1,6 glycosidic bonds
What is the function of starch in plants?
Storage form of glucose
Which of the following is a characteristic of amylose?
Long unbranched chain of glucose units
What is the difference between starch and glycogen in terms of branching?
Starch has a much lower degree of branching
Study Notes
Disaccharides
- Disaccharides are formed by joining two monosaccharides with a glycosidic linkage.
- Examples of disaccharides include:
- Maltose (malt sugar) = glucose + glucose
- Sucrose (table sugar) = glucose + fructose
- Lactose (milk sugar) = glucose + galactose
- Sucrose has no reducing properties due to the lack of a free anomeric carbon.
Reducing Sugars
- Reducing sugars are capable of reducing Benedict's solution, which is an alkaline cupric solution.
- A sugar is a reducing sugar if it possesses a free anomeric carbon.
- Examples of reducing sugars include:
- All monosaccharides
- Disaccharides: maltose, lactose
- Examples of non-reducing sugars include:
- Sucrose
Oligosaccharides
- Oligosaccharides are saccharide polymers containing a small number (typically three to ten) of simple sugars (monosaccharides).
- Examples of oligosaccharides include:
- Maltotriose (3 glucose units, α-1,4 linkage)
- Dextrin (6-8 glucose units)
- Oligosaccharides also occur in glycoproteins and glycolipids, which are proteins and lipids to which oligosaccharides are covalently attached.
Polysaccharides
- Polysaccharides are high molecular weight polymers composed of more than 10 monosaccharide units linked together.
- Polysaccharides are insoluble in water.
- Polysaccharides can be polymers of hexose or pentose sugars.
- Homopolysaccharides are composed of a single monosaccharide building block, while heteropolysaccharides are composed of more than one type of monosaccharide.
- Polysaccharides can be linear or branched polymers.
- Examples of homopolysaccharides include:
- Starch (storage form of glucose in plants)
- Glycogen (storage form of glucose in animals)
- Cellulose (structural element of plants)
- Chitin (structural element in the exoskeletons of insects)
- Inulin (found in roots of some plants)
Starch
- Starch is a storage polysaccharide in plants composed of alpha glucose.
- Its structure is identical to glycogen, except for a much lower degree of branching (every 20-30 residues).
- Starch consists of two types of molecules:
- Unbranched chains called amylose (15-20%)
- Branched chains called amylopectin (80-85%)
- Amylose is a continuous, unbranched chain of glucose units linked by α-1,4 glycosidic bonds.
- Amylopectin is a branched-chain polysaccharide with α-1,4 glycosidic bonds between the glucose units and α-1,6 bonds to branches.
Glycogen
- Glycogen is the storage form of glucose in animals.
- It is stored in the liver and muscle.
- Glycogen is a homopolymer of glucose in α-1,4 linkage.
- It is highly branched, with α-1,6 branch linkages occurring every 8-11 residues.
- Glycogen has the same overall structure as amylopectin but with more branching in the molecule.
- Glycogen is a very compact structure that results from the coiling of the polymer chains.
Structural Polysaccharides
- Cellulose is a structural polysaccharide in plants composed of beta glucose units.
- It is a major constituent of plant cell walls and provides structure and support.
- Cellulose is indigestible to humans because it cannot be broken down by human enzymes.
- Chitin is a structural polysaccharide in the exoskeletons of insects, providing protection and support.
- It is a polymer of N-acetylglucosamine units linked by β-1,4 glycosidic bonds.
- Inulin is a structural polysaccharide found in the roots of some plants.
Learn about disaccharides, a type of carbohydrate formed by two simple sugars joined together. This quiz covers maltose, sucrose, and lactose, including their composition and properties.
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