Polysaccharides

What is the definition of a polysaccharide?

Polymers containing many monosaccharides linked by glycosidic bonds

How are polysaccharides formed?

Formed by condensation reactions

What is starch made from?

Many alpha glucose molecules

What are the two types of starch?

• amylose (20 percent of starch)

• Amylopectin (80 percent of starch)

What is the structure of amylose?

A linear helix

What is the structure of amylopectin

Branched starch

What are some characteristics of amylopectin?

• highly branched

• Can be hydrolysed more quickly than amylose

• Plants store it then hydrolyse it for energy supply

What are the bonds in amylopectin?

Alpha glucose molecules joined by 1-4 glycosidic bonds with a 1-6 branches every 20 to 30 monomers

What is the main use of starch?

• major carbohydrate storage in plants

How is starch usually stored in plants?

As intracellular starch gains in organelles called plastids

what are the main uses of starch in plants?

produced from glucose during photosynthesis and is broken down during respiration and also used as a source of carbon for other molecules

which is the most abundant organic polymer?

cellulose

which is strong, starch or cellulose?

cellulose

what is the structure of cellulose?

long chains of beta glucose molecules joined by 1-4 glycosidic bonds

properties of cellulose:

• main structural sugar in plants

• structural component of plant cell walls

• very strong

• permeable to numerous substances

• 33% of plant matter

• most common organic compound on earth

why is cellulose unable to coil or make branches?

because the only way for beta glucose to join in a chain is if every alternate beta glucose is upside down

what is the difference between glycogen and amylopectin?

glycogen has the same subunits but is much more branched

features of glycogen:

• storage sugar found in animals

• made mostly by the liver and muscles

• stored as granules in the cytoplasm of cells

• can be quickly hydrolysed when energy supply needed

which is less dense and more soluble: glycogen or starch

glycogen

what does the fact that glycogen can be broken down more rapidly than starch show?

indicates a higher metabolic requirement of animals compared to plants