2.2.3 carbohydrates

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What is an isomer?

where a molecule has two different forms- same chemical formula but different structures (glucose)

What is an OH group known as?

hydroxyl group

What are the two isomers of glucose?

(Alpha)α-glucose and (Beta)β-glucose

Whats the difference between α-glucose and β-glucose?

In α-glucose the OH group at carbon 1 points below the ring whereas in β-glucose, the OH group points above the ring

Whats the structure of glucose?

What are examples of carbohydrates?

sugar and starch

Whats the formula for glucose?

C₆H₁₂O₆

What are the only elements carbohydrates contain?

carbon, hydrogen and oxygen

What are monosaccharides with 6 carbon atoms called? Whats an example?

hexose monosaccharides - glucose

Whats a monosaccharides?

singles sugar molecules

What are exampes of monosaccharides?

fructose, galactose and glucose

What does a molecule being hydrophillic mean?

they dissolve in water

Whats the solubility of glucose like? Why is it useful?

Its structure makes it very soluble because its the main energy source in animals and plants so needs to be easily transported

What are monosaccharides with 5 carbon atoms called? Whats an example?

pentose monosaccharides - ribose

Whats the stucture of ribose?

What happens when a disaccharide is formed?

two monosaccharides are joined together by glycosidic bonds in a condensation reaction - during synthesis a hydrogen atom on one monosaccharide bonds to a hydroxyl group on the other, releasing a water molecule

what happens when disaccharides are broken down?

the reverse of the synthesis reaction is through a hydrolysis reaction- a water molecule reacts with the glycosidic bond, breaking it apart

what happens when two a-glucose molecules form a disaccharide?

they are joined together by a glycosidic bond to form maltose

when is the disaccharide sucrose formed?

when a-glucose and fructose join together

when is the disaccharide lactose formed?

when galactose and either a/b glucose join together

when does a polysaccharide form?

when more than two monosaccharides join together

what happens when many a-glucose join to form a polysaccharide?

they are joined together by glycosidic bonds to form amylose

what are 3 examples of polysaccharides?

starch, glycogen and cellulose

What is the main energy storage material in plants?

starch

How do glucose and starch link within plants?

plant cells get energy from glucose and plants then store excess glucose as starch for when they need more(starch gets broken down into glucose again)

Why is starch good for storage?

its insoluble in water =doesnt cause water to enter cells by osmosis which would make them swell

glucose is soluble so gets stored as starch

what polysaccharides is starch a mixture of? What are they formed from?

amylose and amylopectin - formed from alpha glucose

Whats the structure of amylose like?

long UNbranched chain of a-glucose linked by 1,4 glycosidic bonds

Why is the structure of amylose good for storage?

the angles of the glycosidic bonds = coiled structure almost cylinder like = makes it compact= good for storage as can fit more in to a small space

Whats the structure of amylopectin like?

long branched chain of a-glucose linked by 1,4 and 1,6(branches) glycosidic bonds

Why is the structure of amylopectin good for releasing glucose quickly?

side branches = allow enzymes to break down the glycosidic bonds easily = glucose released quickly

How do you test for starch?

iodine solution= turns from orange/brown to blue/black

What is the main energy(glucose) storage material in animals?

glycogen

What is the structure of glycogen like?

highly branched chain of alpha glucose units linked by 1,4 and 1,6 (branches) glycosidic bonds

How is glycogen good for storage?

loads of branches=stored glucose can be released quickly as glycosidic bonds can be broken easier

very compact molecule= more can fit in to a small place easier

Why is glycogen more branched than starch?

animals are more metabolically active than plants so they need more glucose readily for glycolysis

What is the major component for cell walls in plants?

cellulose

Whats the structure of cellulose like?

long straight UNbranched chains of beta glucose linked by 1,4 glycosidic bonds

How are cellulose chains linked together?

via hydrogen bonds

What do many cellulose chains linked together create?

microfibrils (strong fibres)

What is the function of microfibrils(strong fibres) in cellulose?

means cellulose provides strong structural support for cells (eg plant cell walls)