biological molecules - 3.12 (carbohydrates)

Question 1

what is a monomer?

Answer 1

monomers are the smaller units from which larger molecules are made

Question 2

what is a polymer?

Answer 2

molecules made from a large number of monomers joined together

Question 3

name 3 examples of monomers

Answer 3

monosaccharides, amino acids, nucleotides

Question 4

what is a condensation reaction?

Answer 4

joining of two molecules, with the formation of a chemical bond and involves the elimination of a molecule of water

Question 5

what is a hydrolysis reaction?

Answer 5

breaks a chemical bond between two molecules and involves the use of a water molecule

Question 6

what are monosaccharides?

Answer 6

the monomers from which larger carbohydrates are made

Question 7

name 3 common monosaccharides

Answer 7

glucose, fructose, galactose

Question 8

what is maltose?

Answer 8

a disaccharide formed by the condensation of two glucose molecules

Question 9

what is sucrose?

Answer 9

a disaccharide formed by condensation of a glucose monomer and a fructose molecule

Question 10

what is lactose?

Answer 10

a disaccharide formed by condensation of a glucose molecule and a galactose molecule

Question 11

what polysaccharides are formed from the condensation of alpha-glucose?

Answer 11

starch, glycogen

Question 12

what polysaccharide is formed from the condensation of beta-glucose?

Answer 12

cellulose

Question 13

what is the structure of a starch molecule?

Answer 13

Chains may be branched or unbranched. Unbranched chain wound into a tight helix shape, making it very compact. Made up of alpha-glucose monosaccharides linked by glycosidic bonds (1-4) formed by a condensation reaction. Branched form has 1-4 and 1-6 alpha-glucose glycosidic bonds. Consists of amylose and amylopectin.

Question 14

What is the main role of starch?

Answer 14

storage of glucose/energy

Question 15

how is the starch structure suited to its function?

Answer 15

-insoluble - doesn’t affect water potential, so water is not drawn into cell by osmosis
- large and insoluble - doesn’t diffuse out of cells
- compact - a lot can be stored in a small space
-when hydrolysed. alpha-glucose is formed which is easily transported and readily used in respiration
-branched form has many ends - each of which can be acted on by enzymes simultaneously meaning glucose monomers are released very rapidly

Question 16

what is the structure of glycogen?

Answer 16

highly branched - alpha-glucose molecules joined by alpha 1-4 glycosidic bonds and alpha 1-6 branches every 20-30 monomers.

Question 17

what is the function of glycogen?

Answer 17

• main carbohydrate storage of glucose in animal cells.

Question 18

how is the structure of glycogen related to its function?

Answer 18

• insoluble - does not tend to draw water into cells by osmosis and doesn’t diffuse out of cells
  -compact - a lot stored in a small space
• ## more highly branched than starch - has more ends that can be acted on simultaneously by enzymes. This rapidly releases glucose monomers, which are used in respiration. Useful as animals are more active than plants and therefore have a higher metabolic rate and therefore higher respiratory rate.

Question 19

what is the structure of cellulose?

Answer 19

straight unbranched chains, joined by 1-4 beta-glucose glycosidic bonds
- these chains run parallel to each other, allowing hydrogen bonds to form cross-links between adjacent chains. The sheer overall number of hydrogen bonds adds collective strength to the molecule, making it the valuable structural material that it is.
- these molecules join together to form microfibrils which in turn are grouped together to form fibres all of which provides yet more strength.

Question 20

what is the function of cellulose?

Answer 20

main structural component of cell walls