Biological molecules

Question 1

. How does the composition of N-acetylglucosamine differ from the composition of a monosaccharide
sugar?

Which monosaccharide sugar does N-acetylglucosamine most closely resemble?

Answer 1

.it contains a nitrogen

.beta glucose

Question 2

Using your knowledge of the formation of structural polysaccharides, describe the formation of the chitin
molecule from its monomer and predict its structure

Answer 2

.glycosidic bonds are formed by condensation
.water is released
.alternate monomers are flipped
.forms a straight chain
.similar to cellulose

Question 3

Name the carbohydrate molecules used to store energy in plants and animals

Answer 3

starch
glycogen

Question 4

Describe and explain how the structure and properties of different carbohydrate and lipid molecules suit
them to their role as energy storage molecules in plants and animals.

Answer 4

Carbohydrates:
.polymers of glucose which is used in resp to release energy
.large molecule = insoluble = dont effect water potential of cell
.have 1-4 glycosidic bonds = easy to break to release monomers
.compact = takes up less space
.amylose unbranched/amylopectin with few branches = no need for rapid release of monomers in plants
.glycogen more branched = allows rapid release of monomers in animals

Lipids:
.more C-C bonds = energy rich = more energy stored in less space
.insoluble = dont effect water potential of cell
.animal fats are saturated = harder = good for protection/insulation and energy storage

Question 5

State two ways in which the molecular structure of cholesterol is similar to the molecular structure of
glucose

Answer 5

.both contain CHO atoms and have OH groups

Question 6

State the physical property of glucose that allows it to be easily transported in the bloodstream.

Answer 6

soluble in water

Question 7

Explain why mammals store glycogen instead of glucose

Answer 7

.insoluble = no effect on WP
.metabolically inactive
.lots stored in a small space
.stores lots of energy
.highly branched = break down quickly

Question 8

State two other structural similarities between lactose and maltose.

Answer 8

.2, 6 membered rings
.1-4 glycosidic bonds
.two CH2OH groups

Question 9

differences between the structures of lactose and maltose.

Answer 9

.Lactose:
.glucose + galactose
.has B glucose
.beta glycosidic bonds
.monomers are flipped

Maltose:
.glucose + glucose
.has A glucose
.alpha glycosidic bonds
.monomers arent flipped

Question 10

Explain how the structure of galactose allows it to be used as a respiratory substrate.

Answer 10

.bonds contains energy and are broken down by enzymes
.soluble so can move within the cell
.can from H bonds with water

Question 11

Give three properties of cellulose that make it suitable as the basis of plant cell walls

Answer 11

insoluble
inert
high tensile strength
.flexible
.forms H bonds

Question 12

Using information from Fig. 19.2, state two similarities and two differences between the structures of chitin and
glycogen

Answer 12

similar:
.both have C6 sugars
.1-4 glycosidic bonds
.have CH2OH side group

Diferences:
.chitin has beta glycosidic bonds
.chitin contain nitrogen

Question 13

Explain how the structure of glycogen differs from that of amylopectin to make it better suited as an
energy store in animals.

Answer 13

.glycogen is more branched
.more coiled
.more compact

Question 14

Describe the differences between the structures of callose and cellulose.

Answer 14

.callose has 1-3 and 1-6
.is branched