Biological molecules- Topic 2

Question 1

What are the main elements in biological molecules

Answer 1

• carbon
• hydrogen
• oxygen
• nitrogen - CHON

may include
- phosphorus
- sulfur

Question 2

What are monomers? and examples

Answer 2

• simplest repeating unit of a polymer
• monosaccharides
• amino acids
• nucleotides
  (fatty acids and glycerol are NOT monomers

Question 3

What are polymers

Answer 3

• monomers are joined end to end by polymerization
• usually condensation in the body
• are considered macromolecules

Question 4

polymerisation

Answer 4

condesation
two molecules combine, removal of water

hydrolysis
- break down using water
- usually dilute hydrochloric acid is used- water breaks down, h+ ions catalyze

Question 5

Carbohydrates

Answer 5

• made of C,H,O
• general formula Cx(H2O)y

Question 6

roles of carbohydrates

Answer 6

• source of energy in respiration
  C-H bonds–> energy–> ATP
• building block for larger molecules eg: RNA, DNA, ATP, glycoproteins, glycolipids
• structural support

Question 7

Monosaccharide

Answer 7

• single sugar molecule
• soluble, sweet
• molecular formula- Cn(H2O)n
  Triose(3C) , pentose (5C) and hexose (6C)

Question 8

Why do ring structures exist

Answer 8

• in pentose and hexose sugars, hains of carbon are long enough to close up itself
• the ring structure is more stable and more common

Question 9

Drawing straigth chain structures

Answer 9

• use right hand law
  bottom three OH on the right
• the alternate
  Carbon 1 has the oxygen double bond

Question 10

Drawing the ring structure

Answer 10

• Ring forms between carbon 1 and 5
• makes a hexagon shape
• carbon 6 emitted from hexagon
• OH on carbon 4 should always be below the plane

Question 11

Why does excess glucose need to be stored as starch and glycogen?

Answer 11

Glucose is:
soluble- decreases water potential of cell causing water to move in and cell to burst (starch and glycogen are insoluble)
reactive- interferes with other reactions in the cell (starch and glycogen are inert)
starch and glycogen are compact and so lare quantity of energy is released when hydrolysed.
- glucose can be mobilised quickly.

Question 12

cellulose- function

Answer 12

• structural role in plant cells
• high tensile strength
• prevents cell bursting
• helps withstand turgor pressure
• fully permeable

Question 13

cellulose- structure

Answer 13

• made of beta glucose
• alternating molecules rotated 180 degrees.
• 1-4 glycosidic bonds.
• unbranched, straight chains that lie parallel to each other
• hydrogen bonds from between cellulose molecules (many OH groups in cellulose)
• forms microfibrils and fibres
• fibres are arrabged in criss- cross manner 9many gaps between fibres make it fully permeable)