[bio] biological molecules Flashcards

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1
Q

definition of condensation reaction

A

chemical reaction whereby 2 or more simple molecules are joined together to form a larger biological molecule with the removal of water

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2
Q

definition of hydrolysis

A

splitting up of a complex biological molecules into its component units with the addition of water

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3
Q

bond formed during condensation reaction?

A

glycosidic bond

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4
Q

elements of carbohydrates

A

carbon, hydrogen, oxygen

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5
Q

special thing about elements present?

A

ratio of hydrogen atoms to oxygen atoms is 2:1

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6
Q

3 main groups of carbohydrates

A

monosaccharides, disaccharides, polysaccharides

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7
Q

examples of monosaccharides

A

glucose, fructose, galactose

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8
Q

properties of monosaccharides

A
  • generally sweet-tasting
  • soluble in water (able to lower water potential in cells)
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9
Q

why do we not store glucose in our bodies?

A

glucose is a monosaccharide, soluble in water, will lower the water potential of our cells, cells will burst when too much water enters

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10
Q

what happens to excess glucose in our bodies?

A

excess glucose goes through condensation reaction to form glycogen, which is insoluble in water

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11
Q

examples of disaccharides & their monomers

A
  1. maltose - glucose + glucose
  2. lactose - glucose + galactose
  3. sucrose - glucose + fructose
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12
Q

types of polysaccharides and their examples and where they are found

A

storage polysaccharides (starch in plants and glycogen in animals) and structural polysaccharides (cellulose in plants)

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13
Q

why are starch and glycogen suitable as storage polysaccharides

A
  1. insoluble in water, won’t affect water potential of cells
  2. compact, take up less space than individual glucose molecules that make up a glycogen/starch molecule
  3. too large to diffuse through the cell membrane, hence they will stay in the cell
  4. easily hydrolysed when needed
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14
Q

structure of starch and glycogen

A

starch - long straight chains (amylose) or branched chains (amylopectin)
glycogen - highly branched chains

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15
Q

how are storage polysaccharides formed

A

condensation reaction of large numbers of glucose molecules

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16
Q

structure of structural polysaccharides

A

can be in long straight/branched chains

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17
Q

properties of cellulose

A
  1. insoluble in water
  2. structure is rigid
    - provide mechanical support for the plant
    - able to resist expansion when water enters by osmosis
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18
Q

functions of carbohydrates

A
  1. forms lubricants like mucus
  2. forms nectar
  3. deoxyribose sugar/ribose sugar are used in the formation of nucleic acids like DNA
  4. glucose is a substrate of respiration
  5. cellulose forms the supporting structure of plants
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19
Q

elements that make up lipids

A

carbon, hydrogen, oxygen

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20
Q

number of oxygen as compared to hydrogen and carbon

A

much less oxygen as compared to carbon and hydrogen

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21
Q

example of lipids

A

triglycerides and phospholipids

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22
Q

properties of lipids

A

insoluble in water, but soluble in organic solvents like alcohol

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23
Q

what makes up a triglyceride

A

3 molecules of fatty acids and 1 molecule of glycerol

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24
Q

what are fatty acids

A

a long hydrocarbon chain that has a carboxyl functional group (COOH)

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25
Q

difference between saturated and unsaturated fatty acids?

A

saturated: absence of carbon-carbon double bonds
unsaturated: presence of 1 or more carbon-carbon double bonds

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26
Q

properties of fatty acids

A
  • hydrophobic (do not mix well with water)
  • uncharged
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27
Q

composition of glycerol

A

C3H8O3

28
Q

what is glycerol?

A

an alcohol

29
Q

properties of glycerol

A
  • generally sweet-tasting
  • colourless
30
Q

how are triglycerides formed?

A

condensation reaction of 3 molecules of fatty acids and 1 molecule of glycerol, removal of 3 water molecules

31
Q

bond between 1 fatty acid and glycerol?

A

ester bond

32
Q

how does ester bond look like? (draw)

A

O
ll
O - C

33
Q

properties of triglycerides

A

compact
insoluble in water

34
Q

functions of triglycerides

A
  1. energy storage
  2. buoyancy in aquatic animals
  3. important component of myelin sheath
  4. protective layer
  5. heat insulator
  6. produces metabolic water
  7. solvent
35
Q

why energy storage?

A

contains more carbon-hydrogen bonds per gram than starch/glycogen
1 gram of triglyceride has about twice as much as energy as 1 gram of carbohydrates
light weight energy store —> has about 1/2 the mass of carbohydrates for an equivalent amount of energy stored

36
Q

where to use as energy storage? (triglyceride)

A
  1. oil in seeds in plants for them to travel far in the air
  2. fats in mammals
    - mammals have specialised cells to store fats under their skin
    - cells are grouped together to form adipose tissue
    - hibernating animals store fats as food reserve
37
Q

why heat insulator? (triglycerides)

A

fats conduct heat slowly, excellent heat insulator against heat loss from deeper regions of the body to the outside

38
Q

where to use as heat insulator? (triglycerides)

A

huge and thick blubber in polar bears and whales

39
Q

why buoyancy in aquatic animals? (triglycerides)

A

triglycerides less dense than water

40
Q

where to use buoyancy? (triglycerides)

A

large animals that live in cold seas like whales and seals, they often have very thick layer of blubber

41
Q

why protective layer? (triglycerides)

A

ability to absorb shock

42
Q

where to use as protective layer? (triglycerides)

A

surrounding delicate and vital organs like heart and kidney

43
Q

why important component of myelin sheath?

A

act as electrical insulator to allow rapid transmission of electrical impulses along myelinated neurons

44
Q

where as important component of myelin sheath? (triglycerides)

A

nerve cells

45
Q

why provides metabolic water? (triglycerides)

A

triglycerides release twice as much water as carbohydrates when oxidases during respiration, because have more hydrogen atoms than carbohydrates, hence a better source of metabolic water

46
Q

where as metabolic water? (triglycerides)

A

important for animals like camels and kangaroos that live in the hot and dry desert where water is scarce

47
Q

why as a solvent?

A

solvent for fat-soluble vitamins A, D, E, K and other vital substances like hormones

48
Q

structure of phospholipids

A

2 molecules of fatty acids (one saturated and one unsaturated)
1 molecule of glycerol
1 phosphate group

49
Q

function of phospholipids

A

major component of biological membranes (made up of 2 layers of phospholipids - phospholipids bilayer)

50
Q

elements in protein

A

carbon, hydrogen, oxygen and nitrogen

51
Q

what happens when proteins are heated?

A

weak bonds in proteins are broken, proteins are denatured, and loses its 3d shape

52
Q

what are amino acids?

A

monomers of proteins

53
Q

how many naturally occurring amino acids are there?

A

20

54
Q

structure of amino acid?

A

every amino acid molecule has a central carbon atom bonded covalently to 4 groups

55
Q

what are the 4 groups the amino acid molecule is bonded to?

A
  • at least one amino group (NH2)
  • a carboxyl group (COOH)
  • a hydrogen atom (H)
  • a variable group (the R group/the side chain)
56
Q

structure of the amino acid? (draw out)

A

H R O
l l ll
N - C - C
l l l
H H OH

57
Q

formation of polypeptide

A

amino acids undergo condensation reaction, forms peptide bond after removing water molecules, forms polypeptide

58
Q

formation of proteins?

A

polypeptide chain folds into a particular 3D shape as a result of 4 other types of bonds
- disulfide bonds/bridges
- ionic bonds
- hydrogen bonds
- hydrophobic interactions

59
Q

functions of proteins?

A
  • synthesis of new cells
  • biological catalysts
  • chemical messenger
  • transport proteins
  • structural proteins
  • defence of body
  • source of energy during starvation
60
Q

how synthesis of new cells?

A

for growth and repair of new cells

61
Q

how biological catalysts?

A

enzymes to speed up rate of chemical reactions

62
Q

how as chemical messengers?

A

hormones such as insulin to stimulate target organs to perform a certain function

63
Q

how as transport proteins?

A

haemoglobin to transport oxygen in red blood cell

64
Q

how as structural proteins?

A

collagen is a component of skin and bones
keratin is a component of hair, nails and feathers

65
Q

how as defence of body?

A

antibodies used to help fight infections in the body

66
Q

how as source of energy during starvations?

A

oxidised after all the carbohydrates and lipids are used up