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biological molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

define inorganic

A

charged particles of elements or their compounds such as potassium ions or nitrate ions

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2
Q

define organic molecules

A

substances containing carbon hydrogen oxygen - required by all living cells

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3
Q

define dipole

A

a molecule with a positive and negative charge, seperated by a very short distance

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4
Q

define hydrogen bond

A

an attractive force between a slight negative charge on one atom

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5
Q

define cohesion

A

the attractive force that holds water molecules together by hydrogen bonding

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6
Q

define specific heat capacity

A

the energy required to raise the temperature of a substance

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7
Q

define latent heat of vaporisation

A

the energy required to convert a liquid into a vapour

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8
Q

define isomer

A

molecules that have the same chemical formula but a different arrangement of atoms

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9
Q

define condensation reaction

A

a reaction in which 2 molecules are linked together by a bond, involving the elimination of water

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10
Q

define hydrolysis

A

a reaction that involves breaking of a bond, involving the chemical insertion of water

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11
Q

define hydrophilic

A

these are polar molecules or charged ions that can interact with water molecules because of their change

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12
Q

define hydrophobic

A

these are non-polar molecules or uncharged ions that cannot interact with water molecules because they have no charge

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13
Q

define saturated fat

A

a fat in which there are no double bonds between carbon atoms

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14
Q

define unsaturated fat

A

a fat in which there is at least one double bond between carbon atoms

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15
Q

define disulphide bond

A

a covalent bond formed between two sulphur containing amino acids

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16
Q

define fibrous protein

A

proteins with a non-specific linear shape
have structural roles and are insoluble in water
e.g collagen

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17
Q

define globular protein

A

proteins with a compact specific 3D shape
their roles involve binding to molecules and they are soluble in water
e.g enzymes

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18
Q

what is the importance of magnesium?

A

constituent of chlorophyll and so is essential for photosynthesis
plants without magnesium in the soil cannot make chlorophyll and so leaves are yellow (chlorosis)

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19
Q

what is the importance of iron?

A

a constituent of haemoglobin, which transports oxygen inside red blood cells
lack of iron in the human diet can lead to anaemia

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20
Q

what is the importance of phosphate?

A

used for making nucleic acids (DNA RNA ATP)
a constituent of phospholipids, found in plasma membranes

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21
Q

what is the importance of calcium?

A

structural component of bones and teeth in mammals
a component of plant cell walls, providing strength

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22
Q

what are carbohydrates made up of?

A

carbon
hydrogen
oxygen

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23
Q

what are the main functions of carbohydrates?

A

storage and release of energy
cellular structures

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24
Q

what are the 3 classes of carbohydrates?

A

monosaccharides
disaccharides
polysaccharides

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25
Q

define monosaccharide

A

monomers which form building blocks for larger carbohydrates

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26
Q

define disaccharide

A

two monosaccharides joined together by glycosidic bonds during a condensation reaction

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27
Q

define polysaccharide

A

large complex carbohydrate formed from very large numbers of monosaccharides joined together by glycosidic bonds

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28
Q

state the 3 main examples of monosaccharides

A

glucose
galactose
fructose

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29
Q

what are the two types of glucose and how do they differ?

A

alpha and beta glucose
the difference is the positioning of the H atom and the OH group on carbon 1 (ABBA)
alpha and beta glucose are isomers

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30
Q

what are the main properties of monosaccharides?

A

due to the small size of monosaccharides they are all soluble in water and therefore they easily dissolve inside the cell and are easily transported in the bloodstream of animals

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31
Q

state the 3 main disaccharides and how are they formed?

A

maltose = glucose + glucose
sucrose = glucose + fructose
lactose = glucose + galactose

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32
Q

state the properties of maltose, sucrose, lactose

A

maltose : found inside seeds and a source of glucose during germination
sucrose : transported through the phloem of all plants
lactose : found in mammalian milk and is an important source of energy for their young

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33
Q

describe polysaccharides

A

polysaccharides are polymers
they are made up of thousands of monomers giving them a large size and makes them insoluble
they either have an energy storage or structural function

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34
Q

what are the properties of polysaccharides?

A
  • insoluble
  • compact
  • easily hydrolysed
  • contain lots of energy
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35
Q

what are the 4 main examples of polysaccharide?

A

starch
glycogen
cellulose
chitin

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36
Q

describe starch

A

starch is an energy storage polysaccharide in plant cells
the starch polymer is made up of thousands of alpha glucose
made up of two different molecules - amylose and amylopectin

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37
Q

describe amylose

A

function - glucose storage
chain type - coiled and unbranched
monomer - alpha glucose
properties - insoluble, compact
type of bond - alpha 1-4

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38
Q

describe amylopectin

A

function - glucose storage
chain type - branched
monomer - alpha glucose
properties - insoluble, highly branched
type of bond - alpha 1-4, alpha 1-6

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39
Q

describe glycogen

A

function - glucose storage
chain type - branched
monomer - alpha glucose
properties - insoluble, highly branched
type of bond - alpha 1-4, alpha 1-6

40
Q

describe cellulose

A

function - structural
chain type - straight
monomer - beta glucose
properties - inelastic, insoluble, strong
type of bond - beta 1-4

41
Q

describe chitin

A

function - structural
chain type - straight
monomer - beta glucose
properties - lightweight, waterproof, strong, insoluble
type of bond, beta 1-4

42
Q

what is the difference between amylose and amylopectin?

A

amylopectin has branches to hydrolyse to release glucose for energy, whereas amylose does not

43
Q

what is the function of cellulose?

A

cellulose gives the plant cell rigidity because the cellulose cell wall is inelastic and has high tensile strength to prevent the plant cells from bursting

44
Q

how does cellulose gain its strength?

A

it has straight chain which fold into each other giving its strength

45
Q

describe the structure of cellulose

A
  • beta glucose monomers joined by glycosidic bonds, with each adjacent beta glucose molecules rotated 180 to each other
  • forms straight chains
  • hydrogen bonds form between OH groups of straight chains
  • many straight chains form a strong microfibril
  • many microfibril form a cellulose bundle
46
Q

how do chitin and cellulose differ?

A

some of the OH groups of each of the beta glucose molecules are replaced by nitrogen containing acetylamine groups

47
Q

what is the function of chitin?

A

forms the exoskeleton of arthropods sch as insects, arachnids such as spides and crustaceans such as crabs
forms the cell wall of fungi

48
Q

what are the two types of lipids?

A

triglycerides
phospholipids

49
Q

what are lipids made up of?

A

carbon
hydrogen
oxygen (less oxygen than carbohydrates)

50
Q

what are triglycerides made up of?
why are triglycerides not polymers?

A

glycerol and 3 fatty acids
they are made up of 2 different types of subunits and not made from identical repeating monomers

51
Q

what are fatty acids made up of?

A

methyl group (CH3)
long hydrocarbon chain (CH2)
carboxyl group (COOH)

52
Q

what are the two types of fatty acids and how do they differ?

A

unsaturated and saturated
saturated fatty acids have no double bonds and carry the maximum amount of hydrogen atoms
however, unsaturated fatty acids have double bonds and do not carry the maximum amount of hydrogen atoms

53
Q

how are triglycerides formed?

A

one glycerol molecule combines with three fatty acid molecules.
each fatty acid is linked to the glycerol by an ester bond

54
Q

why are unsaturated fats bad for you?

A

unsaturated fats increase the level of LDL cholesterol
fatty material can block major arteries and cause a myocardial infarction

55
Q

name some health implications that high fat intake can cause

A
  • obesity
  • cancer
  • coronary heart disease
  • atheroma
56
Q

what are the properties of lipids?

A
  • insoluble in water but soluble in organic solvents
  • fats are solid at room temperature
  • oils are liquid at room temperature
57
Q

what are the functions of lipids?

A
  • energy storage
  • protection of vital organs
  • thermal insulation
  • buoyancy
  • metabolic water
  • waterproofing
58
Q

what are phospholipids made up of?
how does the structure of phospholipids help to enable its function?

A

they are made up of : glycerol, 2 fatty acids, phosphate group
the tail of the fatty acid is hydrophobic, the head is hydrophilic so the tail repels water for the membrane

59
Q

what is the importance of phospholipids?

A

they are an important component of cell membranes

60
Q

what are amino acids made up of?

A

carbon
hydrogen
oxygen
nitrogen
sometimes sulphur

61
Q

what is the R group?

A

the R group is the variable group and represent the rest of the molecule (20 different lists)

62
Q

what is a dipeptide bond and how are they formed?

A

two amino acids can be joined together to form a dipeptide
they combine in a condensation reaction

63
Q

what are polypeptides?

A

they are formed by many amino acids joined together by peptide bonds.
they are polymers
polypeptides form proteins

64
Q

what does the primary structure of a polypeptide refer to?

A

the number and sequence of amino acids in a polypeptide chain

65
Q

describe the secondary structure of a protein

A

the primary structure coils together to form either an alpha helix or a beta-pleated sheet

66
Q

describe the alpha helix

A
  • held in a spiral shape by hydrogen bonds
  • some fibrous proteins have alpha helixes linked into rope-like strands (e.g keratin and collagen)
67
Q

what is keratin for?

A

hair and nails

68
Q

what is collagen?

A

found in connective tissue and skin

69
Q

give an example of a beta pleated sheet

A

protein silk

70
Q

describe the tertiary structure

A
  • the secondary structure folds to give complex 3D shape
  • these are globular proteins (enzymes, hormones, plasma, cell membrane proteins)
  • held by bonds or interactions that form between R groups of some of the amino acids in the polypeptide chain
71
Q

state and explain the bonds in the tertiary structure

A
  • hydrogen bonds (form between O and OH)
  • ionic bonds (form between oppositely charged R groups)
  • disulphide bonds (form between S atoms)
  • hydrophobic R group (inside of the protein)
  • hydrophilic R group (outside of the protein)
72
Q

describe the quaternary structure

A
  • more than one polypeptide chain combine to form a larger protein complex
  • bonds similar to tertiary structure
73
Q

give an example of a quaternary structure protein and describe it

A

haemolgobin
a protein that carries oxygen in mammalian blood
made of 4 polypeptide chains each with a tertiary structure
also has non-protein components called haem groups (contain iron Fe)

74
Q

what are the two types of proteins?

A

globular
fibrous

75
Q

what are fibrous proteins?
give examples
give properties

A

keratin and collagen
tough - non specific - insoluble

76
Q

what are globular proteins?
give examples
give properties

A

enzymes - antibodies - plasma proteins - hormones
they can be tertiary proteins and quarternary proteins
- compact and folded into spherical molecules
- have a specific shape
- soluble in water

77
Q

describe collagen

A

collagen is made up of three alpha helix polypeptide chains twisted into rope like strands

78
Q

what is the test for reducing sugar?
what is the positive result?
what is the negative result?

A

add benedict’s reagent to the test sample and boil in a water bath
positive result - turns brick red (heat)
negative result - stays light blue

79
Q

explain how the result of reducing sugar test may be graduated

A

the more concentrated the reducing sugar, the nearer brick-red the colour will be

80
Q

what is the test for non-reducing sugars?
what is the positive result?
what is the negative result?

A
  • add HCL to the test sample and boil (hydrolyse any glycosidic bonds)
  • add hydrogen carbonate powder to neutralise
  • add benedict’s reagent and boil
    positive result - turns brick red/orange
    negative result - no colour change
81
Q

what is the test for starch?
what is the positive result?
what is the negative result?

A

iodine solution turns from an orange brown colour to a blue black colour

82
Q

what is the test for proteins?
what is the positive result?
what is the negative result?

A
  • Biuret test
  • positive result - light blue to purple
  • negative result - stays blue
83
Q

what type of test is the test for starch?

A

a qualitative test and an accurate concentration can not be determined

84
Q

what type of molecule is water and what does this mean?

A

a polar molecule (has an uneven distribution of charge)
oxygen has a slight negative charge
hydrogen has a slight positive charge

85
Q

describe the structure of water

A

2 hydrogen atoms covalently bonded to 1 oxygen atom

86
Q

what type of bond do water molecules form between each other?

A

weak hydrogen bond
this forms a strong lattice

87
Q

what do the hydrogen bonds form?

A

cohesion between molecules

88
Q

describe surface tension as a property of water

A

water molecules form hydrogen bonds with other nearby water molecules
this cohesion produces an uneven distribution of force called surface tension
this forms a skin which can support aquatic plants and insects (e.g pond skater)

89
Q

describe universal solvent as a property of water

A
  • water is a solvent
  • water will attract and dissolve other charged particles such as io s snd other polar molecules (e.g glucose)
  • acts as a transport medium (blood in animals and xylem vessel in plants)
90
Q

describe metabolite as a property of water

A
  • water is a reactant in photosynthesis and hydrolysis.
  • produced during aerobic respiration and condensation reactions
91
Q

describe high specific heat capacity as a property of water

A
  • what has a high specific heat capacity (a lot of energy is needed to break the hydrogen bonds)
  • provides a more stable environment for aquatic organisms
  • allows enzymes to efficiently catalyse important chemical reactions without becoming denatured
92
Q

describe high latent heat capacity as a property of water

A
  • water has a high latent heat capacity (a lot of energy is needed to break the hydrogen bonds and change state)
  • a lot of energy is required for water to evaporate from the surface of an organism
  • provides a significant cooling effect
93
Q

describe density as a property of water

A
  • ice is less dense than liquid water (therefore it floats on the surface of water)
  • forms an insulating layer for aquatic organisms to survive underneath ice
  • provides a habitat for organisms (e.g polar bears)
94
Q

describe transparency as a property of water

A

a transparent substance that allows light to pass through to underwater aquatic plants and enables them to photosynthesise effectively

95
Q

why do lipids not dissolve in water?

A

they are non polar so repel water

96
Q

explain how the structures of starch and cellulose are related to their functions as storage and structural molecules respectively. (4 marks)

A

STARCH :
- amylose or amylopectin
- glycosidic bonds
- molecules coil or branch

biology - core concepts (6 decks)

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