biological molecules Flashcards
1
Q
define inorganic
A
charged particles of elements or their compounds such as potassium ions or nitrate ions
2
Q
define organic molecules
A
substances containing carbon hydrogen oxygen - required by all living cells
3
Q
define dipole
A
a molecule with a positive and negative charge, seperated by a very short distance
4
Q
define hydrogen bond
A
an attractive force between a slight negative charge on one atom
5
Q
define cohesion
A
the attractive force that holds water molecules together by hydrogen bonding
6
Q
define specific heat capacity
A
the energy required to raise the temperature of a substance
7
Q
define latent heat of vaporisation
A
the energy required to convert a liquid into a vapour
8
Q
define isomer
A
molecules that have the same chemical formula but a different arrangement of atoms
9
Q
define condensation reaction
A
a reaction in which 2 molecules are linked together by a bond, involving the elimination of water
10
Q
define hydrolysis
A
a reaction that involves breaking of a bond, involving the chemical insertion of water
11
Q
define hydrophilic
A
these are polar molecules or charged ions that can interact with water molecules because of their change
12
Q
define hydrophobic
A
these are non-polar molecules or uncharged ions that cannot interact with water molecules because they have no charge
13
Q
define saturated fat
A
a fat in which there are no double bonds between carbon atoms
14
Q
define unsaturated fat
A
a fat in which there is at least one double bond between carbon atoms
15
Q
define disulphide bond
A
a covalent bond formed between two sulphur containing amino acids
16
Q
define fibrous protein
A
proteins with a non-specific linear shape
have structural roles and are insoluble in water
e.g collagen
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
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)
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
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
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
22
Q
what are carbohydrates made up of?
A
carbon
hydrogen
oxygen
23
Q
what are the main functions of carbohydrates?
A
storage and release of energy
cellular structures
24
Q
what are the 3 classes of carbohydrates?
A
monosaccharides
disaccharides
polysaccharides
25
define monosaccharide
monomers which form building blocks for larger carbohydrates
26
define disaccharide
two monosaccharides joined together by glycosidic bonds during a condensation reaction
27
define polysaccharide
large complex carbohydrate formed from very large numbers of monosaccharides joined together by glycosidic bonds
28
state the 3 main examples of monosaccharides
glucose
galactose
fructose
29
what are the two types of glucose and how do they differ?
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
30
what are the main properties of monosaccharides?
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
31
state the 3 main disaccharides and how are they formed?
maltose = glucose + glucose
sucrose = glucose + fructose
lactose = glucose + galactose
32
state the properties of maltose, sucrose, lactose
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
33
describe polysaccharides
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
34
what are the properties of polysaccharides?
- insoluble
- compact
- easily hydrolysed
- contain lots of energy
35
what are the 4 main examples of polysaccharide?
starch
glycogen
cellulose
chitin
36
describe starch
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
37
describe amylose
function - glucose storage
chain type - coiled and unbranched
monomer - alpha glucose
properties - insoluble, compact
type of bond - alpha 1-4
38
describe amylopectin
function - glucose storage
chain type - branched
monomer - alpha glucose
properties - insoluble, highly branched
type of bond - alpha 1-4, alpha 1-6
39
describe glycogen
function - glucose storage
chain type - branched
monomer - alpha glucose
properties - insoluble, highly branched
type of bond - alpha 1-4, alpha 1-6
40
describe cellulose
function - structural
chain type - straight
monomer - beta glucose
properties - inelastic, insoluble, strong
type of bond - beta 1-4
41
describe chitin
function - structural
chain type - straight
monomer - beta glucose
properties - lightweight, waterproof, strong, insoluble
type of bond, beta 1-4
42
what is the difference between amylose and amylopectin?
amylopectin has branches to hydrolyse to release glucose for energy, whereas amylose does not
43
what is the function of cellulose?
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
how does cellulose gain its strength?
it has straight chain which fold into each other giving its strength
45
describe the structure of cellulose
- 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
how do chitin and cellulose differ?
some of the OH groups of each of the beta glucose molecules are replaced by nitrogen containing acetylamine groups
47
what is the function of chitin?
forms the exoskeleton of arthropods sch as insects, arachnids such as spides and crustaceans such as crabs
forms the cell wall of fungi
48
what are the two types of lipids?
triglycerides
phospholipids
49
what are lipids made up of?
carbon
hydrogen
oxygen (less oxygen than carbohydrates)
50
what are triglycerides made up of?
why are triglycerides not polymers?
glycerol and 3 fatty acids
they are made up of 2 different types of subunits and not made from identical repeating monomers
51
what are fatty acids made up of?
methyl group (CH3)
long hydrocarbon chain (CH2)
carboxyl group (COOH)
52
what are the two types of fatty acids and how do they differ?
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
how are triglycerides formed?
one glycerol molecule combines with three fatty acid molecules.
each fatty acid is linked to the glycerol by an ester bond
54
why are unsaturated fats bad for you?
unsaturated fats increase the level of LDL cholesterol
fatty material can block major arteries and cause a myocardial infarction
55
name some health implications that high fat intake can cause
- obesity
- cancer
- coronary heart disease
- atheroma
56
what are the properties of lipids?
- insoluble in water but soluble in organic solvents
- fats are solid at room temperature
- oils are liquid at room temperature
57
what are the functions of lipids?
- energy storage
- protection of vital organs
- thermal insulation
- buoyancy
- metabolic water
- waterproofing
58
what are phospholipids made up of?
how does the structure of phospholipids help to enable its function?
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
what is the importance of phospholipids?
they are an important component of cell membranes
60
what are amino acids made up of?
carbon
hydrogen
oxygen
nitrogen
sometimes sulphur
61
what is the R group?
the R group is the variable group and represent the rest of the molecule (20 different lists)
62
what is a dipeptide bond and how are they formed?
two amino acids can be joined together to form a dipeptide
they combine in a condensation reaction
63
what are polypeptides?
they are formed by many amino acids joined together by peptide bonds.
they are polymers
polypeptides form proteins
64
what does the primary structure of a polypeptide refer to?
the number and sequence of amino acids in a polypeptide chain
65
describe the secondary structure of a protein
the primary structure coils together to form either an alpha helix or a beta-pleated sheet
66
describe the alpha helix
- 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
what is keratin for?
hair and nails
68
what is collagen?
found in connective tissue and skin
69
give an example of a beta pleated sheet
protein silk
70
describe the tertiary structure
- 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
state and explain the bonds in the tertiary structure
- 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
describe the quaternary structure
- more than one polypeptide chain combine to form a larger protein complex
- bonds similar to tertiary structure
73
give an example of a quaternary structure protein and describe it
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
what are the two types of proteins?
globular
fibrous
75
what are fibrous proteins?
give examples
give properties
keratin and collagen
tough - non specific - insoluble
76
what are globular proteins?
give examples
give properties
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
describe collagen
collagen is made up of three alpha helix polypeptide chains twisted into rope like strands
78
what is the test for reducing sugar?
what is the positive result?
what is the negative result?
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
explain how the result of reducing sugar test may be graduated
the more concentrated the reducing sugar, the nearer brick-red the colour will be
80
what is the test for non-reducing sugars?
what is the positive result?
what is the negative result?
- 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
what is the test for starch?
what is the positive result?
what is the negative result?
iodine solution turns from an orange brown colour to a blue black colour
82
what is the test for proteins?
what is the positive result?
what is the negative result?
- Biuret test
- positive result - light blue to purple
- negative result - stays blue
83
what type of test is the test for starch?
a qualitative test and an accurate concentration can not be determined
84
what type of molecule is water and what does this mean?
a polar molecule (has an uneven distribution of charge)
oxygen has a slight negative charge
hydrogen has a slight positive charge
85
describe the structure of water
2 hydrogen atoms covalently bonded to 1 oxygen atom
86
what type of bond do water molecules form between each other?
weak hydrogen bond
this forms a strong lattice
87
what do the hydrogen bonds form?
cohesion between molecules
88
describe surface tension as a property of water
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
describe universal solvent as a property of water
- 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
describe metabolite as a property of water
- water is a reactant in photosynthesis and hydrolysis.
- produced during aerobic respiration and condensation reactions
91
describe high specific heat capacity as a property of water
- 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
describe high latent heat capacity as a property of water
- 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
describe density as a property of water
- 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
describe transparency as a property of water
a transparent substance that allows light to pass through to underwater aquatic plants and enables them to photosynthesise effectively
95
why do lipids not dissolve in water?
they are non polar so repel water
96
explain how the structures of starch and cellulose are related to their functions as storage and structural molecules respectively. (4 marks)
STARCH :
- amylose or amylopectin
- glycosidic bonds
- molecules coil or branch
CELLULOSE :
-
