biological molecules Flashcards
1
Q
What type of molecule is water?
A
polar
2
Q
what is the strength of hydrogen bonds?
A
weak
3
Q
water’s thermal properties
A
- high SHC helps maintain optimum temp for enzyme activity
- is a temp buffer for chemical reactions
- ice is less dense than water (temp decrease = KE decrease so maximum number of bonds can form, and molecules spread out and form a lattice)
- this means water under ice remains water and ice acts as an insulator
4
Q
waters solvent properties
A
- ions are attracted to water as it is polar
- allows for the uptake of minerals by organisms
eg. nitrate for amino acids or phosphate for ATP - dilute toxic solutions
5
Q
water’s transport function
A
- transpiration stream
- transport dissolved metabolites
6
Q
what is a condensation reaction?
A
two molecules combine and water is formed
7
Q
what is hydrolysis?
A
water is added and one molecue splits into 2
8
Q
what is the bond between two amino acids?
A
peptide bond
9
Q
what is the primary structure of a protein?
A
the order of amino acids
10
Q
what is the secondary structure of a protein?
A
- folding of the peptide chain
- alpha helix spirals and is held together with hydrogen bonds
- beta pleated sheets fold into anti-parallel chains and each one is held with hydrogen bonds
11
Q
what is the tertiary structure of proteins?
A
globular proteins fold into a 3D shape
12
Q
how do R groups interact to determine tertiary structure?
A
- disulfide bridges between cysteine
- hydrogen bonds
- ionic bonds between oppositely charged R groups
- hydrophilic heads on outside to interact with water
- hydrophobic tails on inside
13
Q
what is the quaternary structure of a protein?
A
chains of polypeptides in a closely packed arrangement
14
Q
what are globular proteins
A
- soluble
- round molecule
- specific 3D shape
15
Q
what three elements are carbohydrates made of?
A
- carbon
- hydrogen
- oxygen
16
Q
examples of monosaccharides
A
- glucose
- fructose
- ribose
17
Q
exampes of disaccharides
A
- lactose
- sucrose
18
Q
examples of polysaccharides
A
- glycogen
- cellulose
- starch
19
Q
what are the two forms of glucose?
A
alpha and beta
20
Q
difference between alpha and beta glucose
A
H-OH are flipped to OH on top on the left in beta
21
Q
what is the bond in sucrose?
A
1-4 glycosidic
22
Q
bond between glucose
A
1-4 glycosidic bonds
23
Q
what is maltose made up of?
A
2 glucose
24
Q
what is sucrose made up of?
A
glucose+fructose
25
what is lactose made up of?
galactose+glucose
26
what is the energy store in plants?
starch
27
what is the energy store in animals?
glycogen
28
what bonds do glycogen have?
1-6 glycosidic
29
why is the energy store in animals different to plants?
-glycogen is less dense and more soluble so can be broken down faster
- animals have higher metabolic demands
30
what is cellulose made of?
beta glucose and 1-4 glycosidic bonds
31
what are the properties of cellulose that make it suitable for plant cell walls?
- insoluble
- unreactive
- beta glucose
- high tensile strength
- flexible
32
what are lipids soluble in?
ethanol
33
bond between fatty acids and glycerol
ester bond
34
structure of triglycerides
- 3 glycerol+fatty acid tails
- 3 ester bonds
35
structure of phospholipids
- hydrophilic heads and hydrophobic tails
- 2 ester bonds
- two fatty acids
36
what is the role of lipids?
- energy store
- protection of organs
- insulator
37
what is the test for starch?
iodine (black=positive)
38
what is the test for lipids?
- ethanol (cloudy precipitate = positive)
- add ethanol then water
39
what is the test for proteins?
biurets (purple=positive)
- add copper sulfate solution and sodium hydroxide and biuret reagent
40
what is the test for reducing sugars?
benedicts (green-red)
compare to known results to become qualitative
41
what is the test for non-reducing sugars?
- add HCl to hydrolyse solution
- sucrose to glucose+fructose
- heat solution in a boiling water bath
- add benedicts solution
42
what is the effect of cholesterol on phospholipids?
affects permeability and flexibility
43
how do R groups interact to form tertiary structure?
- oppositely charged R groups form strong ionic bonds
- R groups with sulfer can form disulfide bonds
- hydrophilic and hydrophobic interactions
- hydrogen bonds with most other R groups
44
how would you obtain amino acids from haemoglobin with RBC's?
haemoglobin is hydrolysed and broken down by protease
45
insulin
- globular protein that regulates blood glucose
- soluble yo be transported in blood
- fits receptors on cell surface mebrane
46
catalase
- enzyme that increases ROR
- globular protein with quaternary
- iron II haem group binds to substrate (usually hydrogen peroxide) to speed up break down
47
haemoglobin
-globular and prosthetic groups
- 2 alpha and 2 beta chains
- 4 groups
- iron ions reversibly binds with oxygen
48
fibrous proteins
- long and insoluble
- lots of hydrophobic R groups
- repetetive
49
collagen
- strong and flexible
- three polypeptide chains wound around eachother to prevent snapping
- formed from glyceine which is the smallest amino acid which allows for a tight configuration
50
keratin
- fibrous protein
- lots of cysteine so disulfide bonds
- number of bonds determines flexibility
51
elastin
- elastic fibres
- can stretch and recoil easily
52
what are the properties and functions of globular proteins?
- specific 3D structure means they make up antibodies for immunity
- hydrophilic exterior for transporting molecules (carrier/channel proteins)
- conjugated to form receptors for cell signalling
- 3D shape complementary to substrates to form enzymes as catalysts
53
what are the properties and functions of fibrous proteins?
- strong and tough to provide structure eg collagen around vessels
- flexible due to elastic properties eg in vessel walls to stretch and recoil
- elongated for the contraction and movement of cilia
54
what is amylopectin?
highly branched chain of alpha glucose
55
what bonds are in amylopectin?
both 1-4 and 1-6 glycosidic
56
why is the structure of amylopectin important?
enzymes can easily access bonds to quickly break it down into glucose monomers
57
what is amylose?
linear chain of alpha-glucose
58
what bonds are in amylose?
1-4 glycosidic
59
why is the structure of amylose important?
chains have a helical structure which allows for tight packing, hence useful for storage
60
what is the difference between glycogen and amylopectin?
- glycogen is the primary storage form of glucose in animals, while amylopectin is the primary storage form of glucose in plants
- glycogen is more soluble than amylopectin, which is insoluble in water
- glycogen has more branches than amylopectin, which makes it more compact and efficient
- glycogen has more α-1,6-glycosidic bonds than amylopectin, which has more α-1,4-glycosidic bonds
61
what are the differences bewteen glycogen and cellulose?
- glycogen is branched and forms coils whereas cellulose forms straight chains
- glycogen has 1-4 and 1-6 whereas cellulose has 1-4
- glycogen is alpha and cellulose is beta
62
how does glycogen act as an energy source?
- glycogen can be hydrolysed to glucose.
- the glucose could then be used to release energy through the process of respiration
63
how is starch adapted to its function in the cells of plants?
- insoluble in water so doesnt affect the cells water potential
- helical shape so can be closely stored
- large so unable to leave the cell
64
why do mammals store glycogen instead of glucose?
- insoluble so no effect on water potential
- metabolically inactive
- compact so can store lots of energy in a smaller space
- highly branched so can hydrolyse to glucose when needed
65
why is collagen is a fibrous protein?
- long chain of amino acids
- no tertiary structure
- insoluble
66
why is collagen so strong?
many covalent and hydrogen bonds
67
outline the method of chromatography that will separate the main amino acids in collagen
- hydrolyse collagen into amino acids
- place sample on chromatography paper
- dry and repeat
- place paper in solvent (ethanoic acid)
68
what are some ways in which the molecular structure of cholesterol is similar to the molecular
structure of glucose?
- both have C and H atoms
- both contain oxygen
- both have a hydroxyl group
69
why can glucose be transported in the bloodstream?
soluble in water
70
how could you improve a chromatography method?
- wear gloves to prevent transfer of amino acids from hands
- put pencil and amino acids higher than solvent line to prevent them mixing
- put a cover over beaker to prevent evaporation
- repeat and find a mean to improve accuracy
- label amino acid samples to prevent confusion
71
what is esterification?
- reaction between fatty acids and glycerol
- condensation reaction
72
how does the structure of glycogen differs from that of amylopectin to make it better suited as an energy store in animals?
- glycogen is more branched and coiled
- more compact
- free ends to easily add or remove glucose when needed
73
how is chitin formed from its monomers and predict its structure
- glycosidic bonds formed by a condensation reaction where a water molecule is released
- forms a linear glucose chain similar to cellulose
74
what is meant by the term conjugated protein
- contains non protein groups
- has prosthetic group of iron which is attached by hydrogen bonds
