Biological molecules 2.2 Flashcards
1
Q
What is a condensation reaction?
A
Reaction that occurs when two molecules are joined together with the removal of water
2
Q
What is a hydrolysis reaction?
A
A reaction that occurs when a molecule is split into two smaller molecules with the addition of water
3
Q
What is a hydrogen bond?
A
A weak interaction that can occur wherever molecules contain a slightly negatively charged atom bonded to a slightly positively charged hydrogen atom
4
Q
What is a monomer?
A
A small molecules which binds to many other identical molecules to form a polymer
5
Q
What is a polymer?
A
A larger molecule made from many smaller molecules called monomers
6
Q
What is a covalent bond?
A
A bond formed by sharing electrons with other atoms outermost shell
7
Q
What elements are in carbohydrates?
A
C, H, O
8
Q
What are the polymer and monomers of carbohydrates?
A
Monosaccharides and polysaccharides
9
Q
What elements do proteins consist of?
A
C, H, O, N, S
10
Q
What are the monomers and polymers proteins
A
Amino acids and polypeptides
11
Q
What elements does nuclei acid consist of?
A
C, H, O, N, P
12
Q
What are the monomers and polymers of nuclei acid?
A
Nucleotides and DNA/ RNA
13
Q
What are the effects of water being a liquid?
A
- provides habitats for living things
- major component of tissues in living organisms
- transport medium
13
Q
What makes water a liquid?
A
- water molecules are constantly moving and making and breaking hydrogen bonds
- water is a liquid at room temperature temperature
14
Q
Density
A
- ice is less dense than water so it floats
- stable environment for organisms to live in
- layer of ice reduces the rate of heat loss
15
Q
Solvent
A
- good solvent for many substance
- water is polar so can cluster around charged particles and separate them to dissolve
- molecules and ions can be transported around living things whilst dissolved
- many reactions happen in the cytoplasm which is 70% water
16
Q
Cohesion and surface tension
A
- hydrogen bonding between molecules pulls them together
- water molecules on the top of the water are more atracted to the water molecules below than the air
- water surface had the ability to resist force applied to it
- columns of water in xylem
17
Q
High specific heat capacity
A
- a lot of energy is required to raise the temperature of water
- prokaryotes and eukaryotes need stable temperature for enzyme reactions
- aquatic organisms need stable environment in which to live
18
Q
High latent heat of vaporisation
A
- lots of energy is required to make water evaporate
- water can help cool living things and keep their temperature stable
19
Q
Reactant
A
- water is a reactant in many reactions
- important for digestion and synthesis of large biological molecules
- used in photosynthesis
20
Q
What are the properties of water?
A
- Liquid
- density
- solvent
- cohesion and surface tension
- reactant
- high SHC
- high LHV
21
Q
What are carbohydrates?
A
- source of energy
- store of energy
- structural units
22
Q
What are monosaccharides?
A
- simplest carbohydrate
- source of energy
- soluble in polar solvents
- alpha and beta glucose
23
Q
What are disaccharides?
A
2 monosaccharides bonded together with glycosidic bonds
24
What are reducing sugars?
- maltose
- lactose
- glucose
25
What are non reducing sugars?
Sucrose
26
a glucose + a glucose = ?
maltose
27
a glucose + fructose = ?
sucrose
28
b glucose + a glucose = ?
lactose
29
b glucose + b glucose = ?
cellulose
30
What are two forms of carbohydrates?
Glucose and ribose
31
What is a glycosidic bond?
A covalent body formed when two carbohydrates molecules are joined together by a condensation reaction
32
What are the three polysaccharides?
Glycogen, starch and cellulose
33
What is a homopolysaccharide
A polysaccharides consisting of one type of monomers
34
What is a heteropolysaccharide?
A polysaccharides that consists of multiple types of monomer
35
Starch
- consists of 2 polysaccharides
- consists of amylose and amylopectin
- storage in plants
- insoluble
- stored as starch grains in plastids
36
Amylose
- chain of alpha glucose
- 1-4 glycosidic bonds
- coiled
- more soluble than amylopectin
- H bonds keep the coiled shape
37
Amylopectin
- chain of alpha glucose
- coiled with branches
- 1-4 and 1-6 glycosidic bonds
- branches allow glucose to be released quickly
38
Glycogen
- main storage material in animals
- coiled a glucose chain and with branches
- 1-4 and 1-6 glycosidic bonds
- stoked as small granules in the liver and muscles
- less dense and more soluble than starch
- broken down faster as animals have higher metabolic rate
39
Cellulose
- b glucose molecules
- unbranded chain
- adjacent molecules are alternatingly flipped over 180 degrees
- 1-2 glycosidic bonds
- linked by hydrogen bonds to form microfibrils
- microfibrils are cross linked to form microfibres
- forms cell walls in plants
- tough, insoluble and fibrous
40
What is a lipid?
- A group of substances that are soluble in alcohol rather than water (triglycerides, phospholipids, glycolipids and cholesterol)
- insoluble
- non polar
41
What is a macromolecule?
A very large organic molecule
42
What is a phospholipid?
Molecule consisting of glycerol, two fatty acids and one phosphate group
43
What is a triglyceride?
Molecule consisting of a glycerol and three fatty acids
44
What does glycerol consist of?
Three carbon atoms with three OH groups attached to them
45
What do fatty acids contain?
- carboxyl acid group
- hydrocarbon tail
46
What does it mean if a fatty acid is unsaturated?
They contain a carbon to carbon double bond
47
What does it mean if a fatty acid is polyunsaturated?
They contain multiple a carbon to carbon double bond
48
What kind of bond forms between a fatty acid and a glycerol?
Ester bond
49
What are the functions of triglycerides?
- energy store
- energy source
- insulation
- buoyancy
- protection
50
Describe the role of triglycerides in pprotection
Humans have fat around delicate organs to act as a shock absorber
51
Describe the role of triglycerides in buoyancy
Fat is less dense than water so aquatic animals can use it to help them stay afloat
52
Describe the role of triglycerides in insulation
Blubber is a storage location for lipids in whales which acts ans an insulator but it also acts as an electrical insulator on nerve cells
53
Describe the role of triglycerides in energy store
Since they are insoluble they dont affect water potential and also due to a higher proportion of hydrogen they also release more energy
54
How does a phospholipid act in water?
- the phosphate head is polar so it forms H bonds with water making it hydrophilic
- the fatty acid tail is non polar so it is not attracted to water making it hydrophobic
55
What two lipids can phospholipids create?
micelles and phospholipid bilayers
56
How is a phospholipid bilayer formed?
The hydrophilic heads start to form h bonds with the water and the hydrophobic tails stat to turn in towards eachother as they are repelled by the water forming a phospholipid bilayer
57
What are some characteristics of a phospholipid bilayer?
- each phospholipid is free to move around
- the membranes are selectively permeable
58
What substances can pass through a phospholipid bilayer?
Small and non polar molecules
59
What is cholesterol?
A steroid alcohol
60
Is cholesterol hydrophobic or hydrophilic?
Hydrophobic
61
What does cholesterol do?
It regulates membrane fluidity
62
How does cholesterol regulate membrane fluidity?
- in hot temperatures it binds to the fatty acid tails to pack them closely together to reduce fluidity
- in low temperatures it spaces the fatty acid tails apart to increase fluidity
63
What is a peptide bond?
The covalent bond formed when two amino acids are joined by a condensation reaction
64
What is the structure of an amino acid?
It contains an amino group, a carboxyl group, an R group and a H all attached to a central carbon
65
How many amino acids are there?
Over 500
66
How many amino acids are proteinogenic?
20
67
What do enzymes do to proteins?
Catalyse the hydrolysis of peptide bonds
68
What is the primary structure of a protein?
The order of amino acids in a molecule
69
What is the secondary structure of a protein?
The coiling or folding of a polypeptide chain forming an alpha helix or a beta pleated sheet
70
What is the tertiary structure of a protein?
The 3D shape of a protein molecule when the coils and the pleats themselves start to fold
71
What is the quaternary structure of a protein?
When the protein structure consists of multiple polypeptide bonds
72
What types of bonds are found in the primary structure?
Peptide bonds
73
What types of bonds are found in the secondary structure?
Hydrogen bonds
74
What types of bonds are found in the tertiary structure?
Hydrogen, ionic, disulfide bonds and hydrophobic interactions
75
What types of bonds are found in the quaternary structure?
Disulfide bonds and non covalent bonds (hydrophobic and london forces)
76
What is a fibrous protein?
A protein that has a relatively long, thin structure, is insoluble and metabolically inactive
77
What is a globular protein?
A protein that has a relatively spherical shape, is soluble and often have metabolic roles
78
What is a conjugated protein?
A globular protein that contains a prosthetic group
79
How is haemoglobins shape sepcific to its function?
- its function is transport
- it consist of 4 polypeptide chains (2 x a globin, 2 x b globin)
- conjugated, 4 haem groups which contain iron
- 1 oxygen binds to each haem group
80
How is insulins shape specific to its function?
- its function is as a hormone
- consist of 2 polypeptide chains (a helix, b pleated sheet)
- chains joined by disulfide bridges
- specifically binds to insulin receptors
- hydrophilic R groups so can dissolve in the blood
81
How is pepsins shape specific to its function?
- its function is as an enzyme
- single polypeptide chain
- catalyses digestion of proteins
- found in the acidic conditions of the stomach
- primary structure with very few basic R groups
- not affected by H+ ions
- held by strong hydrogen and disulfide bonds
82
What are the three globular proteins you should know about?
Haemoglobin, insulin and pepsin
83
How is collagens shape specific to its function?
- its function is to provide mechanical strength and allow structures to withstand high pressure
- it consists of parallel polypeptide chains with covalent cross links
- this means the polypeptide chains have staggered ends and lots of hydrogen bonds
- making it very stong and suitable as a connective tissue
84
How is keratins shape specific to its function?
- its function is mechanical protection
- it does this by making up nails, claws, hair, fur and feathers
- rich in cystein so has many disulfide bridges
- it is insoluble and very strong
- it creates an impermeable barrier to infections and water borne pollutants
85
How is elastins shape specific to its function?
- it allows structures to stretch and return back to their original shape
- it can be found in the skin, lungs and blood vessels
- cross linking and coiling allows the structures to adapt their shape
- it does so by being very strong and extensible
86
What is the function of calcium?
- Ca+2
- increase rigidity of bone, teeth and cartilage
- important in clotting blood
- stimulates muscle contraction
- regulates permeability of cell membranes
87
What is the function of sodium?
- Na+
- involved in regulation of osmotic pressure
- affects absorption of carbs in the intestine
- contributes to nervous transmission
88
What is the function of potassium?
- K+
- involved in control of water levels in body fluid
- assists in active transport across the cell membrane
- involved in the synthesis of glycogen and protein
89
What is the function of hydrogen?
- H+
- involved in photosynthesis and respiration
- involved in regulation of blood PH
- involved in transport of oxygen and carbon dioxide in the blood
90
What is the function of ammonium?
- NH4+
- component of amino acids
- essencial component of nucleic acids
- involved in maintenance of body PH
- component of the nitrogen cycle
91
What is the function of nitrate?
- NO3-
- component of amino acids
- essential component of nucleic acids
- component of the nitrogen cycle
92
What is the function of hydrogencarbonate?
- HCO3-
- involved in regulation of blood PH
- involved in transport of carbon dioxide in and out of the blood
93
What is the function of chloride?
- Cl-
- helps with the production of urine
- involved in transport of carbon dioxide in and out of the blood
- involved in regulation of blood PH
- used to produce hydrochloric acid in the stomach
94
What is the function of phosphate?
- PO4-3
- increases rigidity of bone, teeth and cartilage
- involved in regulation of blood PH
- helps root growth in plants
- component of ATP, nucleic acids and phospholipids
95
What is the function of hydroxide?
- OH-
- involved in regulation of blood PH
96
How do you test for reducing sugars?
Using benidicts solution
97
How do you test for non-reducing sugars?
Using benidicts solution and also boiling the samples in HCl
98
How do you test for carbohydrates (starch)
Using iodine solution
99
How do you test for lipids?
Using the emulsion test
100
How do you test for proteins?
Using the biuret solution
101
How do you carry out a test for reducing sugars?
- heat a reducing sugar with benidicts solution
- will turn from blue to brick red
- if benidicts solution is in excess the intensity of the colour is proportional to the conc. of the colour
102
How do you carry out a test for non-reducing sugars?
- first test the sample to check there are none in the first place
- boil the sample with hydrochloric acid
- cool the sample
- neutralise it with sodium hydrogencarbonate
- heat with benidicts solution
103
How do you carry out a test for carbohydrates (starch)?
- add iodine solution to the sample in a white drop tile
- if starch is present the colour will change from brown to blue/black
104
How do you carry out a test for lipids?
- mix the sample thorougly with ethanol
- filter out the solution
- pour the solution into a clean test tube filled with water
- mix the solution
- if the solution turns cloudy, lipids are present
105
How do you carry out a test for proteins?
- add biuret solution to the sample in a white drop tile
- if protein is present the colour will change from blue to lilac
106
What are the qualitatative tests?
The tests for starch, lipids, proteins, reducung and non-reducing sugars
107
What is the quantitative test?
The test for reducing sugars
108
How do you do a quantitative test for reducing sugars?
- take a series of know concentrations of a reducing sugar
- carry out the benidicts test on each sample
- use the colorimeter to record the percentage transmission of each sample (red filter)
- plot these results on a graph
- test the unknown concentration, place it in the colourimeter and compare its result to the graph
109
What is the equation to find the Rf value?
Rf=pigment spot/solvent front
110
What is the aim of chromatography?
To separate a mixture into its constituents
111
What is the stationary phase in chromatography?
The chromatography paper or the thin layer chromatography (TLC)
112
What is the mobile phase in chromatography?
The solvent for the biological molecules
113
How do you carry out a chromatography test?
- on the chromatography paper draw a line in pencil and a dot at the bottom to show where you will place your solution mixture
- spot the solution mixture onto the pencil dot several times using a capillary tube
- wait for the spot to dry before putting the next one on, the spot should be as thin as possible
- lower the paper into the solvent where it should reach below the pencil line
- cover the beaker with a glass plate
- let the apparatus run until he solvent has nearly reached the top then lay on a white tile to dry
114
If the results of chromatography are colourless what are the solutions?
- UV light - the TLC will glow except the places where the spots have reached
- ninhydrin - to see amino acids spray it with ninhydrin and allow to dry, showing purple spots
- iodine - place in enclosed container with iodine crystals so the iodine gas binds to the molecules in each spot
