Biological Molecules Flashcards
(107 cards)
1
Q
What are biological molecules?
A
Groups of chemicals found in living organisms
2
Q
What are the 3 most common bonds in biology?
A
Covalent bonding
Ionic bonding
Hydrogen bonding
3
Q
What is a covalent bond?
A
Atoms share a pair of electrons in their outer shell forming molecules
4
Q
What is ionic bonding?
A
Electrostatic attraction between two ions
5
Q
What is hydrogen bonding?
A
Weak electrostatic bonds between a negative region of a polarised molecule and positively charged region
6
Q
What is a monomer?
A
A small molecule that combines with other small molecules to form a larger molecule called a polymer
7
Q
What is a polymer?
A
A large molecule made up of repeating smaller molecules called monomers
8
Q
What is the process of joining monomers to make a polymer called?
A
Polymerisation
9
Q
What element are monomers usually based on?
A
Carbon
10
Q
What is condensation?
A
A chemical process where two molecules combine to form a more complex molecule often creating water
11
Q
What is hydrolysis?
A
The breaking down of large molecules into smaller molecules by the addition of water
12
Q
What is metabolism?
A
The chemical process that take place in living organisms
13
Q
What is a monosaccharide?
A
A sweet tasting carbohydrate
14
Q
What is the formula for monosaccharides?
A
(CH20)n where n iOS any number from 3 to 7
15
Q
List the 3 monosaccharides
A
Glucose (a and b)
Fructose
Galactose
16
Q
What is the difference between alpha glucose and beta glucose?
A
Aloha has a hydrogen atom next to oxygen
Beta has OH next to the oxygen atom
17
Q
What is a reducing sugar?
A
A monosaccharide (and some disaccharides such as maltose) that can reduce another chemical
18
Q
What is the test for a reducing sugar?
A
Benedicts Test
19
Q
What is Benedicts reagent?
A
An alkaline solution of copper (II)sulphate
20
Q
How do you carry out the Benedicts test?
A
Add Benedicts reagent to a substance and heat
21
Q
What are the results for the Benedicts test?
A
Brick red signals high amounts of reducing sugars
remains blue: no reducing sugars are present
22
Q
What is a disaccharide?
A
A pair of monosaccharides chemically bonded by a glycosidic bond
23
Q
What is a glycosidic bond?
A
The carbon-oxygen-carbon bond between two monosaccharide molecules
24
Q
Alpha glucose + Alpha glucose =
A
Maltose
25
Maltose is broken down by
Maltase
26
Alpha glucose + fructose =
Sucrose
27
Sucrose is broken down by
Sucrase
28
Alpha glucose + galactose =
Lactose
29
Lactose is broken down by
Lactase
30
List three disaccharides
Maltose
Sucrose
Lactose
31
What is the test for non-reducing sugars?
Hydrolyse the reducing sugar into its monosaccharides
Add Benedicts reagent and heat
32
What is a polysaccharide?
A polymer chain of many monosaccharide molecules joined by glycosidic bonds
33
What are the common features of a polysaccharide?
Large molecules
Insoluble
Good for storage
Can be hydrolysed into disaccharides and monosaccharides
34
What is the test for starch?
Add potassium iodide solution (iodine solution)
Shake or stir
35
What are the results for the test for starch?
Blue-Black starch is present
36
What is starch?
A polysaccharide found in plants in the form of small fm grains
37
What is starch made up from?
200-100,000 alpha glucose monosaccharides
38
What is amylose?
An unbranched coiled chain of starch
39
What is amylopectin?
A long branched chain of starch
40
What is the main role of starch?
Energy storage
41
How is starch suited for its function?
It's insoluble and doesn't affect water potential
Large so it doesn't diffuse out of cells
Compact so it can be stored in small space
Produces a glucose when hydrolysis E for easy transportation and respiration
Branched can be catalysed rapidly
42
What is glycogen?
A polysaccharide found in animal cells stored as small granules
43
What is the function of glycogen?
Major carbohydrate storage for animals (particularly in the liver)
44
How does the structure of glycogen make it suitable for its job?
Insoluble doesn't affect water potential
Insoluble so doesn't diffuse out of cells
Compact can be stored in small space
More branches broken down rapidly into glucose for respiration
45
Why is rapid glucose production more important to animals than plants?
It is used in respiration
Animals have a higher metabolic rate
Therefore a higher respiratory rate as they are more active
46
What is cellulose made from?
Alpha glucose monosaccharides
47
What is cellulose?
A polysaccharide found in fibre like strands
48
What is cellulose made from?
Beta glucose monosaccharides
49
Describe the structure of cellulose
Straight unbranched chains running parallel to one another allowing hydrogen bonds between chains
Grouped together to form microfibres which group together to form fibres
50
What is the function of cellulose?
Provides rigidity to plant cell walls
Prevents cells bursting from oso modus by exerting inward pressure
Keep non-woody parts of plants turgid
51
How is cellulose adapted to its function?
Hydrogen bonds forming cross links between chains gives collective strength
Microfibres turn into fibres providing more strength
52
What is a lipid?
Insoluble fats that provide energy, insulation and protections for organisms
53
What properties do lipids have?
Carbon hydrogen oxygen based (in smaller amounts than carbohydrates)
Insoluble in water
Soluble in organic solvents (eg alcohol and acetone)
54
What are the main lipid groups?
Triglycerides and phospholipid
55
What is the role of lipids in cell membranes (cell-surface and around organelles?)
Phospholipids contribute to flexibility and transfer of lipid so liable substances
56
What are the roles of lipids?
Energy source
Waterproofing
Insulation
Protection
57
How do lipids work as a source of energy?
Provide water and more than twice as much energy than carbohydrates when oxidised
58
How do lipids work as waterproofing?
Insoluble in water
Plants and insects have waxy lipid cuticles that conserve water
Mammals produce an oily secretion from sebaceous glands in the skin
59
How do lipids provide insulation?
Fats are slow conductors of heat and help retain body heat when stored beneath the surface of the body
Act as electrical insulators as the myelin sheath in nerve cells
60
How do lipids act as protection?
Fat is stored around delicate organs such as the kidney and heart
61
What are the differences between fats and oils?
Fats : saturated fatty acids, solid at room temperature (10-20C)
Oils: unsaturated fatty acids, liquid at room temperature (10-20C)
62
What is a triglyceride?
Glycerol and three fatty acids
63
What is an ester bond?
The bond that forms between H and HO in glycerol and fatty acids
64
What causes different properties in fats and oils?
The combinations and variations of fatty acids
65
How many fatty acids are there?
Over 70
66
What structure do all fatty acids have?
A carboxyl group with a hydrocarbon chain
67
What is a saturated fatty acid?
A hydrocarbon chain with no carbon-carbon double bonds
68
What is a monounsaturated fatty acid?
A hydrocarbon chain with one carbon-carbon double bond
69
What is a polyunsaturated fatty acid?
A hydrocarbon chain with more than one carbon-carbon double bond
70
Why are triglycerides a good energy source?
High ratio of energy storing carbon-hydrogen bonds to carbon atoms
Low mass to energy ratio- more energy stored in small volume
Insoluble so no affect on water potential and osmosis in cells
Provide water when oxidised
71
What are phospholipids?
Similar to a lipid it has fatty acid tails however has a phosphate molecule
72
What is an important feature of phospholipids?
Polar molecule / solvable
Fatty acids are hyrophobic
Phosphate molecule is hydrophilic
73
What does hydrophilic mean?
Interacts with water but not fat
74
What does hydrophobic mean?
Interacts with fat but not water
75
Which parts of the phospholipids are hydrophobic and which are hydrophilic?
Head - hydrophilic
| Tail - hydrophobic
76
How does phospholipids being bipolar relate to its function?
Forms a bilateral within cell surface membranes Forming a hydrophobic barrier between the inside and outside of a cell
Help hold the surface of the cell membrane
Allows formation of glycolipids important for cell recognition
77
What is the test for lipids?
The emulsion test
78
How do you carry out an emulsion test?
Add ethanol
| Shake thoroughly to dissolve any lipids in the sample
79
What are the results of an emulsion test?
Cloudy - lipid present
Clear - no lipid present
80
What is a protein?
A very large molecule important in living organisms that differs greatly from organism to organism
81
What is an amino acid?
A monomer unit that combines with other amino acids to form dipeptides and polypeptides
82
How many amino acids are there?
About 100
| 20 of which naturally occur in proteins
83
What is the structure of an amino acid?
An amine group
A carboxyl group
A hydrogen atom
A functional group
84
What is a dipeptide?
Two amino acid monomers joined by a condensation reaction and a peptide bond
85
What is a peptide bond?
A bond between a carbon and nitrogen atom involving the formation of water
86
What is the primary structure of a protein?
A polypeptide chain formed by polymerisation
87
What is polymerisation?
When many amino acids condense to form a polypeptide chain
88
How is the primary structure of a protein formed?
The sequence of amino acids determined by DNA
89
What is the importance of the primary structure of a protein?
It determines the final shape of a protein and hence its function
90
A proteins function depends on its...
Shape
91
What is the secondary structure of a protein?
Alpha helix
Beta pleated sheets
92
How does the secondary structure of a protein form?
Hydrogen bonds form between H+ and O- in different amino acids
This causes the polypeptide to bend or coil
93
What is the tertiary structure of a protein?
Further 3D structures develop due to more twisting and folding
94
What bonds are found in the tertiary structure of proteins?
Disulphide bridges
Ionic bonds
Hydrogen bonds
95
What causes the bonds to occur in specific places in a protein?
The primary structure / amino acid sequence
96
Why is the 3D shape of a protein important?
It makes each protein distinctive
Allows it to interact with other molecules due to its shape
97
What is the quaternary structure of proteins?
More than one polypeptide chain bonded together
98
What may the quaternary structure of a protein have that no other structure has?
A prosthetic group (eg. Haem)
99
What is the test for proteins?
Biuret test
100
What is the biuret test?
Add biuret (copper sulphate solution) reagent to the sample
101
What is the result of a biuret test?
Purple - Protein present
Blue - No protein present
102
What are the two basic types of protein?
Globular
| Fibrous
103
What is a fibrous protein?
A protein with structural function
104
What are the properties of fibrous proteins?
Long polypeptide chains that run parallel linked by cross-bridges
105
Give an example of a fibrous protein
Collagen
| Keratin
106
What is a globular protein?
A protein carrying out metabolic functions
107
Give an example of a globular protein?
Enzymes
| Haemoglobin
