Biological Molecules Flashcards
1
Q
Macronutrient
A
Organic compounds required in large amounts
- Proteins
- Lipids
- Carbohydrates
2
Q
Protein
A
An organic macromolecule essential to life.
Formed from one or more polypeptides
3
Q
Enzymes
A
Globular proteins that act as biological catalysts to increase the rate of reactions
4
Q
Uses of protein
A
Enzymes which catalyse chemical reactions
- Forming muscle, bone and other structural features
- Emergency energy source
5
Q
Elements in protein
A
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
- Other elements like iron and sulphur
6
Q
Condensation reaction
A
When 2 molecules join together, with water as a byproduct
7
Q
Hydrolysis reaction
A
When 2 molecules break apart when water is added
8
Q
Bonding of protein
A
- Peptide bonds between amino acids
- Regular covalent bonds within the amino acid
- Ionic, hydrogen, disulfide, or hydrophobic bonds on secondary and tertiary levels
9
Q
Hydrogen bond
A
A weak interaction between a negative ion and a positive hydrogen atom
10
Q
Covalent bond
A
A strong interaction resulting in the sharing of electrons in the outer shell.
E.g. disulfide, phosphodiester, peptide, glycosidic
11
Q
Cyclic form
A
The shape formed by a molecule where the final atom is attached to the first
12
Q
Straight line form
A
The shape formed by a molecule where all the atoms are in a line
13
Q
Amino acid
A
A monomer of proteins with 20 different types
- Amphoteric and a buffer
- Composed of the same basic structure, but with a unique R group
14
Q
Amphoteric
A
A compound that is able to react with both bases and acids.
E.g. Amino acids, water, hydrogen carbonate ions
15
Q
Peptide bond
A
A strong chemical bond between two amino acids, formed through a condensation reaction.
- When aqueous, the amino group goes from NH₂ to NH₃⁺ (+H⁺)
- The Carboxyl group goes from COOH to COO⁻ (-H⁺)
- The carboxyl and amino acids then bind, with water as a byproduct
16
Q
Amino acid structure
A
- Hydrogen group
- Amino group
- Carboxyl group
- R group / side chain
17
Q
Carboxyl group
A
- COOH
- Acidic
- Found in single bonded monosaccharides
- Found in amino acids
18
Q
Dipeptide
A
Two amino acids that have combined together with a condensation reaction between the amino and carboxyl groups, resulting in the release of water
19
Q
Polypeptide
A
A chain of multiple amino acids
20
Q
Primary structure
A
The order of amino acids in a protein.
Has peptide bonds between amino and carboxyl groups
21
Q
Secondary structure
A
When chains of amino acids coil or fold
36 amino acids per 10 turns
- Two different types: α-helix, β-pleated sheet
- Lots of hydrogen bonds between -NH group and -CO group further down the chain
- Stable at optimal temperatures
22
Q
Alpha helix
A
A form of secondary structure of amino acids where the amino acids that bind are 4 places apart. Resulting in a twirl shape
23
Q
Beta pleated shee
A
A form of secondary structure where a zig-zag structure is formed as the chains folds over itself
24
Q
Tertiary structure
A
When coiled chains of amino acids are folded into precise shapes, usually either supercoiled or spherical.
Mostly exhibited in globular proteins, with fibrous proteins often stopping at secondary structure
- Variety of bonds, including ionic, hydrogen,hydrophilic, hydrophobic, disulfide
25
Ionic bonds
Bonds formed between oppositely charged groups on amino acids. Formed in tertiary structures
26
Disulfide bonds
A bond between the sulfide components of the R-group of cysteines.
A form of strong covalent bonds
27
Quaternary structure
A combination of multiple polypeptide chains.
Almost exclusively found in globular proteins
28
Fibrous proteins
A form of tertiary structure of proteins where the chains of amino acids are arranged in long patterns.
Usually insoluble in water
29
Examples of fibrous proteins
- Keratin
- Collagen
- Elastin
29
30
Collagen
A fibrous protein where every 3rd amino acid is glycine, giving strength due to the small size of glycine.
- Composed of 3 chains of around 1000 amino acids each. Bonded with hydrogen bonds
- Structural protein that gives strength to skin, bones, tendons and forms cartilage.
- Found in artery walls, bones, and connective tissue
31
Keratin
A fibrous protein rich in cysteine, with lots of disulfide bridges
- Strong, waterproof, barrier
- Found in hair, nails, claws, hoofs
32
Elastin
A fibrous protein with many cross-links and coils to give strength and elasticity
- Found in skin, lungs, bladder, blood vessels
33
Globular protein
A protein of a roughly spherical shape.
- Hydrophobic parts are towards the centre, and hydrophilic towards the surface, making the protein water soluble.
- Often have very specific shapes
34
Examples of globular proteins
- Haemoglobin
- Insulin
- Pepsin
- Most enzymes
35
Conjugated protein
A protein to which another chemical is attached
E.g. glycoprotein, lipoprotein
36
Haemoglobin
A globular protein formed from 2 alpha and 2 beta chains, each with a haem group attached.
- Held together in a specific shape
37
Insulin
A globular protein made of 2 polypeptide chains, with both alpha and beta folding
- Soluble to water
- Increases the uptake of glucose in the liver
38
Pepsin
A globular protein made up of a single polypeptide chain of 327 amino acids
- Able to work in acidic conditions due to the high proportion of acidic R groups compared to basic R groups
- Breakdowns enzymes in the stomach
39
ab
40
com
41
Biuret test
A qualitative test for proteins
42
Carbohydrate
A compound made of carbon, hydrogen and oxygen. Also a form of macronutrient that is the primary energy source for humans
43
Elements in carbohydrates
- Carbon
- Oxygen
- Hydrogen
44
Uses of carbohydrates
- Primary energy source of humans
- Structural units
- Energy store
45
Bonding in carbohydrates
- Glycosidic bonds between monosaccharides
- Hydrogen bonds between carbon and hydrogen
46
Sugar
Small, water soluble carbohydrates that taste sweet. Either monosaccharides or disaccharide
47
Monosaccharide
A singular sugar molecule that forms the basis for polysaccharides
48
Examples of monosaccharides
- Glucose (C₆H₁₂O₆)
- Fructose (C₆H₁₂O₆)
- Galactose (C₆H₁₂O₆)
- Ribose (C₅H₁₀O₅)
- Deoxyribose (C₅H₁₀O₄)
49
Isomer
A compound with the same formula but different structure
50
Alpha glucose
A hexose sugar that's a form of glucose where the
-OH molecule is on the bottom.
C₆H₁₂O₆
Energy source, component of glycogen and starch
- Large portion of bonds broken during respiration
- OH groups forms hydrogen bonds, making it water soluble
51
Beta glucose
A hexose sugar that's a form of glucose where the
-OH molecule is on the top
C₆H₁₂O₆
Energy source, component of cellulose
- Forms hydrogen bonds with other identical molecules to become insoluble
- Alternate shape gives chains strength and prevents spiralling
52
Ribose
A pentose sugar that's a component of RNA, ATP and NAD
C₅H₁₀O₅
53
Deoxyribose
A pentose sugar that's a component of DNA
C₅H₁₀O₄
54
Disaccharide
A form of sugar that is formed when two monosaccharides undergo a condensation reaction, producing a water by-product
- Cellobiose (β glucose + β glucose)
- Maltose (α glucose + α glucose)
- Lactose (α glucose + galactose)
- Sucrose (α glucose + fructose)
55
Cellobiose
Disaccharide formed from 2 β-glucose monomers.
Used as an indicator for Crohn's disease
56
Maltose
Disaccharide formed from 2 α-glucose monomers.
Has 1-4 glycosidic bond
Formation triggers germination
57
Lactose
Disaccharide formed from α-glucose and galactose monomers.
Provides energy for infant mammals
- Fed to infant mammals to provide gradual release of monosaccharides
58
Sucrose
Disaccharide formed from α-glucose and fructose monomers.
Produced by photosynthesis
Primary sugar in plants
59
Polysaccharide
A carbohydrate polymer formed by more than two monosaccharides
60
Homopolysaccharide
A polysaccharide made up of all the same type of monosaccharide monomer
E.g. cellulose, starch, glycogen, amylose
61
Advantages of polysaccharides as energy stores
- Compact
- Easily 'snipped off' when monosaccharides are required for respiration
- Branching allows for quick release of lots of energy
- Less water soluble than monosaccharides, preventing cytolysis
62
Glycosidic bond
A type of covalent bond formed by a condensation reaction between two monosaccharides
63
Amylose
A single long chain of α-glucose with 1-4 glycosidic bonds.
-- Hydrogen bonds between units to form coil
- Not water soluble due to hydroxyl groups on carbon 2 situated inside the coil
- Multiple chains make up starch
64
Amylopectin
A single long chain of α-glucose with 1-4 glycosidic bonds, with other chains coming off it with 1-6 glycosidic bonds
- Coiled into a spiral shape, with branches coming off it
65
Cellulose
A form of polysaccharide made from β-glucose' with 1-4 glycosidic bonds.
- Forms long and straight molecules.
- Hydrogen bonds between bundles
- Not water soluble
- Forms cell walls in plant cells
- Difficult to digest
- High tensile strength
66
Glycogen
A form of polysaccharide made from α-glucose with 1-4 glycosidic bonds; with other chains coming off it with 1-6 glycosidic bonds.
- Shorter branches than amylopectin, but with more branches
- Some hydrogen bonds in between units
- Not water soluble
67
Starch
A polysaccharide used for storing glucose in plants
(C₆H₁₂O₅)ₙ
68
Features of plant cell walls
- Enough strength to support the whole plant
- Space for flow of water and ions
- Permeable
- High tensile strength
- Able to be reinforced by other substances
69
Peptidoglycan
A polysaccharide that forms the basis of bacterial cell walls
70
Reducing sugar
All monosaccharides and some disaccharides
- Can give electrons to other molecules
- Can be tested for with Benedict's reagent
71
Non-reducing sugar
Cannot be easily oxidised
- A sugar that accepts electrons from other chemicals
- Made up of 'reducing groups' i.e. can be broken down into reducing sugars
- Usually more more complex disaccharides E.g. sucrose
72
Benedict's test
A semi-qualitative test for reducing and non-reducing sugars
73
Reagent strips
Qualitative test for reducing sugars (used as urine test for glucose)
74
Iodine test
Qualitative test for starch
75
Lipid
A molecule formed from fatty acids and glycerol.
Includes triglycerides, phospholipids, glycolipids, and cholesterol
76
Elements in lipids
- Carbon
- Hydrogen
- Oxygen
- Sometimes phosphorus, nitrogen, sulphur, etc
77
Uses of lipids
Energy store / source
- Insulation and protection
- Source of nutrients
- Cell membranes
- Buoyancy
78
Energy store / source
- Insulation and protection
- Source of nutrients
- Cell membranes
- Buoyancy
The alcohol group in glycerol and the carboxyl group in fatty acids bond to form the lipid, known as ester bonds
- Hydrogen bonds between carbons
79
Triglyceride
Triglyceride
A lipid formed from three fatty acids bonded to a glycerol molecule.
Bonded through esterification
Unsaturated versions are liquid, saturated versions are solid
- Insoluble in water
80
Esterification
The condensation reaction between an alcohol group and carboxyl group, resulting in an ester.
A water molecule is also released
81
Glycerol
A type of alcohol with three carbon atoms. It forms the basis of most lipids
- Has 3 free -OH groups, for fatty acids to attach to
- Water soluble
82
Fatty acids
A carboxyl group attached to a hydrocarbon tail.
2-20 carbons long
- Ionises to release H⁺, making it an acid
83
Saturated fatty acids
Fatty acids that contain the maximum amount of hydrogen atoms as possible (only C-C single bonds)
- High melting point, solid at room temp
- No double bonds in hydrocarbon
- Straight hydrocarbon chains
- Increases risk of heart disease
84
Unsaturated fatty acids
Fatty acids that do not contain the maximum amount of hydrogen atoms (contains C=C double bonds).
- Kink in the structure makes it more fluid
- Low melting point, liquid at room temp
- One or more double bonds in hydrocarbon
- Kink in hydrocarbon chains
- Doesn't increase risk of heart disease
85
Polyunsaturated fatty acids
Fatty acids that do not contain the maximum amount of hydrogen atoms (contains multiple C=C double bonds).
86
Condensation reactions in triglycerides
- Glycerol and 3 fatty acids join
- Releases 3H₂O
- Creates 3 ester bonds
87
Hydrolysis reactions in triglycerides
- Molecule breaks apart
- Requires 3H₂O
- Breaks 3 ester bonds
88
Phospholipids
A form of lipid that consists of glycerol, two fatty acids (1 saturated, 1 unsaturated) and a phosphate group.
- Hydrocarbon tails are usually 16-18 carbons long
- Cell membranes are formed from a double layer of this
- Amphipathic: hydrophobic tail, hydrophilic head
- Forms micelles when submerged in water
- Insoluble in water
89
Amphipathic
A molecule with both hydrophobic and hydrophilic parts
90
Micelles
Tiny balls of phospholipids with the tails in the centre, and the heads sticking out
91
Phospholipid bilayer
A dual layer of phospholipids with the tails facing towards each other, and the heads facing away
Forms the backbone of cell membranes
- Selectively permeable, only small non-polar molecules can pass through
92
Cholesterol
A type of lipid sterol (steroid alcohol).
Consists of 4 carbon-rings called isoprene units
- Small and hydrophobic, it often sits between the phospholipids of a membrane, giving stability, preventing it from becoming too stiff or fluid.
- Mainly made in the liver
- Insoluble in water
93
Uses of cholesterol
- Membranes
- Makes up oestrogen
- Makes up testosterone
- Makes up Vitamin D
94
Emulsion test
Qualitative test for lipids
95
Inorganic ion
A charged molecule that is not carbon based but still essential to bodily functions
- Cations or anions
96
Cation
A positively charged ion (less electrons)
- Ca²⁺
- Na⁺
- K⁺
- H⁺
- NH₄⁺
97
Anion
A negatively charged ion (more electrons)
- NO₃⁻
- HCO₃⁻
- Cl⁻
- PO₄³⁻
- OH⁻
98
Calcium
Essential cation
- Increases rigidity of bone, teeth and cartilage
- Component on exoskeleton of crustaceans
- Enzyme activator
- Stimulates muscle contraction
- Regulates nerve transmission
- Regulates membrane permeability
- Cell wall development
- Triggers exocytosis
- Moves vesicles to the cell membrane
99
Sodium
Essential cation
- Osmotic pressure regulation
- Water level regulation
- Buffer
- Carbohydrate absorption
- Muscle contraction
- Maintains turgidity in plants
- Nerve transmission
100
Potassium
Essential cation
- Control of water levels
- Active transport
- Protein and glycogen synthesis
- Flower and leaf health
- Nerve transmission
- Muscle contraction
- Turgidity in plants
101
Ammonium and nitrate
Essential ions, one cation and one anion
NH₄⁺ and NO₃⁻
- Component of amino acids, vitamins, chlorophyll
- Component of protein-based hormones
- Essential in nucleic acids
- Buffer
- Component of nitrogen cycle
102
Hydrogencarbonate
Essential ion
HCO₃⁻
- Buffer
- Transport of carbon dioxide
103
Chloride
Essential ion
- Production of urine
- Transport of carbon dioxide
- Haemoglobin regulation
- Buffer
- Production of HCl
104
Phosphate
Essential ion
PO₄³⁻
- Bone, teeth and cartilage regulation
- Component of exoskeletons in crustaceans
- Buffer
- Root growth in plants
- ATP
105
Uses of water
- Solvent
- Transport medium
- Reactant in metabolic reactions
- Maintain turgidity of cells
- Lubricant
- Soften skin
- Cushion joints
- Adhesion / cohesion
106
Cohesion
Attraction of 2 molecules of the same type
107
Adhesion
Attraction of 2 molecules of different types
108
Specific heat capacity
The amount of energy needed to raise the temperature of 1kg of a substance by 1°c
109
Properties of water
- Polar
- High specific heat capacity
- Solvent
- Unique density (solid < liquid)
- Forms surface tension
- Cohesiveness in xylem
- Resists changes in heat
110
Density of water
Due to the structure of water molecules, ice is less dense than liquid water. This means that ice floats on top of water.
- This provides stable aqueous environments
- Bodies of water become insulated by the layer of ice
111
Solvency of water
The polarity of water attracts both positive and negative parts of solutes, increasing the range of molecules it can dissolve.
- This allows molecules and ions to react within water
- Means water can act as a transport medium
- Means water can act as a medium for metabolic reactions
- Allows water to dilute toxic substances
- Allows separation of ionic compounds
- Means organisms can take in minerals / ions / gas / food
112
Cohesiveness of water
Hydrogen bonds keep the molecules together, increasing their attractiveness to each other, rather than other molecules like air
- Creates surface tension
- Chains of water molecules can move up xylem vessels in plants
- Allows some insects to walk on water
113
Stable temperature of water
High specific heat capacity (4.2kJ/kg) creates a stable environment for life, both aqueous and not
High Latent heat allows water to stabilise temperatures and cool things down
- Useful in temperature regulation systems
