Y12 Biological Molecules Flashcards
1
Q
Reducing sugar
A
Sugars that readily lose electrons to another substance and become oxidised
Examples include glucose and fructose
2
Q
Amylose
A
The unbranched sections of starch that form tight coils held together by hydrogen bonds
3
Q
Microfibril
A
A structure formed by many cellulose molecules joined together through hydrogen bonds
4
Q
Condensation reaction
A
A reaction that joins two molecules together with the formation of a chemical bonds and involves the elimination of a water molecule
5
Q
Non-reducing sugar
A
Sugars that are not readily oxidised and do not reduce other substances, such as sucrose
6
Q
Monomer
A
The smaller units from which larger molecules are made. Many are based on carbon.
7
Q
Maltose
A
A disaccharide formed by condensation of two glucose molecules
8
Q
Hydrolysis reaction
A
A reaction that breaks a chemical bonds between two molecules and involves the use of a water molecule
9
Q
Lactose
A
A disaccharide formed by the condensation of a glucose molecule and a galactose molecule
10
Q
Disaccharide
A
A carbohydrate formed by the condensation of two monosaccharides
11
Q
a-1,4-glycosidic bonds
A
Chemical bonds that form straight lines between polysaccharides like glycogen and starch
12
Q
Glycosidic bond
A
A chemical bond formed between two monosaccharides through a condensation reaction
13
Q
Monosaccharide
A
The monomers from which larger carbohydrates are made. Examples include glucose, galactose and fructose.
14
Q
Polymer
A
Molecules made from a large number of monomers joined together
15
Q
Cellulose
A
A polysaccharide made of b-glucose molecules with no branches, found in plant cell walls providing rigidity and strength
16
Q
Starch
A
A polysaccharide made of a-glucose molecules, less branches than glycogen, used for energy storage in plants
17
Q
Amylopectin
A
The branched sections of starch
18
Q
Glycogen
A
A highly branched polysaccharide made of many a-glucose molecules, used for energy storage in animals and stored in liver and muscle cells
19
Q
a-1,6-glycosidic bonds
A
Chemical bonds that form branches in polysaccharides like glycogen and starch
20
Q
Sucrose
A
A disaccharide formed by condensation of a glucose molecule and a fructose molecule
21
Q
Phospholipids
A
A type of lipid where one of the fatty acids of a triglyceride is substituted by a phosphate-containing group, resulting in a hydrophilic head and hydrophobic tails
22
Q
Phospholipid bilayer structure
A
Two layers of phospholipids where hydrophilic heads are exposed to water on inside and outside of cell, while hydrophobic tails are hidden inside the bilayer
23
Q
Triglyceride
A
A type of lipid formed by the condensation of one molecule of glycerol and three molecules of fatty acids
24
Q
Properties of triglycerides
A
-Contain lots of chemical energy
-Are not soluble in water (hydrophobic)
-Form small droplets
-Do not affect water potential
-Provide insulation in animals
-Energy source for germination in plants
25
Properties of phospholipids
-Insoluble in water but have a hydrophilic head due to negative charge
-Can form single or double layers
-Make up the cell membrane bilayer
26
Unsaturated fatty acids
Fatty acids contain carbon to carbon double bonds, causing a kink in the fatty acids chain
27
Ester bond
The type of bond formed by a condensation reaction between glycerol and a fatty acid
28
Lipase
An enzyme that hydrolyses triglycerides, causing a decrease in pH during the reaction
29
Saturated fatty acids
Fatty acids that contain no carbon to carbon double bonds
30
Lipid biochemical test
Shake food substance with ethanol to dissolve, then add water. A positive result shows a milky white emulsion
31
Function of Triglycerides in organisms
In animals they are found in adipose tissue providing insulation, while in plants they are found in seeds as energy source for germination
32
Biuret test
A biochemical test that detects peptide bonds, showing a colour change from blue to lilac when proteins are present
33
Hydroxylation
The addition of a hydroxyl group (OH) to a molecule, as seen in the conversion of phenylalanine to tyrosine
34
Secondary structure
The first folds in a protein formed by hydrogen bonds between the NH and C=O groups, resulting in either an a-helix coiled or a b-pleated sheet
35
R group
A side chain of an amino acid that makes each amino acid uniquw
36
Condensation reaction (proteins)
A reaction between two amino acids where water is removed to form a peptide bond
37
Amino acids
The monomers from which proteins are made. The twenty amino acids common in all organisms differ only in their side (R) group.
38
B-pleated sheet
A type of secondary structure formed by folding of the polypeptide chain
39
Collagen
A fibrous protein with quaternary structure and cross-linkages between polypeptide chains
40
Protein structure levels
The four levels of protein organisation:
-Primary (Amino acid sequence)
-Secondary (Initial folding)
-Tertiary (3D structure)
-Quaternary (Multiple chains)
41
Quaternary structure
The structure formed when a protein consists of more than one polypeptide chain
42
Dipeptide
A molecule formed when two amino acids join together through a peptide bond
43
Peptide bond
A bond formed between two amino acids through a condensation reaction where H20 is removed, forming a dipeptide
44
Fibrous protein
Proteins that are insoluble in water and serve structural roles, such as collagen
45
A-helix
A type of secondary structure where the polypeptide chain is twisted into a spiral shape
46
Tertiary structure
Further twisting and folding of the secondary structure into more specific 3D structures, maintained by various bonds
47
Globular proteins
Proteins that are soluble in water with 3D shapes that support their function, such as enzymes
48
Keratins
A group of proteins that differ in primary structure and consist of several polypeptide chains wound into a spiral or helix
49
Primary structure
The sequence of amino acids in a protein chain, determined by DNA
50
Hydrogen bonds
Bonds that form between the H of the NH group and the O of the C=O group in proteins, contributing to secondary structure
51
Polypeptide
A chain formed when many amino acids join together through peptide bonds
52
Optimum pH
Specific pH level at which an enzyme functions most effectively, activity decreases as pH moves away from this point
53
Denaturation
Process where enzymes lose their shape and function due to breaking of bonds in its structure, often caused in extreme temperature or pH
54
Substrate concentration effect
As substrate concentration increases more enzyme-substrate complexes from until active site becomes denatured
55
Active site
Specific region on enzyme where substrate binding occurs and chemical reaction takes place
56
Enzyme
Proteins with a tertiary structure that lower the activation energy of specific reactions they catalyse
57
Induced-fit model
Model showing that the active site forms as the enzyme and substrate interact, where proximity of.a substrate leads to a change in enzyme that forms functional active site
58
Allosteric site
Alternative binding site on enzyme where non-competitive inhibitors attach
59
Enzyme specificity
The ability of an enzyme to combine with only one specific substrate due to the complementary shape of its active site
60
Competitive inhibitors
Molecules with similar shape to the substrate that compete for the active site, their effect can be reduced by increasing substrate concentration
61
Enzyme saturation
State where all enzyme active sites are occupies and increasing substrate concentration no longer increases reaction rate
62
Enzyme concentration effect
Increasing enzyme concentration increases reaction rate until substrate concentration becomes limiting factor
63
Heavy metal poisoning
Permanent change in enzyme active site shape caused by heavy metals like lead, mercury, copper, and silver
64
Activation energy
The minimum amount of energy needed to activate a reaction
65
Non-competitive inhibitors
Molecules that bind to the enzyme at allosteric site, not active site, changing the shape of active site and decreasing reaction rate
66
Lock and key model limitations
Original model disproven because scientists observed molecules could bind to enzymes in sites other than active site and enzyme structure is flexible not rigid
67
Enzyme substrate complexes
Formation that occurs when an enzyme combines with its complementary substrate at the active site
68
Anabolic reactions
Building up of molecules where energy is taken from surroundings
69
Catabolic reactions
Breaking down of molecules where energy is released to surroundings
70
End product inhibition
Process where end product acts as inhibitor of enzyme - higher end product concentration leads to more inhibition and vice versa
71
Optimum temperature
Temperature at which enxyme works best, below this there is less kinetic energy and above this bonds break leading to denaturation
72
Active Transport
A process that moves substances across membranes against concentration gradients, requiring energy from ATP breakdown
73
ATP synthase
The enzyme that catalyses the synthesis of ATP from ADP and Pi during photosynthesis or respiration
74
ADP
Adenosine diphosphate:
Formed when ATP loses one phosphate group through hydrolysis
75
ATP synthesis
The condensation reaction between ADP and Pi to form ATP, catalysed by ATP synthase
76
ATP
Adenosine triphosphate:
A nucleotide derivative formed from ribose, adenine, and three phosphate groups
77
Pi
Inorganic Phosphate:
Released during ATP hydrolysis and can be used to phosphorylate other compounds
78
Phosphorylation
The process of adding a phosphate group to other compounds using Pi from ATP hydrolysis, often making them more reactive
79
ATP hydrolase
The enzyme that catalyses the breakdown of ATP to ADP and inorganic phosphate (Pi)
80
AMP
Adenosine monophosphate:
A molecule similar to ATP and ADP but containing only one phosphate group
81
ATP hydrolysis
The breakdown of ATP to ADP and Pi, which can be coupled to energy-requiring reactions within cells
82
Unusual properties of water
Due to its dipole nature and hydrogen bonding, water has unique properties that make it essential for cellular function
83
Water molecule composition
Made up of 2 hydrogen atoms and 1 oxygen atom, with no overall charge but electrons are pulled towards oxygen creating a polar molecule
84
ATP hydrolysis products
When water is used to hydrolyse ATP, it produces two products
85
Polar nature of water
Oxygen atoms have a slightly negative charge while hydrogen atoms have a slightly positive charge, making water molecules polar
86
Water in plant transport
The cohesive properties of water allow it to form columns in the tube-like transport cells of plants
87
Water as a solvent
Water serves as an important solvent in which metabolic reactions occur
88
Heat capacity of water
Water has a relatively high heat capacity which helps buffer changes in temperature
89
Cohesion in water
Water molecules have strong cohesion between them, supporting water columns in plant cell transport and producing surface tension where water meets air
90
Water as a metabolite
Water participates in many metabolic reactions, including condensation and hydrolysis reactions
91
Latent heat of vaporisation
Water has a relatively large latent heat of vaporisation which provides a cooling effect with minimal water loss through evaporation
92
Effect of high temperatures on membranes
Above 45.C the bilayer starts to melt, water expands, and membrane proteins deform, increasing membrane permeability
93
Hydrophobic centre function
Allows lipid-soluble substances to event and leave the cell but prevents water-soluble substances from passing through
94
Normal temperature range for membrane function
Between 0.C and 45.C the membrane remains partially permeable, with permeability increasing as temperature rises
95
Glycoproteins
Proteins with polysaccharide chains attached that act as receptors and recognition sites
96
Membrane permeability factors
Include temperature and certain solvents like ethanol that can affect how easily substances pass through the membrane
97
Phospholipid structure
-Made up of a glycerol molecule with two fatty acid chains (tails) and a hydrophilic head
-Heads are polar and attracted to water
-Tails are hydrophobic and repelled by water
98
Channel proteins
Membrane proteins that span the entire membrane and allow large molecules and ions to pass through
99
Receptor proteins
Proteins embedded on the cell surface that detect chemicals released from other cells, such as insulin
100
Effect of low temperatures on membranes
Below 0.C protein can deform and ice crystals form holes in the membrane, leading to high permeability when thawed
101
Glycolipids
Lipids with polysaccharide chains that extend into the surrounding environment, helping stabilise the membrane and act as receptors and recognition sites
102
Cell surface membrane function
Controls which substances enter and leave the cells acts as a barrier between the cell and its environment
103
Aquaporins
Special protein channels that allow water molecules to pass through the cell membrane
104
Phospholipid bilayer
Basic structure of all cell membranes consisting of two layers of phospholipids with tails pointing inward and heads on the outside
105
Membrane self-sealing property
Phospholipids make the membrane flexible and able to repair itself when damaged
106
Fluid Mosaic Model
Membrane structure where phospholipids can move relative to another (fluid) and proteins are embedded like tiles (mosaic)
107
Small molecule diffusion
Small molecules like oxygen and carbon dioxide can diffuse directly across the cell membrane without repairing transport proteins
108
Cholesterol function
Fits between phospholipids and binds hydrophobic tails together, making the membrane less fluid and more rigid
109
Carrier proteins
Transport proteins embedded in the membrane that help move substances across the cell membrane
110
Effect of ethanol on membrane
Shifts lipid molecules out of place and breaks up their orderly arrangement, making the membrane more liquid-like and increasing permeability
111
Partially permeable membrane
Allows some substances through but not others, depending on size, polarity, and lipid solubility
