3.1: Biological Molecules Keywords Flashcards
Covalent Bond
Type of chemical bond in which two atoms share a pair of electrons
Ionic Bond
A bond between a positive ion which has lost an electron(s) and a negative ion which has gained an electron(s)
Hydrogen Bond
Chemical bond formed between the positive charge on a hydrogen atom
Polar molecule
A molecule which has a partially positive charge in one part of the molecule and completely negative charge in another part (a dipole)
Monomer
One of many small molecules that combine together to form a polymer
Polymer
Large molecules made up of many repeating smaller molecules (monomers)
Polymerisation
The process of making a polymer
Condensation
- Chemical process in which two molecules combine to form a more complex one with the elimination of a simple substance, usually water
- Many biological polymers (e.g. polysaccharides, polypeptides) are formed by condensation
Hydrolysis
The breaking down of large molecules into smaller ones by the addition of water molecules
Metabolism
All the chemical processes that take place in living organisms
Mole
The mass of a substance containing the same number of fundamental units as there are atoms in exactly 12g of 12C
Molar (M) Solution
An aqueous solution that contains 1 mole of solute in 1 litre of solution
Carbohydrate
- Compounds made from carbon, hydrogen and oxygen
- Either monosaccharides, disaccharides and polysaccharides
Monosaccharide
A single sugar e.g. glucose
Organic Molecule
- Molecules containing carbon that can be found in living things
- Four classes are carbohydrates, proteins (chain of amino acids), lipids and nucleic acids
Disaccharide
- Made up of two sugar units that are formed by a condensation reaction
- Monosaccharides are joined by a glycosidic bond
Polysaccharide
- Made of many sugar units that are formed by a condensation reaction
- Monosaccharides are joined by a glycosidic bond
Hexose sugar
A sugar made up of 6 carbons
Glucose
- C6H12O6
- A single sugar which is used in respiration
Reducing sugar
- A sugar that serves as a reducing agent
- All monosaccharides are reducing sugars along with some disaccharides
Reducing sugar’s test
- Heat solution with Benedict’s reagent
- Brick red = present
Benedict’s reagent
Blue solution which is used to test for reducing and non-reducing sugars
Glycosidic bond
Bond between sugar molecules in disaccharides and polysaccharides
Non-reducing sugar
- A sugar which cannot serve as a reducing agent
- An example is sucrose
Non-reducing sugar’s test
- Following a negative reducing sugars test, heat solution with HCl to hydrolyse the non-reducing sugars into its monosaccharides
- Perform the Benedict’s test again and if positive result then present
Starch
A polysaccharide found in plant cells made up of alpha-glucose - comprised of amylose (alpha-1,4 glycosidic bonds) and amylopectic (alpha-1,4 and alpha-1,6 glycosidic bonds)
Glycogen
A highly branched polysaccharide made up of alpha-glucose found in animal cells (alpha-1,4 and alpha-1,6 glycosidic bonds)
Cellulose
A polysaccharide made up of beta-glucose found in plant cells (beta-1,4 glycosidic bonds)
Alpha glucose
An isomer of glucose that can bond together to form starch or glycogen
Beta glucose
An isomer of glucose that can bond together to form cellulose
Lipid
- A class of organic compounds with fatty acids as their derivatives and are insoluble in water but soluble in organic solvents
- Include triglycerides, phospholipids, waxes and steroids
Triglyceride
- An individual lipid molecule made up of a glycerol molecule and three fatty acids
- Contains ester bonds
Fatty acid
A carboxylic acid with a hydrocarbon tail
Glycerol
- A molecule which combines with three fatty acids to form triglycerides
- It’s a 3 carbon chain with 3 hydroxyl groups
Saturated fatty acid
A fatty acid in which there are no double bonds between carbon atoms
Mono-unsaturated fatty acid
A fatty acid which possesses a carbon chain with a single double bond between carbon atoms
Poly-unsaturated fatty acid
A fatty acid which possesses a carbon chain with many double bonds between carbon atoms
Phospholipid
- Triglyceride in which one of the three fatty acid molecules is replaced by a phosphate molecule
- Important in structure and functioning of plasma membranes
Hydrophilic
Section of a molecule which is attracted to water
Hydrophobic
Section of a molecule which is repulsed by water
Emulsion test
- Test for lipids
- Mix sample with ethanol and add water
- If a white cloudy emulsion forms, then a lipid is present
Protein
- A polymer which is made up of amino acids linked by peptide bonds
- May also contain prosthetic groups as part of its quaternary structure
Amino acid
- A monomer which makes up proteins
- Has a central carbon atom which is bonded to a carboxylic group, an amine group, a hydrogen atom and a R group
Amino group
The -NH2 group of an amino acid
Carboxyl group
The -COOH group of an amino acid
R-group
Each of the 20 amino acids have a different R group - determines the bonding that the amino acid can carry out
Peptide bond
The type of bond that is formed between two amino acids
Polypeptide
Many amino acids joined together by peptide bonds
Primary protein structure
The sequence of amino acids that makes up the polypeptides of a protein
Secondary protein structure
The way in which the chain of amino acids of polypeptides of a protein are folded
Tertiary protein structure
The folding of a whole polypeptide chain in a precise way, as determined by the amino acids of which it’s composed
Disulfide bridge
Bond formed between Sulphur atoms in R groups of amino acids
Quaternary protein structure
A number of polypeptide chains linked together, and sometimes associated with non-protein groups to form a protein
Biuret test
A simple biochemical reaction to detect presence of protein, if Biuret’s solution turns purple then protein is present
Enzyme
A protein that acts as a catalyst and so lowers the activation energy needed for a reaction
Activation energy
Energy required to bring about a reaction
Active site
A group of amino acids that makes up the region of an enzyme into which the substrate fits in order to catalyse a reaction
Substrate
- A substance that is acted on or used by another substance or process
- Fits into the active site of an enzyme
Enzyme-substrate complex
The intermediate formed when a substrate molecule interacts with the active site of an enzyme
Complimentary
Describes the relationship between the active site of an enzyme and the substrate molecule - the way in which they fit together
Specific
Describes how enzymes catalyse a certain chemical reaction
Induced Fit
- A mechanism of interaction between an enzyme and a substrate
- As the substrate fits into the active site, the active site of the enzyme changes shape in order to allow an enzyme-substrate complex to be formed
Lock and Key
An analogy for how enzymes work - only the correctly sized key (substrate) fits into the keyhole (active site) of the lock (enzyme)
Rate of reaction
The speed of a chemical reaction - can be worked out by looking at the decrease in concentration of a reactant over time or increase in concentration of a product over time
Kinetic energy
The energy of motion, observable as the movement of an object, particle or set of particles
pH
- A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acidic and higher values are more alkaline.
- Equivalent to -log10[H+].
Inhibitor
A substance which reduces the activity of an enzyme
Competitive Inhibitor
A form of inhibitor which binds to the active site of the enzyme, preventing the binding of substrate
Non-competitive inhibitor
A form of inhibitor which does not bind at the active site of the enzyme and prevents the binding of substrate
DNA
- Deoxyribonucleic acid which is present in nearly all living organisms as the carrier of genetic information
- A double helix made up of two polynucleotide chains, running antiparallel to each other, with the sugar-phosphate backbone on the outside and organic bases bonded together by Hydrogen bonds in the centre of the helix
- The nucleotides have a deoxyribose sugar and the bases adenine, thymine, guanine or cytosine
Nucleotide
- Complex chemicals made up of an organic base, a sugar and a phosphate
- They are the basic units of which the nucleic acids DNA and RNA are made
Polynucleotide
A polymer of monomers called nucleotides
Phosphodiester bond
The bond formed by a condensation reaction between the phosphate group of one nucleotide and the pentose sugar of another nucleotide
Organic base
Part of a nucleotide - either adenine, thymine, cytosine, guanine or uracil
RNA
- A polynucleotide which contains nucleotides that have the pentose sugar ribose rather than deoxyribose and contains the bases adenine, uracil, guanine or cytosine
- Can be either mRNA, tRNA or rRNA.
Complimentary base pairing
- Specific rules for how the bases pair together
- Adenine pairs with thymine with 2 hydrogen bonds
- Guanine binds with cytosine with 3 hydrogen bonds.
Double helix
Structure of DNA made up of 2 strands of nucleotides running in opposite directions
Semi-conservative replication
The process in which the double helix of a DNA molecule unwinds and each strand acts as a template on which a new strand is constructed
DNA helicase
Enzyme that acts on a specific region of the DNA molecule to break the hydrogen bonds between the bases causing the two strands to separate and expose the nucleotide bases in that region
DNA polymerase
Enzyme that joins DNA nucleotides together in a condensation reaction (forming phosphodiester bonds) during DNA replication
ATP (Adenosine triphosphate)
- An activated nucleotide found in all living organisms, which is produced during respiration and acts as an energy carrier
- The hydrolysis of ATP (catalyzed by ATP hydrolase) leads to the formation of adenosine diphosphate (ADP) and inorganic phosphate, with the release of energy
ADP
A nucleotide which combines in a condensation reaction, catalysed by ATP synthase, with a phosphate molecule to form ATP
ATP Synthase
An enzyme which catalyses the formation of ATP.
ATP Hydrolase
An enzyme which catalyses the hydrolysis of ATP
Polymerases
Group of enzymes that catalyse the formation of polymers from monomers
Specific heat capacity
The amount of energy needed to change the temperature of 1kg of the substance by 1℃
Latent heat of Vaporisation
The heat energy needed to change the substance from a liquid at its boiling point into gas at the same temperature
Cohesion
- Attraction between molecules of the same type
- It is important in the movement of water up a plant
Surface tension
The tension of the surface film of a liquid caused by the attraction of the particles in the surface layer by the bulk of the liquid
Solvent
The liquid in which a solute is dissolved to form a solution
Inorganic ions
Formed when an element or compound, that does not contain carbon, gains or looses electrons to become negatively or positively charged, for example: hydrogen ions, phosphate ions, iron ions and sodium ions
Transparent
A material that allows light to pass through so that objects behind can be distinctly seen
