Biology F212 Biological Molecules Key Words

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Metabolism

Sum total of all the biochemical reactions taking place in the cells of an organism 

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Covalent Bonds

Very strong bonds formed when electrons are shared between atoms. 

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Carbohydrates

Make up a group of molecules containing, hydrogen and oxygen. 

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Monosaccharides

The monomers of carbohydrates

Soluble in water 

Sweet tasting 

Form crystals 

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Polysaccharides

Polymers of monosaccharides

Consists of hundreds of monomers bonded together to fomr a single large molecule 

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Glycosidic Bond

Covalent bond formed when carbohydreate molecules join together in condensation reactions

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Condensation Reaction

Type of chemical reaction where two molecules are joined together by a convalent bond.

A water molecule is released 

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Hydrolysis

The reaction where a molecule is broken down into two smaller molecules by the addition of a water molecule and the breaking of a covalent bond 

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Cellulose

A carbohydrate polymer made by bonding many beta glucose molecules 

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Maltose

Two alpha glucose molecules bonded together

Small, soluble, sweet and crystalline

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Glucose

6 carbon monosaccharide sugar 

Small, soluble, sweet and crystalline 

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Deoxyribose

5 carbon sugar in DNA nucleotides 

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Starch + Glycogen

Large molecules of alpha glucose joined by condensation reactions 

Insoluble in water 

Forms grains/grandules 

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Amino Acids

The monomers of all proteins 

Structure: amino group, carbon, acid group (N-C-C)

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Peptide Bond

The covalent bond formed when amino acids are joined together in condensation reactions.

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Protease

The enzyme responsible for forming and breaking the peptide bonds in organisms

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Deamination

Removal of the amine group of the amino acid 

In the liver 

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Primary Structure

The sequence of amino acids found in a protein molecule 

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Secondary Structure

The coiling or folding parts of a protein molecule due to the formation of hydrogen bonds formed as the protein is synthesised

Alpha helix and beta pleated sheets 

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Tertiary Structure

The overall 3D shape of a protein molecule 

the result of interactions between hydrogen bonding, formation of disulfide bridges, ionic bonds and hydrophobic interactions

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Quarternary Structure

Protein structure whwere a protein consists of more than one polypeptide chain

e.g Haemoglobin and insulin

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Globular Proteins

Proteins with relatively spherical molecules

Soluble in water 

metabolic roles in organisms 

e.g Hb + plasma proteins

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Fibrous Proteins

A protein with a relatively long, thin structure 

Insoluble in water 

Metabolically innactive 

Structural role in organisms 

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Haemoglobin

Globular Protein 

Soluble in water 

Wide range of amino acid constituants in primary structure 

Contains a prosthetic group -haem 

Much of the molecule is wound into Alpha helix structures 

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Collagen

A structural fibrous protein

Insoluble in water 

Mostly left handed helix structures

Found in connective tissue, bone, skin and cartilage

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Lipids

A diverse group of chemicals

Dissolve in organic solvents such as alcohol but not water 

Include fatty acids, tryglycerides and cholesterol

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Ester Bond

The bond formed when fatty acid molecules are joined to gylcerol molecules in condensation reactions 

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Glycerol

3-carbon molecule that forms the basis of lipids 

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Triglycerides

A molecule consisting of a glycerol molecule and three fatty acid molecules covalently bonded together 

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Cholesterol

A lipid molecule found in all cell membranes and involved in the synthesis of steroid hormones

Structure: 4-carbon based ring structures, small narrow and hydrophobic 

Sits between the phosphlipid tails 

Regulate fluidity and strength of the membrane 

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Phospholipid

Gylcerol molecule plus two fatty acids and a phosphate group

Part hydrophobic part hydrophillic 

Forms the basis of cell membranes 

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Hydrogen Bond

Weak bond formed when partially positively charged groups come close to partially negatively charged groups

In water molecules and secondary and tertiary structure 

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Cohesion

The attraction between water molecules due to hydrogen bonding creating surface tension

Makes water columns very strong and difficult to break

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Starch Test

Add iodine to the sample 

Positive = brown to blue black 

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Reducing sugar test

Add Benadicts solution and heat to 80ºC 

Positive = blue to orange-red 

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Non-reducing sugar

If reducing test negative

Boil with HCL

Cool and neutralise with sodium hydrogencarbonate solution or sodium carbonate 

Repeat Benedicts test 

Positive = blue to orange-red 

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Biuret test

Add biuret reagent 

Positive = blue to lilac 

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Ethanol emulsion test

Add ethanol to extract 

Dissolve lipid 

Pour solution into water in another test tube

Positive = white emulsion forms near top of water 

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Nucleotides

The monomers of nucleic acids 

Formed by honding a phosphate group, sugar molecule and a nitrogenous base 

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Gene

A length of DNA That codes for one or polypeptides.

Each gene occupies a specific place on a chormosome 

Diff versions of the same gene are called allels 

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Base pairing rules

DNA = A-T C-G 

RNA = A-U C-G

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DNA

A stable polynucleotide molecule 

Acts as an info store - bases projecting from the backbone act as a coded sequence

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Pyrimidine

Thymine, cytosine and uracil 

Nitrogenous bases consisting of a single ring structure 

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Purine

Adenine and guanine 

Nitrogenous bases consisting of a double ring structure 

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RNA

Ribonucleic acid 

Single-strand molecule that exists in three forms

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tRNA

Transfer RNA 

The RNA polynucleotide that is involved in protein synthesis

It transports amino acids to the ribosomes to be added to the growing polypeptide chain

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rRNA

Ribsomal RNA found in the ribosomes

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mRNA

Messenger RNA carries the info coding for a polypeptide from the nulceus to the ribosomes in the cytoplasm 

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Transcription

The assembly of an mRNA molecle that is a copy of the DNA coding strand and complementary to the template strand

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Enzyme

A protien that acts as a biological catalyst 

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Catalyst

A molecule that lowers the activation energy needed for a chemical reaction (speeds the reaction up) but does not get used up in the reaction 

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Lactase

Catalyses the breakdown of milk sugar lacose into glucose and galactose monomers

Lactose intolerant people cannot produce lactase 

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Catalase

Catalyses the breakdown of hydrogen peroxide to water and oxygen 

Produced by most organsims as hydrogen peroxide is a toxic by-product of some metabolic reactions 

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Rubisco

Catalyses the binding of carbon dioxide to ribulose bisphosphate for use in photosynthesis 

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ATP-ase

Catalyses the breakdown of ATP to produce ADP and a phosphate group

Releases energy that is used to drive processes such as active transport 

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Glycogen synthetase

Catalyses the joining together of glucose molecules to build up glycogen 

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Extracellular Enzymes

Catalyse reactions outside the cell

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Intracellular Enzymes

Catalyse reactions inside the cell 

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Activation Energy

The amount of energy that must be applied for a reaction to proceed 

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Lock-and-key hypothesis

The theory of enzyme action where there enzlyme active site is complementary to the substrate molecule

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Induced-fit hypothesis

The theory of enzyme action in which the enzyme molecule changes shape to fit the substrate molecule more closely as it binds to it 

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Inhibitor

Slows down an enzyme controlled reaction

Slows down or prevents the formation of enzyme-subsrate complexses  

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Competitive Inhibitor

A substance that reduces the reate of an enzyme-controlled reaction by binding to the enzymes active site 

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Denaturation

Changes the tertiary structure of an enzyme such that it cannot function and its function cannot be restored 

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Limiting Factor

In a situation where if all other conditions are kept constant, increasing the concentration of that factor will increase the rate of reaction

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Cofactors

Any substance that must be present to ensure enzyme-controlled reactions take place at the appropriate rate 

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Coenzyme

An organic non-protein molecule that binds temporarily with the substrate to an enzyme active site

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Prosthetic Groups

A coenzyme that is a permanent part of the enzyme molecule

Contribute to the final 3D shape and other properties of the molecule 

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Non-competitive inhibitor

Binds to the enzyme molecule in a region away from the active site to inhibit an enzyme controlled reaction 

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Initial rate of reaction

Rate of reaction at the beginning of the reaction 

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Turnover number

the number of reactions an enzyme can catalyse in one second 

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