Biochem Flashcards
Buffer
Makes the overall solution resistant to pH change because it reacts with both added bases and acids
Law of mass action
Addition of reactants accelerates the reaction. Likewise, removal of products accelerates the reaction.
Hydroxyl
R—OH; Alcohols; Highly polar so makes compounds more soluble through hydrogen bonding with water. May also act as weak acid and drop proton
Phosphate
O
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R—O—P—O- ; Organic Phosphate;
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O-
When several phosphate groups are linked together, breaking O—P bonds between them releases large amounts of energy
Sulfhydryl
R—SH; Thiols; When present in proteins, can form disulfide (S—S) bonds that contribute to protein structure
Amino
R
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H—N—H ; Amines; Acts as a base—tends to attract a proton to form R—NH3
Carbonyl
O
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R—C—H ; Aldehydes ; react with certain compounds to produce larger molecules with ending =O —H
R—C—R ; Ketones
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O
Carboxyl
O
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R—C—OH ; Carboxylic acids; Acts as an acid—tends to lose a proton in solution to form =O —O-
Marcromolecule
Large molecule containing a very large number of atoms (e.g. proteins, nucleic acids, carbohydrates)
Polymerisation
bonding together of monomers
Condensation reaction
Monomer bonded to HO in, H2O out (all monomers also bonded to H -> HO—Monomer—H)
Hydrolysis
H2O in, monomer bonded to HO out (all monomers also bonded to H -> HO—Monomer—H)
Protein
Polymers of amino acids
Range in size from a few amino acids to thousands (typical protein = 200-300)(largest protein = 33,000)
Polypeptide chain
String of amino acids connected together by peptide bonds.
Make up proteins.
Start with amino group and end with carboxyl group.
Numbering system
Start at N-terminus (5’) and end at C-terminus(3’)
Peptide bond
Polypeptides flex because groups on either side of each peptide bond can rotate about their single bonds
Tertiary structure
Fully folded protein arrangement
Side chain interactions determine tertiary structure
Coiled coils
Arise when two a-helices have hydrophobic amino acids at every 4th position. Fibrous structural proteins (e.g. keratins) consist mainly of a-helices arranged as coiled coils.
Disulfide bonds
Covalent interactions formed between the sulfur atoms of two cysteine residues
Dimer
Polymer formed from two molecules of a monomer
Transcription factor
Protein that help turn specific genes “on” or “off” by binding to nearby DNA
Tetramer
Polymer formed from four monomers (e.g. hemoglobin)
Ribonuclease
Cuts RNA
Protein turnover
Half-life. Occurs constantly in cells
Chaperones
Specialised proteins that help keep other proteins (temporarily exposed hydrophobic regions) from interacting inappropriately with each other.
Do this by isolating/hiding some newly synthesised proteins to give them time to fold
Nitrogenous Bases
Pyrimidines (Cytosine, Thymine, Uracil) - 1 aromatic ring
Purines (Guanine, Adenine) - 2 aromatic rings
Phosphodiester linkage
ester bonds that form between sugar and phosphate to form the backbone of nucleic acids. Always 3’ hydroxyl group to 5’ phosphate group
Metabolism
All the chemical reactions that take place in the body
Anabolic reactions
Link simple molecules together to make complex ones. Energy storing reactions (require energy)
Catabolic reactions
Break down complex molecules into simpler ones (release energy)
First Law of Thermodynamics
Energy is neither created nor destroyed
Second Law of Thermodynamics
The dispersing of energy is the driving force for energy conversions
Exergonic Reaction
ΔG < 0 always
Endergonic
ΔG > 0 always