Introduction to biochemistry Flashcards
Describe the three atomic particles.
Proton- Charge 1+ and mass of 1
Neutron- No charge and mass of 1
Electron- Charge 1- and negligible mass
How are covalent bonds formed?
By sharing of electrons between atoms.
How are orbitals filled?
Electrons fill up orbitals singally, then pair up
Order the strength of molecular bonds (Strongest to weakest)
Covalent Ionic Hydrogen Hydrophobic interactions Van der waals forces
What is meant by a stable atom?
One in which the outermost orbital is completely occupied by electrons.
What are the three classes of carbohydrates?
Monosaccharides, Disaccharides and Polysaccharides.
Give examples of monosaccharides.
Glucose
Fructose
Galactose
Give examples of disaccharides.
Sucrose
Lactose
Maltose
Give examples of polysaccharides.
Starch (Storage)
Glycogen (Storage)
Cellulose (Structural)
How are disaccharides formed?
By the bonding of two monosaccharides via a condensation reaction
What is the first law of thermodynamics?
Energy is not created not destroyed, but rather converted from one form to another.
What is the second law of thermodynamics?
When energy is converted from one form to another, some of that energy becomes unavailable for work. I.e no reaction is 100% efficient.
What is an exergonic reaction?
Reactions where the total free energy of the products is less than the total free energy of the reactants.
What is an endergonic reaction?
Reactions where the total free energy after the reaction is greater than the total free energy of the reactants.
What are standard conditions for biochemists?
Temperature of 298 K
1 atmosphere of pressure
1M concentratoon of reactant (Except for H+)
pH=7
Describe electronegativity. What is electronegativity dependant on?
When electrons are shared unequally between atoms in a molecule. This is dependant on the electronegativity of these atoms.
What kind of substances dissolve in water?
Polar (Hydrophilic) substances
What does D and L refer to when applied to amino acids?
The stereochemistry of the amino acid.
How many “L” amino acids make up all proteins and polypeptides?
20
What bonds are present in the folding of proteins?
Peptide bonds
Which enzyme catalyses peptide bond formation?
Peptidyl transferase
Describe acids in terms of donation or acceptance of Hydrogen ions.
Acids are Hydrogen ion donators.
Describe bases in terms of donation or acceptance of Hydrogen ions.
Bases are Hydrogen ion acceptors.
What determines the strength of an acid?
How readily it donates a proton to a base.
What is pH?
The measurement of the amount of protons in a solution.
What is a buffer solution?
A solution that controls the pH of a reaction mixture.
What does the Henderson-Hasselbalch equation connect?
The Ka of a weak acid with the pH of a solution containing this acid.
What is a zwitterion?
A molecule with a positive and a negative charge, hence no net charge.
What is the isoelectric pH?
The pH at which a molecule has no net charge.
What is meant by catabolism?
Breaking down complex molecules into smaller one releasing energy.
Is a catabolic reaction endergonic or exergonic, and oxidation or reduction?
Endergonic and oxidation
What is meant by anabolism?
Synthesising complex molecules out of smaller ones in energy consuming reaction.
Is an anabolic reaction endergonic or exergonic, and oxidation or reduction?
Endergonic and reduction.
What is meant by the term amphipathic?
Molecules that have hydrophobic and hydrophilic properties.
Name and describe the 4 protein structures.
Primary- Sequence of amino acids.
Secondary- Localised conformation of the polypeptide backbone
Tertiary- 3D structure of an entire polypeptide, including all it’s side chains.
Quaternary- Spatial arrangement of polypeptide chains in a protein with multiple subunits
Name the three distinct secondary protein structures.
Helix
Beta sheets 1
Beta sheets 2
Name the two different types of tertiary protein.
Fibrous
Globular
Name the forces which stabilise tertiary structures. (5)
Covalent disulphide bonds
Electrostatic interactions
Hydrogen bonds
Hydrophobic interactions
Complex formation with metal ions.
What types of physical conditions disrupt protein structures? (4)
Heat
Extremes of pH
Detergents such as urea and guanidine hydrochloride
Thiol agents (Reducing agents
Describe sickle cell anaemia.
A single nucleotide sequence change in coding region of the Beta chain of Haemoglobin A results in an altered protein (Valine instead of glutamic acid) causing SCA.
