Bioenergetics 2 - 2020 Flashcards
What are the main types of biochemical reactions?
Group transfer reactions, oxidation and reduction, elimination, isomerisation and rearrangement, reactions that make or break carbon-carbon bonds.
What is a covalent bond?
A covalent bond consists of an electron pair shared between two atoms.
What is heterolytic bond cleavage?
Heterolytic bond cleavage breaks a bond leaving the electron pair with one atom.
What is homolytic bond cleavage?
Homolytic bond cleavage breaks a bond leaving each atom with one electron.
Which type of bond cleavage is more common in biochemistry?
Heterolytic bond cleavage.
What is produced from the heterolytic cleavage of a C-H bond?
Protons or hydride ions.
What are nucleophiles?
Electron rich compounds that are negatively charged or have unshared electron pairs, easily forming covalent bonds with electron deficient centers.
What are electrophiles?
Electron deficient compounds that may be positively charged or contain an unfilled valence electron shell.
Name some important nucleophiles in biochemistry.
- Hydroxyl group
- Sulfhydryl group
- Ammino group
- Imidazole group
Name some important electrophiles in biochemistry.
- Protons
- Metal ions
- Carbonyl carbon atom
- Cationic imine
What occurs during the reaction of nucleophiles and electrophiles?
Electron rearrangement.
What is nucleophilic substitution?
A reaction type where an electrophilic group is transferred from one nucleophile to another.
What are the most common groups transferred in biochemical reactions?
- Acyl groups
- Phosphoryl groups
- Glycosyl groups
What is the hexokinase reaction?
A phosphoryl group transfer involving glucose and ATP, resulting in glucose-6-phosphate.
What do redox reactions involve?
The loss and gain of electrons.
What type of bonds are typically cleaved in redox reactions during metabolism?
C-H bonds.
What is the ultimate electron acceptor in aerobic organisms?
O2.
What are the products of elimination reactions?
Typically water (H2O) or ammonia (NH3).
What is oxidative elimination?
A process that removes two hydrogens and two electrons to generate a double bond.
What is the most important isomerisation in biochemistry?
Aldose-ketose interconversion.
What do rearrangements produce?
Altered carbon skeletons.
What is the most common electrophile used for carbon-carbon bond formation?
The carbonyl group of aldehydes, ketones, esters, or CO2.
What is aldol condensation?
A reaction that forms a new C-C bond from a ketone and a resonance stabilized carbanion.
What is decarboxylation?
A reaction that removes a carboxyl group, important in metabolism.
What general principles can biochemical reactions be broken down into?
- Group transfer reactions
- Oxidation and reduction
- Eliminations
- Isomerisation
- Rearrangements
- Reactions that break or form C-C bonds
What type of centers do biochemical reactions occur between?
Centers with high electron density (nucleophiles) and centers with low electron density (electrophiles).
True or False: Forward and reverse reactions are often found in metabolism.
True.
What often follows reactions in metabolism?
Electron/bond rearrangement to find the most stable form.
