Biochem (2024)

• Dipole - Dipole interactions

  Positive end of one dipole is attracted to the negative end of a second dipole
• Hydrogen bonds

  A Hydrogen atom with a partial positive charge attached to a N, O, or F with a partial negative charge
• Dispersion forces

  very weak attractive forces that occur between nonpolar molecules

  occur when movement induces a temporary distortion of the electrons in a molecule creating a temporary dipole

  allows nonpolar molecules to exist as liquid and solids
• What is Hybridisation

  hybridisation involves the promotion of one of the 2s electrons to the vacant 2p orbital and the subsequent 'mixing' of the valence atomic orbitals
• Alkanes

  Single bonds between the carbons

  all carbons are sp3

  functional group is the C-H

  Cycloalkanes: sp3 carbons forming a ring
• Alkenes

  C=C double bonds are present in the molecule and this is their functional group sp2 carbons

  cycloalkenes: double bond in a ring
• Alkynes

  Triple bonds are present btw the carbon atoms (functional grp), sp carbons

  unsaturated
• Aromatic

  hydrocarbon containing a benzene ring (functional group)
• Alkanes general formula

  CnH2+2

  saturated hydrocarbons
• Cyclic alkenes (cylcoalkenes) general formula

  CnH2n
• Alkynes bond type

  triple carbon bond
• Alkenes

  hydrocarbons that contain carbon-carbon double bonds
• anabolic vs catabolic

  Anabolic is the build-up of large molecules from small ones known as biosynthesis.

  catabolic is the breakdown of large molecules to small molecules
• monosaccharides key info

  fructose, glucose, galactose, ribose

  ketone or aldehyde functional group

  formula = (CH2O)n

  aldehyde groups bonded on the terminal

  ketone group is bonded in the middle
• monosaccharides of biological significance

  trioses (c3,h6, O3) - aldoses (glycerose) - ketoses (dihydroxyacetone)

  Tetroses  (C4H8O4)  -      

  Pentoses (C5H10O5)  -     

  Hexoses  (C6H12O6)  -     

  Heptoses (C7H14O7)  -                                              
• D and L sugars

  known as spatial orientation or stereochemistry

  In the D form, the -OH group attached to the carbon atom adjacent to the terminal primary alcohol group ( D form attaches to the right)

  In the L form the -OH group attached to the left
• Pentoses are

  monosaccharide class with 5 carbons

  aldose = ribose

  Ketoses = ribulose
• Trioses are

  monosaccharides with 3 carbons

  aldoses = glycerose

  ketoses = dihydroxyacetone
• Hexoses are

  monosaccharides with 6 carbons

  aldoses = glucose

  ketoses = fructose
• stereoisomers

  same chemical formula differ in the position of the hydroxyl group on one or more of the asymmetric carbons
• Enantiomers

  stereoisomers that are non-superimposable mirror images of each other

  same connectivity

  same atoms

  same arrangement
• Anomers

  different arrangement at the carbonyl carbon ( hemiacetal or hemiketal carbon)
• Epimers

  stereoisomers that differ in the position of the hydroxyl (-OH) group only at one asymmetric carbon
• how can monosaccharides form di-, oligo-, or polysaccharides

  can be linked together through glycosidic bonds

  the reaction is thermodynamically unfavored requiring activated substrates
• oligo- and polysaccharides can be linked together to form

  glycoproteins
• Hemiacetals and Hemiketals

  hemiacetals = alcohol added to aldehyde

  hemiketals = alcohol added to ketone

  reversible reaction

  monosaccharides with 5 or 6 atoms
• five important reactions of monosaccharides

  oxidation of monosacs

  reduction of monosacs

  phosphate ester formation

  amino sugar formation
• reduction of monosaccharide

  reduction of the carbonyl group on a sugar produces alditols

  naturally occurring ones are D-glucitol (sorbitol)
• oxidation of monosaccharides

  Benedicts reagent (CU2+/ OH-)

  adds oxygen to carbon-hydrogen single bond of functional group
• non-reducing sugars

  donate electrons to other molecules
• reducing sugar

  sugar that has lost an OH group and is therefore a reducing agent
• example of no reducing sugar

  sucrose - disaccharide - aldehydic or ketonic group are bonded
• What is a glycosidic bond?

  A covalent bond between a sugar molecule and another molecule.
• Difference between hydrolysis and dehydration?

  Hydrolysis: Breaking down a compound by adding water. Dehydration: Release of water from a compound (known as condensation)
• A positive iodine test means that the sample contains?

  unsaturated bonds (double bonds)
• What is Ammonium sulphate salt ((NH4)2SO4) used for?

  used in salting protein purification to separate proteins based on their solubility in the presence of a high concentration of salt.

  salt stabilizes charged groups on protein molecules and enhances the polarity of water, thus attracting protein into the solution and enhancing the solubility of protein (salt in)

  a threshold is reached of salt concentration where the salt concentration is too high and proteins are no longer soluble.

  salt out occurs at threshold

  different proteins salt out at different concentrations
• what is Column Chromatography?

  a preparative technique used to purify compounds depending on their polarity 
• How does column chromatography work?

  The protein solution layered on top of the column percolates into solid matrix

  percolates

  protein solution forms a band in the mobile phase of the collum

  the more a protein interacts with the matrix, the later it will elute from the column
• Quantitative Protein Assays: Analytical Techniques
• Coomassie dye (Bradford) protein assays