Biochemistry: Amino Acids, Proteins, Water and PH - Lecture 3 Flashcards
If something dissolves in water what is it said to be?
Hydrophilic
Why is water a dipolar molecule?
Due to electronegative oxygen and unequal sharing of electrons
What does Dipolar mean?
Dipolar means that it is more charged on one side than the other
What shape does water have?
Has a tetrahedral shape.
What are the interactions of water?
Ion to dipole interactions
Dipole to dipole interactions
What shape are H-bonds?
These bonds tend to be linear
How do Non-polar substance react in water?
Non polar substance are insoluble in water - hydrophobic
Powerful attraction between water molecules - water molecules push non-polar molecules
together.
What effect is shown when water reacts with oil?
Hydrophobic effect
What are Amphipathic Molecules?
Have domains that are either hydrophobic/hydrophilic
What are Micelles?
lipids that have a hydrophilic head and a hydrophobic tail form in water - Heads on the Outside, tails in the inside
What is the general structure of an amino acid?
Amino Group - C(H)R - Caroxylic acid group
What type of carbon is at the centre of an amino acid?
An Alpha carbon
What will Hydrophobic amino acids react with?
They will react with lipid and other non polar substances. Common in
membrane spanning parts of the protein.
What will Polar uncharged Amino Acids react with?
These amino acids are able to hydrogen bond with water therefore are partially soluble
What are Acid/Basic Amino acids used?
Useful as a buffer
How is peptide bond formation catalysed?
Catalysed by peptidyl transferase
What shape are Peptide bonds?
Planar
What types of molecules are acids?
Acids are molecules that donate a proton
What types of molecules are bases?
Bases are proton acceptors
What is the equation for Ka?
Ka=[H+][A−]/[HA]
What is the equations for pH?
pH=−log[H+]
pH= pKa + log[A-]/[HA]
What does Ka measure?
The numerical value of Ka is used to predict the extent of acid dissociation. A large Ka values indicates stronger acids (more of the acid dissociates) and small Ka values indicates weaker acids (the reaction does not go to completion).
What is a buffer?
A buffer is a solution to control the pH of a reaction mixture -amino acids are work as a buffer
Why do amino acids have two pKa values?
Two Titratable groups
Amino group postivie
Carboxyl group negative
What is a Zwitterion?
A Neutral amino acid, with a positive and negative charge
