Protein structure and function Flashcards
What are proteins built from?
Amino Acids
What is the equation for protein formation?
L - amin acid Protein
–> = condensation reaction
What are the bonds between proteins?
Peptide
What are the 2 processes that are required when initially building a protein?
Transcription and translation
What is being translated when building a protein?
Genetic code
Give a brief summary of transcription and translation: (2)
Genes are transcribed into mRNA by RNA polymerase
mRNA is translated by tRNA - ribosome
What is the structure of an amino acid?
Alpha carbon, carboxyl group, amine group, R-group .............. H ............... | \+H3N -- C -- COO- ............... | ............ (R)
What is a naturally occurring optical isomer called?
Enantiomers
What type of mixture is formed by chemical synthesis of an amino acid?
A racemic mixture
What type of isomers are amino acids always? (D or L)
L - isomers (homochirality)
What does aliphatic mean?
R-group is NOT branched
What does aromatic mean?
R-group is based on a benzene ring
What does polar mean?
the R-group carries a small charge
Which part of the amino acid can be ionised and what is that called? (2)
Carboxyl and amine
Amphoteric
What is pKA?
pKa is the pH at which a group has equal amounts of protonated and unprotonated forms
What is the point of pKa?
Proton binding affinity - low pKa means it has low pba
What is a zwitterion?
The pH of the amino acid has no net overall charge - least soluble
What is the hydropathy index and what do the values mean?
Hydropathy index is how hydrophobic/hydrophilic an R group is
Negative value = hydrophilic
Positive value = hydrophobic
What are the fundamental forces in biology? (4)
Electrostatic interactions (ionic bonds) Polar interactions (hydrogen bonds) van der Waals interactions (dipole) hydrophobic interactions
all NON-COVALENT
What are the 4 forces crucial for? (2)
Chemical reactivity of proteins as enzymes
Ability of a protein to fold into the correct shape
What are electrostatic/ionic attractions?
Occur between oppositely charged ions
Water weakens their strength
What is Coulomb’s law?
Magnitude of the electrostatic force between 2 charges is directly proportional to the product of the 2 charges
What is an example of an essential ionic bond in enzyme activity?
ATP - converting energy from food/sun to energy for cells
What are polar bonds? (2)
Hydrogen bonding
Water
What are van der Waals forces? (2)
Electron cloud alignment
Atoms never collide
What are hydrophobic forces? (3)
Not polar
Useful for separation
Increase with increasing temp and salt
