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
