20 Questions
What is a characteristic of the R-group in amino acids?
R-groups have different physical and chemical properties, such as size, shape, polarity, charge, hydrophobicity and hydrogen-bonding capacity
What is the significance of the α-carbon in amino acids?
It is the attachment point for the R-group and the amino and carboxyl groups
What is the difference between the 20 common amino acids found in proteins?
Their R-group
What is a characteristic of amino acids that are involved in the synthesis of neurotransmitters?
They have specific R-groups
What is the role of glutamate and glutamine in the human body?
They are involved in the transport and removal of ammonia
What is the characteristic of the R-group of glycine that makes it an exception among the 20 α-amino acids?
It has a hydrogen atom
What is the difference between the 'D' and 'L' classification of amino acids and the '+' and '-' notation?
The 'D' and 'L' classification refers to the spatial arrangement of atoms, while '+' and '-' notation refers to the optical activity of the amino acid
What is the reason for the stereospecificity of biomolecular interactions involving enantiomers?
The difference in their non-covalent interactions with other chiral molecules
What is the consequence of the peptide bond formation on the amino acid's amine and carboxylate groups?
The amine group is transformed into an amide group, and the carboxylate group is transformed into a carbonyl group
What is the characteristic of the peptide bond that restricts rotation around it?
Its partial double-bond character
Which type of atoms are attached to the carbon atom in an amino acid?
NH3+, COO-, H, and R-
Why do most amino acids exhibit chiral stereoisomers?
Because they have non-superimposable mirror images
Which amino acids have conjugated ϖ-electron systems and show weak fluorescence?
Tryptophan, Tyrosine, Phenylalanine, Histidine
At which wavelength do Trp and Tyr show maximum UV light absorbance?
280 nm
What is the main reason aromatic amino acids are used to quantify proteins?
They have conjugated ϖ-electron systems
What is the net charge of the peptide YPYDVPDYA and what is the reason for this charge?
The net charge of the peptide YPYDVPDYA is -2 and it is acidic due to the presence of two Asp residues.
What is the term used to describe an amino acid that has an equal number of both negative and positive charges in its structure?
A zwitterion.
What is the term used to describe the pH at which an amino acid or protein has a net zero charge?
The isoelectric point (pI).
Why do amino acids have different physical and chemical properties in proteins?
The ionization state of amino acids can greatly affect their physical and chemical properties in proteins.
What is the property of amino acids that allows them to act as buffers?
Their ability to act as acids and bases (amphoteric).
Learn about the stereochemistry of amino acids including distinguishing D and L forms using the CORN rule, Natta or stereochemical projection, and Fischer projections. Understand that 19 out of the 20 α-amino acids are chiral, with glycine being the exception due to its R-group.
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