Week 3: Amino Acids Flashcards
What are the major classes of biomolecules?
- Amino acids and proteins
- Nucleotides and nucleic acids (DNA and RNA)
- Carbohydrates
- Lipids
These classes represent the fundamental building blocks of biological systems.
How many different amino acids are there?
20 different amino acids
These amino acids can combine in various ways to form proteins.
What is the range of amino acids typically found in proteins?
50-2,000 amino acids
The length of proteins can vary significantly based on their function.
What is the general structure of an amino acid?
- Variable side chain (R group)
- Amino group
- Carboxyl group
- Hydrogen atom
The specific R group determines the properties of each amino acid.
What type of amino acids are found in proteins?
α-amino acids
These are the standard amino acids used in protein synthesis.
What is the significance of the α-carbon in amino acids?
The α-carbon always has four substituents and is tetrahedral.
This structure is critical for the chirality of amino acids.
What are stereoisomers?
Isomers with the same molecular formula but different chemical structure.
This includes enantiomers, which are non-superimposable mirror images.
What is a chiral carbon atom?
A carbon atom that has four different groups bonded to it.
Chirality is important for the function of amino acids in proteins.
What is the classification of amino acids based on their R substituents?
- Nonpolar, aliphatic
- Aromatic
- Polar, uncharged
- Positively charged
- Negatively charged
This classification helps in understanding their chemical behavior.
What defines nonpolar, aliphatic R groups?
They do not contain the benzene ring or a derivative of it.
These groups are crucial for the hydrophobic interactions in proteins.
What is the difference between glutamic acid and glutamate?
Glutamic acid is the protonated form, while glutamate is the deprotonated form.
This distinction is important in biochemical contexts.
How are amino acids linked together?
By peptide bonds to form polypeptide chains.
Peptide bonds are formed through a condensation reaction.
What are the two ends of a peptide called?
- N-terminal
- C-terminal
These designations are important for the directionality of polypeptides.
What is a kilodalton (kDa)?
A unit of mass equal to 1,000 Daltons (Da).
Dalton is a unit of mass equal to that of a hydrogen atom.
What is the typical molecular weight of glycine?
75 Da
Glycine is the smallest amino acid.
What is the molecular weight of tryptophan?
204 Da
Tryptophan is one of the larger amino acids.
Fill in the blank: Amino acids are linked by _______ to form polypeptide chains.
peptide bonds
True or False: All amino acids are hydrophobic.
False
Amino acids can be hydrophobic or hydrophilic based on their side chains.
What is the role of water in relation to amino acids?
Water is polar and affects the solubility of amino acids based on their charge and polarity.
This property is critical for protein folding and interactions.
