30 Questions
Which group can function as a neurotransmitter in the brain?
Gamma
How can proteins be distinguished according to the text?
By the number, composition, and sequence of amino acid residues
At pH 7, what is the state of the carboxyl group?
Acidic form
What type of ion is the amino group at pH 7?
Conjugate acid form (ammonium ion)
Which amino acid is a precursor of the vitamin pantothenic acid?
Glycine
What type of molecule are amino acids primarily used to synthesize?
Polypeptides
What stabilizes both α-helix and β-sheet structures in proteins?
Hydrogen bonding
Which type of helical turn is an α-helix?
Right-handed
In α-helical formation, where do the hydrogen bonds occur?
Within the same chain
What structural feature defines a β-sheet in proteins?
Parallel or antiparallel alignment of polypeptide chain segments
Which amino acid disrupts α-helical formation due to its flexibility?
Proline
What causes some amino acids not to foster α-helical formation?
Rigidity or flexibility of their side chains
Which property of amino acids is responsible for giving them their unique properties?
The placement of R group within the amino acid structure
How are amino acids classified based on their capacity to interact with water?
Based on their ability to form hydrophobic interactions with water
Which group of amino acids primarily contain hydrocarbons in their R groups?
Hydrophobic amino acids
Which class of amino acids is known for forming hydrophobic interactions with water?
Hydrophobic amino acids
What is the key concept behind classifying amino acids into different categories?
Their interaction with water molecules
Which feature defines the unique properties of each amino acid?
The specific R group present in their structure
Which type of interaction stabilizes the tertiary structure of globular proteins?
Ionic interactions between side chains
In the context of proteins, what does the term 'Greek key' refer to?
A motif with patterns of alpha-helix and beta-sheet structures
What is the primary factor responsible for stabilizing beta-sheets in proteins?
Hydrogen bonding between adjacent chains
Which type of bond is characteristic of the 'Greek key' supersecondary structure?
Hydrogen bonds within the same chain
What provides the information necessary for the folding of a globular protein into its unique three-dimensional structure?
The amino acid sequence of the protein
In protein folding, what forces bring distant amino acids into close proximity?
Hydrogen bonds
What type of bond is formed when the R-groups of two non-adjacent cysteines are oxidized?
Disulfide bond
What is the function of glutathione in cells?
Protects cells from oxidation
Which process does glutathione participate in among the following?
Toxic substance metabolism
What is the tripeptide structure of glutathione?
Glu – Cys – Gly
In what form does H2O2 oxidize the iron of hemoglobin in red blood cells?
Ferric form
Which enzyme catalyzes the conversion of glutathione from reduced (GSH) to oxidized (GSSG) form?
Glutathione peroxidase
Learn about the process of disulfide bond formation between non-adjacent cysteine residues in peptides, which helps stabilize the structure of proteins. Understand the role of oxidation-reduction reactions in creating reversible disulfide bonds.
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