91 Questions
Which one of the following is true about proteinogenic amino acids?
They are incorporated into proteins during translation
What is the function of proteins?
All of the above
Which level of protein structure refers to the overall 3D structure of a single polypeptide chain?
Tertiary structure
What are the two bond angles that biochemists look at within an amino acid chain?
φ and ψ angles
Which type of amide bond is overwhelmingly preferred in proteins?
Trans amide bonds
What are the two ends of a peptide/protein chain called?
N-terminus and C-terminus
Which secondary structure is stabilized by intermolecular hydrogen bonds?
Alpha helix
Which direction is more energetically favorable for alpha helices to turn?
Right-handed (clockwise)
Which amino acid is less common in alpha helices due to its ring structure and lack of N-H bond?
Proline
What is the function of alpha helices in proteins?
Membrane spanning motifs
Which secondary structure is made up of linear strands of adjacent peptides?
Beta sheet
How can the adjacent strands of peptides in a beta sheet run?
In opposite directions (antiparallel)
Which of the following is true about proteinogenic amino acids?
They are incorporated into proteins during translation
Which of the following is NOT a group in which proteinogenic amino acids are typically divided based on their side chains?
Hydrophobic and hydrophilic
Which of the following is a hydrophobic/non-polar amino acid?
Valine
Which of the following is an acidic amino acid?
Aspartic acid
Which of the following is true about the ionization of amino acids?
Amino acids exist as zwitterions at physiological pH
Which of the following is true about the ionization of acidic amino acids?
Aspartic acid side chain is >99% ionized at physiological pH
Which type of amino acids can be used to synthesize proteins?
L-amino acids
Why are amino acids considered chiral?
Because the α carbon has four different substituents
What system is typically used to describe the chirality of amino acids?
R/S system
How are proteins synthesized using amino acids?
By condensation reactions
Which type of bond is responsible for stabilizing tertiary structures of proteins?
Covalent bonds
Which of the following is NOT a post-translational modification of proteins?
Acetylation
What is the role of RNA polymerase II in protein synthesis?
Transcribing DNA into precursor mRNA
What is the most common post-translational modification of proteins?
Phosphorylation
What is the 3D structure of multiple polypeptide chains assembled together to form a protein called?
Quaternary structure
What are the two types of subunits in antibodies?
Heavy and light chains
What is the process called when DNA is used as a template to synthesize mRNA?
Transcription
What are the enzymes responsible for attaching phosphate groups to proteins/small molecules called?
Kinases
Which amino acid is phosphorylated by kinases?
All of the above
Which amino acid can undergo O-linkage glycosylation?
Serine
What system is typically used to describe the chirality of amino acids?
D/L system
Which amino acid is achiral?
Glycine
Which type of bond is responsible for stabilizing secondary structures of proteins?
Hydrogen bond
What are the two ends of a peptide/protein chain called?
N-terminus and C-terminus
Which type of amino acid can undergo O-linkage glycosylation?
Serine
Which of the following is a non-proteinogenic amino acid?
Tryptophan
Which of the following groups are proteinogenic amino acids typically divided into based on their side chains?
Polar vs non-polar
Which of the following is a hydrophobic/non-polar amino acid?
Valine
At physiological pH, what is the charge of zwitterions?
Neutral
What is the pKa range for carboxylic acid groups in amino acids?
1.5-2.5
What is the pKa range for amino groups in amino acids?
9.5-10.5
Which of the following is true about the Ramachandran plot?
It shows the different bond angles observed within proteins.
What is the function of alpha helices in proteins?
They can be DNA-binding motifs.
Which of the following is true about beta sheets?
They are made up of linear strands of adjacent peptides.
What is the primary difference between parallel and antiparallel beta sheets?
The direction in which the adjacent strands of peptides run.
What is the function of protein domains?
They are able to form a particular function within a protein.
What is the tertiary structure of a protein?
The 3D shape of a protein.
Which of the following is true about the primary structure of proteins?
It is determined by the sequence of amino acids in the protein.
Which of the following is true about the secondary structure of proteins?
It consists of various structural motifs within proteins.
Which of the following is true about the tertiary structure of proteins?
It refers to the overall 3D structure of a single polypeptide chain.
Which of the following is true about the quaternary structure of proteins?
It is the arrangement of multiple polypeptide chains in a protein.
Which of the following bond angles do biochemists look at within an amino acid chain?
φ and ψ angles
Which type of bond is responsible for stabilizing tertiary structures of proteins?
Hydrogen bond
Which of the following is true about quaternary protein structure?
Quaternary structure refers to the 3D structure of multiple polypeptide chains assembled together to form a protein.
Which of the following is responsible for synthesizing precursor mRNA?
RNA polymerase II
Which of the following is NOT a post-translational modification of proteins?
Phosphorylation
Which amino acid is most commonly phosphorylated by kinases?
Tyrosine
What is the addition of sugar molecules to a protein called?
Glycosylation
Which of the following is true about antibodies?
Antibodies consist of two heavy chains and two light chains.
Which of the following is NOT a characteristic of proteinogenic amino acids?
Can be intermediates in biosynthetic pathways
Which group of proteinogenic amino acids is based on their side chain polarity?
Polar and non-polar
Which amino acid side chain has a pKa value of 6.04 and is 4% ionized at physiological pH?
Histidine
Which type of bond is responsible for stabilizing tertiary structures of proteins?
Hydrogen bond
Which amino acid is most commonly phosphorylated by kinases?
Tyrosine
What is the primary difference between parallel and antiparallel beta sheets?
Direction of hydrogen bonding
Which of the following secondary structures is more extended and less tightly coiled compared to alpha helices?
Beta sheet
What is the most common membrane-spanning motif for proteins?
Alpha helix
Which of the following is NOT a common structural motif observed in proteins?
Random coil
Which of the following bond angles do biochemists look at within an amino acid chain?
Phi and psi angles
Which of the following is true about protein domains?
Protein domains are regions of a protein that are able to form a particular function
What is the function of alpha helices?
Alpha helices can be DNA-binding motifs
Which of the following is true about the structure of amino acids?
Amino acids contain four constituents: amino group, carboxylic acid, hydrogen atom, and side chain
Which of the following is true about the chirality of amino acids?
All proteins use exclusively L-amino acids
How are amino acids typically grouped?
Based on their side chains
What is the function of protein domains?
To bind to specific molecules
What is the primary difference between parallel and antiparallel beta sheets?
The direction of the adjacent strands
What system is typically used to describe the chirality of amino acids?
R/S system
Which of the following is true about peptide bonds?
Peptide bonds have less flexibility than would be expected for a normal single bond.
What is the primary structure of a protein?
The amino acid sequence of a protein.
Which of the following is true about the cis and trans isomers of amide bonds?
Trans amide bonds are overwhelmingly preferred in proteins.
What is the charge of zwitterions at physiological pH?
Neutral
What is the function of alpha helices in proteins?
Structural support
What are the two bond angles that biochemists look at within an amino acid chain?
φ and ψ
Which of the following is true about post-translational modifications of proteins?
Phosphorylation is the most common post-translational modification
Which of the following is true about glycosylation of proteins?
Glycosylation is the addition of sugar molecules to a substrate
Which of the following is true about the quaternary structure of proteins?
Quaternary structures are stabilized by disulfide bonds
Which of the following is true about proteinogenic amino acids?
Proteinogenic amino acids can be identified by their 1-letter abbreviation
Which of the following is true about the secondary structure of proteins?
Alpha helices and beta sheets are examples of secondary structures
Which of the following is NOT one of the three amino acids commonly phosphorylated by kinases?
Asparagine
Test your knowledge of amino acids and proteins with this quiz. Learn about the ionization of side chains and the classification of amino acids.
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