p.16
Impact of R-groups on Protein Structure and Function
What does a negative value in a hydropathy plot indicate?
A hydrophilic region of the protein.
p.14
Zwitterions in Amino Acids and Proteins
What are zwitterions?
Molecules that have both a positive and a negative charge.
p.13
Protein Charge and Ionization
What determines the overall charge on a protein?
The ionization of its amino acid R-groups.
p.12
Net Charge of Amino Acids
What is the net charge at pH values of +2, +1, 0, and -1?
The net charge varies from +2 to -1 depending on the pH.
p.16
Impact of R-groups on Protein Structure and Function
What do hydropathy plots analyze?
The hydrophobic and hydrophilic regions of a protein.
p.5
Ionization States of Amino Acids
What is the relationship between pKa and acid strength?
The lower the pKa, the stronger the acid.
p.3
Selenocysteine Characteristics
What structural feature is necessary for the production of selenocysteine?
A stem-loop structure in the 3’ untranslated region of the mRNA.
p.15
Protein Charge and Ionization
How can the charge of proteins change?
Depending on the pH of the solution.
p.4
Isoelectric Point (pI) of Amino Acids
What is the isoelectric point (pI) of an amino acid?
The pH at which an amino acid is electrically neutral.
p.3
Selenocysteine Characteristics
What role does the seleno group in selenocysteine commonly play?
Acts as a nucleophile and has antioxidant activity.
p.7
Ionization States of Amino Acids
What does pKa represent in relation to a chemical group?
The pH value at which the chemical group loses a H+.
p.9
Isoelectric Point (pI) of Amino Acids
How is the pI of glycine calculated?
By taking the average of its two pKa values.
p.15
Impact of R-groups on Protein Structure and Function
What can the charge of proteins influence?
Their structure and function.
p.5
Ionization States of Amino Acids
How does pH affect the ionization state of an amino acid?
The ionization state of an amino acid varies with pH.
p.18
Impact of R-groups on Protein Structure and Function
What role do R-groups play in protein folding?
R-groups contribute to the stability and conformation of proteins through hydrophobic, ionic, and hydrogen bonding interactions.
p.10
Isoelectric Point (pI) of Amino Acids
What does pI represent in relation to Glutamate?
The midpoint between two transition points.
p.3
Selenocysteine Characteristics
Which codon encodes selenocysteine?
The UGA codon, which is typically a stop codon.
p.18
Impact of R-groups on Protein Structure and Function
Why are R-groups important in protein function?
They dictate the specificity of protein interactions with other molecules, influencing biological activity.
p.15
Isoelectric Point (pI) of Amino Acids
What does knowing the isoelectric point (pI) of a protein provide?
Predictive power regarding solubility, structure, function, and regulation.
p.16
Impact of R-groups on Protein Structure and Function
How are hydropathy plots useful in protein studies?
They help predict the topology of membrane proteins.
p.9
Isoelectric Point (pI) of Amino Acids
What is the isoelectric point (pI) of glycine?
It is the mean of the two pKa values, calculated as pI = 1/2(pK1 + pK2).
p.6
Ionization States of Amino Acids
At what pH does the amino group of amino acids become protonated?
Until a basic (high) pH is achieved.
p.12
Isoelectric Point (pI) of Amino Acids
What is the isoelectric point (pI) shift compared to glycine?
The pI shifts to 7.59 due to an additional NH2 group.
p.17
Impact of R-groups on Protein Structure and Function
How does altering the charge of amino acids affect proteins?
It affects their structure and function.
p.8
Effect of pH on Amino Acid Charge
How does high pH affect H+ concentration?
It results in low H+ concentration.
p.5
Ionization States of Amino Acids
What is pH a property of?
A particular solution that depends on the concentrations and identities of the components.
p.9
Effect of pH on Amino Acid Charge
What information can be derived from the titration curve of glycine?
The charge of glycine at different pH levels.
p.14
Zwitterions in Amino Acids and Proteins
Do amino acids exist as zwitterions?
Yes, amino acids alone and in a polypeptide can be zwitterions.
p.14
Zwitterions in Amino Acids and Proteins
What is the charge characteristic of zwitterions?
They have both a positive and a negative charge.
p.9
Titration Curves and Buffering Capacity
What does the titration curve for glycine illustrate?
Buffering capacity and charge of an amino acid at a certain pH.
p.8
Effect of pH on Amino Acid Charge
How does low pH affect H+ concentration?
It results in high H+ concentration.
p.17
Impact of R-groups on Protein Structure and Function
How do R-groups affect protein structure?
They influence the charge interactions, which can alter structure and function.
p.13
Ionization States of Amino Acids
Which groups in amino acids can be ionized when they are part of proteins?
Only the terminal amino and carboxyl groups.
p.5
Ionization States of Amino Acids
What does pKa indicate about a compound?
It tells us how acidic the compound is.
p.16
Impact of R-groups on Protein Structure and Function
What does a positive value in a hydropathy plot indicate?
A hydrophobic region of the protein.
p.16
Impact of R-groups on Protein Structure and Function
What is the typical scale used in hydropathy plots?
The Kyte-Doolittle scale.
p.3
Selenocysteine Characteristics
What is selenocysteine?
A naturally occurring amino acid in both eukaryotic and prokaryotic organisms, serving as a building block of selenoproteins.
p.18
Impact of R-groups on Protein Structure and Function
How do R-groups influence protein interactions?
R-groups determine the chemical properties and interactions of amino acids, affecting protein folding and function.
p.6
Ionization States of Amino Acids
What happens to the carboxylic acid group of amino acids at low pH?
It is protonated, existing as -COOH.
p.5
Ionization States of Amino Acids
Why does each group in an amino acid have its own pKa?
Because each group has different ionization characteristics.
