Podcast
Questions and Answers
Which of the following amino acids are nutritionally essential for the human organism?
Select one or more:
Which of the following amino acids are nutritionally essential for the human organism? Select one or more:
- Valine (correct)
- Phenylalanine (correct)
- Methionine (correct)
- Cysteine
- Proline
Which of the following amino acids are nutritionally non-essential for the human organism?
Select one or more:
Which of the following amino acids are nutritionally non-essential for the human organism? Select one or more:
- Proline (correct)
- Valine
- Tyrosin (correct)
- Methionine
- Cysteine (correct)
Thr and/or Leu residues tend to disrupt an a-helix when they occur next to each other in a protein because:
Select one:
Thr and/or Leu residues tend to disrupt an a-helix when they occur next to each other in a protein because: Select one:
- Both amino acids are highly hydrophobic
- The R group of either amino acid can form a hydrogen bond
- Of steric hindrance between the bulky Thr and/or Leu side chains (correct)
- Of the possible covalent interaction between the Thr and/or Leu side chains
- Of electrostatic repulsion between the Thr and/or Leu side chains
Amino acid residues commonly found at the end of b turn are:
Select one:
Amino acid residues commonly found at the end of b turn are: Select one:
A sequence of amino acids in a certain protein is found to be -Ser-Gly-Pro-Gly-. The consequence is most probably part of:
Select one:
A sequence of amino acids in a certain protein is found to be -Ser-Gly-Pro-Gly-. The consequence is most probably part of: Select one:
The three-dimensional conformation of a protein may be strongly influenced by amino acid residue that are very far apart in sequence. This relationship is in contract to secondary structure, where the amino acid residues are:
Select one:
The three-dimensional conformation of a protein may be strongly influenced by amino acid residue that are very far apart in sequence. This relationship is in contract to secondary structure, where the amino acid residues are: Select one:
Which if the following statements is false?
Select one:
Which if the following statements is false? Select one:
A small molecule that decreases the activity if an enzyme by binding to a site other than the catalytic site is termed a:
Select one:
A small molecule that decreases the activity if an enzyme by binding to a site other than the catalytic site is termed a: Select one:
How is trypsinogen converted to trypsin?
Select one:
How is trypsinogen converted to trypsin? Select one:
Select the correct statements!
Select one or more:
Select the correct statements! Select one or more:
What kind of reactions are the best targets for metabolic control?
Select one:
What kind of reactions are the best targets for metabolic control? Select one:
What is true about the flux control coefficient?
Select one:
What is true about the flux control coefficient? Select one:
How is catalytic amplification achieved in the regulation of metabolic pathways?
Select one:
How is catalytic amplification achieved in the regulation of metabolic pathways? Select one:
How is the most efficient signal amplification achieved in the regulation of metabolic pathways?
Select one:
How is the most efficient signal amplification achieved in the regulation of metabolic pathways? Select one:
Which of the amino acids below have a small polar side chain containing a hydroxyl group?
Select one or more:
Which of the amino acids below have a small polar side chain containing a hydroxyl group? Select one or more:
Which of the following amino acids have a positively charged side chain at neutral pH?
Select one or more:
Which of the following amino acids have a positively charged side chain at neutral pH? Select one or more:
Which of the following statements are true for the isoelectric form of amino acids?
Which of the following statements are true for the isoelectric form of amino acids?
Lysine at its isoelectric point has....
Lysine at its isoelectric point has....
Select the correct statements
Select the correct statements
What is the dominant form of Arginine at pH = 6.0?
(pKa values of Arginine are : 2.2, 9.0 and 12.5)
What is the dominant form of Arginine at pH = 6.0? (pKa values of Arginine are : 2.2, 9.0 and 12.5)
What is the dominant form of Histidine at pH = 8.0?
(pKa values of histidine are 1.8, 6.0, and 9.2)
What is the dominant form of Histidine at pH = 8.0? (pKa values of histidine are 1.8, 6.0, and 9.2)
Lysine at low pH (pH = 1) have...
Lysine at low pH (pH = 1) have...
Which of the amino acids below have small polar side chain containing a hydroxyl group?
Which of the amino acids below have small polar side chain containing a hydroxyl group?
Which of the following amino acids have a negatively charged side chain at neutral pH?
Which of the following amino acids have a negatively charged side chain at neutral pH?
Which amino acid had a guanidine group on its side chain?
Which amino acid had a guanidine group on its side chain?
Which of the following amino acids have a positively charged side chain at neutral pH?
Which of the following amino acids have a positively charged side chain at neutral pH?
Which of the following amino acids have four carbon atoms?
Which of the following amino acids have four carbon atoms?
Which of the following amino acids have five carbon atoms?
Which of the following amino acids have five carbon atoms?
Which of the following amino acids have six carbon atoms?
Which of the following amino acids have six carbon atoms?
Which of the following amino acid chains are nonpolar?
Which of the following amino acid chains are nonpolar?
Which of the following amino acid side chains are polar?
Which of the following amino acid side chains are polar?
Pair the amino acids with their character!
- Proline 2. Arginine 3. Glutamate
a. Neutral b. Acidic c. Basic
Pair the amino acids with their character!
- Proline 2. Arginine 3. Glutamate a. Neutral b. Acidic c. Basic
Pair the amino acid with their character!
- Glutamine 2. Lysine 3. Aspartate
a. Neutral b. Acidic c. Basic
Pair the amino acid with their character!
- Glutamine 2. Lysine 3. Aspartate a. Neutral b. Acidic c. Basic
Select the correct statements!
Select the correct statements!
Select the correct statement:
Select the correct statement:
Select the correct statement!
Select the correct statement!
What is the dominant form of glutamate at pH=7.0
(pKa values of glutamate are 2.2, 3.6, and 9.2)
What is the dominant form of glutamate at pH=7.0 (pKa values of glutamate are 2.2, 3.6, and 9.2)
What is the dominant form of Glycin at low pH (pH=1)?
What is the dominant form of Glycin at low pH (pH=1)?
Which of the following amino acids have sulfur-containing side chains?
Which of the following amino acids have sulfur-containing side chains?
At neutral pH a tetrapeptide of glyceralanylarginylglutamate has....
At neutral pH a tetrapeptide of glyceralanylarginylglutamate has....
The arginyllysylaspartate tripeptide has:
The arginyllysylaspartate tripeptide has:
The chirality of an amino acid results from the fact that its a-carbon:
The chirality of an amino acid results from the fact that its a-carbon:
Of the 20 standard amino acids, only .......... is not optically active. The reason is that its side chain .......
Of the 20 standard amino acids, only .......... is not optically active. The reason is that its side chain .......
Which of the following statements about formation of cysteine is correct?
Which of the following statements about formation of cysteine is correct?
In a highly basic solution, pH=13, the dominat form of glycine is:
In a highly basic solution, pH=13, the dominat form of glycine is:
For amino acids with neutral side chain, at any pH below pI of amino acid, the population of amino acids in solution will:
For amino acids with neutral side chain, at any pH below pI of amino acid, the population of amino acids in solution will:
An octapeptide composed of four repeating glycylalanyl units has:
An octapeptide composed of four repeating glycylalanyl units has:
At the isoelectric pH of a tertrapeptide:
At the isoelectric pH of a tertrapeptide:
Which of the following describes the overall three-dimentional folding of a polypeptide?
Which of the following describes the overall three-dimentional folding of a polypeptide?
By adding SDS (sodium dodecyl sulfate) during the electrophoresis of proteins, it is possible to:
By adding SDS (sodium dodecyl sulfate) during the electrophoresis of proteins, it is possible to:
Specific enzymes activity:
Specific enzymes activity:
The backbone of two amino acid residues in a protein can be described as (where Ca is C-alpha):
The backbone of two amino acid residues in a protein can be described as (where Ca is C-alpha):
Which of the following bond-pairs within a peptide backbone show free rotation around both bonds?
Which of the following bond-pairs within a peptide backbone show free rotation around both bonds?
In the a helix the hydrogen bonds:
In the a helix the hydrogen bonds:
In a helix, the R groups on the amino acid residues:
In a helix, the R groups on the amino acid residues:
A D-amino acid would interrupt an a helix made of L-amino acids. Another naturally occurring constraint on the formation of an a helix is the presence of:
A D-amino acid would interrupt an a helix made of L-amino acids. Another naturally occurring constraint on the formation of an a helix is the presence of:
Thr and/or Leu residues tend to disrupt an a helix when they occur next to each other in a protein because:
Thr and/or Leu residues tend to disrupt an a helix when they occur next to each other in a protein because:
Amino acids residues commonly found at the end of beta turns are:
Amino acids residues commonly found at the end of beta turns are:
A sequence of amino acids in the certain protein is found to be -Ser-Gly-Pro-Gly-. The sequence is most probably part of:
A sequence of amino acids in the certain protein is found to be -Ser-Gly-Pro-Gly-. The sequence is most probably part of:
The three-dimentional conformation of a protein may be strongly influenced by amino acid residues that are very far apart in sequence. This relationship is in contrast to secondary structure, where the amino acid residues are:
The three-dimentional conformation of a protein may be strongly influenced by amino acid residues that are very far apart in sequence. This relationship is in contrast to secondary structure, where the amino acid residues are:
Which of the following statements is false:
Which of the following statements is false:
To alter the shape of the a-keratin chains, as in hair waving, the a-keratin chains have undergone one chemical step resulting the conversion of disulfid bridges to Cysteins. What subsequent steps are required?
To alter the shape of the a-keratin chains, as in hair waving, the a-keratin chains have undergone one chemical step resulting the conversion of disulfid bridges to Cysteins. What subsequent steps are required?
Which of the following statements about oligomeric proteins is false?
Which of the following statements about oligomeric proteins is false?
Which of the following statements about proteins is false?
Which of the following statements about proteins is false?
Which of the following statements about proteins is true?
Which of the following statements about proteins is true?
When oxygen binds to a heme-containing protein, the two open coordination bonds of Fe2+ are occupied by:
When oxygen binds to a heme-containing protein, the two open coordination bonds of Fe2+ are occupied by:
In the binding of oxygen to myoglobin, the relationship between the concentration of oxygen and the fraction of binding sites occupied can best be described as:
In the binding of oxygen to myoglobin, the relationship between the concentration of oxygen and the fraction of binding sites occupied can best be described as:
Myoglobin and the subunits of hemoglobin have:
Myoglobin and the subunits of hemoglobin have:
In hemoglobin, the transition from T state to R state (low to high affinity) is triggered by:
In hemoglobin, the transition from T state to R state (low to high affinity) is triggered by:
Which of the following is not correct concerning 2,3-bisphospgoglycerate (BPG)?
Which of the following is not correct concerning 2,3-bisphospgoglycerate (BPG)?
The amino acid substitution of Val for Glu in hemoglobin S results in aggregation of the protein. Which interactions are formed between the molecules in this case?
The amino acid substitution of Val for Glu in hemoglobin S results in aggregation of the protein. Which interactions are formed between the molecules in this case?
An allosteric interaction between a ligand and a protein is one in which:
An allosteric interaction between a ligand and a protein is one in which:
Which of the following statements is true of enzyme catalysts?
Which of the following statements is true of enzyme catalysts?
Which of the following statements is false?
Which of the following statements is false?
Enzymes differ from other catalysts in that enzymes:
Enzymes differ from other catalysts in that enzymes:
The concept of "induced fit" refers to the fact that:
The concept of "induced fit" refers to the fact that:
The benefit of measuring the initial rate (V) of a reaction is, that at the beginning of the reaction:
The benefit of measuring the initial rate (V) of a reaction is, that at the beginning of the reaction:
Which of the folowing statements about a plot V vs. [S] for an enyme that follows Michaelis-Menten kinetics is false?
Which of the folowing statements about a plot V vs. [S] for an enyme that follows Michaelis-Menten kinetics is false?
The Lineweaver-Burk plot is used to:
The Lineweaver-Burk plot is used to:
The double-reciprocal transformation of the Michaelis-Menten equation, also called the Lineweaver-Burk plot, is given by 1/V=Km/ (Vmax [S]) + 1/Vmax. To determine Km from a double-reciprocal plot, you would:
The double-reciprocal transformation of the Michaelis-Menten equation, also called the Lineweaver-Burk plot, is given by 1/V=Km/ (Vmax [S]) + 1/Vmax. To determine Km from a double-reciprocal plot, you would:
For enzymes in which the slowest (rate-limiting) is the reaction step k2 ES, Km becomes equivalent to:
For enzymes in which the slowest (rate-limiting) is the reaction step k2 ES, Km becomes equivalent to:
To calculate the turnover number of an enzyme you need to know the:
To calculate the turnover number of an enzyme you need to know the:
In a plot of 1/V against 1/ [S] for an enzyme-catalyzed reaction, the presence of a competitive inhibitor will alter the:
In a plot of 1/V against 1/ [S] for an enzyme-catalyzed reaction, the presence of a competitive inhibitor will alter the:
In competitive inhibition, an inhibitor:
In competitive inhibition, an inhibitor:
Which of these statements about enzyme-catalyzed reactions is false?
Which of these statements about enzyme-catalyzed reactions is false?
Vmax for an enzyme-catalyzed reaction:
Vmax for an enzyme-catalyzed reaction:
Enzyme X exhibits maximum activity at pH=6.9. X shows a fairly sharp decrease in its activity when the pH goes much lower than 6.4. One likely interpretation of this pH activity is that:
Enzyme X exhibits maximum activity at pH=6.9. X shows a fairly sharp decrease in its activity when the pH goes much lower than 6.4. One likely interpretation of this pH activity is that:
A good transition-state analog:
A good transition-state analog:
A transition-state analog:
A transition-state analog:
Both water and glucose share an -OH that can serve as a substrate for a reaction with the terminal phosphate of ATP catalyzed by hexokinase. Glucose, however, is about a million times more reactive as a substrate than water. The best explenation is that:
Both water and glucose share an -OH that can serve as a substrate for a reaction with the terminal phosphate of ATP catalyzed by hexokinase. Glucose, however, is about a million times more reactive as a substrate than water. The best explenation is that:
Which of the following statements about allosteric control of enzymatic activity is false?
Which of the following statements about allosteric control of enzymatic activity is false?
A small molecule that decreases the activity of an enzyme by binding to a site other than the catalytic site is termed a:
A small molecule that decreases the activity of an enzyme by binding to a site other than the catalytic site is termed a:
How is trypsinogen converted to trypsin?
How is trypsinogen converted to trypsin?
Select the correct statement:
Select the correct statement:
Which of the following statements is TRUE for enzymes?
Which of the following statements is TRUE for enzymes?
The velocity of an enzyme catalyzed reaction does NOT depend on...
The velocity of an enzyme catalyzed reaction does NOT depend on...
Vmax of an enzyme is 25 uM/min, while Km is 6uM. What is Vi (uM/min) when [S] is 4 uM?
Vmax of an enzyme is 25 uM/min, while Km is 6uM. What is Vi (uM/min) when [S] is 4 uM?
Km of an enzyme is 6uM, we measure 30U activity when [S] is 3uM. What is Vmax?
Km of an enzyme is 6uM, we measure 30U activity when [S] is 3uM. What is Vmax?
Trypsin cleaves peptide bonds next to side chains of:
Trypsin cleaves peptide bonds next to side chains of:
Which statements is FALSE for the serine protease catalytic mechanism?
Which statements is FALSE for the serine protease catalytic mechanism?
What is TRUE for competitive inhibitor?
What is TRUE for competitive inhibitor?
What type of function describes the O2 saturation of hemoglobin?
What type of function describes the O2 saturation of hemoglobin?
In deoxy-hemoglobin the Fe2+ ion...
In deoxy-hemoglobin the Fe2+ ion...
Which factor decrease the O2-binding affinity of hemoglobin?
Which factor decrease the O2-binding affinity of hemoglobin?
Which hemoglobin form refers to pathological conditions?
Which hemoglobin form refers to pathological conditions?
Which of the following statements are true for the enzyme at the rate-limiting step of a metabolic pathway?
Which of the following statements are true for the enzyme at the rate-limiting step of a metabolic pathway?
Which statement is FALSE for myoglobin?
Which statement is FALSE for myoglobin?
Which factor does NOT shift hemoglobin's O2 saturation to the right?
Which factor does NOT shift hemoglobin's O2 saturation to the right?
Which input path of a branched metabolic pathway is more relevant physiologically?
Which input path of a branched metabolic pathway is more relevant physiologically?
Which of the following statements is true when the rate-limiting steo of a reaction pathway is unhibited?
Which of the following statements is true when the rate-limiting steo of a reaction pathway is unhibited?
Which of the following statements is true for a reaction pathway under conditions of steady-state?
Which of the following statements is true for a reaction pathway under conditions of steady-state?
Which of the following statements is TRUE for serine protease?
Which of the following statements is TRUE for serine protease?
We measure the following [S]-v pairs (mM and uM/min): 2-22, 5-42, 7-50, 493-99, 1000-100. What is the km (in mM) of the enzyme?
We measure the following [S]-v pairs (mM and uM/min): 2-22, 5-42, 7-50, 493-99, 1000-100. What is the km (in mM) of the enzyme?
Which of the following statements is TRUE for an enzymatic reaction with large negative DeltaG?
Which of the following statements is TRUE for an enzymatic reaction with large negative DeltaG?
What is plotted on the x and y axis of the Lineweaver-Burk plot, respectively?
What is plotted on the x and y axis of the Lineweaver-Burk plot, respectively?
Enzymes are potent catalysts. They:
Enzymes are potent catalysts. They:
The term specific activity differs from the term activity in that specific activity:
The term specific activity differs from the term activity in that specific activity:
Which of the following statements is true of enzyme catalysts?
Which of the following statements is true of enzyme catalysts?
The role of an enzyme in an enzyme-catalyzed reaction is to:
The role of an enzyme in an enzyme-catalyzed reaction is to:
Which of the following statements is true of enzyme catalysts?
Which of the following statements is true of enzyme catalysts?
Which of the following statements is false?
Which of the following statements is false?
Enzymes differ from other catalysts in that enzymes:
Enzymes differ from other catalysts in that enzymes:
The benefit of measuring the intial rate of the reactio, V, id that at the beginning of a reaction:
The benefit of measuring the intial rate of the reactio, V, id that at the beginning of a reaction:
Which of the following statements about a plot of V vs. [S] for an enzyme that follows Michaelis-Menten kinetics is false?
Which of the following statements about a plot of V vs. [S] for an enzyme that follows Michaelis-Menten kinetics is false?
The double-reciprocal transformation of the Michaelis-Menten equation, also called the Lineweaver-Burk plot, is given by 1/v = km/Vmax x 1/[S] + 1/Vmax. To determine Km from a double-reciprocal plot, you would:
The double-reciprocal transformation of the Michaelis-Menten equation, also called the Lineweaver-Burk plot, is given by 1/v = km/Vmax x 1/[S] + 1/Vmax. To determine Km from a double-reciprocal plot, you would:
To calculate the turnover number of an enzyme you need to know the:
To calculate the turnover number of an enzyme you need to know the:
The number of substrate molecules converted to product in a given unit f time by a single enzyme molecule at saturation is reffered to as the:
The number of substrate molecules converted to product in a given unit f time by a single enzyme molecule at saturation is reffered to as the:
In a plot of 1/V against 1/[S] for an enzyme-catalyzed reaction, the presence of a competitive inhibitor will alter the:
In a plot of 1/V against 1/[S] for an enzyme-catalyzed reaction, the presence of a competitive inhibitor will alter the:
What is the characteristic of a competitive inhibitor:
What is the characteristic of a competitive inhibitor:
Vmax for an enzyme-catalyzed reaction:
Vmax for an enzyme-catalyzed reaction:
Which of the following statements about allosteric control of enzymatic activity is false?
Which of the following statements about allosteric control of enzymatic activity is false?
A small molecule that decreases the activity of an enzyme by binding to a sote other than the catalystic site is termed as:
A small molecule that decreases the activity of an enzyme by binding to a sote other than the catalystic site is termed as:
What is true about a cofactor?
What is true about a cofactor?
Which feature is common for all isoenzymes of the same enzyme?
Which feature is common for all isoenzymes of the same enzyme?
What is true about serine proteases?
What is true about serine proteases?
Which parameter characterizes the specificity of the enzyme?
Which parameter characterizes the specificity of the enzyme?
Which statement is NOT valid concerning the Km?
Which statement is NOT valid concerning the Km?
Which statement is NOT valid concerning the Km?
Which statement is NOT valid concerning the Km?
Which statement is NOT valid concerning the Kcat?
Which statement is NOT valid concerning the Kcat?
Which one is the most efficient isoenzyme of the same enzyme at [S] >> Km?
Which one is the most efficient isoenzyme of the same enzyme at [S] >> Km?
Which of the following statements is true for the action of serpins?
Which of the following statements is true for the action of serpins?
What kind of reactions are the best targets for metabolic control?
What kind of reactions are the best targets for metabolic control?
Study Notes
Sorting Signals
- Sorting signals are specific amino acid sequences within a protein that direct the protein to its correct cellular location.
- These signals act as addresses, guiding the protein to its target compartment or organelle within the cell.
- Sorting signals can be located at the amino or carboxyl terminus of the protein or internally within the polypeptide chain.
- Different types of sorting signals direct proteins to different destinations, reflecting the complexity of intracellular trafficking pathways.
- They mediate the process of protein targeting, enabling cellular organization and function.
Ubiquitination
- Ubiquitination is a protein modification that marks proteins for degradation.
- It involves the covalent attachment of ubiquitin, a small protein, to target proteins.
- Ubiquitination tags proteins for degradation by the proteasome, a large protein complex that breaks down proteins into smaller peptides.
- This process plays a critical role in protein homeostasis and regulating various cellular pathways.
- Unlike sorting signals that direct proteins to specific destinations, ubiquitination signals are associated with targeted destruction rather than transport.
Degradation Signals
- Degradation signals are specific sequences or structures within a protein that mark it for destruction.
- These signals often involve amino acid motifs or post-translational modifications that target the protein for proteolytic degradation.
- These signals are distinct from sorting signals, which direct the protein to a specific compartment.
- Different cellular processes like quality control, cellular response to stress, and receptor recycling utilize degradation signals.
- Degradation signals are crucial for maintaining a controlled cellular environment due to their role in eliminating damaged or unwanted proteins.
Apoptotic Signals
- Apoptotic signals regulate programmed cell death, a naturally occurring process essential for development and homeostasis.
- The signals can trigger a cascade of events leading to the dismantling and removal of the cell.
- These signals are unrelated to directing proteins to their correct cellular locations or targeting them for degradation.
- Unlike sorting or degradation signals, they lead to the entire cell's demise.
- In summary, they initiate a distinct cellular response, unlike the other signals listed.
Hydroxylation
- Hydroxylation is a post-translational modification where a hydroxyl group is added to an amino acid residue in a protein.
- This modification can influence protein stability, activity, and interactions with other molecules.
- While specific hydroxylation signals can be involved in targeting certain proteins, their primary function is not directed transport or degradation.
- Hydroxylation often plays a role in protein stability, or function, but not in transport or direct targeting as sorting signals do.
- Hydroxylation modifications are crucial in orchestrating intricate molecular mechanisms within the cell.
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