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Questions and Answers
What functional groups are present in all a-amino acids?
What functional groups are present in all a-amino acids?
Which statement accurately describes proline among amino acids?
Which statement accurately describes proline among amino acids?
What distinguishes different a-amino acids from each other?
What distinguishes different a-amino acids from each other?
In what way does proline differ from other a-amino acids?
In what way does proline differ from other a-amino acids?
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Which amino acid has a hydrogen atom as its side chain?
Which amino acid has a hydrogen atom as its side chain?
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What configuration is designated when the hydroxyl group is on the left in a Fischer projection?
What configuration is designated when the hydroxyl group is on the left in a Fischer projection?
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In a Fischer projection, if the hydroxyl group is on the right, what is the designation of that molecule?
In a Fischer projection, if the hydroxyl group is on the right, what is the designation of that molecule?
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Which amino acid configuration corresponds to L-glyceraldehyde?
Which amino acid configuration corresponds to L-glyceraldehyde?
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For D-amino acids, where is the a-amino group located in a Fischer projection?
For D-amino acids, where is the a-amino group located in a Fischer projection?
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What is the reference carbon for determining the D and L configurations in amino acids?
What is the reference carbon for determining the D and L configurations in amino acids?
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How many absolute configurations can amino acids have?
How many absolute configurations can amino acids have?
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Which of the following amino acids is ribosomally incorporated into proteins in the L-configuration?
Which of the following amino acids is ribosomally incorporated into proteins in the L-configuration?
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What does the designation D refer to in molecular terms?
What does the designation D refer to in molecular terms?
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Which type of amino acids are commonly found in ribosomally synthesized proteins?
Which type of amino acids are commonly found in ribosomally synthesized proteins?
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What is the basis for the preference of L-amino acids over D-amino acids in proteins?
What is the basis for the preference of L-amino acids over D-amino acids in proteins?
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Which system is most useful for describing the configuration of chiral compounds?
Which system is most useful for describing the configuration of chiral compounds?
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In the RS System, how is priority among substituents on a chiral carbon determined?
In the RS System, how is priority among substituents on a chiral carbon determined?
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What type of antibiotics contain D-amino acids?
What type of antibiotics contain D-amino acids?
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Which amino acid is used to illustrate the prioritization of groups around a chiral carbon?
Which amino acid is used to illustrate the prioritization of groups around a chiral carbon?
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Which statement is true regarding D-amino acids?
Which statement is true regarding D-amino acids?
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Which factor does NOT influence the priority ranking in the RS system?
Which factor does NOT influence the priority ranking in the RS system?
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What is true about enantiomers?
What is true about enantiomers?
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Which statement correctly describes diastereomers?
Which statement correctly describes diastereomers?
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What distinguishes enantiomers from conformations?
What distinguishes enantiomers from conformations?
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What is an achiral amino acid?
What is an achiral amino acid?
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How does the DL system relate to amino acids?
How does the DL system relate to amino acids?
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Which of the following statements is incorrect?
Which of the following statements is incorrect?
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What happens when the configuration of a molecule is altered?
What happens when the configuration of a molecule is altered?
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Which of these compounds is achiral?
Which of these compounds is achiral?
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What units are used for the concentration of a sample in optical activity measurements?
What units are used for the concentration of a sample in optical activity measurements?
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For a compound's specific rotation denoted as [α], what is the path length standardized to?
For a compound's specific rotation denoted as [α], what is the path length standardized to?
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Which notation indicates the use of a sodium lamp with a wavelength of 589 nm in optical activity measurements?
Which notation indicates the use of a sodium lamp with a wavelength of 589 nm in optical activity measurements?
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What is the specific rotation value when the observed optical rotation is 0.671° with a concentration of 0.025 g/mL and path length of 0.5 dm?
What is the specific rotation value when the observed optical rotation is 0.671° with a concentration of 0.025 g/mL and path length of 0.5 dm?
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What defines standard (or proteinogenic) amino acids?
What defines standard (or proteinogenic) amino acids?
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How many different amino acids participate in protein synthesis?
How many different amino acids participate in protein synthesis?
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What type of acids are all standard amino acids classified as?
What type of acids are all standard amino acids classified as?
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Which of the following best describes the term 'specific rotation'?
Which of the following best describes the term 'specific rotation'?
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Which amino acids contain hydroxyl groups in their side chains?
Which amino acids contain hydroxyl groups in their side chains?
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What type of group does arginine contain in its side chain?
What type of group does arginine contain in its side chain?
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At neutral pH, which amino acids contain negatively charged groups?
At neutral pH, which amino acids contain negatively charged groups?
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Which amino acid has a side chain that contains a thiol group?
Which amino acid has a side chain that contains a thiol group?
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What distinguishes histidine's side chain from the others mentioned?
What distinguishes histidine's side chain from the others mentioned?
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Lysine and arginine are categorized under which type of amino acid based on their side chains?
Lysine and arginine are categorized under which type of amino acid based on their side chains?
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What type of amino acids does serine belong to based on the nature of its side chain?
What type of amino acids does serine belong to based on the nature of its side chain?
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Which of the following amino acids does not have a charged polar side chain?
Which of the following amino acids does not have a charged polar side chain?
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Study Notes
Amino Acids and Proteins
- Amino acids are organic compounds that contain carbon, hydrogen, oxygen, and nitrogen.
- They are monomers that form proteins.
- A-amino acids have an amino group (-NH2) and a carboxyl group (-COOH) attached to the same alpha carbon (α-carbon).
- The side chain (R group) varies between different amino acids, making them unique.
- Proline is a secondary amino acid, with a secondary amino group (-NH-).
- Many naturally occurring amino acids aren't found in proteins; these structures differ from α-amino acids.
Amino Acid Structure
- The R group attached to the α-carbon distinguishes each amino acid.
- Glycine has a hydrogen atom as its R group.
- Lysine has a longer side chain.
- Proline's secondary amino group makes it unique.
Amino Acids as Acids and Bases
- Amino acids contain both amino (-NH2) and carboxyl (-COOH) groups.
- At physiological pH (~7.2), amino groups are protonated (-NH₃⁺) and carboxyl groups are deprotonated (-COO⁻).
- This creates a zwitterion form (a dipolar ion) in solution, with a positive and a negative charge balancing each other.
- The ionization of amino acids changes with pH.
Isomers
- Isomers are compounds with the same molecular formula but different structures.
- Constitutional isomers have different atomic connectivities.
- Stereoisomers have the same atomic connectivity but differ in spatial arrangement.
- Enantiomers are non-superimposable mirror images, while diastereomers are not mirror images.
- Chiral molecules have no plane of symmetry, and exist as enantiomers.
Absolute Configuration
- All amino acids except glycine are chiral.
- Chiral amino acids exist as two non-superimposable mirror images called enantiomers and have different configurations denoted as D or L based on glyceraldehyde's configuration.
- The absolute configuration is identified by the absolute configuration of the a-carbon determining the L or D isomer.
Optical Activity
- Chiral molecules (except glycine) can rotate plane-polarized light.
- Dextrorotatory (+): rotations clockwise
- Levorotatory (-): rotations counterclockwise
- Specific rotation, a measure of a sample's optical activity, uses a polarimeter.
Titration of Amino Acids
- Amino acids are titrated using a strong base (like NaOH) to determine the effect of pH on net charge.
- Different amino acids, with and without ionizable side chains, can be titrated to understand their pKa values for better prediction.
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Description
Test your knowledge on amino acids, their functional groups, and configurations. This quiz covers key concepts like proline differences and the Fischer projection system. Perfect for students studying biochemistry or molecular biology.
