48 Questions
Match the following characteristics with the correct type of amino acid:
Amphoteric = Amino acid that can be both acid and base Basic = Amino acid that can donate H+ Acidic = Amino acid that can accept H+ Neutral = Amino acid that is neither acid nor base
Match the following elements with their presence in amino acids:
Oxygen = Present in amino group and carboxyl group Nitrogen = Present in amino group Sulfur = Present in some amino acids (e.g. cysteine) Carbon = Present in the R-group
Match the following characteristics with the correct type of amino acid structure:
Aromatic ring = Present in some amino acids (e.g. phenylalanine) R-group = Unique side chain of an amino acid Carboxyl group = Present in all amino acids Amino group = Present in all amino acids
Match the following properties with the correct type of amino acid:
Can donate H+ = Acidic amino acid Can accept H+ = Basic amino acid Can donate or accept H+ = Amphoteric amino acid Cannot donate or accept H+ = Neutral amino acid
Match the following statements with the correct type of amino acid:
Can be protonated = Basic amino acid Can be deprotonated = Acidic amino acid Has two stereoisomers = All amino acids (except glycine) Has a unique R-group = All amino acids
Match the following terms with their correct definitions:
Stereoisomers = Non-superimposable mirror images of a molecule L-form = One type of stereoisomer of amino acids D-form = Another type of stereoisomer of amino acids R-group = The side chain of an amino acid
Match the following terms with their correct definitions:
Amino group = A functional group that can donate H+ Carboxyl group = A functional group that can accept H+ R-group = A functional group that can participate in acid-base reactions Aromatic ring = A functional group that can donate or accept H+
Match the following terms with their correct definitions:
Basic amino acid = Amino acid that can accept H+ Acidic amino acid = Amino acid that can donate H+ Amphoteric amino acid = Amino acid that can both donate and accept H+ Neutral amino acid = Amino acid that is neither acid nor base
Match the following statements with the correct type of amino acid:
Has a neutral pH = Neutral amino acid Has a pH above 7 = Basic amino acid Has a pH below 7 = Acidic amino acid Has a pH that depends on the environment = Amphoteric amino acid
Match the following elements with their correct functions in amino acids:
Oxygen = Helps to form the peptide bond Nitrogen = Helps to form the peptide bond Sulfur = Helps to form disulfide bonds Carbon = Helps to form the backbone of the amino acid
Match the following properties with the characteristic of carboxyl group:
Deprotonated = Basic receives H+ Soluble in polar solvents = Due to ionic character Structure of R influences = Solubility Acidic = Losely bonded to H+
Match the following terms with their descriptions in amino acids:
Three-letter = Abbreviation for amino acid names One-letter = Abbreviation for amino acid names Ionic character = Reason for solubility in polar solvents COO- = Carboxyl group in amino acid
Match the following statements with the correct characteristic of amino acid:
Amino acids are soluble = In polar solvents due to ionic character Carboxyl group is = Deprotonated and basic Structure of R group = Influnces solubility of amino acid Amino acids are referred = By three-letter or one-letter abbreviation
Match the following terms with their characteristics in amino acids:
COO- = Carboxyl group which is deprotonated +NH = Amino group which receives H+ R group = Influences solubility of amino acid Polar solvents = Solvents in which amino acids are soluble
Match the following statements with the correct characteristic of amino acid:
Carboxyl group is deprotonated = And becomes basic Amino group receives = H+ to become basic R group influences = Solubility of amino acid Amino acids are referred = By three-letter or one-letter abbreviation
Match the following terms with their characteristics in amino acids:
COO- = Carboxyl group which is acidic +NH = Amino group which is basic R group = Influences solubility of amino acid Polar solvents = Solvents in which amino acids are soluble
Match the following statements with the correct characteristic of amino acid:
Amino acids are soluble = In polar solvents due to ionic character Carboxyl group is = Deprotonated and basic Structure of R group = Influences solubility of amino acid Amino acids are referred = By three-letter or one-letter abbreviation
Match the following terms with their characteristics in amino acids:
COO- = Carboxyl group which is deprotonated and acidic +NH = Amino group which receives H+ R group = Influences solubility of amino acid Polar solvents = Solvents in which amino acids are soluble
Match the following amino acids with their characteristic R-groups:
Alanine (Ala) = Small R-group Glutamine (Gln) = Contains oxygen Cysteine (Cys) = Forms disulfide bridges Proline (Pro) = Rigid structure
Match the following amino acids with their primary characteristics:
Glycine (Gly) = Non-polar and flexible Tyrosine (Tyr) = Polar and hydroxyl group present Methionine (Met) = Polar and sulfur-containing Isoleucine (Ile) = Non-polar and branched chain
Match the following amino acids with their functionality:
Asparagine (Asn) = Involved in hydrogen bonding Valine (Val) = Contains hydrophobic R-group Leucine (Leu) = Contains hydrophobic R-group Threonine (Thr) = Polar and hydroxyl group present
Match the following amino acids with their structural properties:
Proline (Pro) = Forms kinks in protein structure Glycine (Gly) = Flexible and non-polar Phenylalanine (Phe) = Contains aromatic R-group Serine (Ser) = Polar and hydroxyl group present
Match the following amino acids with their R-group properties:
Cysteine (Cys) = Forms disulfide bridges and contains sulfur Methionine (Met) = Contains sulfur and is polar Alanine (Ala) = Small and non-polar R-group Tyrosine (Tyr) = Contains hydroxyl group and is polar
Match the following amino acids with their polarity:
Isoleucine (Ile) = Non-polar and hydrophobic Serine (Ser) = Polar and hydroxyl group present Glycine (Gly) = Non-polar and flexible Asparagine (Asn) = Polar and involved in hydrogen bonding
Match the following amino acids with their R-group properties:
Phenylalanine (Phe) = Contains aromatic R-group Leucine (Leu) = Contains hydrophobic R-group Valine (Val) = Contains hydrophobic R-group Threonine (Thr) = Polar and hydroxyl group present
Match the following amino acids with their structural properties:
Proline (Pro) = Forms kinks in protein structure Glycine (Gly) = Flexible and non-polar Cysteine (Cys) = Forms disulfide bridges Methionine (Met) = Contains sulfur and is polar
Match the following amino acids with their R-group properties:
Tyrosine (Tyr) = Contains hydroxyl group and is polar Asparagine (Asn) = Involved in hydrogen bonding Glutamine (Gln) = Contains oxygen and is polar Alanine (Ala) = Small and non-polar R-group
Match the following amino acids with their functionality:
Isoleucine (Ile) = Involved in hydrophobic interactions Leucine (Leu) = Involved in hydrophobic interactions Valine (Val) = Involved in hydrophobic interactions Phenylalanine (Phe) = Involved in aromatic interactions
Match the following terms with their definitions in acid-base chemistry:
pH = Concentration of hydrogen ions pK = Power of hydrogen ion concentration pKR = Constant of dissociation of acid pOH = Concentration of hydroxide ions
Match the following characteristics with their corresponding acid-base properties:
Partly dissociates in water = Weak acid Fully dissociates in water = Strong acid High concentration of hydrogen ions = Acidic Low concentration of hydrogen ions = Basic
Match the following groups with their corresponding acid-base properties in amino acids:
COOH = Acidic NH3+ = Basic COO- = Basic NH2 = Acidic
Match the following reactions with their corresponding acid-base properties:
Gain of proton = Acidic Loss of proton = Basic Gain of hydroxide ion = Basic Loss of hydroxide ion = Acidic
Match the following pH ranges with their corresponding acid-base properties:
pH < 7 = Acidic pH > 7 = Basic pH = 7 = Neutral pH > 14 = Extremely basic
Match the following terms with their definitions in acid-base chemistry:
pK1 = First acid dissociation constant pK2 = Second acid dissociation constant
Match the following characteristics with their corresponding acid-base properties in amino acids:
Fully protonated = pH < 2.2 Partly protonated = pH 2.2-9.4 Fully deprotonated = pH > 9.4 Not applicable = pH 7
Match the following terms with their definitions in acid-base chemistry:
log[H+] = Concentration of hydrogen ions log[OH-] = Concentration of hydroxide ions
Match the following reactions with their corresponding acid-base properties:
Forward reaction = Loss of proton Backward reaction = Gain of proton
Match the following terms with their definitions in acid-base chemistry:
Reversible reaction = Equilibrium reaction Irreversible reaction = Non-equilibrium reaction Forward reaction = Acidic reaction Backward reaction = Basic reaction
Match the amino acid with its abbreviation:
Glycine = Gly Alanine = Ala L-Glutamate = Glu Aspartate = Asp
Match the amino acid classification with its characteristic:
Non-essential = Produced in the body Essential = Not produced in the body Polar = Facing water Non-polar = Facing away from water
Match the amino acid property with its description:
Hydrophilic = Water-loving Hydrophobic = Water-fearing Aromatic = Ring structure Basic = Positive charge
Match the amino acid classification with its example:
Non-essential = Glycine Essential = Alanine Polar = Serine Non-polar = Phenylalanine
Match the amino acid chain characteristic with its description:
Polar chain = Water-loving Non-polar chain = Water-fearing Aliphatic chain = Chain with carbon atoms Aromatic chain = Chain with ring structure
Match the amino acid classification with its solubility:
Polar = Soluble in water Non-polar = Insoluble in water Essential = Soluble in organic solvents Non-essential = Insoluble in organic solvents
Match the amino acid property with its effect on the body:
Hydrophilic = Repelled by the body Hydrophobic = Attracted to the body Aromatic = Stabilizes the body Basic = Alkalizes the body
Match the amino acid classification with its location in the body:
Extrinsic = Outside the body Intrinsic = Inside the body Polar = In membranes Non-polar = In proteins
Match the amino acid chain characteristic with its function:
Polar chain = Cell signaling Non-polar chain = Energy storage Aliphatic chain = Structural support Aromatic chain = Catalysis
Match the amino acid property with its origin:
Hydrophilic = Synthesized in the body Hydrophobic = Dietary intake Aromatic = Synthesized in the gut Basic = Supplemented in the diet
Study Notes
Amino Acid Structure
- Amino acids have an amino group (NH₂) and a carboxyl group (COOH)
- They are amphoteric, meaning they can act as both acids and bases
- Amino groups are protonated (gain H+) and behave as bases, while carboxyl groups are deprotonated (lose H+) and behave as acids
Stereoisomers
- Except for glycine, amino acids have two stereoisomers: L and D forms
Solubility
- Amino acids are soluble in polar solvents due to their ionic character
- The structure of the R group also influences solubility
Classification of Amino Acids
- Amino acids are classified into two main categories: essential and non-essential
- Essential amino acids cannot be produced by the human body and must be obtained through diet (10 out of 20)
- Non-essential amino acids can be produced by the human body (10 out of 20)
Properties of Amino Acids
- Some amino acids have aromatic ring structures
- Some amino acids are hydrophilic (water-loving), while others are hydrophobic (water-fearing)
- The R group of an amino acid can be polar or non-polar, affecting its solubility
Abbreviations
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Amino acids are referred to by three-letter or one-letter abbreviations (e.g., Gly for glycine, Ala for alanine)### Amino Acids
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There are 20 standard amino acids, each with a unique R-group
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Glycine (Gly) and Alanine (Ala) have small R-groups
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Serine (Ser) and Threonine (Thr) have R-groups with a hydroxyl (-OH) group
-
Cysteine (Cys) has an R-group with a sulfur atom, which can form a disulfide bridge with another Cysteine
-
Tyrosine (Tyr) and Tryptophan (Trp) have large, rigid R-groups
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Proline (Pro) has a unique, rigid structure that can cause kinks in protein chains
-
Valine (Val) and Isoleucine (Ile) have non-polar, hydrophobic R-groups
-
Asparagine (Asn) and Glutamine (Gln) have R-groups with an amide group
-
Methionine (Met) has a sulfide group in its R-group, making it easily soluble in water
-
Leucine (Leu) has a non-polar, hydrophobic R-group
Polarity of Amino Acids
- Amino acids can be classified as polar or non-polar based on their R-group
- Polar amino acids have R-groups with a hydroxyl (-OH) or amide group
- Non-polar amino acids have R-groups with hydrocarbon chains or sulfur atoms
- Glycine (Gly) and Serine (Ser) are polar amino acids
- Alanine (Ala) and Valine (Val) are non-polar amino acids
- Proline (Pro) is a non-polar amino acid, but its rigid structure makes it unique
Protein Structure
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Disulfide bridges can form between two Cysteine (Cys) residues, stabilizing protein structure
-
Hydrogen bonds and weak interactions between amino acids help stabilize protein structure
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Proline (Pro) can cause kinks in protein chains due to its rigid structure### Acid-Base Properties of Amino Acids
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pH Scale: pH = -log[H+]
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Weak acids and weak bases: dissociate partly in water, resulting in a mixture of protonated and deprotonated forms
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Acidic conditions: [H+] > 10^-7, pH < 7
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Basic conditions: [OH-] > 10^-7, pH > 7
Carboxyl Group (COOH)
- Acidic group: dissociates partly in water to release H+ ions
- pK1 ~ 2.2: the pH below which the carboxyl group is protonated
- Example: CH₃CH₂COOH (acetate) has a pK1 of 2.2, meaning it is protonated at pH values below 2.2
Amino Group (NH2)
- Basic group: accepts H+ ions
- pK2 ~ 9.4: the pH above which the amino group is deprotonated
- Example: NH₄+ (ammonium) has a pK2 of 9.4, meaning it is deprotonated at pH values above 9.4
Titration of Glycine
- Glycine: an amino acid with a carboxyl group (COOH) and an amino group (NH2)
- pK1 (-COOH) = 2.34, pK2 (-NH3+) = 9.6
- At pH < 2.34, the carboxyl group is protonated (COOH) and the amino group is protonated (NH3+)
- At pH > 9.6, the carboxyl group is deprotonated (COO-) and the amino group is deprotonated (NH2)
- At pH = 2.34, the carboxyl group is 50% protonated and 50% deprotonated
- At pH = 9.6, the amino group is 50% protonated and 50% deprotonated
This quiz covers the basics of chemistry, including atomic structure, molecular bonding, and chemical properties of elements such as Oxygen, Nitrogen, and Sulfur.
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