Chemistry of Atoms and Molecules
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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:

<p>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</p> Signup and view all the answers

Match the following statements with the correct type of amino acid:

<p>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</p> Signup and view all the answers

Match the following terms with their correct definitions:

<p>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</p> Signup and view all the answers

Match the following terms with their correct definitions:

<p>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+</p> Signup and view all the answers

Match the following terms with their correct definitions:

<p>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</p> Signup and view all the answers

Match the following statements with the correct type of amino acid:

<p>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</p> Signup and view all the answers

Match the following elements with their correct functions in amino acids:

<p>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</p> Signup and view all the answers

Match the following properties with the characteristic of carboxyl group:

<p>Deprotonated = Basic receives H+ Soluble in polar solvents = Due to ionic character Structure of R influences = Solubility Acidic = Losely bonded to H+</p> Signup and view all the answers

Match the following terms with their descriptions in amino acids:

<p>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</p> Signup and view all the answers

Match the following statements with the correct characteristic of amino acid:

<p>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</p> Signup and view all the answers

Match the following terms with their characteristics in amino acids:

<p>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</p> Signup and view all the answers

Match the following statements with the correct characteristic of amino acid:

<p>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</p> Signup and view all the answers

Match the following terms with their characteristics in amino acids:

<p>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</p> Signup and view all the answers

Match the following statements with the correct characteristic of amino acid:

<p>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</p> Signup and view all the answers

Match the following terms with their characteristics in amino acids:

<p>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</p> Signup and view all the answers

Match the following amino acids with their characteristic R-groups:

<p>Alanine (Ala) = Small R-group Glutamine (Gln) = Contains oxygen Cysteine (Cys) = Forms disulfide bridges Proline (Pro) = Rigid structure</p> Signup and view all the answers

Match the following amino acids with their primary characteristics:

<p>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</p> Signup and view all the answers

Match the following amino acids with their functionality:

<p>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</p> Signup and view all the answers

Match the following amino acids with their structural properties:

<p>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</p> Signup and view all the answers

Match the following amino acids with their R-group properties:

<p>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</p> Signup and view all the answers

Match the following amino acids with their polarity:

<p>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</p> Signup and view all the answers

Match the following amino acids with their R-group properties:

<p>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</p> Signup and view all the answers

Match the following amino acids with their structural properties:

<p>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</p> Signup and view all the answers

Match the following amino acids with their R-group properties:

<p>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</p> Signup and view all the answers

Match the following amino acids with their functionality:

<p>Isoleucine (Ile) = Involved in hydrophobic interactions Leucine (Leu) = Involved in hydrophobic interactions Valine (Val) = Involved in hydrophobic interactions Phenylalanine (Phe) = Involved in aromatic interactions</p> Signup and view all the answers

Match the following terms with their definitions in acid-base chemistry:

<p>pH = Concentration of hydrogen ions pK = Power of hydrogen ion concentration pKR = Constant of dissociation of acid pOH = Concentration of hydroxide ions</p> Signup and view all the answers

Match the following characteristics with their corresponding acid-base properties:

<p>Partly dissociates in water = Weak acid Fully dissociates in water = Strong acid High concentration of hydrogen ions = Acidic Low concentration of hydrogen ions = Basic</p> Signup and view all the answers

Match the following groups with their corresponding acid-base properties in amino acids:

<p>COOH = Acidic NH3+ = Basic COO- = Basic NH2 = Acidic</p> Signup and view all the answers

Match the following reactions with their corresponding acid-base properties:

<p>Gain of proton = Acidic Loss of proton = Basic Gain of hydroxide ion = Basic Loss of hydroxide ion = Acidic</p> Signup and view all the answers

Match the following pH ranges with their corresponding acid-base properties:

<p>pH &lt; 7 = Acidic pH &gt; 7 = Basic pH = 7 = Neutral pH &gt; 14 = Extremely basic</p> Signup and view all the answers

Match the following terms with their definitions in acid-base chemistry:

<p>pK1 = First acid dissociation constant pK2 = Second acid dissociation constant</p> Signup and view all the answers

Match the following characteristics with their corresponding acid-base properties in amino acids:

<p>Fully protonated = pH &lt; 2.2 Partly protonated = pH 2.2-9.4 Fully deprotonated = pH &gt; 9.4 Not applicable = pH 7</p> Signup and view all the answers

Match the following terms with their definitions in acid-base chemistry:

<p>log[H+] = Concentration of hydrogen ions log[OH-] = Concentration of hydroxide ions</p> Signup and view all the answers

Match the following reactions with their corresponding acid-base properties:

<p>Forward reaction = Loss of proton Backward reaction = Gain of proton</p> Signup and view all the answers

Match the following terms with their definitions in acid-base chemistry:

<p>Reversible reaction = Equilibrium reaction Irreversible reaction = Non-equilibrium reaction Forward reaction = Acidic reaction Backward reaction = Basic reaction</p> Signup and view all the answers

Match the amino acid with its abbreviation:

<p>Glycine = Gly Alanine = Ala L-Glutamate = Glu Aspartate = Asp</p> Signup and view all the answers

Match the amino acid classification with its characteristic:

<p>Non-essential = Produced in the body Essential = Not produced in the body Polar = Facing water Non-polar = Facing away from water</p> Signup and view all the answers

Match the amino acid property with its description:

<p>Hydrophilic = Water-loving Hydrophobic = Water-fearing Aromatic = Ring structure Basic = Positive charge</p> Signup and view all the answers

Match the amino acid classification with its example:

<p>Non-essential = Glycine Essential = Alanine Polar = Serine Non-polar = Phenylalanine</p> Signup and view all the answers

Match the amino acid chain characteristic with its description:

<p>Polar chain = Water-loving Non-polar chain = Water-fearing Aliphatic chain = Chain with carbon atoms Aromatic chain = Chain with ring structure</p> Signup and view all the answers

Match the amino acid classification with its solubility:

<p>Polar = Soluble in water Non-polar = Insoluble in water Essential = Soluble in organic solvents Non-essential = Insoluble in organic solvents</p> Signup and view all the answers

Match the amino acid property with its effect on the body:

<p>Hydrophilic = Repelled by the body Hydrophobic = Attracted to the body Aromatic = Stabilizes the body Basic = Alkalizes the body</p> Signup and view all the answers

Match the amino acid classification with its location in the body:

<p>Extrinsic = Outside the body Intrinsic = Inside the body Polar = In membranes Non-polar = In proteins</p> Signup and view all the answers

Match the amino acid chain characteristic with its function:

<p>Polar chain = Cell signaling Non-polar chain = Energy storage Aliphatic chain = Structural support Aromatic chain = Catalysis</p> Signup and view all the answers

Match the amino acid property with its origin:

<p>Hydrophilic = Synthesized in the body Hydrophobic = Dietary intake Aromatic = Synthesized in the gut Basic = Supplemented in the diet</p> Signup and view all the answers

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

  • Amino acids are referred to by three-letter or one-letter abbreviations (e.g., Gly for glycine, Ala for alanine)### Amino Acids

  • There are 20 standard amino acids, each with a unique R-group

  • Glycine (Gly) and Alanine (Ala) have small R-groups

  • 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

  • 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

  • Disulfide bridges can form between two Cysteine (Cys) residues, stabilizing protein structure

  • Hydrogen bonds and weak interactions between amino acids help stabilize protein structure

  • Proline (Pro) can cause kinks in protein chains due to its rigid structure### Acid-Base Properties of Amino Acids

  • pH Scale: pH = -log[H+]

  • Weak acids and weak bases: dissociate partly in water, resulting in a mixture of protonated and deprotonated forms

  • Acidic conditions: [H+] > 10^-7, pH < 7

  • 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

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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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