Biochemistry: Peptide Bond and Amino Acids

Questions and Answers

What type of reaction occurs when peptide bonds are formed?

Synthesis

Hydrolysis

Condensation (correct)

Decomposition

Proteolysis refers to the process of forming peptide bonds.

False

What are proteolytic enzymes responsible for in the body?

Cutting proteins at specific amino acids.

The unique amino acid that forms a five-membered ring is called ___ .

proline Signup and view all the answers

Match the amino acids with their classifications:

Glycine = Non-polar Aspartic Acid = Acidic Lysine = Basic Serine = Polar Signup and view all the answers

Which of the following amino acids has a simple hydrogen as its variable group?

Glycine Signup and view all the answers

Hydrolysis requires the consumption of a water molecule.

True Signup and view all the answers

What is the basic backbone structure of amino acids composed of?

Nitrogen, alpha carbon, and carbonyl. Signup and view all the answers

Amino acids can be organized by their properties such as ___, non-polar, acidic, and basic.

polar Signup and view all the answers

Which of the following statements is true regarding the amino acids used by living organisms?

Glycine is the only amino acid that is not chiral. Signup and view all the answers

All amino acids are recognized by enzymes in their D form.

False Signup and view all the answers

What are the two main classifications of amino acids based on their side chains?

Polar and non-polar Signup and view all the answers

Glycine is unique among amino acids because it has a variable ______ group.

hydrogen Signup and view all the answers

Match the following categories of amino acids with their descriptions:

Non-polar = Amino acids that typically do not interact with water Polar = Amino acids that interact well with water Chiral = Amino acids with non-superimposable mirror images Amino Acids = Building blocks of proteins Signup and view all the answers

What effect does proline have on protein structure?

Creates a characteristic kink Signup and view all the answers

Methionine and tryptophan are classified as polar amino acids.

False Signup and view all the answers

What are the three-letter codes for glycine?

GLY Signup and view all the answers

____ amino acids include serine, threonine, cysteine, asparagine, tyrosine, and glutamine.

Polar uncharged Signup and view all the answers

Match the following amino acids with their classification:

Methionine = Non-polar Tryptophan = Aromatic Serine = Polar uncharged Phenylalanine = Aromatic Signup and view all the answers

Which amino acid can undergo phosphorylation?

Serine Signup and view all the answers

Which amino acid is known for forming disulfide bridges due to its SH group?

Cysteine Signup and view all the answers

All aromatic amino acids are polar.

False Signup and view all the answers

Lysine, arginine, and histidine are classified as acidic amino acids.

False Signup and view all the answers

Name one method through which proteins can interact.

Hydrogen bonding Signup and view all the answers

What state do lysine and arginine predominantly adopt at physiological pH?

Conjugate acid form Signup and view all the answers

____ is the amino acid classified with a sulfur atom.

Methionine Signup and view all the answers

Tyrosine is classified as a polar uncharged amino acid and is also known as an ______ amino acid.

aromatic Signup and view all the answers

Which enzyme is known to cut after aromatic amino acids?

Chymotrypsin Signup and view all the answers

Match the following amino acids with their classifications:

Cysteine = Polar amino acid due to SH group Lysine = Basic amino acid Asparagine = Polar uncharged amino acid Tyrosine = Aromatic amino acid Signup and view all the answers

Which amino acid is not considered to be polar due to its structure?

Phenylalanine Signup and view all the answers

What is the monomer that makes up proteins?

Amino acids Signup and view all the answers

The SH group of cysteine is considered to participate in hydrogen bonding in biochemistry.

True Signup and view all the answers

At physiological pH, amino acids exist primarily in their protonated form.

False Signup and view all the answers

What do we call the form that amino acids take at physiological pH?

Zwitter ion Signup and view all the answers

Name two examples of amide group amino acids.

Asparagine and Glutamine Signup and view all the answers

The functional group that generally gives amino acids a basic property is the __________ group.

amine Signup and view all the answers

At pH levels lower than the pKa, basic amino acids will exist primarily in their ______ form.

conjugate acid Signup and view all the answers

Which functional property is directly affected by the presence of positively charged amino acids?

Protein folding Signup and view all the answers

Match the parts of an amino acid with their descriptions:

Amine group = Basic functional group Carboxylic acid group = Acidic functional group Alpha carbon = Central carbon atom Variable group = Determines the identity of the amino acid Signup and view all the answers

What is the charge of the amine group in an amino acid at pH 7?

Positive Signup and view all the answers

Amide linkages form between the amine and carboxylic acid groups when amino acids polymerize.

True Signup and view all the answers

What is the primary structure of a protein?

A linear sequence of amino acids Signup and view all the answers

The backbone of an amino acid consists of __________, alpha carbon, and carbonyl.

amine nitrogen Signup and view all the answers

Which of the following best describes the role of enzymes in biological systems?

Catalyze chemical reactions by lowering activation energy Signup and view all the answers

Study Notes

Peptide Bond Formation and Reactions

Peptide bonds are formed through condensation reactions, which involve the loss of OH and H, resulting in water molecules.
Hydrolysis is the reverse reaction, utilizing water to break peptide bonds, and in the case of proteins, it's termed proteolysis.
Proteolytic enzymes like chymotrypsin and trypsin cleave proteins at specific amino acid sites during digestion.

Structure of Amino Acids

Amino acids consist of an amino group, a carboxylic acid group, and a variable side chain (R group) attached to an alpha carbon.
The general backbone structure of proteins follows a sequence of nitrogen, alpha carbon, carbonyl.

Types of Amino Acids

There are 20 naturally occurring amino acids grouped by characteristics such as polarity and charge:
- Non-polar Amino Acids: Glycine, Alanine, Valine, Leucine, Isoleucine, Methionine, Phenylalanine, Tryptophan (many consist solely of carbons and hydrogens).
- Polar Amino Acids: Serine, Threonine, Cysteine, Asparagine, Glutamine, Tyrosine. Notably, cysteine with SH group can form disulfide bridges.
- Basic Amino Acids: Lysine, Arginine, Histidine are positively charged at physiological pH due to their conjugate acid forms.
- Acidic Amino Acids: Aspartic acid, Glutamic acid, which possess carboxyl groups in their side chains.

Unique Characteristics of Amino Acids

Proline's structure creates a ring, introducing kinks in protein structure.
Cysteine has a sulfhydral group, contributing to disulfide bridges between proteins.
The alpha carbon of amino acids is chiral in 19 of the 20 amino acids; glycine is the only exception as its variable group is a hydrogen.
L-amino acids are primarily used in biological systems; D-amino acids are typically not utilized by living organisms.

Physiological State of Amino Acids

At physiological pH (~7), amino acids exist predominantly as zwitterions; positively charged amine group on one end and negatively charged carboxyl group on the other.

Importance of Amino Acid Groups

Amino acids can be classified based on their side chains affecting protein behavior:
- Polar side chains can form hydrogen bonds, influencing protein structure and function.
- Non-polar side chains tend to be hydrophobic and typically reside within the protein's core.

Enzymatic Recognition and Utilization

Enzymes in biological systems are selective for L-amino acids, underlining the specificity of biological molecules in metabolic processes.

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Description

Test your knowledge on peptide bond formation, hydrolysis, and the structure of amino acids. This quiz covers the reactions involving peptides and the classification of the 20 naturally occurring amino acids. Prepare to dive into the molecular world of proteins and their building blocks.

Biochemistry: Peptide Bond and Amino Acids

Questions and Answers

What type of reaction occurs when peptide bonds are formed?

Proteolysis refers to the process of forming peptide bonds.

What are proteolytic enzymes responsible for in the body?

The unique amino acid that forms a five-membered ring is called ___ .

Match the amino acids with their classifications:

Which of the following amino acids has a simple hydrogen as its variable group?

Hydrolysis requires the consumption of a water molecule.

What is the basic backbone structure of amino acids composed of?

Amino acids can be organized by their properties such as ___, non-polar, acidic, and basic.

Which of the following statements is true regarding the amino acids used by living organisms?

All amino acids are recognized by enzymes in their D form.

What are the two main classifications of amino acids based on their side chains?

Glycine is unique among amino acids because it has a variable ______ group.

Match the following categories of amino acids with their descriptions:

What effect does proline have on protein structure?

Methionine and tryptophan are classified as polar amino acids.

What are the three-letter codes for glycine?

____ amino acids include serine, threonine, cysteine, asparagine, tyrosine, and glutamine.

Match the following amino acids with their classification:

Which amino acid can undergo phosphorylation?

Which amino acid is known for forming disulfide bridges due to its SH group?

All aromatic amino acids are polar.

Lysine, arginine, and histidine are classified as acidic amino acids.

Name one method through which proteins can interact.

What state do lysine and arginine predominantly adopt at physiological pH?

____ is the amino acid classified with a sulfur atom.

Tyrosine is classified as a polar uncharged amino acid and is also known as an ______ amino acid.

Which enzyme is known to cut after aromatic amino acids?

Match the following amino acids with their classifications:

Which amino acid is not considered to be polar due to its structure?

What is the monomer that makes up proteins?

The SH group of cysteine is considered to participate in hydrogen bonding in biochemistry.

At physiological pH, amino acids exist primarily in their protonated form.

What do we call the form that amino acids take at physiological pH?

Name two examples of amide group amino acids.

The functional group that generally gives amino acids a basic property is the __________ group.

At pH levels lower than the pKa, basic amino acids will exist primarily in their ______ form.

Which functional property is directly affected by the presence of positively charged amino acids?

Match the parts of an amino acid with their descriptions:

What is the charge of the amine group in an amino acid at pH 7?

Amide linkages form between the amine and carboxylic acid groups when amino acids polymerize.

What is the primary structure of a protein?

The backbone of an amino acid consists of __________, alpha carbon, and carbonyl.

Which of the following best describes the role of enzymes in biological systems?

Study Notes

Peptide Bond Formation and Reactions

Structure of Amino Acids

Types of Amino Acids

Unique Characteristics of Amino Acids

Physiological State of Amino Acids

Importance of Amino Acid Groups

Enzymatic Recognition and Utilization

Studying That Suits You

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