Protein Structure and Function Quiz
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Questions and Answers

What is the central idea in Biology that explains the relationship between structure and function?

Structure dictates function.

What are the three levels of structure that are shown in the diagram of insulin?

  • Tertiary, quaternary, and pentary
  • Primary, tertiary, and quaternary
  • Primary, secondary, and tertiary
  • Secondary, tertiary, and quaternary (correct)

A single polypeptide can have different functions depending on its level of structure.

True (A)

Which level of structure is the active form of insulin, responsible for controlling blood glucose levels?

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

Which level of biological organization is focused on in Theme B: Form and Function?

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

What are the three key words associated with proteins?

<p>Amino acids, Polypeptide, Protein (C)</p> Signup and view all the answers

All proteins contain only one polypeptide chain.

<p>False (B)</p> Signup and view all the answers

How many different amino acids are used to assemble polypeptides?

<p>20</p> Signup and view all the answers

The sequence of amino acids in a polypeptide is usually random.

<p>False (B)</p> Signup and view all the answers

What is the name of the type of bond that links amino acids together to form polypeptides?

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

What type of chemical reaction is responsible for forming peptide bonds?

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

The R-group of an amino acid influences the formation of the peptide bond.

<p>False (B)</p> Signup and view all the answers

What is the name given to polypeptides that contain fewer than 20 amino acids?

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

Where does the formation of polypeptides occur within a cell?

<p>Ribosomes (B)</p> Signup and view all the answers

Which of the following chemical groups is present at position X in the diagram of the protein?

<p>-COOH (A)</p> Signup and view all the answers

Most plants can synthesize all 20 amino acids.

<p>True (A)</p> Signup and view all the answers

Animals obtain their essential amino acids from which source?

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

What are the two main types of amino acids based on their dietary requirements?

<p>Essential and non-essential (D)</p> Signup and view all the answers

What is the term used to describe the condition that occurs when the body does not receive enough essential amino acids from the diet?

<p>Protein deficiency malnutrition</p> Signup and view all the answers

Vegan diets cannot provide all the essential amino acids needed for a healthy diet.

<p>False (B)</p> Signup and view all the answers

What cellular component is responsible for linking amino acids together during protein synthesis?

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

What is the name given to the complete set of proteins produced by a cell, tissue or organism?

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

The proteome of an individual remains constant throughout their lifetime.

<p>False (B)</p> Signup and view all the answers

The proteome of identical twins is always identical.

<p>False (B)</p> Signup and view all the answers

Which technique is used to separate and identify proteins extracted from a tissue?

<p>Electrophoresis (B)</p> Signup and view all the answers

What is the name of the natural pain killer that is a polypeptide of 31 amino acids?

<p>Beta-endorphin</p> Signup and view all the answers

The enzyme alpha amylase can only break down a small amount of starch before it is fully digested

<p>False (B)</p> Signup and view all the answers

What is the name of the largest polypeptide discovered so far?

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

What type of protein is collagen?

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

Collagen makes up about 25% of the total protein in the human body.

<p>True (A)</p> Signup and view all the answers

What is the term used to describe the three-dimensional structure of a protein?

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

What factor determines the conformation of a protein?

<p>Primary structure (C)</p> Signup and view all the answers

What is the term used to describe the process that alters the conformation of a protein, often making it lose its function?

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

Denaturation is a reversible process for all proteins.

<p>False (B)</p> Signup and view all the answers

What can cause denaturation of proteins?

<p>Extremes of pH or Heat</p> Signup and view all the answers

Proteins are all equally sensitive to changes in temperature.

<p>False (B)</p> Signup and view all the answers

What is the name of the protein-digesting enzyme that functions optimally in the acidic environment of the stomach?

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

What is the purpose of using a colorimeter in an experiment?

<p>To measure the amount of light that passes through a sample (C)</p> Signup and view all the answers

A colorimeter can be used to quantify the extent of denaturation of a protein.

<p>True (A)</p> Signup and view all the answers

What is the name given to polypeptides or proteins that are less than 20 amino acids long?

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

The amino acid sequence of a polypeptide determines its three-dimensional structure.

<p>True (A)</p> Signup and view all the answers

Proteins that experience denaturation always return to their original structure once the denaturing conditions are removed.

<p>False (B)</p> Signup and view all the answers

The proteome of an individual is fixed and does not change throughout their lifetime.

<p>False (B)</p> Signup and view all the answers

What is the name of the technique used to identify and characterize the total set of proteins produced by a cell or organism?

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

Flashcards

Amino Acid

The fundamental building block of proteins.

Protein

A molecule composed of one or more polypeptide chains.

Polypeptide

A chain of amino acids linked together.

Generalized Structure of an Amino Acid

Central carbon (alpha carbon) bonded to an amine group (-NH2), a carboxyl group (-COOH), a hydrogen atom, and an R-group.

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R-group

The variable part of an amino acid; gives each amino acid its unique properties.

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Condensation Reaction

A reaction that joins two amino acids together, releasing a water molecule.

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Dipeptide

Two amino acids joined together by a peptide bond.

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Peptide Bond

The covalent bond that forms between two amino acids in a condensation reaction.

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Dietary Requirements for Amino Acids

Essential amino acids must be obtained from the diet, as the body cannot synthesize them.

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Infinite Variety of Possible Peptide Chains

The immense number of possible sequences of amino acids in a polypeptide chain.

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Effect of pH on Protein Structure

Changes in pH can disrupt the hydrogen bonds and ionic interactions stabilizing the protein's structure.

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Effect of Temperature on Protein Structure

High temperatures can break the weak bonds holding protein structure together.

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Chemical Diversity in R-groups

The differing chemical properties of R-groups create a vast array of protein shapes and functions.

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Primary Structure

The specific sequence of amino acids in a polypeptide chain.

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Secondary Structure

Local folding of the polypeptide chain.

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Tertiary Structure

The overall 3D shape of a polypeptide chain.

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Quaternary Structure

The arrangement of multiple polypeptide chains in a protein.

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Globular Proteins

Compact, spherical proteins typically involved in metabolic reactions or transport.

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Fibrous Proteins

Long, structural proteins like collagen and keratin.

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Hydrogen Bonds

Weak bonds between hydrogen and electronegative atoms that stabilize protein structure.

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Ionic Bonds

Chemical bonds between oppositely charged ions in proteins.

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Disulfide Covalent Bonds

Strong bonds between sulfur atoms in protein chains.

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Hydrophobic Interactions

Forces that drive non-polar amino acids to cluster together in protein interiors.

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Study Notes

Protein Structure and Function

  • Proteins are essential for numerous functions in living organisms.
  • Structure dictates function. Analyzing the structure of insulin at the secondary, tertiary, and quaternary levels reveals the importance of polypeptide variation.
  • Polypeptides have different amino acid combinations, leading to diverse properties and functions.
  • Even a single polypeptide's function is affected by its structure, hence, the level of protein structure is crucial.
  • The tertiary structure of insulin controls blood glucose levels. Other forms exist, but the active form is tertiary.

Amino Acids

  • Amino acids are the building blocks of proteins.
  • Each amino acid has a central carbon atom (alpha carbon) bonded to four groups: an amine group (-NH2), a carboxyl group (-COOH), a hydrogen atom (H), and a variable R-group.
  • The R-group differentiates the 20 different amino acids in terms of chemical properties.

Peptide Bonds

  • Peptide bonds form between the carboxyl group of one amino acid and the amine group of another amino acid.
  • This is a condensation reaction, resulting in the loss of water.
  • Several amino acids can be joined to form chains : dipeptides, oligopeptides and polypeptides.
  • Polypeptides have variable lengths – a single polypeptide chain, or multiple polypeptide chains.

Protein Folding

  • After amino acids are bonded, the polypeptide chain folds into its three-dimensional structure.
  • This shape determines the protein's function.
  • The bonds and interactions within the R-groups influence the folding and shape.

Factors Affecting Protein Function

  • pH and temperature can affect protein structure and denature a protein.
  • Denaturation is the disruption of the protein's three-dimensional structure, affecting function.
  • Denatured proteins may not return to their normal shape.

Polypeptide Variety

  • The sequence of amino acids in a polypeptide is central to its function and structure.
  • The number of different amino acid sequences is theoretically infinite because of the enormous diversity possible in lengths and orders of amino acids.
  • Proteins are much longer than words that use our alphabet; they contain hundreds or thousands of amino acids.
  • Only a fraction of possible sequences are produced in an organism. The complete set of proteins produced by an organism is its proteome.

Determining the Proteome

  • Different cells in the same organism produce different proteins at different times, based on their needs.
  • The proteome of two people varies, except for identical twins. The proteomes of identical twins may change over time.
  • Scientists use tools like electrophoresis to separate and identify proteins to characterize the proteome. Determining the proteome helps to understand the current state of cellular activity and functions within an organism.

Essential and Non-Essential Amino Acids

  • Humans need 20 amino acids to build proteins, but only 9 are "essential," meaning they cannot be synthesized by the body.
  • The body needs amino acids from food; these essential amino acids are needed for growth, maintenance, and repair of tissue and organs.
  • Deficiency can lead to malnutrition and disease.
  • Non-essential amino acids can be produced by the organism.
  • Some amino acids might be essential during specific stages of growth or conditions.

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Test your knowledge on protein structure and function, focusing on the role and significance of polypeptides and amino acids. Explore how the structure of proteins like insulin affects their function in biological systems, and understand the importance of peptide bonds in protein formation.

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