General Biochemistry I - Proteins Quiz
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Questions and Answers

What is the name of the course in which topics like proteins and their functions are studied?

BCH 201: General Biochemistry I

Who is the instructor for the first seven weeks of the course?

Dr. Adedeji Nelson Ademakinwa

Where is the course held?

PFA

What are proteins composed of?

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

What is the primary sequence of amino acids critical for?

<p>correct folding of the protein into its functional native structure</p> Signup and view all the answers

The human body naturally stores proteins in large amounts.

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

Which of the following is NOT a biological function of proteins?

<p>Energy storage (D)</p> Signup and view all the answers

Match the types of proteins with their respective examples:

<p>Collagens = Bones, tendons, cartilage Elastins = Lungs, ligaments Keratins = Hair, feathers, horns, nails Myosins = Muscle tissue</p> Signup and view all the answers

Which of the following categories of proteins are water-soluble and generally 'reactive'?

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

Proteins are linear heteropolymers of alpha-amino acids.

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

Which of these properties are NOT associated with amino acids?

<p>Lack of chemical functionality (E)</p> Signup and view all the answers

Which of the following amino acids is considered non-essential?

<p>Alanine (D)</p> Signup and view all the answers

Which of these is NOT an essential amino acid?

<p>Glutamine (E)</p> Signup and view all the answers

All naturally occurring alpha-amino acids are chiral, except for the amino acid glycine.

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

The common name of amino acids often ends in what?

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

Which of the following amino acids is classified as aromatic?

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

Common amino acids can be categorized into four main groups based on their R substituents.

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

What is the term used to describe the interaction or attraction between molecules of the same kind?

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

What is the term used to describe the interaction or attraction between molecules of different kinds?

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

Which amino acid has a sulfhydryl group in its R-group?

<p>Cysteine (D)</p> Signup and view all the answers

Which of these amino acids is classified as acidic?

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

Which amino acid has a guanidino group in its R-group?

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

What is the term used to describe molecules that can act as both an acid and a base?

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

Amino acids exist in a zwitterionic form at neutral pH.

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

What is the term used to describe the pH at which a protein or amino acid carries no net electrical charge?

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

Which of the following amino acids has the highest isoelectric point?

<p>Lysine (E)</p> Signup and view all the answers

Amino acids can act as buffers in solution.

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

The pKa of the carboxyl group of an amino acid is typically higher than the pKa of the amino group.

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

The pKa values of the amino and carboxyl groups in amino acids are constant, irrespective of the specific amino acid.

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

What is the term used to describe the covalent bond that links amino acids together in a polypeptide chain?

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

Peptide bonds are formed through hydrolysis.

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

How many different naturally occurring amino acids are commonly found in proteins?

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

What is the general term used for chains of amino acids, regardless of length?

<p>Polypeptides (E)</p> Signup and view all the answers

Which of the following is an example of a polypeptide?

<p>All of the above (E)</p> Signup and view all the answers

The N-terminus of a polypeptide is always the same.

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

Which of the following is the appropriate three-letter code for the amino acid glycine?

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

What is the chemical reagent commonly used to detect amino acids?

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

When ninhydrin reacts with proline, a yellow-orange product is formed.

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

Ninhydrin reacts with all amino acids, forming a purple color.

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

One method to identify amino acids is by using ion-exchange chromatography, which separates amino acids based on their differences in polarity.

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

The carboxyl group of an amino acid can react with an alkali to form a carboxylate ion.

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

The reaction of an amino acid with an alcohol produces an amine.

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

What is the name of the reagent that reacts with alpha-amino acids to produce a yellow-coloured derivative?

<p>Sanger's reagent</p> Signup and view all the answers

Sanger's reagent is used for breaking peptide bonds.

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

Study Notes

General Biochemistry I - BCH 201

  • Course taught by Dr. Adedeji Nelson Ademakinwa in Deanry, Room 46 (Floor One)
  • Course held in PFA 9-11 on Tuesdays
  • Course outline includes topics like introduction, proteins, amino acids, enzymes, carbohydrates, nucleic acids, buffers, and metabolism studied across weeks 1-11.
  • Specific lecturers for each topic are mentioned in the outline.

Proteins

  • Proteins are naturally occurring biopolymers composed of amino acids.
  • The function of a protein is determined by its three-dimensional structure.
  • The primary sequence (order of amino acids) contains all information required for correct folding into a functional protein.
  • Amino acid properties influence protein folding and function.
  • Average adult contains ~10kg of protein; ~300g is replaced daily by recycling and intake.
  • Daily protein intake varies with age, size, and energy demand (infants: 1.8g/kg/day; children: 1.0g/kg/day; adults: 0.8g/kg/day) and dietary needs. Daily intake is also associated with a ~15% of daily caloric intake.
  • Proteins are not stored in significant amounts in the body and are constantly broken down and rebuilt to get major N-source.
  • Proteins lost include urine, fecal material, sweat, hair/nails, and skin.
  • Protein functions include catalysis (e.g., enolase, DNA polymerase), transport (e.g., hemoglobin, lactose permease), structure (e.g., collagen, keratin), and motion (e.g., myosin, actin).
  • Proteins can be classified as simple (fibrous, insoluble, structural, like hair and horn, and globular, soluble, reactive, like enzymes) or conjugated (lipo-, glyco-, hemo-).
  • Examples of fiborous proteins include collagens (bones, tendons, cartilage), elastins (lungs, ligaments), keratins (hair, nails, feathers, horns) and myosins (muscles).
  • Examples of globular proteins include albumins (egg whites) and globulins (antibodies, enzymes).

Amino Acids

  • Amino acids are the building blocks of proteins.

  • They are linear heteropolymers of α-amino acids.

  • Key properties include: capacity to polymerize, useful acid-base properties, and varied physical/chemical properties including functionality.

  • Essential amino acids (10) are needed in our diet: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine (and arginine in infants).

  • Non-essential amino acids (10) can be synthesized in the body.

  • Amino acids are organized into groups by R substituents (nonpolar, aliphatic, aromatic, polar, uncharged, positively charged, negatively charged).

  • A list of 20 major amino acids, their one and three-letter codes, and their categories is provided alongside their respective chemical structures and examples.

  • Each amino acid has a carboxyl group (-COOH) and an amino group (-NH2), which are attached to a central carbon atom (α-carbon).

  • All naturally-occurring amino acids (except glycine) are chiral and are L-stereoisomers.

  • Amino acids vary in size, structure, electric charge, and solubility in water

  • Amino acids can act as buffers due to multiple pKa values (e.g. the a-carboxyl group with pKa ~2.3 and the a-amino group with pKa ~9.6) allowing variations in the peptide's net charge at various pH levels.

  • Ionizable side chains in amino acids, such as histidine, influence the pI of the protein and these side chains can be titrated.

  • Acid/base properties and ionization/titration processes are described including the different forms an amino acid may exist (cation, anion, or zwitterion) and their respective pKa values.

Peptides

  • Peptides are short chains of amino acids.
  • Formed via condensation reactions.
  • Broken by hydrolysis.
  • Can perform various functions (hormones, pheromones, neuropeptides, antibiotics, toxins, etc.).
  • Peptides are named from N-terminal to C-terminal, using abbreviated names/full amino acid names.
  • Techniques for amino acid analysis and peptide chemistry are described such as acid hydrolysis of peptides (6M HCl, 24hrs), separation by ion-exchange chromatography, detection by ninhydrin, and automated methods.

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BCH 201 General Biochemistry I Lecture One PDF

Description

Test your knowledge on proteins and their functions as part of the General Biochemistry I course. This quiz covers protein structure, amino acids, and the role of proteins in metabolism based on the course outline. Explore essential concepts about protein folding, dietary intake, and the significance of amino acid properties.

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