Protein Classification and Function
38 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which characteristic is true of fibrous proteins?

  • They primarily perform regulatory functions.
  • They are mainly involved in transport.
  • They catalyze biological reactions.
  • They provide mechanical properties and support. (correct)

What defines globular proteins?

  • They have a compact, spherical shape and often perform various functions. (correct)
  • They are particularly rigid and inflexible.
  • They consist only of basic amino acids.
  • They are primarily involved in structural support.

Which of the following statements differentiates keratin from collagen?

  • Keratin has regulatory functions, whereas collagen catalyzes reactions.
  • Both keratin and collagen are globular proteins.
  • Keratin provides support while collagen is involved in transport.
  • Keratin is a fibrous protein, mainly found in hair and nails, while collagen is found in connective tissues. (correct)

Which protein category includes molecules other than amino acids?

<p>Conjugated proteins. (D)</p> Signup and view all the answers

What function does myoglobin primarily serve?

<p>It stores and transports oxygen in muscle tissues. (B)</p> Signup and view all the answers

What is the primary characteristic of fibrous proteins?

<p>Not soluble in water (C)</p> Signup and view all the answers

Which of the following proteins is classified as mesenchymal?

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

What role do disulfide bonds play in keratin?

<p>Provide structural integrity (C)</p> Signup and view all the answers

How does the cysteine content in hair keratin affect its properties?

<p>More cysteine increases hardness (C)</p> Signup and view all the answers

What percentage of total protein does collagen constitute in the human body?

<p>30% (C)</p> Signup and view all the answers

What primary function does myoglobin serve in the human body?

<p>Storage of oxygen in muscles (D)</p> Signup and view all the answers

What structural feature allows hemoglobin to bind up to four molecules of oxygen?

<p>Quaternary structure formed by four polypeptide chains (B)</p> Signup and view all the answers

Which characteristic distinguishes globulins from albumins?

<p>Globulins consist of immunoglobulins, among other types (D)</p> Signup and view all the answers

What role does the heme pocket in hemoglobin play?

<p>Prevents water from interfering with oxygen binding (A)</p> Signup and view all the answers

Which function is least associated with the albumin protein family?

<p>Carrying oxygen in the bloodstream (B)</p> Signup and view all the answers

What is the composition of adult hemoglobin HbA?

<p>2 α-like and 2 β-like subunits (B)</p> Signup and view all the answers

In which state does hemoglobin have a low affinity for oxygen?

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

Which of the following hemoglobins is associated with fetal development?

<p>Hb Gower 1 (B)</p> Signup and view all the answers

How does the glycosylation ratio of hemoglobin relate to glucose concentration?

<p>It increases as glucose concentration increases. (B)</p> Signup and view all the answers

What happens when O2 is released from hemoglobin?

<p>Hemoglobin can bind both CO2 and hydrogen. (B)</p> Signup and view all the answers

What type of cross-links are present in elastin?

<p>Desmosin and Lysine-Norleucine cross-links (B)</p> Signup and view all the answers

How does collagen differ structurally from elastin?

<p>Collagen forms a triple helix. (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of silk fibroin?

<p>It possesses multiple strong covalent bonds. (B)</p> Signup and view all the answers

What is a common feature of globular proteins?

<p>High solubility in water. (B)</p> Signup and view all the answers

What is the presence of hydroxylysine in collagen indicative of?

<p>Increased mechanical strength. (B)</p> Signup and view all the answers

In the context of elastin, what does the term 'random coils' refer to?

<p>The flexible nature that provides elasticity. (C)</p> Signup and view all the answers

Which type of modification is present in elastin but absent in collagen?

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

What governs the stability of silk fibroin?

<p>Weak bonds like hydrogen and van der Waals (A)</p> Signup and view all the answers

Which of the following is a feature of collagen?

<p>It is composed of elongated peptides during biosynthesis. (D)</p> Signup and view all the answers

Which amino acid is in high concentration in silk fibroin?

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

What causes the decrease in oxygen affinity in hemoglobin in response to increased carbon dioxide concentration?

<p>Higher carbon dioxide concentrations lower the pH. (C)</p> Signup and view all the answers

What role does 2,3-BPG play in the oxygen transport process?

<p>It binds to hemoglobin and decreases oxygen affinity. (A)</p> Signup and view all the answers

Why is 2,3-BPG important for transfused blood?

<p>It ensures oxygen can be released to tissues. (C)</p> Signup and view all the answers

What is one consequence of a decrease in pH on the hemoglobin dissociation curve?

<p>The curve shifts to the right. (A)</p> Signup and view all the answers

What happens to 2,3-BPG during the storage of blood for transfusion?

<p>It is degraded and may be lost. (A)</p> Signup and view all the answers

Which of the following explains the chloride shift in relation to carbon dioxide transport?

<p>Chloride ions move into red blood cells to balance bicarbonate. (C)</p> Signup and view all the answers

What is the primary consequence of carbon monoxide exposure on hemoglobin?

<p>It forms a stable complex with hemoglobin, reducing oxygen transport. (D)</p> Signup and view all the answers

In the presence of 2,3-BPG, how does hemoglobin's affinity for oxygen change?

<p>Affinity decreases, promoting oxygen release in the tissues. (C)</p> Signup and view all the answers

Flashcards

Protein Classification

Proteins are categorized based on their shape or composition.

Fibrous proteins

Structural proteins with elongated shapes, providing support and protection.

Globular proteins

Proteins with complex shapes, crucial for regulation, catalysis, and transport.

Simple proteins

Proteins composed only of amino acids.

Signup and view all the flashcards

Conjugated proteins

Proteins containing non-amino acid components (metals, lipids, carbohydrates).

Signup and view all the flashcards

Apoprotein

The protein part of a conjugated protein.

Signup and view all the flashcards

Heteroproteins

Another name for conjugated proteins, which contain additional non-protein components besides amino acids.

Signup and view all the flashcards

Scleroproteins

A type of fibrous protein that is insoluble in water, cannot be digested, and is resistant to heat.

Signup and view all the flashcards

Collagen: Structure

Collagen consists of three polypeptide chains intertwined in a triple helix.

Signup and view all the flashcards

Collagen: Function

Provides structural support in tissues like skin, bones, tendons, and ligaments.

Signup and view all the flashcards

Albumin

The most common protein in blood plasma; carries ions, hormones, fatty acids, and other molecules.

Signup and view all the flashcards

Globulin

A type of protein, larger than albumin, less soluble in water, categorized into alpha, beta, and gamma classes.

Signup and view all the flashcards

Immunoglobulin

A type of gamma globulin, responsible for immune defense; also known as antibodies.

Signup and view all the flashcards

Heme

A molecule containing a porphyrin ring with a central iron atom, essential for oxygen binding in proteins.

Signup and view all the flashcards

Myoglobin: Function

A muscle protein that binds and stores oxygen, enabling muscles to function even during intense activity.

Signup and view all the flashcards

Elastin Cross-links

Elastin has unique cross-links, Desmosine and Lysine-Norleucine, that contribute to its elasticity and resilience. These cross-links are formed from four lysine residues.

Signup and view all the flashcards

Collagen vs. Elastin: Genetic Types

Collagen has multiple genetic types (different genes code for different collagen types), while elastin is encoded by a single gene.

Signup and view all the flashcards

Collagen vs. Elastin: Structure

Collagen forms a triple helix structure with repeating (Gly-X-Y)n sequences, while elastin has a random coil structure with no structured repeats.

Signup and view all the flashcards

Collagen vs. Elastin: Hydroxylysine

Hydroxylysine is present in collagen but absent in elastin.

Signup and view all the flashcards

Collagen vs. Elastin: Carbohydrate Modification

Collagen has carbohydrate modifications, while elastin does not.

Signup and view all the flashcards

Collagen vs. Elastin: Cross-links

Collagen has aldol cross-links, while elastin has Desmosine and Lysine-Norleucine cross-links.

Signup and view all the flashcards

Collagen vs. Elastin: Biosynthesis

Collagen forms elongated peptides (tails) during biosynthesis, while elastin does not add extra parts during biosynthesis.

Signup and view all the flashcards

Silk Fibroin: Structure

Silk fibroin is composed of a β-pleated sheet structure, with nearly half of its amino acids being glycine.

Signup and view all the flashcards

Silk Fibroin: R Groups

In silk fibroin, the R groups of alanine and serine are placed opposite to the R group of glycine in the β-pleated sheet.

Signup and view all the flashcards

Silk Fibroin: Stability

Silk fibroin's structure is stabilized by many weak bonds, including hydrogen bonds and van der Waals forces.

Signup and view all the flashcards

Hb Gower 1

An embryonic hemoglobin (Hb) type found in the yolk sac, composed of two ζ and two ε subunits. It's the earliest form of Hb during development.

Signup and view all the flashcards

HbF (Fetal Hemoglobin)

The main type of Hb in fetal development, composed of two α and two γ subunits. It binds oxygen more strongly than adult Hb.

Signup and view all the flashcards

HbA (Adult Hemoglobin)

The main type of Hb in adults, composed of two α and two β subunits.

Signup and view all the flashcards

HbA2 (Minor Adult Hemoglobin)

A minor type of Hb in adults, composed of two α and two δ subunits.

Signup and view all the flashcards

DeoxyHb vs. OxyHb

Deoxyhemoglobin (DeoxyHb) is the form of Hb without bound oxygen, while Oxyhemoglobin (OxyHb) is the form with bound oxygen. DeoxyHb adopts a tense (T) state with low O2 affinity, while OxyHb is in a relaxed (R) state with high O2 affinity.

Signup and view all the flashcards

Bohr Effect

A phenomenon where the oxygen affinity of hemoglobin decreases in response to a lower blood pH caused by increased carbon dioxide concentration.

Signup and view all the flashcards

Carbonic anhydrase

An enzyme that catalyzes the reversible conversion of carbon dioxide and water into carbonic acid (H2CO3). This reaction plays a crucial role in the transport of CO2 in blood.

Signup and view all the flashcards

Chloride shift

The movement of chloride ions (Cl-) from plasma into red blood cells to maintain electrical neutrality during the transport of bicarbonate ions (HCO3-) out of the red blood cells.

Signup and view all the flashcards

How does the Bohr Effect affect oxygen delivery?

The Bohr Effect causes hemoglobin to release more oxygen in tissues with higher carbon dioxide concentrations and lower pH. This ensures efficient oxygen delivery to active tissues needing it most.

Signup and view all the flashcards

2,3-BPG

2,3-bisphosphoglycerate is a molecule produced during glycolysis. It binds to hemoglobin, decreasing its oxygen affinity and promoting oxygen release in tissues.

Signup and view all the flashcards

Why is 2,3-BPG important in transfused blood?

Transfused blood may lack 2,3-BPG due to degradation. This can hinder oxygen release to tissues. Adding 2,3-BPG to the blood before transfusion helps restore normal oxygen delivery.

Signup and view all the flashcards

HbO2 dissociation curve shift

The HbO2 dissociation curve shifts to the right in lower pH environments. This indicates a lower oxygen affinity of hemoglobin, reflecting the Bohr Effect.

Signup and view all the flashcards

Carbon monoxide poisoning

Carbon monoxide binds to hemoglobin with a much higher affinity than oxygen, preventing oxygen transport and leading to tissue hypoxia.

Signup and view all the flashcards

Study Notes

Protein Classification and Function

  • Proteins are classified based on shape (structural) and composition.
  • Structural proteins have shapes determined by their amino acid sequence.
  • Fibrous proteins provide structural support, shape, and mechanical properties. Examples include keratin, collagen, elastin, silk fibroin, and muscle proteins (tropomyosin, myosin).
  • Globular proteins are typically round and soluble in water. Functions include regulation, catalytic activity, transport, and form hormones and receptors.
  • Compositional classification divides proteins into simple and conjugated.
  • Simple proteins are composed solely of amino acids (homoproteins).
  • Conjugated proteins contain non-amino acid components (heteroproteins). These components include metals (metalloproteins), lipids (lipoproteins), carbohydrates (glycoproteins), etc.
  • Some conjugated proteins have prosthetic groups; these are non-amino acid parts.

Learning Objectives

  • Classify proteins based on shape and composition.
  • Describe the structural properties of fibrous proteins.
  • Explain the structural differences among keratin, collagen, and elastin.
  • Define globular proteins and their structural properties.
  • Explain the structure and function of myoglobin and its oxygen saturation.
  • Explain the structure and function of hemoglobin and its oxygen saturation.

Fibrous Proteins

  • Scleroproteins are insoluble in water, not digestible, and resistant to heat (thermostable).
  • They provide mechanical strength, like in hair, nails, horns, and connective tissues. Keratin, collagen, and elastin are examples.
  • Collagen forms the triple helix structure, giving strength and flexibility to connective tissues.
  • Elastin is crucial in tissues that need elasticity, providing recovery after being stretched.
  • Silk fibroin contains amino acids glycine and alanine, forming a β-sheet structure. It provides flexibility and strength.
  • Muscle proteins like tropomyosin and myosin are fibrous proteins supporting movement.

Classification of Proteins

  • Structural (shape): Fibrous (supports cell shape, protective roles, mechanical properties) vs. Globular (regulation, catalytic activity, transport, hormones, receptors).
  • Composition: Simple (only amino acids) vs. Conjugated (non-amino acid components).

Keratin

  • Keratin structure consists of α-helices, coiled to form fibers.
  • Cysteine content affects keratin's properties (e.g., hardness).
  • Disulfide bonds contribute to keratin's insolubility.
  • Cysteine is lower in skin keratin compared to hair or nails.

Collagen

  • Collagen is ~30% of total body protein and 6% of body weight.
  • There are varying types with different functions.
  • Physical properties (elasticity, hardness) depend on the collagen type.
  • Collagen's structure includes a triple helix and hydroxyproline (Hyp).
  • Collagen is a critical component of connective tissues.

Elastin

  • Elastin provides durability and flexibility, found in skin, blood vessels, and lungs.
  • Elastin is a hydrophobic protein, rich in glycine, alanine, and lysine, and has small amounts of hydroxyproline, but no hydroxylysine.
  • Cross-linking is crucial for elastin's elasticity, via Lysyl oxidase.

Silk Fibroin

  • Silk fibroin forms a β-sheet structure made from amino acids glycine and alanine.
  • The β-sheet structure contributes to its strength and flexibility.
  • Many weak bonds (hydrogen and van der Waals) contribute to silk's stability.

Globular Proteins

  • High solubility in water.
  • Mostly conjugated (bound with different molecules besides amino acids).
  • Diverse functions (catalysis, transport, storage, gene regulation, immunity).
  • Examples include albumins and globulins, myoglobin, and hemoglobin.

Albumins

  • Common in blood, ~50% of the plasma proteins.
  • Transport substances like hormones, fatty acids, and ions.
  • They connect between substances and send signals.

Globulins

  • Larger than albumins, less soluble in water.
  • Three major classes: alpha, beta, and gamma globulins.
  • Gamma globulins include antibodies, critical for the immune system.

Globin (Globulin subclass)

  • Contains a heme group—a ferrous iron atom connected to a porphyrin ring.
  • Has oxygen-binding properties.
  • Examples: Myoglobin and Hemoglobin.

Myoglobin

  • Single polypeptide, stores oxygen in muscles.
  • Binds oxygen even at low concentrations.
  • Single polypeptide chain.

Hemoglobin

  • Four polypeptide chains (2 alpha, 2 beta), carries oxygen in the blood.
  • Binds oxygen at high concentrations and releases it at low concentrations.
  • Can bind CO2 and hydrogen.
  • 4 heme groups can bind 4 oxygen molecules.

Hemoglobin Types

  • Different types of hemoglobin exist including HbA, HbA2, HbF. These exist in different concentrations at different stages of life.

Glycosylated Hemoglobin (HbA1c)

  • Glycosylation ratio is dependent on blood glucose concentration.
  • Indicator of diabetes control

2,3-BPG binding to Hemoglobin

  • 2,3-BPG is a side product of glycolysis.
  • It binds to hemoglobin and decreases its affinity for oxygen, promoting oxygen release in tissues.
  • Affects the Hb oxygen dissociation curve.

Carbon Monoxide

  • A toxicant, binds to heme's iron, reducing blood's oxygen-carrying capacity.
  • The binding is highly reversible, which allows for treatments to restore the oxygen-binding capacity of hemoglobin

Bohr Effect

  • CO2 and H+ levels affect hemoglobin's oxygen-binding affinity.
  • When CO2 increases, the affinity decreases (Bohr effect).

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Protein Classification and Function PDF

Description

This quiz explores the classification of proteins based on their shape and composition. You'll learn about structural and globular proteins, as well as the differences between simple and conjugated proteins. Test your knowledge on examples and functions of various protein types.

More Like This

Protein Classification Quiz
10 questions

Protein Classification Quiz

HandySeal avatar
HandySeal
COVID-19 Structure and Proteins Quiz
6 questions

COVID-19 Structure and Proteins Quiz

EasyToUseAsh avatar
EasyToUseAsh
Protein Classification and Structure
12 questions

Protein Classification and Structure

VictoriousHarpy567 avatar
VictoriousHarpy567
Biology: Proteins in Biological Systems
22 questions

Biology: Proteins in Biological Systems

ExcitingUvarovite6019 avatar
ExcitingUvarovite6019
Use Quizgecko on...
Browser
Open
Browser
Browser