30 Questions
What is a characteristic of globular proteins?
Compact shape with rounded structure
What type of proteins are myoglobin and hemoglobin?
Conjugated proteins
What is the function of myoglobin?
Oxygen storage in muscle tissue
Where is hemoglobin found in the body?
Erythrocytes
What is the prosthetic group in myoglobin and hemoglobin?
Heme group
What type of structure does myoglobin present?
Tertiary structure
What are the biological functions performed by globular proteins?
Enzymatic, transport, motor, regulatory, and immune functions
What gives the name 'heme proteins' to myoglobin and hemoglobin?
The Heme group
What is the Apoprotein part in myoglobin and hemoglobin?
Amino acid sequence well folded
What is a prosthetic group in proteins?
Something non-proteinic attached to the protein that accomplishes some function
What is the main difference between fibrous proteins and globular proteins?
Fibrous proteins are insoluble in water and have a high concentration of hydrophobic amino acid residues, while globular proteins are soluble in water.
Which protein is a main component of connective tissue and is the most abundant protein in mammals?
Collagen
What is the general structure of the primary chain of collagen?
Gly-X-Y, where X is often Proline, and Y is often 4-Hydroxyproline, repeated multiple times.
What is the consequence of a mutation affecting Collagen type I?
High fragility to bones
What causes Scurvy, a condition characterized by symptoms such as small hemorrhages, tooth loss, and poor wound healing?
Lack of Vitamin C
What is the function of Myosin in muscle cells?
Endogenous cell transport and muscle contraction
What is G-actin considered to be in relation to actin filaments?
The monomer of actin filaments
What forms the core of the contractile unit on muscle cells?
Thick filaments (myosin)
What is the consequence of a lack of Vitamin C in relation to actin filaments and muscle contraction?
General degeneration of connective tissue
What is the main function of thin filaments in muscle cells?
Cell movement and muscle contraction
What is the function of hemoglobin in erythrocytes?
Transport oxygen from lungs to tissues and CO2 from tissues to lungs
What is the quaternary structure of hemoglobin?
Four protein subunits, each containing a prosthetic Heme group
What is the function of the Heme group in hemoglobin?
Allows for the storage and transportation of oxygen
Where is the Heme group positioned in myoglobin?
Within a hydrophobic pocket of the apoprotein
What amino acid residues are well-conserved in myoglobin and hemoglobin?
Proximal Histidine (His F8) and Distal Histidine (His E7)
How many polypeptide chains and heme groups does hemoglobin have?
4 polypeptide chains and 4 heme groups
What type of protein is hemoglobin?
Allosteric protein
How does BPG affect hemoglobin's oxygen binding efficiency?
Decreases hemoglobin's oxygen affinity
What effect do protons and CO2 have on hemoglobin's affinity for oxygen?
Reduce hemoglobin's affinity for oxygen
What is the main function of myoglobin?
Facilitate oxygen storage in muscle tissues
Study Notes
Hemoglobin and Myoglobin: Structure and Function
- Hemoglobin in erythrocytes transports oxygen from lungs to tissues and CO2 from tissues to lungs
- Hemoglobin has a quaternary structure with four protein subunits, each containing a prosthetic Heme group
- The Heme group allows for the storage and transportation of oxygen, containing a complex organic ring structure coordinated with an iron atom in its ferrous state
- Myoglobin and hemoglobin both consist of an apoprotein (proteinic part) and a non-proteinic prosthetic group (Heme group)
- Myoglobin's heme group is positioned within a hydrophobic pocket of the apoprotein, protecting it from oxidation and preventing CO from binding
- Specific well-conserved amino acid residues in myoglobin and hemoglobin include Proximal Histidine (His F8) and Distal Histidine (His E7)
- Hemoglobin is an oligomeric protein with 4 polypeptide chains and 4 heme groups, arranged in symmetric pairs without covalent bonds
- Hemoglobin is an allosteric protein, transitioning between T state (no oxygen binding) and R state (oxygen bound) through T to R transition
- Hemoglobin's oxygen binding efficiency is affected by protons, CO2, and 2,3-biphosphoglycerate (BPG)
- Protons and CO2 reduce hemoglobin's affinity for oxygen, promoting oxygen release to tissues and binding of CO2
- BPG affects physiological adaptation to high altitudes by decreasing hemoglobin's oxygen affinity, leading to faster oxygen release
- Fibrous proteins are adapted for structural functions, conferring strength and flexibility to structures where they are present
Test your knowledge of hemoglobin and myoglobin with this quiz on their structure and function. Explore the intricate details of their roles in transporting oxygen, the impact of specific amino acid residues, the influence of factors like protons, CO2, and BPG on oxygen binding efficiency, and their adaptation to high altitudes.
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