Podcast
Questions and Answers
What is a primary function of the extracellular matrix (ECM)?
What is a primary function of the extracellular matrix (ECM)?
- It supports cell division.
- It regulates gene expression.
- It generates cellular energy.
- It maintains the positional homeostasis of organs. (correct)
Which component is NOT considered a major molecule of the extracellular matrix?
Which component is NOT considered a major molecule of the extracellular matrix?
- Elastin
- Proteoglycans
- Hemoglobin (correct)
- Collagens
How does the structure of the ECM change during development?
How does the structure of the ECM change during development?
- It becomes more rigid and less diverse.
- It remains static and unchanging.
- It avoids any interaction with cells.
- It evolves in response to growth and injury. (correct)
Which of the following is a role of glycosaminoglycans (GAGs) in the ECM?
Which of the following is a role of glycosaminoglycans (GAGs) in the ECM?
What factor primarily determines the variation in the composition of the ECM in different organs?
What factor primarily determines the variation in the composition of the ECM in different organs?
What is a primary characteristic of the extracellular matrix (ECM)?
What is a primary characteristic of the extracellular matrix (ECM)?
Which component contributes significantly to the hydration of the extracellular matrix?
Which component contributes significantly to the hydration of the extracellular matrix?
How does the extracellular matrix change during injury?
How does the extracellular matrix change during injury?
What primarily determines the steady-state levels of ECM components?
What primarily determines the steady-state levels of ECM components?
What type of structure does collagen primarily exhibit?
What type of structure does collagen primarily exhibit?
Which of the following molecules is a major component of the extracellular matrix?
Which of the following molecules is a major component of the extracellular matrix?
What is the approximate size of tropocollagen?
What is the approximate size of tropocollagen?
Which of the following functions is NOT associated with the extracellular matrix?
Which of the following functions is NOT associated with the extracellular matrix?
What is the primary structure of collagen primarily characterized by?
What is the primary structure of collagen primarily characterized by?
Which of the following is NOT a role of glycosaminoglycans (GAGs)?
Which of the following is NOT a role of glycosaminoglycans (GAGs)?
What characteristic of collagen allows it to form a stable triple helix structure?
What characteristic of collagen allows it to form a stable triple helix structure?
Which component is a major part of the basement membrane in the extracellular matrix?
Which component is a major part of the basement membrane in the extracellular matrix?
What is the predominant function of proteoglycans in the extracellular matrix?
What is the predominant function of proteoglycans in the extracellular matrix?
The secondary structure of collagen consists of which configuration?
The secondary structure of collagen consists of which configuration?
Which molecule is known to provide compressive stiffness in the extracellular matrix?
Which molecule is known to provide compressive stiffness in the extracellular matrix?
In the context of ECM components, what regulates the activities of growth factors?
In the context of ECM components, what regulates the activities of growth factors?
Study Notes
The Extracellular Matrix (ECM)
- Insoluble, macromolecular networks
- Determines the shape of animals
- Maintains positional homeostasis of organs
- Structure and chemical makeup varies between organs
- Not static; changes during:
- Development/growth
- Injury
- Disease
Major ECM Molecules
- Collagens
- Elastin
- Proteoglycans and glycosaminoglycans (GAGs)
- Cell adhesion molecules:
- Fibronectin, laminin
- ECM is ~ 65% water
Collagens: Diversity, Structure, Biosynthesis, and Cross-Linking
- Collagens have a unique primary, secondary, and tertiary structure.
- Primary: Gly-X-Y repeat
- Secondary: Left-handed alpha helix
- Tertiary: Right-handed triple helix
Collagen Structure
- Three polypeptide chains (alpha chains) with repeating Gly-X-Y amino acid sequence, staggered by one residue relative to each other
- Individual chains are left-handed helices (~1000 amino acids)
- Three chains are wrapped around each other in a right-handed supercoiled helix
Collagen Biosynthesis
- Prolyl Hydroxylases
- Lysyl Hydroxylases
- Glycosyl Transferases
- Lysyl Oxidase
Tropocollagen, Fibrils and Fibers
- Tropocollagen: ~300 nm
- Fibrils: ~1 µm
- Fibers: ~10 µm
Proteoglycans and Glycosaminoglycans (GAGs)
- GAGs are long repeating disaccharides (unbranched polysaccharides)
- Examples of GAGs:
- Hyaluronan
- Keratan sulfate
- Chondroitin sulfate
- GAGs are negatively charged
- They bind growth factors
- They provide compressive stiffness
- They can be linked to a protein to form proteoglycans (PG)
Laminin
- A major component of basement membranes
ECM Life Cycle
- Secretion
- Activation
- Assembly
- Binding
- Degradation
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Description
Explore the intricate details of the extracellular matrix (ECM) and the crucial role of collagens within it. This quiz focuses on the structure, biosynthesis, and functions of major ECM molecules, as well as the dynamics of ECM changes during development, injury, and disease.
