60 Questions
What is the diameter of microtubules?
25 nm
What is the function of intermediate filaments?
All of the above
What type of junction forms a virtually impermeable barrier between cells?
Tight junction
What type of molecule connects cells through their intermediate filaments?
Cadherin
What is the main function of the extracellular matrix?
Provide structure and mechanical support for tissues
What is the most abundant protein in the human body?
Collagen
What is the function of proteoglycans in the ECM?
Lubricate the ECM
What type of molecule acts as a matrix receptor?
Integrin
What type of structure connects cells to basement membranes?
Hemidesmosome
What is the diameter of actin filaments?
8-12 nm
Approximately how many cells are found in the human body?
Ten trillion
What is the primary function of the infrastructure holding cells together?
To cope with stress and changing environments
What is the diameter of actin filaments?
5-9 nanometers
What is the characteristic of microtubules?
They are hollow cylinders
What is the function of intermediate filaments?
To provide mechanical strength to the cell
What is the characteristic of the cytoskeleton?
It is extremely dynamic and constantly re-organising
What happens to actin filaments as a cell senses its environment?
They extend and contract constantly
What is the diameter of intermediate filaments?
8-12 nm
What is the function of the nuclear lamina?
To anchor chromosomes and the nuclear pore complex
What happens to the entire actin network as cells move?
It is remodelled extremely rapidly
What is the primary function of tight junctions between cells?
To form a virtually impermeable barrier
What is the role of cadherins in cell-cell interactions?
To recognize and connect identical cells
What is the composition of the extracellular matrix (ECM)?
A mixture of molecules secreted by cells
What is the primary function of integrins in the cell-ECM interaction?
To connect cells to the ECM and transmit signals
What is the role of hemidesmosomes in the cell-ECM interaction?
To connect the ECM to intermediate filaments in the cell
What is the diameter of individual actin filaments?
5-9 nm
What is the major structural protein in the human body?
Collagen
What is the function of proteoglycans in the ECM?
To lubricate the ECM
What is the role of desmosomes in the cell-cell interaction?
To connect intermediate filaments between cells
What is the primary function of the cytoskeleton in the cell?
To provide structural support and shape
What is the primary purpose of the connection between cadherins and the actin cytoskeleton?
To allow recognition and connection between similar cells
What is the role of fibronectin in the ECM?
To facilitate cell adhesion to the ECM
What is the function of the extracellular matrix in the body?
To provide structural support to cells and tissues
What is the characteristics of the cytoskeleton that allows cells to rapidly change shape?
Dynamic nature
What is the function of hemidesmosomes in the cell-ECM interaction?
To connect cells to the ECM
What is the role of proteoglycans in the ECM?
To modify the activity and stability of other ECM molecules
What is the characteristic of collagen that makes it a major structural protein?
Its ability to form molecular cables that strengthen tendons and bones
What is the primary function of tight junctions between cells?
To form a virtually impermeable barrier between cells
What is the role of integrins in the cell-ECM interaction?
To connect the cell to the ECM and transmit signals
What is the function of desmosomes in cell-cell interactions?
To connect cells through their intermediate filaments
What is the primary function of the infrastructure that holds cells together in multicellular organisms?
To maintain tissue and organ structure and function
What is the characteristic of actin filaments that allows them to cope with stress and changing environments?
Their ability to be bundled together into thicker filaments
What is the primary function of the cytoskeleton in maintaining cell structure and function?
To provide mechanical support and shape to the cell
What is the characteristic of microtubules that distinguishes them from actin filaments?
Their larger diameter and hollow cylindrical structure
What is the role of intermediate filaments in maintaining tissue and organ structure?
To connect cells together in tissues
What is the dynamic characteristic of the cytoskeleton that allows it to adapt to changing cellular environments?
Its constant re-organisation and remodelling
What is the primary function of the nuclear lamina in maintaining cell structure and function?
To anchor chromosomes and the nuclear pore complex
What is the characteristic of the infrastructure that holds cells together in multicellular organisms that allows it to cope with stress and changing environments?
Its ability to be malleable and adapt to changing environments
What is the role of actin filaments in maintaining cell structure and function?
To extend and contract in response to environmental changes
What is the characteristic of the cytoskeleton that allows it to respond to changes in the cellular environment?
Its ability to reorganise and remodel in response to environmental changes
What is the main difference between microtubules and actin filaments in terms of their structure?
Microtubules are hollow and more rigid, while actin filaments are solid and flexible.
How do cadherins contribute to cell-cell interactions?
By recognising and forming connections between similar cells.
What is the primary function of the extracellular matrix in the context of cell-ECM interaction?
To provide structure and biochemical support to the tissues.
What is the characteristic of the cytoskeleton that allows cells to rapidly change shape or direction of movement?
Its dynamic and constantly re-organising nature.
What is the function of proteoglycans in the extracellular matrix?
To lubricate the ECM and modify the activity of other proteins.
How do cells adapt to the extracellular matrix?
By differentiating into different types of cells depending on the ECM.
What is the role of collagen in the human body?
It forms molecular cables that strengthen the tendons and bones.
What is the function of intermediate filaments in the context of cell-cell interactions?
To connect cells through desmosomes.
How do cells connect to the basement membrane?
Through hemidesmosomes.
What is the primary function of integrins in the context of cell-ECM interaction?
To transmit signals into the cell and allow it to sense and respond to its environment.
Study Notes
Cytoskeleton
- Actin filaments: 5-9 nm in diameter, can be bundled together into thicker filaments, dynamic and constantly re-organizing
- Microtubules: larger than actin filaments with an outer diameter of 25 nm, hollow cylinders, more rigid than actin filaments
- Intermediate filaments: more diverse than microtubules or actin filaments, composed of a wider range of proteins, provide mechanical strength to the cell and connect cells together in tissues, form nuclear lamina, rope-like fibers typically 8-12 nm in diameter
Cell-Cell Adhesion
- Tight junctions: cells joined tightly together, produce a virtually impermeable barrier between cells, tight junction proteins link to actin cytoskeleton
- Cadherins: cell surface molecules, allow similar cells to recognize and form connections, different types of cadherin molecules join different types of cells together (e.g. E-cadherin joins epithelial cells)
- Desmosomes: connect cells through intermediate filaments, gap between cells is much wider than tight junctions
Extracellular Matrix (ECM)
- Scaffolding that surrounds cells, provides structure and mechanical and biochemical support for tissues
- Cells adapt to the ECM, stem cells placed on different ECMs will differentiate into different types of cells
- Forms basement membrane, thin sheets of ECM at the base of tissues such as skin
- Composition: long protein fibers (e.g. collagen), large sugar coated proteins (e.g. proteoglycans), and specialized molecules (e.g. fibronectin)
ECM Components
- Collagen: most abundant protein in the body (about 1/4 of all protein), major structural protein, forms molecular cables that strengthen tendons and bones, provides structure to the body
- Proteoglycans: proteins heavily glycosylated, contain long chains of sugar molecules, can lubricate the ECM, modify activity and stability of other proteins
- Integrins: cell surface molecules, act as matrix receptors, connect cell to ECM, transmit signals into the cell allowing it to sense and respond to its environment
Learn about the importance of cell structure and communication in multicellular organisms, including the challenges of connectivity and coordination. Discover how cells work together to form functional tissues and organs. Explore the intricate infrastructure that holds our bodies together.
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