The Extracellular Matrix Flashcards
What is the extracellular matrix?
An insoluble mesh work composed of proteins and polysaccharides
What are proteoglycans?
Proteins with chains of polysaccharides
How do the different forms of extracellular matrices vary?
The amount, type, and organization of the proteins and polysaccharides that make them up
What are four functions of the extracellular matrix?
- Cell adherence
- Communication between cells
- Cell shape/mechanical support/structural integrity
- Provides a barrier for the cell
In plants, what does the extracellular matrix form?
The cell wall
What is one of the most complex and diverse examples of an extracellular matrix?
The plant cell wall
Where is the cellulose polymer used to expand the cell wall assembled?
Outside the cell on, on the extracellular surface fo the plasma membrane
How are the glucose molecules used to form the cellulose polymers that expand the cell wall and the enzymes that attach them delivered to the cell surface?
By arrays of microtubules
What are the three layers that compose the cell wall?
- The middle lamella
- The primary cell wall
- The secondary cell wall
Which layer of the cell wall is used as the main mechanism by which plant cells adhere to one another?
The middle lamella
Which layer of the cell wall is composed of a gluelike complex carbohydrate?
The middle lamella
Which layer of the cell wall is synthesized during the late stages of cell division?
The middle lamella
Which layer of the cell wall consists primarily of cellulose, but also contains pectin?
The primary cell wall
Which layer of the cell wall is laid down while the cells are still growing?
The primary cell wall
Which layer of the cell wall is constructed in many plant cells once cell growth has stopped?
The secondary cell wall
Which layer of the cell wall consists primarily of cellulose, but also contains lignin?
The secondary cell wall
What does lignin do for the cell wall?
Hardens the cell wall and makes it matter resistant
What does the animal extracellular matrix contain that makes it unique from plants?
Large fibrous proteins
Where are fibrous proteins embedded in the extracellular matrix of animals?
In a gel-like polysaccharide matrix
What is the charge of the polysaccharide matrix in which fibrous proteins are embedded?
Matrix is negatively charged
Where can the extracellular matrix be found in abundance in animals?
Connective tissue
What makes connective tissue an unusual tissue type?
It’s dominated by the extracellular matrix and has a low cell density
What determines the properties of different types of connective tissue?
The extracellular matrix
What are the two functions of connective tissue?
- Provide connection to various parts of the body
- Provide support to various parts of the body
What are the two main functions of connective tissue necessary for?
Multicellularity
What underlies all epithelial tissue?
Connective tissue
What is the main cell type in the dermis?
Fibroblasts
How do fibroblasts contribute to the extracellular matrix?
They synthesize most of the extracellular matrix proteins
What is the most abundant protein in the extracellular matrix of animals?
Collagen
Where is collagen located to provide strong, durable support for the epidermis?
The underlying dermis
What is the structure of collagen?
Composed of three polypeptides wound around each other in a triple helix
What does a bundle of collagen molecules form?
A fibril
What are fibrils assembles into?
Fibres
What are multiple fibres assembled into?
Ligaments or tendons
What does the misrepair-accumulation aging theory suggest?
That wrinkles develop from incorrect repairs of injured elastin and collagen fibres
What is the basal lamina?
A specialized layer of extracellular matrix present beneath all epithelial tissues
What makes up the basal lamina?
Several proteins, including a special type of collagen
T or F: Cells continue to interact with the extracellular matrix long after they have synthesized it or moved into it.
True
Some cellular responses are the result of interactions between the extracellular matrix and ___________ on the surface of cells?
Integrins
What acts as receptors that relay signals from the extracellular matrix to the cell interior as the first step in the signal transduction pathway?
Integrins
What happens to fibroblasts cultured on a two-dimensional surface coated with extracellular matrix proteins?
They attach to the matrix and flatten out
What happens to fibroblasts cultured in a three-dimensional gel of extracellular matrix?
They look and behave like fibroblasts present in living connective tissues
T or F: The structure and composition of the extracellular matrix has no influence on gene expression.
False
Which element of the extracellular matrix can influence the expression of albumin by hepatocytes?
Laminin
How does the level of milk protein (beta-casein) being secreted from mammary cells when grown in 2D vs 3D collagen matrices?
Mammary cells synthesis and secrete high levels of beta-casein when growth in a three-dimensional collagen matrix, but not in a two-dimensional collagen matrix
What are non-malignant/benign tumours?
Encapsulated masses of cells that divide continuously because regulation of cell division has gone awry
What are Malignant tumours?
Masses that contain cells able to metastasize and break away from the main tumour and travel to distant sites in the body
What do metastatic tumour cells have an enhanced ability to adhere to?
Extracellular matrix proteins, especially those in the basal lamina
What structure have many studies compared between metastatic and non-metastatic cancer cells in search for potential treatments?
The integrins
In some types of cancers, what can integrins on the cell surface be used to indicate
The metastatic potential of cells
