BLG 143 Study Guide - Final Guide: Middle Lamella, Primary Cell, Cell Membrane
27 Apr 2018
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Chapter 8 – Cell-Cell Interactions
Key Concepts
• Extracellular material strengthens cells and helps bind them together
• Cell-cell connections help adjacent cells communicate
• Intercellular signals are responsible for creating an integrated whole from many
thousands of independent parts
• In target cells, intercellular signals are received, processed, responded to and
deactivated
• If the signal is received at the cell surface, the processing step involves production of
an intracellular signal
8.1 The Cell Surface
The Structure and Function of an Extracellular Layer
Most cells possess a layer or wall that forms just beyond the membrane.
The extracellular material helps define the cell’s shape and either attaches it to another cell
or acts as a first line of defence against the outside world.
Thanks to the combination of tension and compression resisting elements, fibre composites
are particularly rugged.
The Cell Wall in Plants
All plants are surrounded by a cell wall, a fibre composite that is the basis of major
industries.
When plants first form, they secrete an initial fibre composite primary cell wall.
➢ Fibrous component long strands of cellulose that’re cross linked by other
polysaccharide filaments and bundled into stout, cable-like structures called
microfibrils; resist tortion and other tensions
➢ Pectins space between microfibrils is filled with this gelatinous polysaccharide;
molecules that’re used to thicken jams and jellies; ground material that resists
compression
➢ Defines the shape of the plant cell
➢ Counteracts turgor pressure force exerting against the wall, water entering the
cell cause of osmosis, incoming water inflates the plasma membrane
As plant cells mature and stop growing, they may secrete a layer of a secondary cell wall
inside the primary cell wall.
➢ Structure correlates with the specific cell’s functions
➢ Lignin in cells that form wood
➢ Middle lamella (pectins) glue cell walls together
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Document Summary
Key concepts: extracellular material strengthens cells and helps bind them together, cell-cell connections help adjacent cells communicate. Intercellular signals are responsible for creating an integrated whole from many thousands of independent parts. In target cells, intercellular signals are received, processed, responded to and deactivated. If the signal is received at the cell surface, the processing step involves production of an intracellular signal. The structure and function of an extracellular layer. Most cells possess a layer or wall that forms just beyond the membrane. The extracellular material helps define the cell"s shape and either attaches it to another cell or acts as a first line of defence against the outside world. Thanks to the combination of tension and compression resisting elements, fibre composites are particularly rugged. All plants are surrounded by a cell wall, a fibre composite that is the basis of major industries.
