BIOL123 Lecture Notes - Lecture 6: Extracellular Matrix, Microscopy, Ultimate Tensile Strength
17 Jun 2018
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1.11 List the three main types of intercellular junctions between cells and the
properties of each
• Cell junctions
o Held together in tissues (especially epithelial tissue)
o Allows cell to cell communication
o Tight junctions:
• Proteins form a seal between cells
• Water resistant
o Anchoring junctions (desmosomes):
• Protein filaments (intermediate) reinforce cytoplasm
• Filaments span between cells
• High tensile strength
o Gap junctions:
• Membranes spanned by trans-protein pores
• Allow ion and water exchange
1.12 Describe the extracellular matrix and explain its main functions
• Extracellular matrix
o Secreted by cells
o Fills the space between cells in tissues (especially connective tissue)
o Consists of: ground substance (gel-like material) and fibres (collagen and
elastin)
o Bound to the cell by integrin proteins
o Functions: binds cells together, resists compression, stretching
TOPIC LEARNING OBJECTIVES
2.1 Demonstrate an understanding of different types of microscopy
instruments available; their application and limitations:
· Light microscopy (compound, dissection and inverted instruments)
• Image magnified by focusing light with glass lenses on a thin tissue
section
• Brightfield illumination is used with specimens stained with coloured
dyes
• Resolution of 0.2μm
or ~1000x greater than the unaided eye
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