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BIO120H1 (1,000)
Lecture

Notes taken during lecture


Department
Biology
Course Code
BIO120H1
Professor
Jean Jiang Nash

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LECTURE 17 Extracellular matrix and cell motility
Human fibroblast cells grown in tissue culture
Cell-Matrix adhesion
Cell to cell attachments 3 main
Cell cell anchoring junction adhering junction actually holds cells together
Tight junction so things cannot pass between cells
Channel forming gap junctions allow small materials pass from cell to cell
Focal adhesion below the left hand bottom paragraph
oContact btw basal surface and extracellular matrix
oImportant for cell migration
ECM drawing of basal surface of cell
Green are transmembrane proteins, integrins
Complex network of proteins and sugars
Mesh is extracellular matrix
By fibroblasts
Fibroblast secretes most of extracellular matrix
Epithelial cell layer apical at top
Basal lamina type of ECM
Basal faces ECM
Yellow line around capillary
Fibroblast secrete most of the ECM
Triangular cell looking at fibroblast
Two major kind of ECM
(Basal lamina)
(connective tissue)”
Muscle contract pulls on basal lamina, which pulls on connective tissue, which
pulls on bone
Capillary endothelial cells attached to basal lamina
oKidney has lining of tubules no tight junctions between cells allows
filtering function SO blood cells not found in urine
ECM
Structure and regulates behaviour
Tensile strength; resistance to compression
Reinforced concrete
Metal beams or wires
Together v strong structure, having tensile strength AND resistance to
compression
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If separated
oChain-link fence easily compressed BUT has resistance to knocking and
stretching forces (AKA tensile strength)
oCement highly resistant to compression but little resistance to knocking
forces
Like reinforced concrete, one for strength one for compression
ECM important because
Defects in ECM lead to human diseases
Collagen fibres not assemble properly scurvy
Ehlers-Danlos syndrome v. stretchy skin
All listed are collagen defects how collagen offers tensile strength to tissue
Two main classes of ECM macromolecules
GAGs made of sugar
Fibrous proteins 4 kinds
GAGs
Amino group included
Disaccharide unite two sugars
Know N-acetylglucosamine + glucurojnic acid example
Chain of sugars can get extremely long******
oImportant for function
oActing as filler so should be very long
OH group in sugar used in covalent linkage btw sugars once linked, becomes
O involved in covalent bond
Negative charge ****
oSulphate groups, carboxy groups
oNegative charges repel each other
oLong molecule repelling itself ERGO straighten out
Negative charges will attract cations ***
oSalty molecule will attract water***
oWater molecules inflate this molecule so this fills a large space ERGO
spongy spacefilling stuff between cells
GAGs
Because of attached sulphate and carboxyl groups
Making proteoglycans
oCovalently attached to proteins
GAGs
Four main groups of GAGs
Hylauronan not linked to proteins
The bottom three are linked to proteins
KNOW THESE NAMES
Cube with single Hyluronan molecule swelled into large area
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