Kate Rowe, Kylina John, Jacqueline Enriquez
description
Transcript of Kate Rowe, Kylina John, Jacqueline Enriquez
EXTRACELLULAR COMPONENTS AND CONNECTIONS BETWEEN CELLS HELP COORDINATE CELLULAR ACTIVITIES
Kate Rowe, Kylina John, Jacqueline Enriquez
Content:
Cell Walls of Plants
Intercellular Junctions of Plant
Cells
ECM of Animal Cells
Intercellular Junctions of Animal
Cells
How the cell wall helps coordinate cellular activity
Protects the plant cell
Maintains its shape
Prevents excessive uptake of
water
Break Down of Cell Wall1. Primary Cell Wall
thin and flexible2. Middle Lamella
sticky, thin layer of pectins 3. Secondary Cell Wall
strong durable matrix
Cell Walls of PlantsSecondary Cell Wall Cell
Membrane
Primary Cell WallMiddle Lamella
Intercellular Junctions in PlantsPlasmodesmata: channels in which plant cell walls are perforated with.
Functions of plasmodesmata include:-Allowing cytosol to pass through, which
connects cells to unify plant into one living thing.
-Water and small solutes pass from cell to cell.-Macromolecules pass through and are
transported on cytoskeleton.
Plasmodesmata in Plant Cells
What is the extracellular matrix (ECM)?Something that is made by virtually all multi-
cellular organisms.Elaborate covering outside animal cell
membranes, occupying the space between cells. It is composed of:◦ Collagen, proteoglycans, and fibronectin,
which the cell secretes.◦ Different from the plant extracellular
matrix, which is composed of cellulose.Many ECM components are involved in cell-
to-cell interactions.
Components of the ECMCollagen
◦ Most abundant glycoprotein (about half of the total protein in the body).
◦ Forms strong fibers outside of the cell. Fibers are embedded in a network made of
proteoglycans.Proteoglycans
◦ Collagen fibers are embedded in a network made from proteoglycans.
◦ Are another class of glycoproteins that consists of a small core protein with many carbohydrate chains covalently attached.
◦ Large complexes can form when hundreds of proteoglycans become non-covalently attached to a single long polysaccharide molecule.
Components (cont.)Fibronectin
◦ Glycoprotein that attaches the ECM to the cell itself.
◦ Binds to cell surface receptors called integrins, which are built into the plasma membrane of the cell.
Integrins◦ Cell surface receptor that connects to
fibronectin, which attaches to the ECM◦ Span the membrane and bind on their
cytoplasmic side to associated proteins attached to microfilaments of the cytoskeleton.
◦ Transmit’s changes between the ECM and the cytoskeleton – it integrates changes occurring outside and inside the cell.
Fig. 6-30
EXTRACELLULAR FLUID
Collagen
Fibronectin
Plasmamembrane
Micro-filaments
CYTOPLASM
Integrins
Proteoglycancomplex
Polysaccharidemolecule
Carbo-hydrates
Coreprotein
Proteoglycanmolecule
Proteoglycan complex
ECM Effect on BehaviorBy communicating with a cell through integrins,
the ECM can regulate a cell’s behavior. ECM can influence the activity of genes in the
nucleus. ◦ Speculated that information probably reaches the
nucleus by a combination of chemical and mechanical signaling pathways. Mechanical includes fibronectin, integrins, and
microfilaments of the cytoskeleton. The cytoskeleton may then trigger chemical signaling
pathways inside the cell, leading to changes in the proteins being made by the cell and therefore in its function.
The ECM may help coordinate the behavior of all the cells within that tissue.◦ Direct connections (intercellular junctions) between cells
also function in this coordination.
Intercellular Junctions in Animal Cells
Tight Junctions: Specific proteins bind cell membranes which are pressed against each other.◦Function: Tight Junctions prevent
extracellular fluid from leaking across epithelial cells.
Intercellular Junctions in Animal Cells
Desmonsomes: also known as “anchoring junctions,” desmonsomes are like rivets that fasten cells together.◦Desmonsomes are anchored to the
cytoplasm by filaments made of keratin proteins.
Intercellular Junctions in Animal Cells
Gap Junctions: also known as “communicating junctions,” gap junctions act as cytoplasmic channels between cells.◦Function: Each pore is surrounded by
membrane proteins which allow ions, sugars, amino acids, and other things cells need to pass from cell to cell.
Intercellular Junctions in Animal Cells
1) http://www.mahalo.com/ extracellular-matrix2) http://kentsimmons.uwinnipeg. ca/cm1504/cellwall.htm3) http://www.copewithcytokines. de/cope.cgi?key
=extracellular% 20matrix4) AP Biology Book