Topic 1: Cell Walls, Extracellular Matrix, and Cell Interactions Flashcards
Why is it helpful for bacteria to have a cell wall?
Helps determine shape of bacteria cell, either rod or spiral. Protects against osmotic pressure, if cell takes up too much water it can burst, regulates in take of water.
Describe the structure of petidoglycan. How does penicillin affect peptidoglycan?
Peptidoglycan is a linear polysaccharide chains, cross linked by peptides. Penicillan kills bacteria by inhibiting enzymes responsible for making sugar crosslinks, without sugar can not protect against osmotic pressure so cell will just burst.
Why do we need to be concerned about the overuse of antibiotics, like penicillin?
overuse of antibiotics like penicillin can cause bacteria to be become resistant to it
How is the structure of plant cell walls different from that of bacterial cell walls?
Made of celluose instead of peptidoglycan. Plant cell walls are fully permeable to small molecules while bacteria cell walls are selective.
What do loose connective tissue, bone, tendons, and ligaments have in common?
They are all composed of the extra cellular matrix with different cells. The extra cellular matrix fills the space between cells and binds cell and tissue together.
What is the general structure of the extracellular matrix?
Made of proteins, like collagen, in a gel-like polysaccharide ground substance. Can have a lot of variation depending on the combination of proteins and sugars and the different ways you can modify these components
What are collagen fibers?
The main family of proteins found in the extra cellular matrix. Forms a triple helix structure from amino acids secreted from the cell, further associate to form collage fibers, which create shapes like actin.
What are glycosaminoglycan (GAGs)?
What makes protein fibers. Links the proteins to form proteoglycan. GAGs have negative charge making the matrix outside attract cations, and water
What are adhesion proteins?
Proteins that link components of the matrix together, like collagen and link cells to the matrix
What do cells use to attach themselves to the extra cellular matrix?
Attachments made by integral proteins for example integrin, the protein will recognize and bind to specific amino acid sequences found in different components of the matrix
What is the relationship between integrins and focal adhesions, and hemidesmosomes?
Integrin is present in focal adhesions and hemidesmosomes. Point of attachment made by integrin for focal adhesions.
Why do cells have multiple types of adhesion junctions?
Some interactions are transient and some are more stable, so depending on what the cell needs they chose which type of adhesion junction applies more
What are adhesion junction cadherin?
Used for contact inhibition. Let cells know there is another cell next to it. Could change behavior of the cell, telling cell not to divide anymore. Loss of cadherin in epithelial cell can lead to cancer.
What are adhesion junction’s desmosome?
Stabel interaction, connect cell to another cell.
How are plasmodesmata similar to gap junctions? How are they different?
They both allow cells to exchange different molecules. Gap junctions are mediated by membrane proteins while plasmodesmata is mediated by plant cell wall. Plasmodesmata, plasma membranes of adjacent cells are continuous with each other, not the same for gap junctions.
