Lecture 17 Flashcards
What are the components of the extracellular matrix (ECM)
Proteins (collagen, glycoproteins, proteoglycans [proteins with chains of polysaccharides])
Molecules and compounds
Components are produced and secreted by cells and assembled into a extracellular network
What are the functions of the ECM
Cell adherence
Communication between cells
Cell shape, mechanical support and structural integrity (most important)
Serves as barrier, filters out some particles
What is the role of anchor proteins?
Interacts with components of the ECM and assist in:
Tissue formation and coordinated cell function
Communication between cells
Give an example of the ECM
Connective tissue of animals (tendons, ligaments, skin)
What is the function of the ECM in non-animal cells
Cells of bacteria, plants and fungi have walls
Plant cell walls = ECM
Made of cellulose, hemicellulose, pectin and proteins
Provides structural support to cell and whole organism
Protects cell from mechanical damage and pathogen attack (enzymes that break down cellulose)
What is signal transduction
The conversion of extracellular signal into intracellular signal
What is the purpose of signal transduction
Allows cells to rapidly respond to the events happening in their environment:
Grow
Divide
Survive
Move
Differentiate
What is a ligand
Small molecule that binds to a receptors
What does the ligand do to the receptor
Changes the conformation of the receptor protein
Ligand DOESN’T enter the cell
Cytosolic side of receptor is also affected by conformation change
How does the conformational change caused by the ligands affect proteins
Causes proteins (in the cytosol or membrane bound) to become activated
What are the 3 stages of signal transduction
1) binding of ligand to receptor
2) signal transduction via second messengers like cAMP, calcium or G-protein
3) cellular response: cellular growth, cell division, store glucose molecules as glycogen
What can happen in the body if signal transduction doesn’t occur properly
Could cause cancer, diabetes and different brain disorders
What happens in glycogenolysis (an example of signal transduction)
Epinephrine activates conversion of glycogen in the liver to glucose
The glycogenin enzyme acts a primer to polymerize the first glucose molecules (other proteins then take over)
Describe the step involved with glycogenolysis
Epinephrine binds to receptor on liver cell
Receptor recruits G-protein and allows binding of GTP to turn on the G-protein
Subunit of the G-protein dissociate and activates adenyl Cyclase enzyme. cAMP accumulates
Phosphorylase-P enzyme releases glucose units
