POGIL Cell Communication Cell Communication CHAPTER 11 Do

POGIL: Cell Communication

Cell Communication CHAPTER 11

Do bacteria communicate? Bonnie Bassler on How Bacteria “Talk”

Video Questions: 1. Why are scientists studying how bacteria (and not just human cells) communicate? 2. What is quorum sensing? 3. Describe how Vibrio fischeri use quorum sensing in squid. 4. According to Bonnie Bassler (Princeton University), what are scientists hoping to use as the next class of antibiotics?

Cell Signaling Animal cells communicate by: 1. _____________ (gap junctions) 2. Secreting ______ regulators (growth factors, ___________) 3. Long distance (______)

Local/short distance; neurotransmitters move across a _________________; hormones travel through bloodstream

3 Stages of Cell Signaling: 1. __________: Detection of a signal molecule (_____) coming from outside the cell 2. _________: Convert signal to a form that can bring about a cellular response (often involves amplification) 3. _________: Cellular response to the signal molecule

Reception

Transduction

Response If in the _____, the response activates genes If in _______, activates enzymes/proteins

1. Reception Binding between signal molecule (______) + ____ is highly specific. Types of Receptors: a) Plasma membrane receptor Bind _________ ligands b) ______receptors (cytoplasm, nucleus) § § __________ or small ligands Eg. _______ or ________ (NO) § Ligand binds to receptor protein changes ______ initiates transduction signal

Plasma Membrane Receptors G-Protein Coupled Receptor (GPCR) Very widespread in animals/humans Work with the help of a __________– binds to ______ (energy molecule similar to ATP) ___transmembrane segments in membrane G protein + GTP activates _____ cell response Tyrosine Kinase Ligand-Gated Ion Channels ________ that act as __________ Region on receptor _________ and acts like a “_____” when signal molecule binds Transfers ___ group from ATP Gates may _____ or ______to to the amino acid regulate flow of specific ions _______ (_________) Activate ________ cellular responses at once Important in ________ system Abnormal RTKs are associated with many ________ Some gated ion channels are controlled by _______ signals instead of ligands. These are ________-gated ion channels

G-Protein-Coupled Receptor

G-Protein-Coupled Receptor G proteins work together with a receptor (GPCR) G protein is a molecular ______. Inactive/off when _____ is bound Active/on when _____ is bound G proteins work together with an enzyme (or other protein)

G-Protein-Coupled Receptor _______ molecule (ligand) binds to cytoplasm side of GPCR Receptor is _____ and changes shape. Cytoplasm side of the receptor then binds ________, causing GTP to displace _______ This activates the ________

G-Protein-Coupled Receptor Activated G protein leaves the receptor and moves down the membrane to an _________ Signaling molecule can _____ many times Activated enzyme changes ____ and triggers next step in cell response.

G-Protein-Coupled Receptor • Changes in G protein and enzyme are _______. • G protein also acts a _______ enzyme (hyrdolyzes bound GTP to GDP) • Everything resets and G protein can be used again.

Receptor Tyrosine Kinase

Receptor Tyrosine Kinase Signal molecules (ligands) binds to both _____ Monomers come together and form a ______ (=dimerization)

Receptor Tyrosine Kinase Each tyrosine kinase adds a ______ from _____ to the _______ on the tails

Receptor Tyrosine Kinase _______ proteins inside the cell bind to specific phosphorylated tyrosine, undergoes a shape change, and then triggers a ________ pathway leading to a _______________.

Ligand-Gated Ion Channel _____ binds to receptor (closed) shape change gate ____ The gate _____ when the ligand ________ flow into the cell through open gate; activates cell in some way

2. Transduction Cascades of molecular interactions relay signals from _____ to _______ molecules Usually involve _____________: enzymes that phosphorylate (transfer a _______ group from _____ to a _____) and activate proteins at next level (turn signal ___) Protein phosphatases: _______ that remove ______ groups and _________ protein kinases (can turn signal _____) Phosphorylation cascade: helps to _______ and _______ signal to allow a greater cellular ________

Second Messengers small, _________ molecules/ions that can relay signal inside cell Eg. cyclic AMP (_____), calcium ions (Ca 2+), inositol triphosphate (IP 3) Once activated, initiate a ________ cascade

c. AMP = _______________ GPCR adenylyl cyclase (convert ATP c. AMP) activate protein kinase A

3. Response Regulate _______ synthesis by turning on/off genes in ______ (gene expression) Regulate activity of ______ (including enzymes) in ______

An Example of Cell Communication http: //learn. genetics. utah. edu/content/begin/cells/cellcom/

Signal Transduction Pathway Problems/Defects: Examples: Diabetes Cholera Autoimmune disease Cancer Neurotoxins, poisons, pesticides Drugs (anesthetics, antihistamines, blood pressure meds)

Cholera Toxin modifies G-protein Disease acquired by drinking contaminated water (w/human feces) Bacteria (Vibrio cholerae) colonizes lining of small intestine and produces toxin involved in regulating salt & water secretion G protein stuck in active form intestinal cells secrete salts, water Infected person develops profuse diarrhea and could die from loss of water and salts

Viagra Used as treatment for erectile dysfunction Inhibits hydrolysis of c. GMP Prolongs signal to relax smooth muscle in artery walls; increase blood flow to penis

Viagra inhibits c. GMP breakdown

Apoptosis = ________ Cell is dismantled and digested Triggered by signals that activate ______ of “suicide” proteins (caspase) Why? ______ neighboring cells from damage Animal _________ & maintenance May be involved in some diseases (________, ________)

Apoptosis of a human white blood cell Left: Normal WBC Right: WBC undergoing apoptosis – shrinking and forming lobes (“blebs”)

Effect of apoptosis during paw development in the mouse