Unit 4: Cell Communication

Unit 4: Cell Communication
Objectives: 2.C.1: Organisms use feedback mechanisms to maintain their internal environments and respond to external environmental changes 2.D.3: Biological systems are affected by disruptions to their dynamic homeostasis 2.D.4: Plants and animals have a variety of chemical defenses against infections that affect dynamic homeostasis 3.C.3: Viral replication results in genetic variation, and viral infection can introduce genetic variation into the hosts 3.D.2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling 3.D.3: Signal transduction pathways link signal reception with cellular response

Warm-UP: Compare the two types of communication in the models at right
Warm-UP: Compare the two types of communication in the models at right. What advantages are there to each? Disadvantages? Why would an organism benefit from being able to do each? Homework DUE tomorrow: 10 Key Ideas 11.1 Due NOW: Cell Communication POGIL Homework DUE Friday: Unit 3 Test Make UP Unit 4 Test: 12/17/15

Unit 4: Cell Communication
Big Idea: The Signal Transduction Pathway is a series of events that begins with (1) a cell receiving an external signal (ligands) that (2) binds to ligand-specific receptors (integral proteins) which causes (3) cells to make changes that result (4) in a response. 3 MODELS: Endocrine: Pancreas cells communicate to liver cells from a distance via hormones in order to regulate blood sugar content Paracrine: Neurons are cells that communicate through direct contact using neurotransmitters. Between Organisms: Antigens (virus particles) bind to antibodies (receptors on immune system cells) cause the specific immune response

Signal Transduction Pathway
Signal (ligand) a molecule that “fits” the receptor protein (ligand specific) produced by other cells effects only target cells Examples: Endocrine: Hormone: insulin Paracrine: Neurotransmitter: adrenaline Between Organisms: Antigens (pieces of viruses): flu Reception Transduction Response

Signal (ligand) Reception ligand binds to receptor protein receptor protein is changed Transduction Response

Signal (ligand) Reception receptor protein is changed Transduction: a series of intracellular (within cell) changes Examples: activation of “other” proteins by phosphorylation activation of DNA that results in new proteins Response

Signal (ligand) Reception receptor protein is changed Transduction Response: cellular change Examples: release of new protein into extracellular fluid activation of integral protein to allow it to function cell division

Warm-UP: Pancreas cells release insulin to target liver cells when blood sugar is high. Speculate: What do you think happens in the liver cell’s signal transduction pathway? Signal Reception Transduction Response Homework: Key Ideas 45.2 Due: Key Ideas 11.1 Unit 4 Test: 12/17/15

Endocrine: Pancreas cells communicate to liver cells from a distance via hormones in order to regulate blood sugar content Hormones ligands secreted into the circulatory system from glands communicate regulatory messages to targets around the body reach all parts of the body, but only target cells capable of responding (i.e. with protein receptors)

Endocrine: Pancreas cells communicate to liver cells from a distance via hormones in order to regulate blood sugar content Hormones ligands secreted into the circulatory system from glands communicate regulatory messages to target cells (i.e. cells with receptors) around the body 2 types: proteins: secreted by exocytosis target surface receptors insulin and glucagon lipids: target receptors on inside of cell diffuse across the cell membrane steroids: testosterone

Endocrine: Pancreas cells communicate to liver cells from a distance via hormones in order to regulate blood sugar content Insulin/Glucagon Model: maintain glucose homeostasis Signal: insulin produced by pancreas due to high blood sugar Reception: Insulin receptor on liver cell Transduction: activation of glut 4 transporter translocation of glut 4 into cell membrane activation of enzymes: glycogen synthase, phosphofructokinase, fatty acid synthase Response: glucose diffusion by facilitated diffusion through glut 4 glycogen polymerization by glycogen synthase glycolysis by phosphofructokinase fatty acid synthesis by fatty acid synthase

Insulin Glucagon Whiteboard
Team Insulin just having bonded to insulin receptor Insulin binding causes transduction Transduction due to insulin causes response: decrease in blood glucose levels Glucagon just having binded to glucagon receptor Glucagon binding causes transduction Transduction due to glucagon causes response: increase in blood glucose levels Guiding Questions: Is the person’s blood sugar hyperglycemic (high), hypoglycemic (low), or at homeostasis (just right)? What has happened to: glucose molecules, integral proteins, enzymes? Why has the cell responded this way? How does what’s shown help an organism maintain homeostasis? Terms to Consider Drawing/Using: phospholipid, integral protein, activation, ligand, ligand receptor, glut 4 transporter, blood, glucose, fatty acid transporter, enzyme, fatty acid synthase, glycogen synthase, glycogen, glucagon, insulin, insulin receptor, glucagon receptor, glycogen phosphorylase

Warm-UP: What could go wrong with this Signal Transduction Pathway
Warm-UP: What could go wrong with this Signal Transduction Pathway? Identify 2 possibilities AND suggest a solution that a medical researcher might investigate. Unit 4 Test: 12/17/15 Due: Key Ideas 45.2 Homework: Diabetes Drawings

Warm-UP: Neurons communicate via paracrine signaling
Warm-UP: Neurons communicate via paracrine signaling. Explain, using the model. Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files. Homework: Concept 48.2 and 3: 10 Total Key Ideas AND Test Fix Unit 4 Test: 12/17/15 Due: Diabetes Drawings

Paracrine: Neurons are cells that communicate through direct contact using neurotransmitters.
Neurons: nerve cells Signal Transduction Pathway: Signal: neurotransmitter Reception: neurotransmitter receptor/gated ion channel Transduction: voltage-gated ion channels send electrical signal down axon Response: neurotransmitter is released to the next neuron Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

Before Signal is received: “Resting” membrane potential= -70mV “Net” negative Active Transport: Na+/K+ pumps use ATP to pump more + out than in Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

creates a concentration gradient
To maximize homeostasis with minimum energy investment, organisms use: simple diffusion (osmosis); surface area to volume ratio; facilitated diffusion; active transport; or endo/exocytosis. Active Transport some molecules must be pumped against entropy (against their concentration gradient) ex: proton pump “pumping” is the result of an energy transfer that changes the shape of the integral protein creates a concentration gradient advantage: a method for getting “all” of a molecule to a desired location disadvantage: requires energy input

Signal: adrenaline from previous neuron Reception: adrenaline gated ion channel (adrenaline receptor) opens Na+ and K+ diffuse with their concentration gradients More + in than out (remember, there were more Na+ out than in, so a net diffusion in) “Action” membrane potential= -55mV Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

Transduction: Voltage gated Na+ channels are stimulated to open Na+ diffuse with their concentration gradients faster Even more + in than out “Action” membrane potential = -55mV Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

Transduction: Voltage gated Na+ channels are stimulated to open Na+ diffuse with their concentration gradients faster Even more + in than out “Action” membrane potential = -50mV Voltage gated Na+ channels stimulate neighboring channels to open “electrical” signal is transferred down the cell’s axon Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

Transduction Voltage gated Na+ channels are stimulated to open Na+ diffuse with their concentration gradients faster Even more + in than out “Action” membrane potential = -50mV Voltage gated Na+ channels stimulate neighboring channels to open “electrical” signal is transferred down the cell’s axon Resting membrane potential is returned= -70mV Voltage gated K+ channels are stimulated to open at =+30mV K+ diffuse with their concentration gradients: more + out than in Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

Transduction Voltage gated Na+ channels are stimulated to open Na+ diffuse with their concentration gradients faster Even more + in than out “Action” membrane potential = -50mV Voltage gated Na+ channels stimulate neighboring channels to open “electrical” signal is transferred down the cell’s axon Resting membrane potential is returned= -70mV Voltage gated K+ channels are stimulated to open at =+30mV K+ diffuse with their concentration gradients: more + out than in At axon terminal, voltage gated Ca+ channels open Ca+ diffuses in, causing vesicles containing neurotransmitter to be released Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

Response: More adrenaline is released into the synapse by exocytosis Next neuron is stimulated OR Muscle contracts Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

Before “NEXT” Signal is received: “Resting” membrane potential is reestablished= -70mV “Net” negative Active Transport: Na+/K+ pumps use ATP to pump more + out than in Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

Warm-UP: Many drugs work by mimicking neurotransmitters
Warm-UP: Many drugs work by mimicking neurotransmitters. For example, morphine (a pain killer) mimics endorphins, a neurotransmitter responsible for stimulating neurons that lower the respiratory rate. Use the model to explain how this works. Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files. Unit 4 Test: 12/17/15 Due: Unit 3 Test Review and 48.1 Homework: Go YOUTUBING: find somepin’ to watch on neurons. Write down some key ideas as you watch (see my website links for ideas).

Neuron Signal Transduction Pathway Movie
Using a whiteboard, make a “movie” showing a neuron in the different parts of the signal transduction pathway. Requirements: your “movie” must be labeled, careful, and show a minimum of 15 steps from beginning to end of the “box”. 4 5 3 6 2 1 7 8. Show the end of the neuron with the response Parts to consider drawing/labeling: cell membrane, adrenaline, K+, Na+, Ca+, Vesicle, Na+/K+ pump, adrenaline gated ion channel, voltage gated Na+ channel, voltage gated K+ channel

Homework: Neuron Function Handout
Warm-UP: When athletes sweat, they drink electrolytes to replenish their lost ions. How does this help neuron function? Use the model to explain. Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files. Unit 4 Test: 12/17/15 Due: Video Notes from a video of your choosing Homework: Neuron Function Handout

Warm-UP: Compare your team’s number to one other. Same/different?
Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files. Unit 4 Test: 12/17/15 Due: Neuron Handout Homework: Neuron Poster due Thursday

Neurotransmitter ion door Ca2+ Neurotransmitter ATP needed?
Team 1 2 3 4 5 6 7 8 K+ Na+ Na+ voltage door K+ voltage door Na+/K+ pump Neurotransmitter ion door Ca2+ Neurotransmitter ATP needed? Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

Which parts of the neuron are stopped?
Neuron Change Poster Draw and label a neuron with one of the following changes: Loss of ions due to sweating during exercise Slight decrease in pH of surrounding fluid due to increase in carbonic acid (from CO2) Cocaine acts as competitive inhibitor for Na+ voltage gated ion channel Lack of calcium in diet Alcohol opens voltage gated K+ channels: causes “hyperpolarization” Lack of ATP due to lack of oxygen in brain cell “Learning” causes extra axons to reach the same dendrite, so more adrenaline is sent. Key Ideas to Highlight Which parts of the neuron are stopped? Which part of the Signal Transduction Pathway is directly affected? Indirectly affected? Signal, Reception, Transduction, Response Describe the overall impact this will have on neuron activity AND the individual. Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

Neuron Change Poster Terms: resting membrane potential ligand K+
action potential Na+ Ca2+ exocytosis vesicle active transport Na+/K+ pump facilitated diffusion Na+ voltage gated channel ATP, ADP, P active site K+ voltage gated channel Ca2+ voltage gated channel signal reception Neurotransmitter receptor/gated ion channel transduction response neurotransmitter

Neuron Change Poster 4 Advanced 3 Proficient 2 Basic 1 Below Basic
Scientific Vocabulary ALL words are used correctly Most words are used correctly Most words are used, some correctly Some words are used correctly Labeled Molecular Drawings Drawings are detailed and help explain Drawings help explain some things Drawings are complete but lack detail Drawings are incomplete Explanations of changes from normal, connects to effects on organism Poster clearly explains the details of how changes can lead to organismal changes Poster explains changes, but lacks details about the process Poster shows changes but lacks complete explanation of how the small changes have organismal effects Project has very little information about changes.

Homework: Neuron Poster due Tomorrow
Warm-UP: When ADULTS drink alcohol, the alcohol (a competitive inhibitor) binds to K+ voltage gated channels and keeps them open, causing a hyperpolarization (making the resting membrane potential even more negative). How does this hurt neuron function? Use the model to explain. Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files. Unit 4 Test: 12/17/15 Homework: Neuron Poster due Tomorrow

Warm-UP: How do immune system cells “communicate”
Warm-UP: How do immune system cells “communicate”? Guess, using the model below: DUE NOW: Neuron Poster Homework: Virus Life Cycle Unit 4 Test: 12/17/15

Between Organisms: Antigens (virus particles) bind to antibodies (receptors on immune system cells) cause the specific immune response Viruses: not cells not alive can’t reproduce themselves (obligate intracellular parasites) require host don’t eat very small parts nucleic acid protein coat (called a capsid) nucleic acid may be: DNA: DNA virus RNA: RNA virus (a retrovirus)

Between Organisms: Antigens (virus particles) bind to antibodies (receptors on immune system cells) cause the specific immune response Viruses: Life Cycle: virus bonds to protein receptors on host cell membrane viral genome enters the host cell either by injecting DNA through protein channels or endocytosis host cell polymerizes viral proteins and DNA viral proteins and DNA assemble into new viruses new viruses exit cell either by lysing host cell or exocytosis Figure 19.4 A simplified viral reproductive cycle

Warm-UP: Watch the video: Compare H5N1 to other flus. Same, different?
As you watch, think about: How do viruses hurt you? Why do some viruses, like the flu, only hurt temporarily, while others, like polio, cause permanent damage? Why can we sometimes fight back and win, but other times we lose? Homework: Immunity POGIL

Between Organisms: Antigens (virus particles) bind to antibodies (receptors on immune system cells) cause the specific immune response Viruses: Life Cycle: virus bonds to protein receptors on host cell membrane viral genome enters the host cell either by injecting DNA through protein channels or endocytosis host cell polymerizes viral proteins and DNA viral proteins and DNA assemble into new viruses new viruses exit cell either by lysing host cell or exocytosis Figure 19.4 A simplified viral reproductive cycle

Between Organisms: Antigens (virus particles) bind to antibodies (receptors on immune system cells) cause the specific immune response The Immune Response Non-specific: macrophages attach to and ingest by endocytosis Vesicle becomes a lysosome when enzymes are added kill foreign bodies indiscriminately b.c. the signal is general Ex: presence of a capsid causes macrophages to attach Specific Cell-Mediated Response Humoral Response Fig 43.1 How do immune cells of animals recognize foreign cells? For the Cell Biology Video Leukocyte Adhesion and Rolling, go to Animation and Video Files. 1.5 µm

Warm-UP: Describe the Signal Transduction Pathway in the helper T cell
Warm-UP: Describe the Signal Transduction Pathway in the helper T cell. How might a breakdown in this part of the immune system affect the rest of the immune response? Fig 43.1 How do immune cells of animals recognize foreign cells? For the Cell Biology Video Leukocyte Adhesion and Rolling, go to Animation and Video Files. Due for a Stamp: Immune System POGIL; Stamp Sheets DUE NOW Homework: ELISA pre-lab questions 1.5 µm

Between Organisms: Antigens (virus particles) bind to antibodies (receptors on immune system cells) cause the specific immune response Non-specific: Specific Cell-Mediated Response: T cells made in the thymus gland 2 kinds: helper T cells Signal: virus, antigen, or antigen presenting cells (macrophage or infected cell) Reception: “correct” T cell: all T cells possible are present at birth; T cells with antigen specific receptor for present virus/antigen receives signal Transduction: production of cytokines Response: release of cytokines (signal that causes killer T cells and B cells to respond) b. Humoral Response Fig 43.1 How do immune cells of animals recognize foreign cells? For the Cell Biology Video Leukocyte Adhesion and Rolling, go to Animation and Video Files. 1.5 µm

Between Organisms: Antigens (virus particles) bind to antibodies (receptors on immune system cells) cause the specific immune response Non-specific: Specific Cell-Mediated Response: T cells made in the thymus gland 2 kinds: killer T cells attach to infected cells release perforin (a nonspecific integral protein) causes lysis of infected cells b. Humoral Response Fig 43.1 How do immune cells of animals recognize foreign cells? For the Cell Biology Video Leukocyte Adhesion and Rolling, go to Animation and Video Files. 1.5 µm

Between Organisms: Antigens (virus particles) bind to antibodies (receptors on immune system cells) cause the specific immune response Non-specific: Specific Cell-Mediated Response Humoral Response: B cells made in the bone marrow 2 types active: Signal: virus/antigen/antigen presenting cell Reception: “selection” of “correct” B cell Transduction: cell division; production of antibodies Response: release of antibodies Fig 43.1 How do immune cells of animals recognize foreign cells? For the Cell Biology Video Leukocyte Adhesion and Rolling, go to Animation and Video Files. 1.5 µm

Between Organisms: Antigens (virus particles) bind to antibodies (receptors on immune system cells) cause the specific immune response Non-specific: Specific Cell-Mediated Response Humoral Response: B cells made in the bone marrow 2 types memory: “correct” B cells are cloned and stored in case of ndry exposure Fig 43.1 How do immune cells of animals recognize foreign cells? For the Cell Biology Video Leukocyte Adhesion and Rolling, go to Animation and Video Files. 1.5 µm

Between Organisms: Antigens (virus particles) bind to antibodies (receptors on immune system cells) cause the specific immune response Non-specific: Specific Cell-Mediated Response Humoral Response: antibodies bind to virus and act as competitive inhibitor to stop virus from infecting more cells Fig 43.1 How do immune cells of animals recognize foreign cells? For the Cell Biology Video Leukocyte Adhesion and Rolling, go to Animation and Video Files. 1.5 µm

Lab: ELISA: Enzyme-linked Immunosorbent Assay
Meow. . . Meow. . . Meoooow! Obviously, it is time for your cat Garfield to come in. You go to the back door and see your big orange cat sitting on the back porch with a gift for you. Usually the gift he brings is small and furry such as a mouse or shrew. He is a very successful hunter and uses the nearby field as his hunting ground. His gift today is definitely unusual, it’s a dead pigeon. There are no signs of obvious trauma to the pigeon. You realize that Garfield was lazy and just brought you a dead bird that he simply found. Your next thought is, “How did it die?” Then you remember hearing in the news about a disease called the bird or avian flu. You get a little worried because you’ve heard that this type of flu may spread from wild birds to other animals like pigs, cats, and possibly humans. You decide that you had better call the county health department to let them know what you found. You are told to wrap the bird up in plastic to prevent contamination, and bring it, as well as Garfield, to the health department so they can be tested for bird flu.

Lab: ELISA: Enzyme-linked Immunosorbent Assay
Question: Does Garfield have antibodies for H5N1?

Pipetting Practice Adjust your micropipette:
50.0 uL, 5.0 uL, or 125 uL Make drops of your volume: 1st stop Into the solution Release Out of the solution Eject: to the 2nd stop Perfection?: TOUCH the drop to “unstick” the last bit REMINDERS No double dipping Close tip box lids Keep your hands, breath, etc. to yourself Sterilize everything: before, during, and after Small volumes DO NOT equal no volume: Use a microcentrifuge!

Sketch the model. Label it with the following: H5 Antigen
Warm-UP: Sketch the model. Label it with the following: H5 Antigen Antibody for H5 Antibody for Antibody for H5 Peroxidase Peroxidase Substrate Homework for tomorrow: Analysis and Conclusion for lab due (I will collect) Unit Test Thursday. Be ready to study in class tomorrow.

Tips for Tips Using your micropippeter:
1st stop Into the solution Release Out of the solution Eject: to the 2nd stop Perfection?: TOUCH the drop to “unstick” the last bit Ensure you have the “right” micropipette and tip for the job. Do not cross-contaminate your wells. Spread out. Keep track of what you’re doing. Use new “transfer” pipettes when you’re unsure if you’ve contaminated something. No double dipping Small volumes DO NOT equal no volume

RECORD COLOR CHANGE on your chart of your 96 well plate CLEAN UP:
BEFORE YOU LEAVE: RECORD COLOR CHANGE on your chart of your 96 well plate CLEAN UP: Garbage: transfer pipettes paper towels used tips used 96 well plate On front table colored minitubes (epitubes) micropipettes in tub tip box Homework for tomorrow: Analysis and Conclusion for lab due (I will collect) Unit Test Thursday. Be ready to study in class tomorrow.

Make sure to label: heavy chain, light chain, disulfide bonds, VDJ segments

HRP (Horseradish Peroxidase)
peroxidase enzyme catalyzes the reduction of hydrogen peroxide (in the wash) to water Substrate: TMB Product: blue color

Warm-UP: Find partners who match your handout
Warm-UP: Find partners who match your handout. One picture, one graph, one description. Sit together. Write a sentence describing what your handouts are about. AND THEN…Describe strategies you used to figure out which partners fit with you.

high blood sugar after a meal
insulin produced and excreted by pancreas insulin receptor has not yet received the signal

activation of glut 4 transporter
activation of enzymes: glycogen synthase, phosphofructokinase, fatty acid synthase blood glucose lowers as glucose diffuses by facilitated diffusion through glut 4 glycogen polymerization by glycogen synthase glycolysis by phosphofructokinase fatty acid synthesis by fatty acid synthase

high blood sugar after a meal
insulin produced and excreted by pancreas insulin receptor is broken and cannot receive the signal glucose concentrations remain high in the blood: hyperglycemia

Before Signal is received “Resting” membrane potential= -70mV
“Net” negative Active Transport: Na+/K+ pumps use ATP to pump more + out than in Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

Voltage gated Na+ channels are stimulated to open
Na+ diffuse with their concentration gradients faster Even more + in than out “Action” membrane potential = -20mV outside of cell Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files. Na+ K+ inside of cell

Signal: adrenaline from previous neuron
Reception: adrenaline gated ion channel (adrenaline receptor) opens Na+ and K+ diffuse with their concentration gradients More + in than out membrane potential “creeps” towards threshold potential = -55mV Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files.

Resting membrane potential is -30mV
Voltage gated K+ channels are stimulated to open K+ diffuse with their concentration gradients: more + out than in outside of cell Figure 48.4 Neuron structure and organization For the Cell Biology Video Dendrites of a Neuron, go to Animation and Video Files. Na+ K+ inside of cell

B cells secrete antibodies
Humoral Response B cells secrete antibodies antibodies bind to virus and act as a competitive inhibitor to stop virus from infecting more cells Fig 43.1 How do immune cells of animals recognize foreign cells? For the Cell Biology Video Leukocyte Adhesion and Rolling, go to Animation and Video Files. 1.5 µm

“correct” B cells are cloned and stored in case of 2ndry exposure
Humoral Response “correct” B cells are cloned and stored in case of 2ndry exposure “correct” antibodies bond to virus before host cells are infected. host avoids being sick Fig 43.1 How do immune cells of animals recognize foreign cells? For the Cell Biology Video Leukocyte Adhesion and Rolling, go to Animation and Video Files. 1.5 µm

attach to and ingest by endocytosis
Non-specific macrophages attach to and ingest by endocytosis kill foreign bodies indiscriminately b.c. the signal is general Fig 43.1 How do immune cells of animals recognize foreign cells? For the Cell Biology Video Leukocyte Adhesion and Rolling, go to Animation and Video Files. 1.5 µm

Between Organisms: Antigens (virus particles) bind to antibodies (receptors on immune system cells) cause the specific immune response Label: Primary Response virus infects the person macrophages kill some virus helper T-cells release cytokines, which activates B cells and cytotoxic T-cells B-cells are actively secreting antibodies Viruses are being eliminated

Between Organisms: Antigens (virus particles) bind to antibodies (receptors on immune system cells) cause the specific immune response Secondary Response: less virus replicated; less cells infected; less time sick more T and B cells with the matching antibody less time for T and B cells to be activated more antibodies secreted, and sooner after infection

insulin binds to receptor glucose diffuses IN insulin released glycogen synthase is made glut4 added to cell membrane glucoseglycogen

vesicle binds to membrane, releases neurotransmitter neurotransmitter binds to ligand gated Na+ /K+ channel voltage gated K+ channel opens voltage gated Na+ channel opens

neurotransmitter released Ca2+ diffuses IN, binds to vesicle Na+ diffuses IN slowly, approaching threshold potential Na+ diffuses IN quickly: depolarization K+ diffuses OUT quickly: repolarization

macrophage and infected host cell present antigen helper T cell binds to antigen presenting cell B cell releases antibodies cytotoxic T cell bonds to infected host cells infected host cells lyse virus attaches to host cell cytotoxic T cell divides infected host cell produces more virus

macrophage kills virus by endocytosis virus enters host cell antibodies bond to virus virus enters host virus antibody complex is excreted by host cytotoxic T cell releases perforin B cell divides helper T cell releases cytokines

Unit 4: Cell Communication

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