Cell Communication: Part 1

Describe the depolarization of a muscle cell, starting with the signal .

1. Action potential reaches the bottom of the axon terminal 2. Voltage gated Calcium channels open and calcium floods in 3. Influx of calcium causes vesicles to exocytose their neurotransmitters (acetylcholine) 4. Once acetylcholine is released into the synapse, the acetylcholine will bind to its receptor (ligand-gated ion channel) on the muscle 5. Sodium floods into the muscle cell causing depolarization Sodium is positively charged The muscle fiber was negatively charged- now becomes more positive- less polarized

Virus-Cell interaction process

1. Binding 2. Release of viral RNA 3. Translation of RNA-dependent- RNA Polymerase (replicates viral RNA) 4. Replication of genomic RNA 5. Replication of structural RNAs 6. Translation of viral proteins 7. Budding of vesicles 8. Assembly of new viruses 9. Exocytosis and release of new virus

GPCR pathway

1. Ligand signaling receptor 2. Receptor changes shape and attatches a GTP to the G-protein 3. GTP activates G-protein 4. Activated G-protein will activate adenylyl cyclase 5. Activated Adenylyl cyclase is responsible for changing ATP to cAMP 6. cAMP is responsible for amplification and activate kinases 7. Kinase will activate other enzymes to cause a response

What makes a molecule a hormone?

A molecule is a hormone when it is a chemical messenger or secreted by an endocrine gland. Hormone is a small, long-distance signaling molecule that typically travels in the blood and comes from the endocrine system

How does ADH increase blood pressure?

ADH- Anti: not, Diuretic: go pee; Not urinate hormone Brain recognizes increase in solute concentration in blood, it releases ADH, causes kidney to reabsorb water

Amplification process of ATP after interaction with adenylyl cyclase

ATP > cAMP > Protein Kinase > Enzyme > Product

Describe quorum sensing.

Bacteria talk to each other be releasing chemicals, and the chemicals are picked up by other bacteria, which is used to determine the population size and coordinate bacteria group responses and/or activities.

In metabolism, what is catabolic vs. anabolic?

Catabolic is breaking large molecules (digestion) Anabolic is building large molecules (synthesis)

How would dexamethasone help with the infection?

Causes transcription of anti-inflammatory and blocks transcription of pro-inflammatory to calm down the immune system.

Positive feedback examples

Fruit ripening, blood clotting, child birth

Endocrine definition

Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells. A cell targets a distant cell through the bloodstream. Ex. pituitary, thyroid, and adrenal glands

presynaptic drug action

If the drug is somehow affecting the neurotransmitter is coming out of the cell or the reuptake back into the cell.

Negative feedback: metabolic pathway product inhibition

Isoleucine inhibits enzyme 1 from making molecule A (overproduction of a product can inhibit an enzyme from further production)

What happens in the signaling portion of cell communication?

Ligand binds to receptor, receptor changes shape and initiates the response

Negative feedback vs. positive feedback- explain them in a way that will make it easy for you to remember which is which.

Negative feedback is maintaining homeostasis and positive feedback is moving away from homeostasis in hopes that it will go back to normal.

Perforin

One of the proteins released by cytotoxic T cells on contact with their target cells. It forms pores in the target cell membrane that contribute to cell killing causing it to lyse or burst.

What are 4 types of cell signalling?

Paracrine, autocrine, endocrine, juxtacrine

What can b cells be differentiated into?

Plasma cells and memory cells

Apoptosis

Programmed cell death, for reasons such as development or that the cells aren't working properly -Cell is signaled, then multiple things happen including opening up lysosomes

Autocrine definition

Signal molecules secreted by a cell bind to receptors on that same cell. Ex. Cytokine interleukin-1 in monocytes: when interlukin-1 is produced in response to external stimuli, it can bind to the cell-surface receptors of the same cell that produced it.

Paracrine Definition

Signal molecules secreted by one cell bind to receptors on other cells in the local area (next to) Ex. neurotransmitters acting in the synaptic gap

What kind of molecule is dexamethasone?

Steroid Lipids (glucocorticoid)

How is the release of ethylene gas an example of positive feedback?

The release of ethylene gas from plants causes the surrounding fruit to ripen at the same time. This is a positive feedback because the production of ethylene gas doesn't stop itself, but stops when it no longer causes an effect. Ethylene gas moves the fruits of plant further from homeostasis to causes response.

Homeostasis

The survivable range for cells/organisms, stable/equilibrium

When B cells are activated, what do they do?

They differentiate to plasma cells and memory cells. Plasma cells release antibodies that are specific to antigens and memory cells remembers the antigens for future pathogen invasions.

B-Cells

Uses the antigens from pathogens to differentiate

pre-synaptic neuron

a neuron that delivers a signal to a synapse

Adjacent plant cells have narrow channels called plasmodesmata that pass through the cell walls of the connected cells and allow a cytoplasmic connection between the cells. Which of the following statements best describes a primary function of plasmodesmata? a. They allow the movement of molecules from one cell to another, enabling communication between cells. b. They prevent the cell membrane from pulling away from the cell wall during periods of drought. c. They eliminate the need to produce signaling molecules and eliminate the need for cells to have receptors for signaling molecules. d. They increase the surface area available for attachment of ribosomes and thus increase protein synthesis.

a.

An antigen can induce an immune response in a host organism. Antigens are targeted by antibodies that are produced by the organism's immune system in response to contact with the antigen. Antibodies are specific to antigens. Many different cell types are involved in immune responses. Which of the following best describes the role of cell-to-cell communication during a response to an invasion of antigens? a. Chemicals that are secreted from antigen-presenting cells then activate helper T cells. b. A macrophage cell engulfs a pathogen in the blood. c. Antigens attaching to receptors on memory B cells stimulate the memory B cells to become plasma cells. d. Antigen-presenting cells engulf antigens at the first exposure.

a.

During a fight-or-flight response, epinephrine is released into the body's circulatory system and transported throughout the body. Some cells exhibit a response to the epinephrine while other cells do not. Which of the following justifies the claim that differences in components of cell signaling pathways explain the different responses to epinephrine? a. Cell signaling depends on the ability to detect a signal molecule. Not all cells have receptors for epinephrine. Only cells with such receptors are capable of responding. b. Cell signaling depends on the transduction of a received signal by the nervous system. Not all cells are close enough to a synapse to receive the signal and respond. c. Cell signaling depends on the signal being able to diffuse through the cell membrane. Epinephrine is incapable of diffusing through some plasma membranes because of the membrane's phospholipid composition. d. Cell signaling requires reception, transduction, and response. All cells can receive epinephrine, all cells respond with a pathway, but only select cells have the proper coding in their DNA to respond.

a.

Fibroblast growth factor receptors (FGFRs) are transmembrane proteins that regulate cellular processes such as cell proliferation and differentiation. The extracellular domains of FGFR proteins bind specifically to signaling molecules called fibroblast growth factors. The intracellular domains of FGFR proteins function as protein kinases, enzymes that transfer phosphate groups from ATP to protein substrates. FGFR activation occurs when binding by fibroblast growth factors causes FGFR proteins in the plasma membrane to become closely associated with each other. The association of two FGFR proteins stimulates protein kinase activity, which triggers the activation of intracellular signaling pathways. A simplified model of FGFR activation is represented in Figure 1. Which of the following changes in the FGFR signaling pathway is most likely to result in uncontrolled cell proliferation? a. The irreversible association of FGFR proteins. b. The loss of the FGFR protein kinase function. c. A decrease in the intracellular concentration of ATP. d. A decrease in the extracellular concentrations of fibroblast growth factors.

a.

Positive Feedback

adding increasing amounts of the signal to make change happen faster (snowball effect)

Metformin is a drug used to treat type 2 diabetes by decreasing glucose production in the liver. AMPK-activated protein kinase (AMPK) is a major cellular regulator of glucose metabolism. Metformin activates AMPK in liver cells but cannot cross the plasma membrane. By blocking AMPK with an inhibitor, researchers found that AMPK activation is required for metformin to produce an inhibitory effect on glucose production by liver cells. Which of the following best describes the component that metformin represents in a signal transduction pathway that regulates glucose production in the liver? a. It is a secondary messenger that amplifies a signal through a cascade reaction. b. It is a ligand that activates the signal transduction pathway of the activation of AMPK. c. It is an allosteric regulator that binds to a crucial section of the DNA that makes the enzymes needed for glucose uptake. d. It is a competitive inhibitor that binds to glucose and prevents it from entering the cell.

b.

Signal transduction may result in changes in gene expression and cell function, which may alter phenotype in an embryo. An example is the expression of the SRY gene, which triggers the male sexual development pathway in mammals. This gene is found on the Y chromosome. a. If the SRY gene is absent or nonfunctional, the embryo will exhibit male sexual development. b. If the SRY gene is absent or nonfunctional, the embryo will exhibit female sexual development. c. An embryo with a male sex chromosome will always exhibit male sexual development. d. An embryo with two male sex chromosomes will always exhibit male sexual development.

b.

The insulin receptor is a transmembrane protein that plays a role in the regulation of glucose homeostasis. The receptor's extracellular domain binds specifically to the peptide hormone insulin. The receptor's intracellular domain interacts with cellular factors. The binding of insulin to the receptor stimulates a signal transduction pathway that results in the subcellular translocation of GLUT4, a glucose transport protein that is stored in vesicles inside the cell. A simplified model of the insulin receptor-signaling pathway is shown in Figure 1. Which of the following statements best predicts the effect of a loss of function of the insulin receptor's intracellular domain? a. The stimulation of the signal transduction pathway will increase. b. The storage of GLUT4 in vesicles inside the cell will increase. c. The number of GLUT4 molecules in the plasma membrane will increase. d. The concentration of glucose inside the cell will increase.

b.

A hydrophilic peptide hormone is produced in the anterior pituitary gland located at the base of the brain. The hormone targets specific cells in many parts of the body. Which of the following best explains a possible mechanism that would enable the hormone to efficiently reach all of the target cells in the body? a. The hormone interacts with the nerves at the base of the brain and directs signals to the target cells through the nervous system. b. The hormone diffuses into target cells adjacent to the anterior pituitary gland, where the hormone is degraded. c. The hormone is released into the bloodstream where it can be transported to all cells with the correct receptors. d. The hormone moves through cytoplasmic connections between cells until it has reached all cells with the correct intracellular binding sites.

c.

Which of the following steps in a signaling pathway typically occurs first once a chemical messenger reaches a target cell? a. Specific genes are activated. b. A second messenger molecule is produced. c. A ligand binds to a receptor. d. Specific proteins are synthesized.

c.

G proteins are a family of receptor proteins that are involved in transmitting signals from outside a cell to inside a cell. When a signaling molecule binds to a G protein, the G protein is activated. The G protein then activates an enzyme that produces a second messenger called cAMP . Which of the following describes a critical role of cAMP during the transduction stage of a G protein signal transduction pathway? a. cAMP carries the signal to the nucleus of the cell and results in new sequences of nucleotides being added to the cell's DNA. b. cAMP binds the extracellular signal molecule and carries it to the intracellular target specified by the signal. c. cAMP modifies a specific monomer so that it can be added to an elongating structural macromolecule. d. cAMP results in the activation of an enzyme that amplifies the signal by acting on many substrate molecules.

d.

The beta-2 adrenergic receptor is a membrane-bound protein that regulates several cellular processes, including the synthesis and breakdown of glycogen. The receptor binds specifically to the hormone epinephrine. The binding of epinephrine to the beta-2 adrenergic receptor triggers a signal transduction cascade that controls glycogen synthesis and breakdown in the cell. A simplified model of the signal transduction cascade is represented in Figure 1. Which of the following outcomes will most likely result from the inactivation of the beta-2 adrenergic receptor? a. The cellular concentration of cyclic AMP will increase. b. The enzymatic activity of protein kinase A will increase. c. The activation of glycogen phosphorylase will increase. d. The rate of glycogen synthesis in the cell will increase.

d.

Pathogen

disease causing organism.

macrophage

eats pathogens in a process called endocytosis (phagocytosis) and breaks the pathogen down and displays the pathogen's antigens. This act of displaying the antigens helps other immune cells activate and fight against the pathogen.

HIV

human immunodeficiency virus- infects and destroys several kinds of WBC's and weakens the immune system.

post-synaptic drug action

if the drug is somehow affecting the neurotransmitter coming to the cell from another cell

How do Macrophages kill pathogens?

ingest pathogens by endocytosis

Helper T cells

interacts with the antigens displayed by macrophages. The help T cells then stimulate and activate Killer T cells and B cells.

Secondary infection

is a bacterial infection that someone may get after a viral infection because their system is weakened. ex. pneumonia

antibiotics

kill non-resistant bacteria but may cause an increase in resistant bacteria.

Plasma Cells

produce special weapons called antibodies to fight specific pathogens. Each antibody only works against one specific antigen. Once a pathogen has been tagged by the antibodies released by plasma cells, it is easier for macrophages to find the antigen or pathogen and destroy them.

Antibody

protein that tags a specific antigen.

Memory Cells

remember the antigen so that the immune system can fight off the pathogen faster the next time it is encountered.

Juxtacrine definition

signaling requires direct contact between two cells (gap junctions)

Antigen

surface protein that helps identify an organism.

Negative feedback examples

temperature, metabolism, blood sugar, osmoregulation

post-synaptic neuron

the neuron on the receiving end of the synapse

How do molecules in a signal pathway know when to do the next step?

the receptor changes shape

Killer T cells

use special weapons (perforin and cytotoxins) to destroy infected body cells. This kills your infected cells to help prevent the spread of the pathogen.

Negative Feedback

when the cell/body get out of homeostatic range, processes bring it back