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BIO 1120 - Exam II
Chapter 11
| Term | Definition |
|---|---|
| Quorum Sensing allows bacteria to adjust their gene expression because Quorum Sensing is | a process of cell-cell communication that enables bacteria cells to exchange information about cell density |
| What are the three steps of cell signaling? | Reception, transduction, response |
| A ligand is | a molecule that binds specifically to another molecule, usually a larger one |
| The three major types of surface transmembrane receptors are | G protein-coupled receptors (GPCRCs), receptor tyrosine kinases, and ion channel receptors |
| GPCRs works with the help of _____. | G protein |
| G protein is a protein that | binds the energy-rich molecule GTP |
| Some examples of signaling molecules that use GPCRs are | yeast mating factors, neurotransmitters, and epinephrine |
| There are over _____ different kinds of GCPRs. | 800 |
| Every GCPR protein has _____ α helices in each polypeptide chain. | 7 |
| The _____ on GCPR protein polypeptides provide sites for ligand binding and G protein-interaction. | loops |
| In humans, _____, _____, and _____ depend on GPCRs. | vision, smell, taste |
| G protein is active when _____ is attached to it. | GTP |
| GTP attaches to a G protein when | a ligand binds to a GCPR protein |
| An _____ is detached to GTP when changing back into GDP | inorganic phosphate |
| Receptor tyrosine kinases (RTKs) are characterized by their _____ activity. | enzymatic |
| RTKs are a type of _____. | enzyme |
| RTKs catalyze the transfer of a phosphate group from _____ to an amino acid called _____. | ATP; tyrosine |
| RTKs generally activate _____ signal pathways. | multiple |
| GCPRs generally activate _____ signal pathway. | one |
| When 2 ligands attache to the binding site of 2 corresponding RTKs, | the two RTKs move very close to one another. |
| A dimer complex is | two RTK monomers in very close proximity (which occurs when ligands bind to RTKs) |
| What activates a RTK? | Dimerization |
| When RTKs are activated, a _____ is added from ATP. | phosphate group |
| A ligand-gated ion channel remains close until | a ligand binds |
| Ligand-gated ion channels open when | a ligand in bound to the receptor protein. |
| Ligand-gated ion channels are very important in the _____ system. | nervous |
| Ligands that bind to intracellular receptor proteins are _____ or _____ enough to cross the cell membrane. | hydrophobic; small |
| Hydrophobic signaling molecules that can bind to intracellular receptor proteins are | steroid hormones and thyroid hormones of animals |
| An example of a small signaling molecule that can bind to intracellular receptor proteins is | nitric oxide (NO) |
| When a ligand binds to an intracellular receptor protein, the receptor changes into a _____ - receptor complex. | hormone |
| The most common response to the binding of a ligand to an intracellular protein receptor is | turning on/off a gene. |
| Cellular signal responses only occur in | cells that contain receptors for the specific ligands. |
| What kind of protein receptor does the hormone Aldosterone bind to? | intracellular receptor protein. |
| When the hormone aldosterone binds to its receptor protein, it becomes | a hormone-receptor complex. |
| Transcription factors are specialized proteins that can | control what genes are turned on. |
| Most water-soluble molecules bind to what kind of receptor proteins? | Extracellular receptor proteins. |
| The _____ of a _____ triggers the first step in signal transduction. | binding; ligand |
| _____ are the most common molecules that can respond to the first step of cell signaling (reception). | Proteins |
| Do signaling molecules PHYSICALLY get passed along the signaling pathway? | No |
| It is not a ligand that passed through the pathway, it is a _____. | signal |
| A protein kinase is an enzyme that transfers _____ from _____ to a protein. | phosphate group; ATP |
| What are the other two common protein kinases (besides tyrosine)? | Serine and threonine |
| A phosphorylation cascade is a series of chemical reactions in which an enzyme (kinase) | phosphorylates and activates another, leading to phosphorylation of many proteins. |
| Phosphorylation can _____ or _____ the activity of the protein. | increase; decrease |
| Protein phosphatases are enzymes that rapidly remove _____ _____ from proteins | Phosphate groups |
| Second messengers are molecules that relay _____ from a _____. | messages; receptor |
| Second messengers are either small, nonprotein, water-soluble molecules or _____. | ions |
| Second messengers participate in which two kinds of extracellular signal receptor proteins? | GPCRs and RTKs |
| What are the two most common second messengers? | Cyclic AMP and calcium ions (Ca2+) |
| cAMP is a small molecule produced from _____. | ATP |
| Adenylyl Cyclase is an enzyme that converts ATP to what? | cAMP |
| When epinephrine binds to the GPCR, you will see a rise in concentration of what? | cyclic AMP |
| What is the order of the signal pathway of epinephrine? | epinephrine - G protein - adenylyl cyclase - cAMP - protein kinases |
| Are calcium ion concentrations higher outside of the cell or in the cytoplasm? | outside of the cell. |
| Inositol triphosphate (IP3) and diacylglycerol (DAG) are involved in _____ release. | calcium |
| When the phospholipid PIP2 is broken apart, _____ and _____ are produced as second messengers. | IP3 and DAG |
| Many signaling pathways regulate _____ synthesis by turning genes on/off. | protein |
| Nuclear responses to a signal involve _____. | turning genes on/off |
| Cytoplasmic responses to a signal include the regulation of _____ activity. | Protein |
| What is the final step of the epinephrine signaling pathway? | An enzyme that catalyzes the breakdown of glycogen is activated. |
| The extent and specificity of the signal response is regulated by what four things? | Signal amplification; diversity between different cells; scaffolding proteins; termination of the signal |
| Signal Amplification is possible because during the signal cascade, | activated proteins/molecules can activate multiple other molecules themselves. |
| Different kinds of cells have _____ collections of proteins. | different |
| Responses from the same signal but in two different cells will differ because | different cells will turn on different sets of genes. |
| What are scaffolding proteins? | They are large relay proteins in which many other relay proteins are attached to. |
| How do scaffolding proteins increase the efficiency of signal transduction? | Scaffolding proteins increase the speed and accuracy os signal transfer between cells. |
| Is the binding of signaling molecules (ligands) to receptors reversible or irreversible? | reversible |
| When the external concentration of ligands decreases, internal cellular response _____. | decreases |
| Controlled cell suicide is referred to as | Apoptosis |
| When undergoing apoptosis, cells _____ in size and becomes lobed. | shrink |
| Lobed, or "blebbing" that occurs during apoptosis is due to the cell parts being packaged in _____. | vesicles |
| True or false. Apoptosis signals can come extracellularly and intracellularly. | True |
| Caspases consist of proteases and nucleases. What are caspases? | Caspases are enzymes that cut up proteins and DNA of a cell. |
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