Term
| What are the three categories of Hormones? |
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Definition
Peptides and Proteins
Tyrosine Derivatives
Steroids |
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Term
| What is a Signal Recognition Complex? |
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Definition
| The complex formed during protein synthesis when the signal recognition particle binds to a docking protein and signal sequence receptor on the ER membrane |
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Term
| Where are secretory proteins packaged into granules for transport? |
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Definition
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Term
| What is the most common form of feedback? |
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Definition
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Term
| What is the Metabolic Clearance Rate? |
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Definition
| It is the volume of plasma cleared of hormone per unit time. It incorporates target cell uptake, metabolic degradation, and clearance of the hormone. |
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Term
| What determines the specificity of hormones? |
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Definition
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Term
| What are the two types of receptors that bind extracellular signaling molecules? |
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Definition
Cell Surface Receptors
Intracellular Receptors |
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Term
| How do cell surface receptors act? |
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Definition
| They bind peptide or polypeptide proteins and generate second messengers. |
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Term
| How do intracellular receptors act? |
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Definition
| Usually bind steroids or thyroid hormones and alter gene expression. |
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Term
| What does the binding of a hormone to a receptor immediately cause? |
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Definition
| It causes a change in the conformation of the receptor, signaling the presence of the hormone to the cell and initiating intracellular signals. |
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Term
| What is the equilibrium dissociation constant? |
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Definition
Kd = [H][R]/[HR] = k2/k1
Kd equals the concentration of hormone that half saturates the receptors. |
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Term
| T/F: Most hormones circulate at concentrations much less than the Kd. |
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Definition
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Term
| T/F: The number of cell receptors are usually not limiting. |
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Definition
| True. Even small fractions of receptors that get saturated can create the maximal response. |
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Term
| A change in the receptor conformation upon extracellular signaling molecule binding is transmitted through what to reach the intracellular domain |
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Definition
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Term
| What do Guanine Nucleotide-Binding Protein-Coupled receptors (GPCRs)signal inside the cell? |
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Definition
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Term
| How many subunits are G-Proteins comprised of? |
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Definition
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Term
| Upon binding GTP which subunit dissociates from the rest in G proteins? |
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Definition
| The alpha (α) subunit dissociates from the β and γ subunits. |
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Term
| What are the second messengers that are associated with GPCRs? |
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Definition
| cAMP, diacylglycerol, inositol triphosphate, and calcium |
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Term
| What does second messenger cAMP bind to? |
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Definition
| cAMP-Dependent Protein Kinase A |
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Term
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Definition
| It causes the release of Ca2+ from intracellular stores by activating IP3 receptors. |
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Term
| Where is most intracellular Ca2+ stored? |
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Definition
| Inside the ER and the mitochondria |
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Term
| In non-muscle cells, what does Ca2+ bind to which then activates phosphorylase kinase and phosphodiesterase. |
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Definition
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Term
| For what does DAG increase the affinity of Protein Kinase C? |
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Definition
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Term
| What is the structure of insulin receptors? |
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Definition
| It exists as paired disulfide-linked heterodimers (αβ)2. |
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Term
| What do tyrosine kinase receptors typically bind to? |
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Definition
| Growth Factors: Insulin, IGF-I, Platelet Derived Growth Factor, EGF |
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Term
| What is the role of mitogen-activated protein (MAP) kinases? |
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Definition
| They serve as the downstream effectors, transit into the nucleus upon activation, and alter gene transcription important for cell proliferation and differentiation. |
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Term
| T/F: Steroids travel freely in the circulation. |
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Definition
| False. Steroids circulate bound to carrier proteins since free hormone is susceptible to degradation. |
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Term
| T/F: Steroids have a higher affinity for their receptors compared to their carrier proteins. |
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Definition
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Term
| T/F: There is an abundance of steroid receptors so they cannot be responsible for limiting the response. |
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Definition
| False. There are only a few thousand receptors, so response can be limited due to receptors. |
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Term
| What is the structure of steroid receptors? |
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Definition
| They contain a DNA binding domain with a zinc finger, 2 hormone binding domains and a hypervariable region. |
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Term
| What is the role of HSP90? |
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Definition
| Then bound to HSP90, steroid receptors can bind to hormone but not DNA. Thus, it allows the receptor to selectively bind hormone over DNA |
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