Bio 210 Test 2 (Chapters 5, 7 And Endocrine) – Qs & As
Receptors for lipophobic messengers are typically located where in the cell?
Right Ans - Plasma membrane
Which of the following are proteins on a target cell that specifically recognize
and bind only one messenger or a class of messengers? Right Ans -
Receptors
Chemical messengers derived from cholesterol fall under which category?
Right Ans - Steroid messengers
Which of the following chemical messengers is characteristically released
from an endocrine gland? Right Ans - Hormone
Hormones can be transported in blood in dissolved form or bound to Right
Ans - Carrier proteins
What type of hormones bind to receptors located on the cell membrane?
Right Ans - Water soluble hormones, such as insulin and epinephrine
Which intracellular substance degrades cAMP, thus inactivating the response
to a hormone? Right Ans - Phosphodiesterase
Growth factor hormones, such as insulin, bind to which type of receptors?
Right Ans - Tyrosine Kinase Receptors
Which is the correct order of events for hormones activating Gs Proteins?
Right Ans - Activation of G protein, binding of GTP, activation of adenylate
cyclose, conversion of ATP to cAMP
Which second messenger causes the release of calcium from the endoplasmic
reticulum> Right Ans - IP3
Which of the following adrenergic receptors increase cAMP levels? Right
Ans - B(beta) receptors
Where in the cell are receptors for cholesterol derived chemical messengers
typically located? Right Ans - Nucleus/Cytosol
,The strength of binding between a messenger and its receptors is known as
Right Ans - affinity
One of the striking features of second messengers is the ability to elicit a
marked response on a target cell by small changes in the concentration of a
chemical messenger. This phenomenon is known as Right Ans - single
amplification
A chemical messenger that is released into the blood stream to travel to its
target would be categorized as a(n) Right Ans - hormone
Chemical messengers that bind to a receptor, preventing a biological response
are Right Ans - antagonists
Direct communication between adjacent cells is provided by Right Ans -
Gap junctions
A change in electrical properties of the cell is most likely the result of a
chemical messenger binding to which type of receptor? Right Ans - An ion
channel
Mechanisms of intercellular communication Right Ans - Direct: Gap
junctions
Indirect: Chemical messengers
Gap Junctions Right Ans - Composed of membrane proteins, link the
cytosol of two adjacent cells, particle movement between cells acts as a signal,
communication is direct, common in smooth and cardiac muscles.
Where are gap junctions common? Right Ans - Smooth and cardian muscles
Chemical messengers Right Ans - Messenger is produced by the source cell
and released often by secretion. The messenger travels to the target cell. The
target cell has receptors for the messenger. Binding of the messenger to the
receptor triggers a target cell response. Communication is indirect.
Paracrine Chemical messenger Right Ans - Chemical that signals a nearby
cell. Example is histamine which is responsible for inflammation response.
, Autocrine Right Ans - A subclass of paracrine. Chemical signals the same
cell that secreted it (talks to itself). Source and target are the same.
Neurotransmitter Right Ans - Messenger produced by neurons. Is released
into the ECF of the synaptic cleft. Ex: ACH, GABA, serotonin.
Hormone Right Ans - Messenger is produced by endocrine cells. Secreted
into the blood via interstitial fluid. EX: insulin, estrogen, thyroxin.
Neurohormone Right Ans - A special class of hormone. Messenger is
produced by neurons. Secreted into the blood. Ex: ADH, oxytocin
Lipophobic ligand Right Ans - Water soluble. Does not cross the cell
membrane, receptors are on the cell membrane. General action of target
response, enzyme activation and membrane permeability changes.
Lipophillic ligand Right Ans - Lipid soluble. Easily crosses cell membrane,
has intracellular receptors. General action of target response is via gene
activation.
Amino acid Right Ans - Lipophobic. Target cell receptors are on the cell
membrane. Only four amino acids function as messengers, all as
neurotransmitters. Ex: glutamate, asparate, glycine, GABA. Amino acids are
synthesized within a neuron, stored in vesicles until needed, and released by
exocytosis.
Amines Right Ans - Most are lipophobic, except thyroid hormones. Target
receptors on the cell membrane. Made or derived from an amino acid.
Contains an amine group. Amines are produced in the cytosol of the source
cell, stored in vesicles of the source, released by exocytosis. The amine
produced is determined by which enzymes are present in the source cell.
Peptide and protein messengers Right Ans - Most abundent type of ligand.
Lipophobic. Target receptors on the cell membrane. Made of chains of amino
acids. (Peptide ligand <50 amino acids, Protein ligand >50 amino acids).
Peptide and proteins are formed by cleaving larger proteins, stored in
secretory vesicles, released by exocytosis.
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