[BIOLOGY 225] - Midterm Exam Guide - Everything you need to know! (24 pages long)

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BIOLOGY 225
MIDTERM EXAM
STUDY GUIDE
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Lecture 3
July 5, 2016
Endocrinology study of hormones (chemical messenger molecules)
o The production of hormones is released from endocrine gland into the blood
circulation
o Hormones travel all around the body, but only produce their action on target cells
that have receptors to recognize the hormone and allow for hormone action
Endocrine vs. Exocrine (ex. Pancreas)
o Endocrine glands do not have any duct that leads hormones to outside; secretion
is released directly into blood circulation (secrete hormones)
o Exocrine glands discrete ducts that are responsible for material made inside
gland and is open to the outside medium
Components of Endocrine System (step-by-step)
o Production Organ (Endocrine)
o Transport Medium (blood)
o Target Organ (receptors)
Types of Chemical Regulation
o Hemocrine (Endocrine) messenger molecule released into bloodstream and acts
on distant target issue
o Paracrine (regulation of neighboring cells) doesn’t get into blood circulation; in
extracellular fluid; cell to cell regulation by local hormones
o Autocrine (self regulation) cell to cell regulation by local hormones
o Direct Cell Signaling gap junction; direct regulation movement from one cell
to other w/o any interference
Hormone Biochemistry
o Structure
Proteins, Peptides and Amino Acid Derivatives
Synthesized in rough ER stored in vesicles
Made and stored in endocrine cell; made in continuous basis
Released by exocytosis; most are hydrophilic
o Dissolve in aqueous medium
o Cannot pass through plasma membrane
Bind to transmembrane receptors on target cell
Ex: Peptide Hormone - Stimulation of the breakage of enzymes
responsible for Pro-OpioMelanoCortin (POMC)
o Opio Endorphin
o Melano Melanocyte Stimulating Hormone (MSH)
(responsible for skin pigmentation only in fish, amphibians,
and reptiles; skin color changes)
o Cortin Corticotropin (ACTH) (hormone of stress)
caused by stimulation of stress
Steroids
Derived from cholesterol
Hydrophobic
o Insoluble in aqueous medium
o Diffuse through plasma membrane
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Lecture 3
July 5, 2016
o Can’t be stored; synthesized on demand – only made once
stimulus arrives
o Transported to target cell by carrier proteins
o Bind to intracellular receptors
Steroid hormone transport (simple diffusion; hydrophobic
molecules)
o Hormone secretion (binding proteins) Target Tissue
(hormone-receptor binding) Receptor Activation
Biological Action
o Solubility in aqueous medium (see above)
o Synthesis & Secretion (see above)
o Transport
o Receptor Binding
Characteristics of Hormone Actions
o Produced in small quantities
o Large effects message amplification
o Diverse biological actions
Many backups for lack of 1 hormone not functioning properly
Hormone Receptor Interactions:
o One hormone may bind to multiple receptors
Receptor isoforms
Expressed on diff. target cells
Diff responses to same ligand
o Hormone-receptor binding may lead to multiple responses
o Hormone may have diff types of receptors on diff target cells diff actions
Agonist looks and acts like hormone molecules making hormone irrelevant
Antagonist hormone activity will be reduced; inhibition
Hormonal Dysfunction
o Hormone Concentration in Blood metabolism; inactive, under-, over-, endocrine
gland
o Receptor Dysfunction mutation or desensitized and no response to hormone
Types of Receptors
o Intracellular (Cytoplasmic, Nuclear receptors)
Thyroid and steroid hormones (T3 & T4) small and hydrophobic
Regulate the transcription of target genes
Hormone internalization hormone receptor binding conformation
change receptor activation look @ ppt
Hormone reacts w/ DNA to begin protein synthesis
RNA transcribes multiple proteins
o Transmembrane receptor
Transmembrane domain hydrophobic
Ligand-binding domain (sticks out in extracellular fluid) specific
hormone will get recognized and will bind here
Intracellular domain hydrophilic changes shape and activation of
receptor occurs
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