Bio 201 1st Edition Lecture 15 Outline of Last Lecture I. Transmembrane TransportA. Simple DiffusionB. Facilitated DiffusionC. Active TransportOutline of Current LectureI. Signaling ModesII. Ligand- Receptor InteractionsA. Cells ResponseIII. Second MessengersCurrent LectureI. Signaling Modes- classified between distance of “sender” and “recipient” cell.-Autocrine- signaling to self, may be un-meaningful. Ex) Cancerous tumor-Juxtacrine- Signaling to immediate adjacent cells. Ex) neurotransmitters -Paracrine- Signaling to a few cell diameters apart. Ex) hair follicles -Endocrine/ Hormonal- Distant signaling, uses blood stream. Ex) estrogen -Contact-mediated- No diffusible signal, mediated by molecules on adjacent cells, using physical contact. II. Ligand- Receptor Interactions-Ligand- Signaling molecule-In order to respond to a signal, the cell must have a receptor protein. -Ligand binding to receptors is specific and high affinity. -Ligand bonding cause conformational change of receptor. -Conformational change in a receptor leads to a cellular response. A. Cell Response-Channel opening-Production ofa Second Messenger (most common) -Direct These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.activation of receptor enzymatic activity -Steroid hormones- gene transcriptionIII. Second Messenger- The most common cellular response to a signal. -Scientists wanted to know how (the step) epinephrine (adrenaline) receptors transformed into glycogen phosphorylase- the catalyst of glycogenglucose. -To do so, they put liver cells into a test tube and centrifuged it to separate cytoplasm and membranes. Next they added epinephrine to membranes and small molecules , then they centrifuged membrane and kept supernatant, “activated cytoplasm”. Then they added supernatant to “inactivated cytoplasm”, and they got glycogen phosphorylase activity. -This substance that’s produced by the membrane and that activated glycogen phosphorylase was Cyclic AMP- the second messenger. -The second messenger is a soluble molecule (not protein), produced in the membrane, that activates a membrane
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