Biology Study Guide Exam 2

Biology Study Guide Exam 2 - STUDY GUIDE FOR EXAM 2 CHAPTER...

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STUDY GUIDE FOR EXAM 2 CHAPTER 11 1. The term signal transduction is the process by which a signal on a cells surface is converted into a cellular response in a series of three steps. 2. see page 206 3. They are common. G protein systems are involved in many human diseases, including bacterial infections. 4. DON’T NEED 5. Protein kinase is the general name for an enzyme that transfers phosphate groups from ATP to a protein. It brings about a “phosphorylation cascade” (page 209). In a phosphorylation cascade, a series of different molecules in a pathway are phosphorylated in turn, each molecule adding a phosphate group to the next one in line. The active and inactive forms of each protein are represented by different shapes to remind you that activation is usually associated with a change in molecular conformation. 6. The advantage is that the phosphorylation cascade involve protein phosphates which are enzymes that rapidly remove phosphate groups from proteins (dephosphorylation). The phosphorylation/dephosphorylation systems acts as a molecular switch in the cell, turning activities on or off as required. 7. Second messengers are small, nonprotein water soluble molecules or ions. Two most widely used second messengers are cyclic AMP and calcion ions. The first messenger activates a G-protein-linked receptor, which activates a specific G protein. In turn, the G protein activates adenylyl cyclase, which catalyzes the conversion of ATP to cAMP. Figure 11.10 8. Cyclic AMP is a second messenger. The immediate effect of cAMP is usually the activation of a serine/threonine kinase called protein kinase. 9. The calcium concentration in the cytosol is much lower than in the exracellular fluid and ER. (figure 11.11) 10. Inositol trisphospate diffuses through the cytosol and binds to an IP3gated calcium channel in the ER membrane, causing it to open. CHAPTER 12 1. 2. Chromatin is a complex of DNA and associated protein molecules. In Interphase, Chromatin is duplicated Prophase- They become tightly coiled, condensing into discrete chromosomes Prometaphase- each of the two chromatids of a chromosome now has a kinetochore located at the centromere Metaphase- Chromosomes convene at the metaphase plate Anaphase- chromosomes move toward opposite ends of a cell Telophase- chromosomes become less condensed. 3. (See chapter 19 #2) Nucleosome- The basic, beadlike unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound around a protein core composed of two copies of each of four types of histone. 4. G0- Nondividing state of the cell. G1- Cell grows S- Continues to grow as it copies chromosomes. (Chromosomes replicate) G2- Grows more as it completes preparations for cell division. M- Mitosis Divides the nucleus and distributes its chromosomes to the daughter nuclei.
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Biology Study Guide Exam 2 - STUDY GUIDE FOR EXAM 2 CHAPTER...

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