Exam 3 Study Notes Cell Bio PDF

Chapter 15: Intracellular Compartments and Protein Transport 1. Protein Transport Pathways - Three main pathways: Nuclear pores, membrane transport, vesicle transport. 2. Nuclear Import - Requires nuclear localizaAon signal (NLS) and imporAn; size limit around 60kDa (550 amino acids) for passi...

Chapter 15: Intracellular Compartments and Protein Transport 1. Protein Transport Pathways - Three main pathways: Nuclear pores, membrane transport, vesicle transport. 2. Nuclear Import - Requires nuclear localizaAon signal (NLS) and imporAn; size limit around 60kDa (550 amino acids) for passive diffusion. - Ran GTPase: GTP form is primarily inside the nucleus, releasing imported proteins upon binding. 3. mRNA Export - Differs from protein export; does not use Ran GTPase but relies on cap-binding proteins. 4. Rough ER Assembly - Ribosomes bind to the ER via signal-recogniAon parAcle (SRP) upon targeAng proteins for secreAon. 5. Protein TranslocaAon into ER - Sequence: SRP binds signal pepAde, docks at SRP receptor, protein translocates across ER membrane. 6. Endocytosis and Exocytosis - Clathrin-mediated endocytosis involves adapAn, clathrin, and dynamin. - Exocytosis uses SNAREs (v-SNARE on vesicle, t-SNARE on target) and Rab GTPase. 7. GlycosylaAon - Occurs in ER, carbohydrate chains are aYached to asparagine residues on proteins. 8. Golgi Apparatus - Structure: cis (nucleus-facing) and trans (cell edge-facing); modifies proteins and synthesizes sphingolipids. 9. Endosome and Lysosome FuncAons - Lysosomes maintain low pH through H+ pumps, which is necessary for enzyme acAvaAon. 10. Transcytosis, Phagocytosis, and Autophagy - Transcytosis: Moves large molecules across cells without direct channel transport. Chapter 16: Cell Signaling 1. Types of Cell-to-Cell Signaling  - Endocrine (hormones, long-distance), Paracrine (local), Autocrine (self-targeAng), and Juxtacrine (contact-dependent). 2. Receptor Types - Cell-surface receptors (for hydrophilic molecules) vs. intracellular receptors (for small, hydrophobic molecules). 3. Signaling Outcomes - Survival, growth/division, differenAaAon, death. 4. Protein PhosphorylaAon & GTP Binding Proteins - Kinases add phosphates, phosphatases remove; GTP-binding proteins like Ras funcAon as molecular switches. 5. RTK Signaling - Ligand binding → dimerizaAon → kinase acAvaAon and auto-phosphorylaAon. - Pathways: Ras-MAPK (growth and division) and PI3-K/Akt (survival and metabolism). 6. GPCR Signaling - Ligand binding acAvates heterotrimeric G protein; key pathways include PKA acAvaAon (affecAng glycogen breakdown, gene expression, and Ca2+ release). 7. Other Signaling Types - NO signaling (unique due to rapid diffusion as a gas), Notch signaling (contact-dependent, development-focused), steroid hormone signaling (intracellular receptor pathway). 8. SH2 Domain - Recognizes phosphorylated tyrosine residues on proteins involved in signaling pathways. Chapter 17: Cytoskeleton 1. Cytoskeleton Types - Microtubules: α/β-tubulin dimers, dynamic, 13 protofilaments, nucleate at centrosome, funcAon in intracellular transport and cell division. - AcAn Filaments: ATP-dependent, forms structures like lamellipodia and filopodia for cell movement, interacts with integrins at the cell membrane. - Intermediate Filaments: Nonpolar, provide structural support; examples include keraAn and nuclear lamins. 2. Microtubule Dynamics - Exhibits dynamic instability; grows with GTP-tubulin at the + end, shrinks as GTP is hydrolyzed. 3. Motor Proteins  - Kinesin (+ end) and Dynein (- end) transport cargo along microtubules. 4. Cilia Structure - 9+2 arrangement, dynein motors produce sliding for movement. 5. Rho GTPase and AcAn Dynamics - Rho GTPases (Rho, Rac, Cdc42) regulate acAn organizaAon, affecAng cell shape and movement. This outline covers the main points for your exam. Let me know if you'd like more detail on specific secAons or need pracAce quesAons. Good luck with your studies!