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AP Biology The Cell Cycle Part 1 One cell becoming two Binary Fission in Prokaryotes Cell wall Origin of replication E. coli cell Chromosome replication begins. Soon thereafter, one copy of the origin moves rapidly toward the other end of the cell. Replication continues. One copy of the origin is now at each end of the cell. Replication finishes. The plasma membrane grows inward, and new cell wall is deposited. Two daughter cells result. Plasma membrane Bacterial chromosome Two copies of origin Origin Origin Chromatin vs. Chromosomes appearance within the cell. Coiling up of Chromatin using histones Somatic cells vs. Germ cells The egg surrounded by sperm. Sister Chromatids Mitosis (1 Division) vs. Meiosis (2 Divisions) AP Biology The Cell Cycle Part 2 Centrioles Interphase Before and after the S phase Interphase cell (Look at the chromatin in the blue nucleus and the yellow cytoskeleton.) AP Biology Chapter 12: The Cell Cycle Checkpoints (Is all going according to plan?) . M G1 S G2 M G1 S G2 M MPF activity Cyclin Time Fluctuation of MPF activity and cyclin concentration during the cell cycle . Cdk Degraded cyclin G2 checkpoint Cyclin is degraded MPF Cdk Cyclin Molecular mechanisms that help regulate the cell cycle . Chromosome movement Microtubule Motor protein Chromosome Kinetochore Tubulin subunits . Cells anchor to dish surface and divide (anchorage dependence). When cells have formed a complete single layer, they stop dividing (density-dependent inhibition). If some cells are scraped away, the remaining cells divide to fill the gap and then stop (density-dependent inhibition). Normal mammalian cells 25 µm . Cancer cells do not exhibit anchorage dependence or density-dependent inhibition. 25 µm Cancer cells Malignant cancer cells from the breast (See the ABNORMAL “crab” shape of the cells.) Mutations and Cancer MUTATION Growth factor Hyperactive Ras protein (product of oncogene) issues signals on its own G protein Cell cycle-stimulating pathway Receptor Protein kinases (phosphorylation cascade) NUCLEUS Transcription factor (activator) DNA Gene expression Protein that stimulates the cell cycle Cell cycle-inhibiting pathway Protein kinases MUTATION UV light DNA damage in genome Active form of p53 DNA Protein that inhibits the cell cycle Defective or missing transcription factor, such as p53, cannot activate transcription AP Biology Cell Communication (Signaling) Part 1 Direct Contact Local and Long Distance within an organism. Phermones Earl Sutherland Step 1: Reception Step 2: Transduction Step 3: Response See the CONFORMATION SHAPE CHANGE by the receptor protein caused by the ligand binding. Signal molecule (ligand) Gate closed Ligand-gated ion channel receptor Ions Plasma membrane Gate open Cellular response Gate closed AP Biology Cell Communication (Signaling) Part 2 Phosphorylation and Hydrolysis Receptor Protein G protein Receptor Tyrosine – Kinase Receptor Ion Channel Receptors Signal molecule (ligand) Gate closed Ligand-gated ion channel receptor Ions Plasma membrane Gate open Cellular response Gate closed Intracellular receptors Secondary Messenger cAMP Phosphodiesterase Adenylyl cyclase Pyrophosphate P ATP H2O Pi Cyclic AMP AMP First messenger (signal molecule such as epinephrine) Adenylyl cyclase G protein G-protein-linked receptor GTP ATP cAMP Second messenger Protein kinase A Cellular responses Secondary Messenger Calmodulin EXTRACELLULAR Signal molecule FLUID (first messenger) G protein DAG GTP G-protein-linked receptor Phospholipase C PIP2 IP3 (second messenger) IP3-gated calcium channel Endoplasmic Ca2+ reticulum (ER) CYTOSOL Ca2+ (second messenger) Various proteins activated Cellular responses AP Biology Cell Communication (Signaling) Part 3 Kinases “turn on” processes Phosphotases “turn off” processes Small signal produces a BIG response The Big picture Growth factor Reception Receptor Phosphorylation cascade Transduction CYTOPLASM Inactive transcription Active transcription factor factor P Response DNA Gene NUCLEUS mRNA Scaffolding Proteins Signal molecule Plasma membrane Receptor Three different protein kinases Scaffolding protein Tyrosine – Kinase Receptor (Evolution – Change over TIME)
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