BIOL K101 1st Edition Lecture 17Outline of Last Lecture External Signals Cell ResponsesDirect ContactGap Junctions/PlasmodesmataLocalParacrineSynapseLong DistanceEndocrinePhosphorylationKinasesPhosphatasesThree Stages of SignalingReceptionSignaling Molecule-LigandPlasma Membrane ReceptorLigand-gated ion channelsEnzymatic (Receptor tyrosine kinases)G Protein coupled receptorsIntracellular (Internal Receptors)Steroid HormonesTransductionSignal Transduction PathwaysProtein Phosphorylation/dephosphorylation (Receptor tyrosine kinases)Phosphorylation cascadeSmall Molecules and Ions (G protein Coupled Receptor)Secondary messangerscAMPCalcium ions and Inisitol trisphosphate (IP3)Outline of Current Lecture Small Molecules and Ions (G protein Coupled Receptor)Secondary messangerscAMPCalcium ions and Inisitol trisphosphate (IP3)MitosisPurposeGrowthThese 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.ReplacementRepairOne duplication: One divisionChromosomesDNA + protein = chromatinCondensed chromatin = chromosomeDuplicated chromosome = 2 chromatidsDivision produces 2 chromosomesCell Cycle and MitosisStagesG1SG2MG0Stages of MitosisProphaseMetaphaseAnaphaseTelophaseCytokinesisAnimalsCleave furrowContractile RingPlantsCell plate (phragmoplast)Current Lecture3rd type of cell signaling is through signaling molecules called ligands. In the presence of the ligand, the ion channel opens and ions flow through causing a cellular response. Calcium and IP3= a second messenger signal transduction pathway. Involves a g-protein, GTP that activates phospholipase C producing IP2 into IP3 (second messenger), which activates the endoplasmic reticulum (ER), which releases Ca through an IP3- gated calcium channel. The Ca binds to calmodulin and activates various proteins causing a cellular response. Phospholipase C can also be activated by the tyrosine-kinase receptor. Look at figure 11.14. Intracellular receptors are in the cytosol or the nucleus. Hydrophobic signals don’t have to stop at the cell membrane, which can impact gene expressions. No second messenger. Apoptosis is programmed cell death.Chapter 12Mitosis is cell division: duplication of DNA as well as replication of the cell, resulting in two identical cells. This is potentially a bad thing because there is no variation. This is great if the environment doesn’t change. But if the environment changes then the cells die. Steps: reproduction, growth and development, tissue renewal. The cell spends the most time in G1 and G2 phases. Each minute your body needs 300 million new cells, which come from other cells. Interphase includes G1, S (DNA synthesis) and G2. G1 preparation for cell division (variable). Synthesis does the same function every time. G2 is variable but less variable than G1. M phase is very short. Embryo cells divide but they don’t grow so G1 and G2 is reduced (most time for embryo cells are spent in S and M). In mitosis the chromosomes are dividing. In the S phase the amount of DNA is doubled but the chromosome number is NOT doubled. The chromosome that is doubled is called a chromatid. Sister chromatids are connected at the center of the chromosome called the centromere. Since each sister chromatid is connected; there is still the same amount of chromosomes. During mitosis, the sister chromatids are divided into two daughter cells. Number of chromosomes is still the same. The stages of the cell cycle are G1, S, G2, Mitosis and G0. The stages of mitosis are: prophase, metaphase, anaphase, telophase. Plant cells form a cell well between the two new cells. In an animal cell, a cleavage furrow comes from the outside in and divides the