BIOL 1411 1st Edition Lecture 15Outline of Last Lecture I. Photosynthesisa. Calvin Cycleb. C4 photosynthesisc. CAMOutline of Current Lecture I. The Cell Cyclea. Cell Divisionb. Check PointsLectureCell Division- Types of Cell Divisiono Prokaryotic cells Binary fission as a mechanism of reproductiono Eukaryotic Cells Mitosis as a mechanism of reproduction (single cell) or growth/repair (multicellular) Meiosis as a mechanism of specialized reproduction cell (gametes)- How they divideo 4 events must occur Reproductive signal Replication of DNA Segregation: distribution of the DNA into the two new cells Cytokinesis: separation of the two new cells- Mitosiso Distinct phases of the cell cycle, divided into interphase and mitosis/cytokinesis Interphase: begins after cytokinesis and ends when mitosis starts. The cellnucleus is visible and cell function including DNA replication occurs. Interphase divided into 3 sub phases: G1, S, and G2 defined by DNA replication M phase: nuclear membrane dissolves, DNA condenses, DNA condenses and divides; division of the cytoplasmThese 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. Twice as much DNA in cell during G2 compared to G1- Interphase: DNA exists as long, threadlike “chromatin”, cell spends most time in interphaseo G1: each chromosome consist of 1 dsDNA (1 double helix)o S: DNA replication produces two identical dsDNA molecules (sister chromatids) for each chromosomeo G2: each chromosome consist of 2 associated dsDNA molecules (sister chromatids)- M-Phase: chromosomes become visible as dense, compact rods, each consisting of 2 chromatids held together at the centromere- DNA structureo Chromatin: packed DNA during, histones packed togethero Nucleosomes: formed by wrapping DNA around histones (proteins with positive charges that attract negative phosphate groups of DNA. Interaction result in the formation of beadlike unitso Condensins coat DNA-packing DNA further- Phases and Chromosome behavior in mitosiso Prophase/protemaphase: compaction of replicated DNA into visible chromosomes; breakdown of nuclear envelopeo Metaphase: duplicated chromosomes line up in middle of cello Anaphase: sister chromatids separate and move to opposite sides of cell (now daughter chromosomes)o Telophase: de-compaction and formation of new nuclear envelope around the 2 separated sets of daughter chromosomeso Cytokinesis: division of the cytoplasm (forms 2 cells) - MTOC: microtubule organizing centero Surrounded by high conc. Of tubulin dimerso Forms/orients the mitotic spindle that will attach to and move the duplicated chromosomes during M-phase- Centrosome: MTOC of animal cellso Consists of 2 centrioles- hollow tubes formed by microtubules- at right angleso Doubles during S phase too; each will move to opposite ends of the nuclear envelope during G2-to-M transitiono Positions determine the spindle orientation and plane of cell division- Plant cells lack centrosomes by have MTOCs- Cohesin: sister chromatids are held together by thisCheck Points- Control the division of cells- Kinases that can regulate processes through the cell cycle- cyclin-dependent kinaseso Check for DNA damageo DNA replication checko Another for damageo Lastly make sure they are attached to spindle- Active only when bound to its partnet protein called
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