Levels of Biological organization Cells Tissues Tissues Organs Organs Organ Systems Organ Systems Organisms From zygote to Trillions of Cells ZygoteCell that forms when sperm and egg join ID: 1042296
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1. Mitosis and Meiosis8.2, 8.3, & 10.2
2. Levels of Biological organizationCells TissuesTissues OrgansOrgans Organ SystemsOrgan Systems Organisms
3. From zygote to Trillions of CellsZygote=Cell that forms when sperm and egg joinSperm gives you DNA from dad, egg gives you DNA from momShortly after sperm fertilizes egg, the zygote splits into a 2nd cellThese 2 cells split into 4, then 8, then 16, etc.Each of these cells contains IDENTICAL DNA (Recall DNA replication)
4. Why must cells divideDiffusion limits cell sizeCells get materials from surroundings through their membrane. This is also how they expel wastesIf the cell gets too large, it would take a long time for these processes to occurDNA also limits cell sizeDNA RNA Proteins There is a limit on how fast this can happen. If the cell is too large, it takes too long to make all of the structures from the proteins.
5. Surface area-to-volume
6. Cell Cycle
7. I-PMATThe cell cycle can be divided into 2 (or 3) stagesInterphase, Mitosis, and Cytokinesis Interphase and Mitosis are further divided by certain events that happenInterphase=G1, S, G2Mitosis=Prophase, Metaphase, Anaphase, TelophaseNEITHER INTERPHASE NOR CYTOKINESIS ARE PARTS OF MITOSIS
8. Interphase (G1, S, G2)Think “Intermission”Most of the cell’s life is spent in InterphasePeriod of growth and developmentG1 (Growth Phase 1)Cell grows in size and synthesizes mRNA and proteins S Phase (Synthesis phase)DNA replicatesG2 (Growth Phase 2)Cell grows again, organelles are duplicated, and proteins are synthesized to prepare for cell division
9. MitosisPeriod of division4 parts (PMAT)Prophase (“Prologue”)Metaphase (“Middle”)Anaphase (“Apart”)Telophase (“Two”)Happens only in somatic (body) cells
10. Prophase (“Prologue”) First and longest stage of mitosisProphase begins as strands of chromatin coil around proteins called histones and become a chromosome (tightly wound strand of DNA and proteins)Each copy of DNA (from Interphase) coils and forms 2 identical strandsCalled sister chromatidsThese sister chromatids join together at the center (called a centromere)Each chromosome has a “partner” (remember, you get one from your mom and one from your dad)These are called homologous chromosomes The nucleus disappears Centrioles move to opposite ends of the cellA structure called a spindle formsMade up of rod-like structures called microtubules
11. DNA to Chromosomes
12. Chromosome Structure
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15. Metaphase (“Middle”)Spindle fibers attach to centromeres of chromosomesSpindles extend from centriole on one side and attach to sister chromatid on that same sideFibers help chromosomes line up in the middleVery important because it ensures that ½ of the chromosomes end up in each cell
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18. Anaphase (“Apart”)Spindle fibers shorten and pull sister chromatids apart at the centromere Each identical sister chromatid moves to one of the sides of the cell
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21. Telophase (“Two”)Chromatids reach opposite endsChromatids begin to unwind into chromatinNuclei form around chromatinSpindle breaks downCells begin to splitThis ends Mitosis
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24. CytokinesisDivision of cytoplasmCell divides and 2 new daughter cells are formedProcess differs in plants and animalsIn plant cells, a structure called a cell plate forms and separates the 2 daughter cellsIn animals cells, the cells “pinch in” until the cells are separated
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26. Control of the Cell cycleCancer=uncontrolled cell divisionProteins (called cyclins) created during protein synthesis help to regulate the cell cycleWhen these proteins are damaged by mutations of DNA, the cell’s normal cycle is disrupted and cells divide out of controlForms a tumorCancer cells take nutrients from healthy cells, and can occasionally move around in the body. When cancer cells move around, it is called metastasis. This forms new tumors throughout the body
27. MeiosisOccurs only in sex cells (males-sperm and female-egg cells)The goal is to cut the original number of chromosomes in halfOffspring need to inherit from both parentsIf the number was not cut in half, the offspring would have 2x the chromosomes as the parentsTermsA diploid cell is a cell that contains 2 of each chromosome (di=2)These are typical body cellsA haploid cell is a cell that contains 1 of each chromosome (hap~half)These have ½ the number of chromosomes as typical cells
28. Phases of Meiosis Very similar to mitosis IPMATPMATStarts with InterphaseOnly occurs once before meiosis beginsBasically does mitosis twiceMeiosis IProphase I, Metaphase I, Anaphase I, Telophase IMeiosis IIProphase II, Metaphase II, Anaphase II, Telophase IIEach ends with cytokinesis
29. Meiosis-InterphaseExactly the same as in MitosisOccurs only before Meiosis I, NOT Meiosis II
30. Meiosis-Prophase IVery similar to Prophase in MitosisOne huge differenceHomologous chromosomes line up and form a structure called a tetrad They tangle up and can actually break portions off and exchange DNAProcess is called crossing overIncreases genetic diversity by potentially allowing you to pass on traits from both grandparents to offspring
31. Meiosis-Metaphase IAgain, similar to Metaphase in Meiosis, but with a key differenceSpindle fibers attach to tetrads, and line them up in the middleThis means that there are 2 chromosomes next to one another in the center, instead of one as was the case in MitosisMitosis Meiosis
32. Meiosis-Anaphase IProbably the most different from MitosisWhereas in Mitosis, sister chromatids separate at the centromere and move towards opposite ends of the cell, in Meiosis, tetrads are pulled apart and chromosomes (the pair of sister chromatids) move to each side of the cellThis ensures that there will be a full chromosome in the daughter cells
33. Meiosis-Telophase IOccurs exactly as it did in Mitosis, except this time there is an entire chromosome (pair of sister chromatids) in each of the 2 new cellsAnother division is necessary to split the genetic material in halfCytokinesis occurs, same as Mitosis2 diploid cells are formed
34. Meiosis IINO INTERPHASEThis process occurs EXACTLY THE SAME AS MITOSISOnly it is occurring in 2 cells at once
35. Results of Mitosis and MeiosisIn Mitosis, 1 cell splits into 2 daughter cellsThe daughter cells are identicalIn Meiosis I, a single cell splits into 2 daughter cellsEach of these cells contains the same amount of chromosomes as the parent cellStill diploid, and not identical In Meiosis II, the 2 daughter cells from Meiosis I undergo another cell division, and split into 2 more daughter cellsEach of these cells contains ½ of the original genetic materialNow haploid, and each unique