Mitosis And Meiosis - Web.biosci.utexas.edu
Genetics: Cell ReproductionMitosis and MeiosisOutline1.Key concepts2.Eukaryotes3.Overview4.Cell cycle5.Mitosis6.Meiosis7.ConclusionsKey Concepts:1.The cell cycle includes Interphase and Mitosis2.Each DNA molecule, with its attached proteins,is a chromosome3.Members of the same species have the samenumber of chromosomes in their cells4.Mitotic cell division is the basis of growth andtissue repair in multicelled eukaryotes5.Meiosis results in gamete production anddivides the chromosome number in half
Eukaryoteslinear chromosomes (in pairs)homologues chromosomes have thesame type of genetic informationgene – function unit codes some trait.Overview of Cell Divisions1.2.Mitosis1.Somatic cells (body cells)2.Growth and repair3.One cell to two cellsMeiosis1.Reproductive organs only2.Form Gametes3.One cell to four cellsChromosome Number1.Chromosome number: sum total ofchromosomes in somatic cells2.Chromosomes are in pairsHumans 23 pairswe can identify them and arrange them from largeto small (except the 23rd pair)2n “diploid”1n “haploid” (germ cells)
ChromosomesChromosomeschromatid – single copy of a chromosomeThe Cell Cycle1.2.A diploid cell produces 2diploid daughter cellsTwo phases in cell cycle1.InterphaseLongest phaseIncrease in mass, doublescomponents, andduplicates DNA2.MitosisNuclear divisionInterphaseG1 - “Gap” - cellgrowth before DNAreplicationS - “Synthesis” - DNAreplicationG2 - “Second Gap” -preparation fordivisionM - Mitosis
The Cell CycleMitosisFour stages1.Prophase - chromosomes condense (Chromosomesare visible) , spindle apparatus forms, nuclearenvelope breaks down2.Metaphase - chromosomes line up at equator of cell3.Anaphase - sister chromatids separate4.Telophase - new nuclear envelopes form,chromosomes decondenseCytokinesisCytoplasmic divisionCell at Interphase
ProphaseMetaphaseAnaphase to Interphase
The process of meiosisDNA replication occurs in interphase prior to meiosisMeiosis I:1.Prophase - chromosomes condense, homologouschromosomes paira) Crossing-over occurs between homologuesb) Spindle forms1.Metaphase - chromosomes line up at equator of cell2.Anaphase - homologues separate, sister chromatidsremain together (Random Segregation)3.Telophase - chromosomes remain condensedNo DNA replication between meiosis I and meiosisIIMeiosis II: (very similar to mitosis)Meiosis IProphase I and Metaphase IMeiosis IAnaphase I and Telophase I
Meiosis IIProphase II and Metaphase IIMeiosis IIAnaphase II and Telophase IIEach daughtercell now has ahaploidchromosomenumberA Closer Look at Meiosis I ProphaseI Chromosomesas homologuesarealigned Chromatids
Diagram of HomologousChromosomes and Crossing OverPossible Outcomes of RandomAlignmentMetaphase IMitosis and Meiosis ComparedMitosis
Mitosis and Meiosis ComparedMeiosis IMitosis and Meiosis ComparedMeiosis IICrossing over
In Conclusion1.A parent cell provides each daughter cell withhereditary instructions2.Eukaryotes divide by mitosis or meiosis andProkaryotes divide by binary fission3.Each chromosome is one DNA molecule withproteins attached4.Cells with a diploid number (2n) contain two ofeach kind of chromosome5.The phases of Mitosis are Prophase, Metaphase,Anaphase, and TelophaseIn Conclusion (meiosis)1.Meiosis consists of two consecutivedivisions2.In meiosis II, sister chromatids areseparated and four haploid cells are theresult3.Crossing over, and random segregationof chromosomes contribute to variationin traits among offspring
Mitosis and Meiosis Outline 1. Key concepts 2. Eukaryotes 3. Overview 4. Cell cycle 5. Mitosis 6. Meiosis 7. Conclusions Key Concepts: 1. The cell cycle includes Interphaseand Mitosis 2. Each DNA molecule, with its attached proteins, is a chromosome 3. Members of the same species have the same number of chromosomes in their cells 4.
Now that you've seen how meiosis works, let's review two key differ-ences between the processes of meiosis and mitosis. Meiosis has two cell divisions. Mitosis has only one cell division. Meiosis results in haploid cells. Mitosis results in diploid cells. On the diagram above, circle the part in the process of meiosis
I II III IV A DNA Replication Mitosis Meiosis Fertilisation B DNA Replication Meiosis 1 Meiosis 2 Fertilisation C Fertilisation Meiosis Mitosis DNA Replication D Mitosis Meiosis 1 Meiosis 2 DNA Replication 4.4 In analysing the number of different bases in a DNA sample, the following result would be consistent with the base-pairing rules: .
Comparison of Meiosis II to Mitosis The events of meiosis II are like those of mitosis except in meiosis II, the nuclei contain the haploid number of chromosomes. At the end of telophase II of meiosis II, there are four haploid daughter cells that are not genetically identical. At the end of mitosis, there are two
Mitosis and meiosis are processes by which animal and plant cells divide. Which statement best describes a difference between mitosis and meiosis? A. Meiosis is a multi-step process. B. Mitosis occurs only in eukaryotic cells. C. Meiosis is used in the repair of an organism.
2. Arrange the remaining chromosomes on the two MEIOSIS sheets, with MEIOSIS I sheet placed above the MEIOSIS II sheet so the arrows flow from sheet to sheet. Remember to show the essential differences between mitosis and meiosis. Be sure to end up with sperm if you are a boy, or an egg with polar bodies if you are a girl.
Cell Division in Sexual Reproduction: Meiosis Meiosis is the mechanism by which eukaryotic cells produce mature sex cells or gametes Meiosis produces four haploid cells (gametes) Meiosis involves partition of both cytoplasmic and nuclear structures Meiosis consists of Meiosis I and Meiosis II. Both phases are followed by .
TAKING NOTES Draw a Venn diagram like the one below to summarize the similarities and differences between meiosis I and meiosis II. chromo-somes condense divides homologous chromosomes divides sister chromatids Meiosis I Meiosis II 6.2 Process of Meiosis KEY CONCEPT During meiosis, diploid ce
TABE 11 & 12 READING PRACTICE TEST LEVEL M. Read the passage. Then answer questions 1 through 7. Whale Watching. Across the blue, rolling waves, a dark hump rises from the sea. It slides out of sight as an enormous tail lifts and falls. As it does, another hump rises beside it and begins the same dance. Several people cheer from the pontoon boat. Some raise their cameras, while others lift .
