1 Chapter 12 Cell Cycle replication of cells 1 When does mitosis occur in organisms hint NOT for the development of gametes but it is for the growth of the already fertilized egg A During growth and repair 1 Difference between somatic cells and gametes 1 Products of mitosis A A copy of nucleus What is the product of the cell cycle A An identical daughter cell diploid 1 Know the sub phases of interphase and what happens in each one A Interphase about 90 of the cell cycle can be divided into subphases B G1 Gap 1 in which the cell grows and functions normally During this time a high amount of protein synthesis occurs and the cell grows to about double its original size more organelles are produced increasing the volume of the cytoplasm number of mitochondria If the cell is not to divide again it will enter G0 C Synthesis S in which the cell duplicates its DNA via semiconservative replication This is also known as the Swanson phase D G2 Gap 2 in which the cell resumes its growth in preparation for division 1 The stage of the cell cycle where each chromosome is composed of two chromatids in preparation for mitosis A S results in the duplication of each chromatid Since there is only one centromere on thy sister chromatids we still call them one chromosome When completed the cells are in G2 and preparing for M Know the phases of mitosis and be able to match either a diagram or a written description to each one 1 What is cytokinesis and when does it occur How is it different for plants and animals A Cytokinesis in animal cells is through a process known as cleavage Cytokinesis is the replication of the rest of the cell cytoplasm etc Cytokenisis in animal cell 1 A Plant cells have a cell wall and no cleavage furrow The plant cell becomes longer and a cell plate is formed in the middle of the cell instead of a contractile ring 1 What are some checkpoints found in the cell cycle ex are all the chromosomes attached during metaphase Regulation of the cell cycle 1 How cell division and thus tissue growth is controlled is very complex The following terms are some of the features that are important in regulation and places where errors can lead to cancer Cancer is a disease where regulation of the cell cycle goes awry and normal cell growth and behavior is lost A Cdk cyclin dependent kinase adds phosphate to a protein along with cyclins are major control switches for the cell cycle causing the cell to move from G1 to S or G2 to M MPF Maturation Promoting Factor includes the CdK and cyclins that triggers B progression through the cell cycle C p53 is a protein that functions to blocks cancer from arising 1 The correct sequence of the cell cycle that is common to eukaryotes G1 S G2 M Cytokinesis A G1 prepared for S and G2 as the time between the completion of S and entry to M Cytokinesis occurs after the other stages to create two daughter cells The Cell Cycle Mitosis Tutorial 1 Interphase A The cell is engaged in metabolic activity and performing its prepare for mitosis the next four phases that lead up to and include nuclear division Chromosomes are not clearly discerned in the nucleus although a dark spot called the nucleolus may be visible The cell may contain a pair of centrioles or microtubule organizing centers in plants both of which are organizational sites for microtubules 1 Prophase A Chromatin in the nucleus begins to condense and becomes visible in the light microscope as chromosomes The nucleolus disappears Centrioles begin moving to opposite ends of the cell and fibers extend from the centromeres Some fibers cross the cell to form the mitotic spindle 1 Prometaphase A The nuclear membrane dissolves marking the beginning of prometaphase Proteins attach to the centromeres creating the kinetochores Microtubules attach at the kinetochores and the chromosomes begin moving 1 Metaphase halves A arrangement of chromosomes in the equatorial plane Chromosomes separate into exactly similar 1 Anaphase A the two groups of daughter chromosomes separate and move along the fibres of the central spindle each toward one of the asters forming the diaster 1 Telophase A two daughter nuclei are formed the cytoplasm divides forming two complete daughter cells Cytokinesis A In animal cells cytokinesis results when a fiber ring composed of a protein called actin around the center of the cell contracts pinching the cell into two daughter cells each with one nucleus In plant cells the rigid wall requires that a cell plate be synthesized between the two daughter cells Chapter 13 Meiosis In animals meiosis only produces gametes Only diploid cells can undergo meiosis to become haploid 1 1 Meiosis I 1 Prophase I A Homologous pairs tetrads find each other and cross 1 Metaphase I A Homologous pairs tetrads line up together Anaphase I A Separating the homologous pairs tetrads 1 Telophase I A Reform nucleus envelope 1 Cytokenisis A 2 haploid cells 1 Meiosis II 1 Metaphase II A Chromosomes line up 1 Prophase II A Chromosomes condenses 1 Anaphase II A Separating sister chromosomes 1 Telophase II A Formation of 4 haploid cells 1 Haploid is the number of sets of chromosomes you have 1 In meiosis I homologous chromosomes separate know what homologous chromosomes are resulting in two haploid cells 1 In meiosis II sister chromatids separate giving the final product of four haploid non identical daughter cells 1 In meiosis I during synapsis a tetrad forms leading to crossing over Non sister chromatids exchange genetic material Hint make sure you know when this happens meiosis I and why it is important exchange of genetic material Another hint make sure you know that the exchange of genetic material is between non sister chromatids not sister chromatids 1 Know this chart 1 What three mechanisms contribute to genetic variation understand what is happening in each one A Independent assortment of chromosomes a The process of random segregation and assortment of chromosomes during anaphase I of meiosis resulting in the production of genetically unique gametes B Crossing over a C Random the exchange of genes between homologous chromosomes resulting in a mixture of parental characteristics in offspring Chapter 14 1 1 Mendelian concepts of inheritance A Law of Segregation a 50 chance of getting either gene from a parent A Law of independent assortment 1 There are alternated versions of a gene accounting for a variation in inherited characteristics Each characteristic in an organism will inherit two alleles one from each parent 2 3