Mitosis How Cells Reproduce Class Discussion I Reproduction A Asexual reproduction Reproduction in which there is one parent that gives rise to an identical offspring 1 What cells use it What organisms use it Single celled organisms singe cells WITHIN an organism liver cells skin cells etc These are called somatic cells 2 Consequence Because they are all genetically the same it is easier to eliminate them but they also cannot easily adapt to changes in the environment B Sexual reproduction Reproduction in which there are two parents with unique offspring Sperm fertilizes egg leading to a unique embryo Mitosis Somatic cells divide Approximately 90 of time spent here Meiosis Sex cells divide to form gametes Come up with a list of actions or events that an animal cell must undergo to achieve division Copy DNA Replicate organelles Membrane 2 cells have to separate Cell must grow prior to splitting II Eukaryotic Cell Cycle 2 phases A Interphase precedes both mitosis and meiosis 3 subphases G1 Gap One The cell grows organelles replicate and various proteins are synthesized S DNA Synthesis The DNA is replicated G2 Gap Two The cell continues to grow more proteins are created and ATP is produced to prepare for mitosis 1 Chromosome in S Chromosome in G1 Daughter cells Two of the original chromosomes Anatomy of chromosomes Chromosome a double stranded DNA molecule Sister chromatids duplicated chromosomes that are connected each chromatid will become a chromosome in the daughter cell Constricted region of a chromosome Centromere Protein complex that forms at the centromere to connect chromatids to microtubule spindle fibers Kinetochore Histones proteins that the DNA double helix winds around Condensed when DNA is tightly wound up visible in light microscope B Mitosis What cells in your body perform this Somatic Body cells M 4 subphases Prophase Metaphase Anaphase Telophase 2 I Interphase P Prophase P Prometaphase M Metaphase A Anaphase T Telophase Interphase Prophase Pro metaphase Equator Metaphase Anaphase Telophase Animal Cell Cytokinesis Cytoskeleton pinching in the middle Plant Cell Cytokinesis Cellulose forming in the middle PRACTICE To the left is a picture of all the chromosomes of an animal cell in G1 of the cell cycle Draw what this cell will look like at 1 G2 2 Metaphase 3 After cytokinesis G2 Metaphase After cytokinesis 3 III Cancer How are cancer cells different from other cells Normal cells are stimulated by growth factors but tumor cells can have the ability to divide without the message from a growth factor Furthermore normal cells have density dependent inhibition whereas tumor cells do not function according to density dependency Furthermore normal cells stay within the cells whereas cancer cells can metastasize 4 Mitosis Cancer and Meiosis Guided Reading Qs Reading from textbook Chapter 8 1 8 9 AND two articles posted AND Chapter 8 10 8 15 Reading Objectives Contrast asexual and sexual reproduction in outcome and types of organisms cells that use each cancer cells Recognize describe the stages of mitosis contrasting animal and plant cells Articulate how the cell cycle differs in normal dividing cells compared to nerve cells or Explain the significance of a mutated BRCA 1 gene in terms of risks and consequences Define and apply the terms somatic cell gamete sister chromatid homologous chromosomes diploid haploid Contrast meiosis from mitosis in the stages and outcomes Explain how meiosis creates such great variation Chapter 8 reading 1 How do many cancer drugs work to kill cancer cells 2 Contrast asexual from sexual reproduction 3 How is DNA condensation analogous to moving to a new apartment 4 True or False Humans have over 100 000 genes 5 True or False Cells of different species have different numbers of chromosomes 6 True or False Sister chromatids are identical DNA molecules joined at the centromere 7 You find a cell that is currently replicating its DNA What part of the cell cycle is it in False True True What will happen next 8 You view an animal cell through a microscope and observe dense duplicated chromosomes lined up in the middle of the cell Which stage of mitosis are you looking at 9 Why does cytokinesis differ between plant and animal cells 5 10 Scientists have learned how to grow cells outside of the body in plastic trays although not all cells of the body cooperate and divide You may find yourself in a lab in the future asked to maintain cells in tissue culture This is what we call this technique Describe not simply list three factors chemical or physical that influence how normal cells divide based on what scientists have learned from these cell cultures 11 How are nerve cells and muscle cells different from many other cells of the human body relative to the cell cycle 12 If the cell cycle is carefully controlled by proteins that are present only temporarily to help turn on the cell cycle i e growth factors and other proteins that halt the cycle checkpoint proteins what do you suppose would happen if a cell was continuously exposed to growth factors What do you supposed would happen to a cell in which checkpoints were faulty 13 From The Miracle Woman By Rebecca Skloot O The Oprah Magazine February 2010 In 1951 at the age of 30 Henrietta Lacks the descendant of freed slaves was diagnosed with cervical cancer a strangely aggressive type unlike any her doctor had ever seen He took a small tissue sample without her knowledge or consent A scientist put that sample into a test tube and though Henrietta died eight months later her cells known worldwide as HeLa are still alive today They became the first immortal human cell line ever grown in culture and one of the most important tools in medicine Research on HeLa was vital to the development of the polio vaccine as well as drugs for treating herpes leukemia influenza hemophilia and Parkinson s disease it helped uncover the secrets of cancer and the effects of the atom bomb and led to important advances like cloning in vitro fertilization and gene mapping Since 2001 alone five Nobel Prizes have been awarded for research involving HeLa cells There s no way of knowing exactly how many of Henrietta s cells are alive today One scientist estimates that if you could pile all the HeLa cells ever grown onto a scale they d weigh more than 50 million metric tons the equivalent of at least 100 Empire State Buildings Today nearly 60 years after Henrietta s death her body lies in an unmarked grave in Clover Virginia But her
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