Lesson chromsomes and the cell cycle


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Powerpoint to accompany cell cycle and mitosis lecture - AS Biology

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  • 9-905
  • The humangenome is the genome of Homo sapiens, which is stored on 23 chromosome pairs. Twenty-two of these are autosomal chromosome pairs, while the remaining pair is sex-determining. The haploid human genome occupies a total of just over 3 billion DNAbase pairs. The Human Genome Project (HGP) produced a reference sequence of the euchromatic human genome, which is used worldwide in biomedical sciences.The haploid human genome contains ca. 23,000 protein-coding genes, far fewer than had been expected before its sequencing.[1][2] In fact, only about 1.5% of the genome codes for proteins, while the rest consists of non-coding RNA genes, regulatory sequences, introns, and (controversially named) "junk" DNA.[3
  • Lesson chromsomes and the cell cycle

    1. 1. Title: Cell cycle (again) Objectives: Today we are learning to answer the following questions: • What are the various stages of the cell cycle • Explain the meaning of the term homologous pair of chromosomes • What is meant by sister chromatids • Describe with the aid of diagrams the main stages of mitosis.
    2. 2. What is DNA ? What is the point of genetic material? What is a gene? DNA (Deoxyribonucleic acid) Provides a code that codes for proteins, controls activity of the cell A sequence of DNA that codes for one protein
    3. 3. • DNA is held on chromosomes • Made of DNA & histone proteins = Chromatin •Humans have 46 chromosomes arranged in 23 homologous pairs •Homologous pair – 2 chromosomes that contain the same genes; humans = 1 maternal, 1 paternal • The number of chromosomes varies between species
    4. 4. Sister Chromatids = 2 identical chromatids connected by a centromere. Original and replicated strand joined at the centromere The Chromosomes replicate during interphase Homologous chromosomes
    5. 5. Put the stages of mitosis in order Then answer the questions: 1.When a cell divides by mitosis how many cells are made? 2.Comment on the similarities and differences of daughter cells to each other and the parent cell. 3.Species such as yeast reproduce by cell division, Describe the genetic make up of yeast colonies.
    6. 6. The process of creating 2 genetically identical daughter cells from 1 parent cell = MITOSIS Division of somatic (body) cells is by mitosis – remember • Mitosis make two cells • Mitosis makes toes
    7. 7. What is happening at each stage of the cell cycle? How many chromosomes are in the nucleus during each stage?
    8. 8. June 2009
    9. 9. Why do cells need to divide? What are the processes by which cells divide? 1. Growth (mitosis) 2. Repair damage (mitosis) 3. Replace worn out cells (mitosis) 4. Gamete creation (meiosis)
    10. 10. Chromosomes visible with light microscope Chromosomes visible with light microscope Chromosomes visible with light microscope Chromosomes visible with light microscope Chromosomes are not visible with light microscope Prophase Metaphase Anaphase Telophase