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Why do cells divide?

Why do cells divide?. -to allow materials to flow in and out more efficiently (get food, eliminate waste easier). SAME: All genetic material All in the nucleus All made of DNA. DIFFERENT: State or shape.

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Why do cells divide?

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  1. Why do cells divide? -to allow materials to flow in and out more efficiently (get food, eliminate waste easier)

  2. SAME: All genetic material All in the nucleus All made of DNA DIFFERENT: State or shape How are chromosomes, DNA and chromatin material the same? How are they different?

  3. 2. What is meant by the term haploid? -a cell with one set of chromosomes or genes 3. What is meant by the term diploid? -a cell with two sets of chromosomes or genes 4. Give an example of a cell that is haploid. -an egg or sperm cell 5. Give an example of a cell that is diploid. -a body tissue cell

  4. N -abbreviation for type or shape of a chromosome • In Humans: • 2N = 46 • Two of • Each type total # chromosomes How many different types? 23

  5. Produces somatic cells (body cells) Purpose: growth & repair Daughter cells genetically identical to parent 2N → 2N Asexual reproduction (runners, budding – essentially clones) Produces gametes (sex cells- egg or sperm) Purpose: reproduction Genetic variation in daughter cells 2N → N Sexual reproduction Egg + Sperm→ zygote N + N → 2N 23 23 46 Mitosis Meiosis

  6. Cell Cycle:

  7. Cell Cycle: • Interphase: -where cell spends most of life -actively living, feeding, doing job -includes: G1 - 1st Growth Phase S – Synthesis (DNA replicated) G2 – 2nd Growth Phase • M – Mitosis (dividing stages) • Cytokinesis – cytoplasm divides into new cells

  8. Interphase – “resting stage” -nucleus & nucleolus present -replication occurs (DNA is completely copied) -chromosomes not visible

  9. Prophase: -chromosomes visible -chromosomes in diad form -major cell changes -nuclear membrane dissolves, spindle fibers formed

  10. Metaphase: -chromosomes line up at equator

  11. Anaphase: -chromatids separate and move to poles -each chromatid is now considered a separate chromosome

  12. Telophase: -cytokinesis occurs -2 new cells formed -cell becomes reorganized (nucleus reforms)

  13. Is the following cell diploid or haploid? • diploid • 2. How do you know? • 2 of each shape present • 3. What do the colors represent? • maternal / paternal chromosomes • Or dominant / recessive traits

  14. Circle a pair of homologous chromosomes. Homologous chromosomes: have the same size & shape & carry the same trait (or alternate forms of the trait)

  15. Regulating the Cell Cycle • Generation time • The time it takes a cell to complete the cell cycle. • Varies widely • Cell Cycle Regulators • Cyclin – proteins that regulate the timing of the cell cycle. • Internal • external

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