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Bell Work: 1/30/12 Draw the three pictures and explain why the third picture is correct.

Bell Work: 1/30/12 Draw the three pictures and explain why the third picture is correct. Objectives. Describe the relationship among genes, chromosomes, and inherited traits. (SPI 0707.4.3)

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Bell Work: 1/30/12 Draw the three pictures and explain why the third picture is correct.

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  1. Bell Work: 1/30/12Draw the three pictures and explain why the third picture is correct.

  2. Objectives • Describe the relationship among genes, chromosomes, and inherited traits. (SPI 0707.4.3) • Sequence a series of diagrams that depict chromosome movement during plant cell division. (SPI 0707.1.4) • Classify methods of reproduction as sexual or asexual. (SPI 0707.4.1)

  3. Mitosis Review • Interphase- DNA is copied • Prophase- Chromatin (DNA wrapped around protein) forms into chromatids (rods) • Metaphase- Chromatids line up in the middle of the cell • Anaphase- Chromatids separate • Telophase- two new nuclei form around the chromatin (separated chromatids) • Cytokinesis- two new cells form

  4. Mitosis Hand Motions

  5. Mitosis: process of a somatic (body) cell dividing to produce an exact copy of itself

  6. Mitosis Interphase DNA copies itself (chromosomes are copied) Centrioles copy

  7. Mitosis Prophase DNA condenses into chromatids (rod-like structures), held together by centromeres Spindle fibers begin to form Centrioles move to opposite sides Nuclear membrane breaks apart

  8. Mitosis Metaphase Chromatids (chromosomes) line up across the center of the cell Spindle fibers attach to the centromere

  9. Mitosis Anaphase Spindle fibers pull the chromatids to opposite ends of the cell

  10. Mitosis Telophase Nucleus forms around the chromatids Chromosomes unwind

  11. Mitosis Cytokinesis Division of the cytoplasm and the rest of the cell

  12. FYI: Chromosomes • Human body cells have 46 chromosomes, or 23 pairs of chromosomes. • Each chromosome contains certain types of genes. • For example, chromosome 21 codes for Down Syndrome, or Trisomy 21. • A sex cell is produced with an extra copy of chromosome 21; the gamete thus has 24 chromosomes. When combined with a normal gamete from the other parent, the embryo now has 47 chromosomes, with three copies of chromosome 21.

  13. MeiosisIn sexual reproduction, two parent cells join together to form offspring that are different from both parents.These parent cells are called sex cells (sperm & egg).Sex cells are made during meiosis.

  14. Meiosisprocess of a cell dividing to produce 4 cells with half the genetic materialWhy do the cells produced in meiosis only need half of the genetic material?

  15. Meiosis Interphase I DNA copies itself (chromosomes are copied) Centrioles copy

  16. Meiosis Prophase I DNA condenses into chromatids, held together by centromeres and attach to the membrane Spindle fibers begin to form Centrioles move to opposite sides Nuclear membrane breaks apart

  17. Meiosis Metaphase I Chromatids line up on each side of the center of the cell Spindle fibers attach to the centromere Meiosis is a bit different because there something called crossing-over happens with the DNA. This crossing over is an exchange of genes. The genes are mixed up, not resulting in a perfect duplicate like mitosis.

  18. Meiosis Anaphase I Spindle fibers pull the chromosome pairs apart to opposite ends of the cell

  19. Meiosis Telophase I Nucleus forms around the chromosomes

  20. Meiosis Cytokinesis Division of the cytoplasm and the rest of the cell

  21. Meiosis Interphase II Cell rests DNA DOES NOT duplicate Centrioles duplicate

  22. Meiosis Prophase II DNA condenses into chromatids, held together by centromeres Spindle fibers begin to form Centrioles move to opposite sides Nuclear membrane breaks apart

  23. Meiosis Metaphase II Chromosomes line up across the center of the cell Spindle fibers attach to the centromere

  24. Meiosis Anaphase II Spindle fibers pull the chromatids to opposite ends of the cell

  25. Meiosis Telophase II Nucleus forms around the chromatids Chromosomes unwind

  26. Meiosis Cytokinesis Division of the cytoplasm and the rest of the cell

  27. Mitosis vs. Meiosis

  28. Mitosis Meiosis • Both are processes of cell division • Both reproduce new cells • Both go through Interphase, Prophase, Metaphase, Anaphase, Telophase, & Cytokinesis • Asexual cell reproduction (only one parent cell is needed) • Produces an exact copy of itself with 46 chromosomes • Reproduces two new cells • Somatic cells: body cells (skin cells, blood cells, bone cells, muscle cells) • Sexual cell reproduction (two parent cells are needed) • Produces cells with half as many chromosomes (23) • Reproduces four new cells • Sex cells (sperm & egg)

  29. Sex Chromosome:Chromosome 23 (XX or XY) xx

  30. Sex chromosomes carry genes that determine the sex or gender of offspring. In humans, females have two X chromosomes and males have one X and one Y chromosome. During meiosis, one of each of the chromosome pairs ends up in a sex cell. Baby boy= XY Baby girl= XX Example: Determining the Sex or Gender of Offspring

  31. Living Things Reproduce 2 Types of Reproduction: Asexual- a single parent produces an offspring identical to the parent Sexual- two parents produce an offspring with traits of both parents

  32. Challenge Questions • When animals go through sexual reproduction, what type of cell division are they going through? • meiosis • When animals go through asexual reproduction, what type of cell division are they going through? • mitosis

  33. Types of Asexual Reproduction In Animals • Budding: happens when a part of the parent organism pinches off and forms a new organism. • The new organism separates from the parent and lives independently. • Jellyfish & hydra

  34. Types of Asexual Reproduction In Animals • Fragmentation: parts of the organism break off and a new organism grows identical to the parent. • Worms & starfish

  35. Types of Asexual Reproduction In Animals • Regeneration: organism loses a body part and that part may develop into a new organism. • Sea star

  36. Asexual Reproduction in Other Organisms • Binary fission is a method of asexual reproduction in which an organism splits into two. • This occurs in bacteria and other single-celled organisms

  37. Asexual Reproduction in Plants • Some plants can reproduce asexually when they are cut or damaged. These plants can sprout new growth from their roots, stems, and leaves. • In wild strawberry plants, stems are capable of arching downward and taking root in the ground, resulting in the formation of a new plant. This is an example of asexual reproduction.

  38. 3-2-1 Reflection 3 differences between mitosis and meiosis 2 different types of asexual reproduction 1 way this relates to your life (real world)

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