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Chapter 4 Reproduction of Organisms

Chapter 4 Reproduction of Organisms.

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Chapter 4 Reproduction of Organisms

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  1. Chapter 4Reproduction of Organisms

  2. Types of Reproduction A. Asexual Reproduction – single parent copies and passes its genes to offspring. (clone) look exactly like parent. B. Sexual Reproduction – two parents each form haploid reproductive cells, which join to form offspring. Similar to parents but not exactly like.

  3. Advantages of . . . A. Asexual Reproduction – No mate needed. Reproduce many in short time. B. Sexual Reproduction– different combinations of genes and variation. Selective breeding to develop desired traits.

  4. Disadvantages of . . . A. Asexual Reproduction– No genetic variation. Mutations are passed to offspring. B. Sexual Reproduction– takes more time and energy. Growth and development. Search for mate. Fertilization cannot take place during pregnancy.

  5. Life Cycle – the entire span in the life of an organism from one generation to the next. A. Eukaryotes have three kinds of sexual life cycles 1. Haploid life cycle – haploid cells give rise to haploid multicellular individuals that produce gametes by mitosis. The gametes fuse to form a diploid zygote, which undergoes meiosis, creating new haploid cells.

  6. 2. Diploid life cycle – haploid gametes are produced by meiosis. The gametes join by fertilization to form a diploid zygote.3. Alternation of generations – spore forming cells in the sporophyte undergo meiosis to produce spores, which develop into gametophytes.l The gametophyte produces gametes by mitosis. The gametes fuse and give rise to the sporophyte.

  7. Eukaryotic cells form chromosomesbefore cell division1.) Genes – segments of DNA that code for proteins.2.)DNA(deoxyribonucleic acid)-information for making proteins.3.) proteins – direct the cell’s activities and determines characteristics.4.) chromosome – DNA tightly coiled around proteins.5.) chromatids – two exact copies of DNA that make up each chromosome.6.) centromere – point that attaches chromatids.

  8. http://gslc.genetics.utah.edu/units/basics/tour/

  9. Chromosome Number and Structure Affect DevelopmentA.Sets of chromosomes 1.) body cell – any other cell than a sperm or egg cell and contains 2 copies of 23 different chromosomes (46) diploid – 2 sets(2n = 46) 2.) gametes – sperm or egg cell contains 1 set of chromosomes (23)haploid –1 set(n = 23) 3.) homologous chromosomes – similar in size, shape, and genetic content. (not identical) 4.) zygote – fertilized egg cell – fusion of 2 haploid gametes to produce diploid

  10. Chromosomes determine your sex1.)autosomes – not involved in determining sex (22 pair)2.) sex chromosomes – determines the sex of an individual (1 pair)- X and Y = two sex chromosomes- XX = female- XY = male – only one that can donate a Y chromosome, therefore, the sex of the offspring is determines by the male.

  11. Changein chromosome number1.) karyotype – photo of the chromosomes in a dividing cell, arranged by size to detect any abnormalities.2.) Missing 1 chromosome of the 46 individuals will not survive.3.) trisomy – more than two copies of a chromosome (Down Syndrome)- nondisjunction – one or more chromosomes fail to separate during meiosis in a gamete. Gametes fuse and an extra copy of that chromosome results.

  12. Changein chromosome structure1.) mutations – change in chromosome structure- deletion – piece of chromosome breaks off completely- duplication – chromosome fragment attaches to its homologous chromosome, then carrying two copies of a certain set of genes.- inversion – chromosome piece reattaches to the original chromosome in a reverse orientaion- translocation – reattaches to a nonhomologous chromosome

  13. MeiosisI. Meiosis Forms Haploid Cells (Gametes = Sex Cells) A. Meiosis– One diploid cell divides making four haploid cells. B. Two divisions occur in meiosis, Meiosis I and Meiosis II. C. Each division consists of the stages. . . 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase

  14. http://www.accessexcellence.org/RC/VL/GG/comparison.html

  15. Prophase I allows for crossing over of the chromatids.Crossing-overoccurs when portions of one chromatid on one homologous chromosome are broken and exchanged with the corresponding portions on one of the chromatids of the other homologous chromosome.

  16. http://www.csuchico.edu/~jbell/Biol207/animations/recombination.htmlhttp://www.csuchico.edu/~jbell/Biol207/animations/recombination.html

  17. Meiosis Allows for Genetic Variation (differences) A. Variation can be caused by three ways. 1. independent assortment – the chromosome that an offspring receives from each of the 23 pairs of homologous chromosomes is selected by chance. It is considered random distribution and results in gametes with different gene combinations.

  18. 2. Crossing0ver – DNA exchanges when a portion of a chromatid on one homologous chromosome are broken and exchanged with the corresponding portions on one of the chromatids of the other. 3. Random Fertilization – the zygote that forms a new individual is created by the random joining of two gametes, resulting in fertilization which squares the number of possible outcomes.

  19. Why is genetic variation important? A. Evolution, agricultural breeding, race horse breedingGamete formation of males and females through meiosis A. Males – Spermatogenesis – sperm (male gamete) is produced. Contained in the testes (male reproductive organ), Sperm goes through Meiosis I and Meiosis II.

  20. B. Females – Oogenesis – eggs (female gamete) is produced. Contained in the ovaries (female reproductive organ), eggs go through cytokinesis and divide unevenly and the resulting cell with the greater cytoplasm will develop the ovum (egg cell)

  21. http://www.sumanasinc.com/webcontent/anisamples/majorsbiology/meiosis.htmlhttp://www.sumanasinc.com/webcontent/anisamples/majorsbiology/meiosis.html

  22. http://www.biologyinmotion.com/cell_division/

  23. Asexual Reproduction • Types of asexual reproduction • Fission • Mitotic Cell Division • Budding • Animal Regeneration • Vegetative Reproduction • Cloning

  24. ChromosomesI. New Cells are Formed by Cell Division A. Bacterial cells divide to reproduce 1.) Binary Fission – asexual reproduction produces identical offspring. 2.) 2 steps. . . - Circular DNA is copied - bacterium is pinched into two new cells. http://greenberg.srhs.net/Student_Products/Mitosis_Animations/BrianLemisterAnimation.swf

  25. Mitotic Cell Division – unicellular eukaryotes form 2 offspring through mitosis and cell division. • Budding – a new organism grows by mitosis and cell division on the body of its parent. (hydra) • Animal Regeneration – an offspring grows from a piece of its parent. (sea stars, sea urchins, sea cucumbers, sponges, and planarians) - Part Regeneration – not asexual reproduction! (salamander regrows a tail, tadpoles, crabs)

  26. Vegetative Reproduction – offspring grow from a part of a parent plant. Roots, stems, and leaves propagate new plants(strawberries, potatoes, raspberries, and geraniums) • Cloning – performed in a laboratory that produces identical individuals from a cell or from clusters of cells taken from a multicellular organism. • Plants – tissue culture through meristems. • Animals – all chromosomes come from one parent, therefore, the clone is genetically identical to its parent.

  27. Differences of Mitosis and Meiosis

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