10.1.3 CROSSING OVER Outline the process of crossing over in : Meiosis 1: • Prophase I - homologous chromosomes are paired up tightly into tetrads‚ then crossing over‚ the exchange of genetic material between the DNA in these tetrads occurs‚ forming a chiasmata‚ an x-shaped structure. • Metaphase I - paired chromosomes line up along the equator of a cell‚ the metaphase plate as the spindle microtubulue apparatus pulls them. • Anaphase I - The spindle microtubules pull homologous chromosomes
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due to the probabilities being higher due to more factors contributing to the cause of variation such as meiosis and fusion of gametes‚ as well as mutation. Genetic differences are due to the different genes that each individual organism possesses. The differences occur arise in living organisms and change from generation to generation. Genetic variation arises as a result of mutations‚ meiosis and fusion of gametes. Mutations are changes in DNA that result in the offspring containing different characteristics
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same genes i. Copies may differ IV. Compare and contrast meiosis and mitosis 1. Meiosis A. Form of nuclear division that divides diploid cells into haploid cells i. Essential for sexual reproduction 2. Mitosis A. Used to repair and replace cells in all organisms i. Used for reproduction in asexually reproducing eukaryotes V. How does meiosis keep our chromosome number constant over several generations? 1. Meiosis regulates chromosomes by dividing until there is a set number
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of skin that keeps the testes close or far from the body at an optimal temperature for sperm development. Somniferous tubules are inside each testis‚ and are where sperm are produced by meiosis. About 250 meters (850 feet) of tubules are packed into each testis. Spermatocytes inside the tubules divide by meiosis to produce spermatids that in turn develop into mature sperm. Sperm production takes place in the testes. The testes are in the scrotum. The scrotum is a sac located outside of
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Human Biology Stage 2B Revision – Test 1 Chapter 10 – Production of Gametes Gonads: Are the primary sex organs Secondary sex organs: Everything else‚ e.g. Seminal Vesicles Males Spermatozoa (sperm): Male gametes Scrotum: Single pouch of skin‚ divided into two sacs internally Lobules: Compartments filled with fine tubes called seminiferous tubules Seminiferous tubules: Fine tubes lined with cells that produce the male gametes. They eventually join together to form a short straight tubule
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the mitochondria (mitochondrial DNA or mtDNA) (U.S. National Library of Medicine‚ January 12‚ 2009‚ p. 1). This paper will explain the structure of DNA‚ discuss how the structure of DNA allows it to serve as the basis for inheritance‚ examine how meiosis allows DNA to be divided into gametes‚ and describe how this relates to Gregory Mendel’s patterns of inheritance. DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary
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The following are events that occur in meiosis. For each name the stage in which it occurs. Remember to specify I or II. __________________ Chromatin condenses __________________ Crossing over occurs. __________________ Chromosomes are at the cells’s equatorial plane‚ but homologs are not
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___________ _______________________________________________________________ _______________________________________________________________ © Houghton Mifflin Harcourt Publishing Company Holt McDougal Biology Options For Inquiry 1 Meiosis and Mendel Section 3: Mendel and Heredity Name _____________________________ Period___________________Date__________________ Probability Practice continued _______________________________________________________________ ______________
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cells. What is the difference in result between mitosis and meiosis?mitosis lines up chromatids while meiosis lines up homologous chromosomes.. What are the resulting cells called? mitosis=diploid while meiosis is haploid. * What is independent assortment?Is the random assortment of chromosomes when gamates are in production. Crossing over? The crossing over of chromosomes during meiosis in homologous pairs. When does it happen?Meiosis * Chromosomes that are the same size and function are called
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References: Audesirk‚ T.‚ Audesirk‚ G.‚ &Byers‚ B. (2008). Biology: Life on Earth with Physiology (8th ed.). Upper Saddle River‚ NJ: Pearson Education. Meiosis. (2007) Retrieved from http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Meiosis.html
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