02 - 9/03 6) A) Homologous Chromosomes -Chromosomes that...

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9/03 6) A) Homologous Chromosomes -Chromosomes that control the same gene type, but contain different DNA coding, and hence diverse characteristics of the same gene. One Chromosome is from the mother and the other is from the father. -For example, one chromosome may have the genes for brown eyes, when the chromosome from the other parent may have the gene for blue eyes. Sex Chromosomes -Chromosomes that determine sex of organism. -In humans they are not always homologous. -Females have homologous X chromosomes. -Males have 1 X chromosome and one Y chromosome. -They are found in gametes (haploid: n), which form in gonads (testes and ovaries of humans) Autosomes -The chromosomes found in somatic cells. -Somatic cells are always diploid (2n) Diploid -Cells with 2 sets of chromosomes. -Humans have 2 sets with 23 chromosomes each. (23 from mother, 23 from father, making altogether 46 chromosomes in all in somatic cells.) -Diploid cells are represented as “2n,” where “n” is the number of chromosomes in one set. -In humans, 2n = 46 -Diploid cells undergo both meiosis and mitosis Haploid -Cells with only 1 set of chromosomes, or half that of somatic cells. -The only haploid cells in humans are gametes (sex cells) -Haploid cells are represented as “n” where n is the amount of chromosomes in 1 set. -In humans, n=23 -Haploid cells CANNOT undergo meiosis. They can only undergo mitosis, as seen in plants during alternation of generations, and fungi. -Plants start out as a zygote. -Then the zygote uses mitosis to make a diploid multicellular organism (sporophyte). -Diploid multicelluar organism undergoes meiosis to make haploid cells (spores). -Haploid cells undergo mitosis to make a haploid multicellular organism (gametophyte). -The haploid multicellular organism undergoes mitosis to make gametes (sex cells). -Lastly, the gametes fuse together to make a new zygote to continue the process. Diagrams on paper labeled “6A” B)
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Animal/Human Plant:Alternation of Generations Fungi/Protist -(2n 2n n) -Cell starts out as a fertilized egg or zygote. -Zygote undergoes mitosis to produce a diploid (2n) multicellular organism. -The diploid organism undergoes meiosis to make 4 gametes. -After gametes are formed, the gametes DO NOT go through mitosis. -Instead they fertilize into another zygote, and the cycle continues. -(2n 2n n n n) -Cell starts out as a zygote , made from the fusion of 2 gametes. -Zygote undergoes mitosis making a diploid multicellular organism called a sporophyte. -The diploid multicellular organism undergoes meiosis to produce haploid cells called spores. -The spores then undergo mitosis to produce more haploid cells called gametophytes which are haploid multicellular organisms. -Gametophytes undergo
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This note was uploaded on 10/02/2011 for the course BIO 210 taught by Professor Lee during the Spring '11 term at San Mateo Colleges.

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02 - 9/03 6) A) Homologous Chromosomes -Chromosomes that...

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