Biology 1002B Lecture Notes - Lecture 10: Sister Chromatids, Metaphase, Nondisjunction
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20 Apr 2016
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These spores divide by mitosis to form multicellular bodies that then make gametes by mitosis. The essence of mitosis is sameness, but meiosis changes both chromosome number and dna sequence. The essence of meiosis is difference: meiosis produces a halved chromosome number and recombined dna sequence. Each cell produced by meiosis therefore: when an egg and sperm cell join in fertilization, the diploid number is restored. Reason why meiosis i is reductional and meiosis ii is equational In meiosis ii, the number of chromosomes remains haploid, but the amount of dna is reduced to (c) Proteins involved in holding homologous chromosomes together. Synaptonemal complex holds the two homologues together during recombination. Sometimes chromosomes line up incorrectly and recombination (the products) are unequal. Each non- homologous chromosomes could go randomly to either cell. The space between the two genes can be narrow so the likelihood of them crossing over is rare.
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Which of the following statements is true?
Question 7 options:
In plants, gametes are produced by meiosis | |
In animals, gametes are produced by mitosis | |
Plants have both a multicellular diploid stage and a multicellular haploid stage | |
Most fungi have a life cycle that includes a multicellular diploid stage. | |
Most animals have a sexual life cycle that includes a multicellular haploid stage. |
Which statement describes a similarity between the diploid and haploid phases of plant life?
both are multicellular |
both are immediately followed by meiosis |
both end in fertilization |
both contain spores |
both contain sporophytes |
A zygote is formed ____.â
by the fusion of male and female somatic cells |
directly by meiosis in fungi |
by the mitotic divisions of spores in plants |
by the fusion of egg and sperm nuclei |
after a fertilized egg undergoes mitotic divisions to mature |
Human skin color is an example of ____, while sickle-cell anemia is an example of ____.â
incomplete dominance; pleiotropy |
pleiotropy; polygenic inheritance |
incomplete dominance; multiple alleles |
polygenic inheritance; pleiotropy |
multiple alleles; epistasis |