BIOL 331 Lecture Notes - Lecture 2: Interphase, Chromatin, Centromere

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29 Aug 2018

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Prophase i: two homologous chromosomes of each type find each other and undergo synapsis: synapsis: process where homologous are held in close proximity to each other and may undergo recombination, stages of prophase i of meiosis: Leptotene: chromatin condenses into chromosomes randomly throughout the nucleus; the homologous are not yet paired. Zygotene: chromosomes continue to condense and homologous begin to pair to each other. C. ) pachytene: chromosomes condense until they double in structure, indicating that there are two paired homologous (bivalents) D. ) diplotene: homologous pair begins to pull away from each other, but their complete separation is prevented by chiasmata (places where the homologous remain associated) Nucleolus disappears, nuclear membrane breaks down, and spindle begin to form. If chiasmata were present, they are terminated, and bivalents assume shape of rings. If chiasmata were not present, they assume the shape of two rods well separated from each other.

Related Questions

Which of the following statements are false about the comparison between mitosis and meiosis? Select all. that apply.

1.Two cytokinesis events occur in mitosis but only one in meiosis

2.Meiosis results in half the number of homologous chromosome pairs as the original cell whereas mitosis has the same number as the original cell

3. Mitosis occurs in somatic cells while meiosis only occurs in germ cells

4.Both haploid and diploid cells undergo mitosis and meiosis

5.Both mitosis and meiosis have one round of DNA replication in the preceding Interphase period

6. Chromosomes undergo disjunction in mitosis but not in meiosis

7.Meiosis leads to a reductive division in the number of chromosomes whereas mitosis does not

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Which of the following statements are false about the comparison between mitosis and meiosis? Select all. that apply. Multiple answers: You can select more than one option A Two cytokinesis events occur in mitosis but only one in meiosis B Meiosis results in half the number of homologous chromosome pairs as the original cell whereas mitosis has the same number as the original cell C Mitosis occurs in somatic cells while meiosis only occurs in germ cells D Both haploid and diploid cells undergo mitosis and meiosis E Both mitosis and meiosis have one round of DNA replication in the preceding Interphase period F Chromosomes undergo disjunction in mitosis but not in meiosis G Meiosis leads to a reductive division in the number of chromosomes whereas mitosis does not Unanswered

-Complete the following sentences: metaphase of mitosis, prophase II of meiosis, crossing over, anaphase I of meiosis, variable, random fertilization, identical, random orientation, metaphase I of meiosis, prophase I of meiosis, metaphase II of meiosis, reduction division

Two processes that occur during meiosis produce genetically ____________ cells.

In a process called ____________ , paired homologous chromosomes align randomly at the cell equator. This occurs during this stage of cell division: ____________ .

In a process called ____________ , genetic material is exchanged between homologous chromosomes. This occurs during this stage of cell division: ____________ .

-Complete the following paragraph to describe nondisjunction and the resulting effects on chromosome number.

words: euploidy, primary nondisjunction, nomal, nondisjunction, secondary nondisjunction, homologous chromosomes, abnormal, trisomy, monosomy, sister chromatids, aneuploid

1.During meiosis I, ____________ separate and move towards opposite ends of the poles.

2.During meiosis II, ____________ separate and move towards opposite ends of the poles.

3.During meiosis I, if both members of a homologous pair go into the same daughter cell, ____________ is said to occur and no normal gametes are produced.

4.During meiosis II, if the sister chromatids fail to separate and both daughter chromosomes go into the same gamete, ____________ is said to occur. Half the gametes are aneuploid while the other half are euploid.

5.If an egg that contains 24 chromosomes instead of 23 chromosomes is fertilized by a normal sperm, ____________ is said to have occurred.

6.If an egg that contains 22 chromosomes instead of 23 chromosomes is fertilized by a normal sperm, ____________ is said to have occurred.

BIOL 331 Lecture Notes - Lecture 2: Interphase, Chromatin, Centromere

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