Chapter 17 - Meiosis

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Terms to Know in This Chapter:

sexual reproduction

gene (sing.) [jean]

chromosome [CROW moe zome]

homolog (sing.) [HOE moe log]

homologous [hoe MOLL oh gus]

diploid [DIP lloyd]

haploid [HAP lloyd]

interphase [IN tur faze]

prophase I [PRO faze]

metaphase I [MET ah faze]

anaphase I [ANN ah faze]

telophase I [TELL oh faze]

prophase II

metaphase II

anaphase II

telophase II

synapsis [seh NAP siss]

crossing over

chiasma (sing.) [kie AZ mah]
chiasmata (pl.) [kie AZ mah tah]

centriole (sing.) [SIN tree olel]

spindle (sing.) [SPIN dull]

centromere (sing.) [SIN trow meer]

What You Need to Know:

You should be able to:

1. distinguish between mitosis and meiosis,
2. define meiosis and explain why it is a reduction division,
3. explain the difference between prophase I of meiosis and prophase of mitosis,
4. explain what is meant by synapsis and crossing over,
5. give the difference between anaphase I of meiosis and anaphase of mitosis,
6. distinguish between diploid and haploid, and
7. tell which genes on a hypothetical chromosome will show the greatest frequency of crossing over.
   

Exercises: Fill in the Blank.

1. begins with a cell with 46 chromosomes and ends with two cells, each with 46 chromosomes. (Mitosis, Meiosis)
2. begins with a cell with 46 chromosomes and ends with four cells, each with 23 chromosomes. (Mitosis, Meiosis)
3. The normal complement of chromosomes in an individual is referred to as the number and half the compliment is referred to as . With this information, 46 chromosomes in humans would be the number and sperm and egg cells with 23 chromosomes would have the number. (haploid, diploid)
4. In meiosis, during prophase I, two events that do not occur in prophase of mitosis occur. These are and . During , the homologous chromosomes pair up and during , the arms of the chromosomes intertwine, break apart, and reform.
5. The two genes are apart on a chromosome, the greater the frequency of crossing over. (farther, closer)
6. An event that occurs during anaphase of mitosis does not take place in anaphase I of meiosis. The event that does not take place is .
   

   Exercises. Multiple Choice. Select the best answer.

7. In anaphase II of meiosis, the:

   (1) same thing occurs in anaphase I of meiosis.
   

   (2) the same thing occurs in metaphase of mitosis.
   

   (3) centromeres divide.
   

   (4) centrioles divide.
   

   (5) centromeres don't divide.

8. Meiosis:

   (1) has only one interphase.
   

   (2) has the process called synapsis and crossing over.
   

   (3) two sucessive events of karyokinesis, each followed by cytokinesis, and only one interphase.
   

   (4) takes cells from the diploid to the haploid condition.
   

   (5) all of these are correct.
   

9. Meiosis:

   (1) is the same as mitosis, it just occurs twice.
   

   (2) is exactly the same as mitosis except for prophase.
   

   (3) is two successive divisions of the nucleus, each preceded by interphase.
   

   (4) takes cells from the haploid to the diploid condition.
   

   (5) none of the above is correct.
   

10. The diploid number of chromosomes:

    (1) occurs at the beginning of meiosis.
    

    (2) is maintained in mitosis.
    

    (3) is maintained in meiosis
    

    (4) is both 1 and 2 are correct.
    

    (5) is both 2 and 3 are correct.