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Bio Chap 7


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Ordinary cell division produces two daughter cells that are genetically identical. Give three functions of cell division.
Cell replacement, growth of an organism, asexual reproduction of an organism
When in the cell cycly does each chromosome consist of two chromatids?
During G2, the last part of interphase, and during prophase and metaphase of the next mitosis
An organism called a plasmodial slime mold is one huge cytoplasmic mass with many nuclei. Explain how this "monster cell" could arise.
Mitosis occurs repeatedly without cytokinesis
In what sense are the two daughter cells produced by mitosis identical?
They have identical genes (DNA)
When a cancer patient is treated with vinblastine, which prevents the mitotic spindle from forming, in what stage of mitosis are dividing cells trapped?
diploid cell
contains two homologous sets of chromosomes
a sex cell; a haploid egg or sperm. The union of two gametes of opposite sex (fertilization) produces a zygote
a cell with o single chromosome set
fertilized egg (diploid)
_____ is to somatic cells as haploid is to _____
Diploid; gametes
If a diploid cell with 18 chromosomes undergoes meiosis, the resulting gametes will each have ______ chromosomes.
Explain how mitosis conserves chromosome number while meiosis reduces the number in half
In mitosis, a single replication of the chromosomes is followed by one division of the cell. In meiosis, a single replication of the chromosomes is followed by two cell divisions.
In what important way is anaphase of meisois II like anaphase of mitosis?
Sister chromatids separate
Name two events during meiosis that contribute to genetic variety among gametes.
Crossing over between homologous chromosomes during prophase I and independant orientation of tetrads at metaphase I
How does the karyotype of a human female differ from that of a male?
A female has two X chromosomes; a male has an X and a Y
What is the chromosomal basis of Down syndrom?
Three copies of chromosome 21 (trisomy 21)
Explain how nondisjunction in meiosis could result in a diploid gamete
A diploid gamete would result if there were nondisjuntion of ALL the chromosomes during meiosis I or II
How is reciprocal translocation different from normal crossing over?
Normal crossing over is an exchange of segments between homologous chromosomes; reciprocal translocation occurs between nonhomologous chromosomes.
Name meiosis/mitosis steps in order
Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis
Describe Interphase of mitosis and meiosis
chromosomes are duplicated but cannot be seen individually
Describe prophase I of meiosis
Chromatin condenses. Chromosomes "cross over" and are rearranged. Spindle forms
Describe Metaphase I of meiosis
tetrads aligned in the middle of the cell. spindle attaches to the centromeres
Describe Anaphase I of meiosis
Chromosomes migrate in pairs to the poles of the cell
Describe Telophase/Cytokenisis I of meiosis
Chromosomes arrive at poles. cell splits.
Describe Prophase(II) of mitosis/meiosis
spindles form. chromosomes are moved to middles of the cells
Describe Metaphase(II) of mitosis/meiosis
aligned in the middle, spindle fibers are attached
Descibe Anaphase(II) of mitosis/meiosis
centomeres are separated and sister chromosomes move to the opposite poles of the cells
Describe Telophase(II)/Cytokenesis of mitosis/meiosis
nuclei form, and cytokinesis (splitting of the cell) occurs at the same time
2 sets of homologous chromosomes (sister chromosomes) stuck together in Prophase I of meiosis

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