Comparing mitosis and meiosis Table 3.1
Point of comparison
Mitosis
Meiosis
Cell type
Som atic
Gam ete
Num ber of d ivisio ns
1
2
Stages
Interphase
Interphase I only
Prophase
Prophase I and II
M etaphase
M etaphase I and II
Anaphase
A n aphase I and II
Telophase
Telophase I and II
C op y DNA?
Yes, interphase
Yes, interphase I; No, interphase II
Tetrads?
No
Yes
Num ber of cells
2
4
Num ber of chrom osom es
per cell
46, or two sets of 23; this m akeup, called diploid,
is identical to the chrom osom es in the starting cell
One set of 23; this m akeup, called haploid, repre-
sents half of the chrom osom es in the starting cell
the genetic material, which allows genetic variation from
one generation to the next. In the first anaphase of meiosis
(anaphase I), the tetrads get pulled
apart. Ultimately, the two stages
of meiosis divide the chromosome
complement of the parent in half,
a status called haploid. Table 3.1
compares mitosis and meiosis.
haploid
Referring to
a cell or an organ-
ism that has only
one (unpaired) set of
chromosomes.
CONCEPT CHECK
1.
How
does the sodium-potassium pump work?
2.
What
happens during transcription and
translation?
3.
How
is mitosis different from meiosis?
Cells Specialize into Various Tissues
LEARNING OBJECTIVES
1.
Identify
the structures and functions of the vari-
ous epithelial tissues.
2.
Describe
the types of connective tissues.
3.
Explain
the locations and functions of each type
of muscle tissue.
4.
Discuss
the classifications and functions of
membranes.
o far, we have discussed the parts of a general-
ized cell and the functions that cells must per-
form during their lifetimes. However, during
development, most of the cells in your body
change from generalized cells into specialized cells that
carry out specific functions (for example, muscle cells,
nerve cells, epithelial cells). Groups of cells and surround-
ing material that work together to perform a specific func-
tion are referred to as tissues. The science that deals with
the study of tissues is called histology (
hiss-TOL-o-je
). A
pathologist (
pa-THOL-o-jist
) is a physician who examines
tissues for changes that indicate damage or disease.
Cells specialize into Various Tissues 71
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