NOTES
CHAPTER 8 – MITOSIS AND MEIOSIS
ZOOLOGY
I.
II.
Chromosomes
a. Objectives
i. Describe the structure of a chromosome
ii. Identify the differences in structure between prokaryotic chromosomes
and eukaryotic chromosomes
iii. Compare the numbers of chromosomes in different species
iv. Explain the differences between sex chromosomes and autosomes
v. Distinguish between diploid and haploid cells
b. Chromosome structure
i. Chromosomes are rod-shaped structures made of DNA and protein
ii. In eukaryotes, DNA wraps around proteins call histones to help maintain
the compact structure of chromosomes
iii. Chromosomes in prokaryotes are simpler in structure than chromosomes
in eukaryoties
c. Chromosome numbers
i. Each species has a characteristic number of chromosomes in each cell
ii. Sex chromosomes and autosomes
1. Sex chromosomes are chromosomes that determine the sex of an
organism
2. All of the other chromosomes in an organism are autosomes
iii. Diploid and haploid cells
1. Cell having two sets of chromosomes are diploid (2n)
2. Haploid cells (1n) have only one set of chromosomes
Cell division
a. Objectives
i. Describe the events of cell division in prokaryotes
ii. Name the two parts of the cell that are equally divided during cell division
in eukaryotes
iii. Summarize the events of interphase
iv. Describe the stages of mitosis
v. Compare cytokinesis in animal cells with cytokinesis in plant cells
vi. Explain how cell division is controlled
b. Cell division in prokaryotes
i. Cell division is the process by which cells reproduce themselves
III.
ii. Binary fission is the process of cell division in prokaryotes
c. Cell division in eukaryotes
i. Cell cycle
1. The cell cycle is the repeating set of events in the life of a cell
2. The cell cycle consists of cell division and interphase
3. Cell division in eukaryotes includes nuclear division, called
mitosis, and the division of cytoplasm, call cytokinesis
ii. Interphase
1. Interphase consists of growth (G1), DNA replication, and
preparation for cell division (G2)
iii. Stages of Mitosis
1. Mitosis is divided into stages: prophase, metaphase, anaphase, and
telophase
2. Mitosis results in two offspring cells that are genetically identical
to the original cell
iv. Cytokinesis
1. During cytokinesis in animal cells, a cleavage furrow pinches in
and eventually separates the dividing cell into two cells
2. In plant cells, a cell plate separates the dividng cell into two cells
v. Control of cell division
1. Cell division in eukaryotes is controlled by many proteins
2. Control occurs at three main checkpoints
3. When control is lost: cancer
a. Cancer may result if cells do not respond to control
mechanisms
Meiosis
a. Objectives
i. Compare the end products of meiosis and those of mitosis
ii. Summarize the events of meiosis I
iii. Explain crossing-over and how it contributes to the production of unique
individuals
iv. Summarize the events of meiosis II
v. Compare spermatogenesis and oogenesis
vi. Define sexual reproduction
b. Formation of haploid cells
i. Meiosis includes prophase I, metphase I, anaphase I, and telophase I
ii. Crossing-over, which is when portions of homologous chromosomes
exchange genetic material, occurs during prophase I and results in genetic
recombination
c.
d.
e.
f.
iii. Meiosis is a process of nuclear division that reduces the number of
chromosomes in new cells to half the number in the original cell
iv. Meiosis leads to four haploid cells (gametes) rather than two diploid cells
as in mitosis
Meiosis I
i. Meiosis I includes prophase I, metaphase I, anaphase I, and telophase I
ii. Crossing over occurs
Meiosis II
i. Meiosis II includes prophase II, metaphase II, anaphase II and telophase II
ii. Four new haploid cells result
Development of gametes
i. Spermatogenesis is the process by which sperm cells are produces
ii. Oogenesis is the process that produces mature egg cells
Sexual reproduction
i. Sexual reproduction is the formation of offspring through meiosis and the
union of a sperm and an egg
ii. Offspring produced by sexual reproduction are genetically different from
the parents