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CHAPTER
8
Cellular Reproduction:
Cells from Cells
Lecture Outline
A. Biology and Society:
Virgin Birth of a Dragon
B. WHAT CELL REPRODUCTION ACCOMPLISHES
1. Reproduction asexually
2. Growth
3. Repair/replacement
C. Mitosis is the type of cell division responsible for:
–
asexual reproduction and
–
growth and maintenance of multicellular organisms.
D. Sexual reproduction requires fertilization of an egg by a sperm using a special
type of cell division called meiosis.
Thus, sexually reproducing organisms use
–
meiosis for reproduction and
–
mitosis for growth and maintenance.
E. Eukaryotic Chromosomes
1. Chromosomes are:
2. DNA in a cell is packaged:
3. Histones are:
4. Nucleosomes:
5. sister chromatids are:
F. The Cell Cycle
1. The cell cycle consists of two distinct phases:
a.
b.
2. Most of a cell cycle is spent in interphase.
During interphase, a cell:
3. The mitotic (M) phase includes two overlapping processes:
a. Mitosis
b. Cytokinesis
G. Mitosis
1. Mitosis consists of four distinct phases:
a. Prophase
b. Metaphase
c. Anaphase
d. Telophase
H. Cytokinesis usually:
1. In animal cells, cytokinesis
2. In plant cells, cytokinesis begins when vesicles containing cell wall material collect
at the middle of the cell and then fuse, forming a membranous disk called the
cell plate.
I. Cancer Cells: Growing Out of Control
1. What Is Cancer?
2. Cancer cells can form tumors, abnormally growing masses of body cells.
3. The spread of cancer cells beyond their original site of origin is metastasis.
4. Malignant tumors can:
5. A person with a malignant tumor is said to have cancer.
6. Cancer treatment can involve
a. surgery:
b. radiation therapy:
c. chemotherapy:
7. Certain behaviors can decrease the risk of cancer:
J. Sexual reproduction
1. Homologous Chromosomes:
2. A human somatic cell
3. A karyotype is an image that reveals an orderly arrangement of chromosomes.
4. Humans have
1. sex chromosomes, X and Y
2. autosomes.
K. Gametes and the Life Cycle of a Sexual Organism
The life cycle of a multicellular organism is the sequence of stages leading from the
adults of one generation to the adults of the next.
1. Humans are diploid organisms with
2. Sexual life cycles involve an alternation of diploid and haploid stages.
L. The Process of Meiosis
1. In meiosis,
M. Review: Comparing Mitosis and Meiosis
1. In mitosis and meiosis, the chromosomes duplicate only once, during the preceding
interphase.
2. The number of cell divisions varies:
3. All the events unique to meiosis occur during meiosis I.
N. The Origins of Genetic Variation
1. Independent Assortment of Chromosomes
For a human,
–
n = 23.
–
With n = 23, there are 8,388,608 different chromosome combinations possible in
a gamete.
2. Random Fertilization
3. Crossing Over
O. The Process of Science:
Do All Animals Have Sex?
P. What happens when errors occur in meiosis?
How Accidents during Meiosis Can Alter Chromosome Number
1. In nondisjunction:
2. Nondisjunction can occur during meiosis I or II:
3. If nondisjunction occurs, and a normal sperm fertilizes an egg with an extra
chromosome, the result is a zygote with a total of 2n + 1 chromosomes.
4. If the organism survives, it will have:
5. Down syndrome:
Abnormal Numbers of Sex Chromosomes
6. Nondisjunction in meiosis
Q. Evolution Connection:
The Advantages of Sex