Cellular Basis of Inheritance
Chapter 9
9.1 All Cells Come From Cells
A. Repair and Growth
a. Replacement of lost or damaged cells
b. Epidermis of Skin
B. Reproduction
a. Asexual Reproduction
i. Offspring inherit genetic material from
just one parent
ii. Cell Division
iii. Regeneration
iv. Budding
b. Sexual Reproduction
i. When two parents are involved in the
production of offspring
ii. Genetic material from each of the two
parents combines
iii. Union of egg and sperm
9.2 The Cell Cycle Multiplies Cells
A. Chromosomes and Cell Division
a. Chromatin
i. Combination of DNA and protein
molecules
b. Chromosome
i. Compact structures of chromatin fibers
c. Sister Chromatid
i. Two chromatids that come together to
form a chromosome
d. Centromere
i. Region where the sister Chromatids are
joined together
B. The Cell Cycle
a. Orderly sequence of events for Cellular
Division
i. Interphase-cell carries out metabolic
functions
ii. Mitotic Phase-Cell actually divides
1. Mitosis-nucleus and duplicated
chromosomes are evenly distributed
2. Cytokinesis-Cytoplasm divides
forming two new cells
9.3 Cells Divide during the Mitotic Phase
A. The Mitosis Dance
a. Spindle-football-shaped framework of
microtubules that guide the movements of
chromosomes.
b. Centromeres-regions of cytoplasmic material
that in animal cells contain structures called
centrioles
c. Steps in Mitosis:
i. Interphase
1. “Resting stage” for the cell
2. Cell makes new organelles and new
molecules
ii. Prophase
1. Chromosomes become visible
iii. Metaphase
1. Chromosomes line up at the equator
(center) of the cell
iv. Anaphase
1. Chromatids separate
v. Telephase
1. Nuclear envelope divides
vi. Cytokinesis
1. Cytoplasm divides forming two new
cells
B. Cytokinesis in Animals and Plants
a. Plant Cells
i. Cell Plate
1. Forms inside the cells and grow
outward
2. Cell wall joins to the two ends of the
cell plate and two new daughter cells
are formed
9.4 Cancer cells grow and divide out of control
A. Tumors and Cancer
a. Benign Tumor-abnormal mass of normal cells
b. Malignant Tumor-Masses of cells that result
from the reproduction of cancer cells
(problematic)
c. Cancer-Severe disruption of the cell cycle
d. Metastasis-spread of cancer cells beyond their
original site
B. Cancer Treatment
a. Surgery
b. Chemotherapy
i. Radiation
ii. High-energy radiation disrupts cell
division
iii. Can cause the damage of cells
1. ovaries/testes
2. Intestinal Cells
3. Hair follicle Cells
9.5 Meiosis Functions in Sexual Reproduction
A. Homologous Chromosomes
a. Meiosis-Cell division that produces four cells,
each with half the number of chromosomes as
the parent cell (occurs in sex organs in
animals)
b. Karyotype-Display of the 46 chromosomes in
the human body
c. Homologous chromosomes- two
chromosomes of each matching pair.
d. Sex Chromosomes-23rd pair of chromosomes,
determines the person’s sex.
C. Diploid and Haploid Cells
a. Diploid
i. Human cells
ii. 2 sets of homologous chromosomes
iii. 46 chromosomes
b. Haploid
i. 1 set of homologous chromosomes
ii. 23 Chromosomes
c. Gametes
i. Egg and sperms cells
ii. Sex cells
d. fertilization
i. the fusion of nuclei along with the
cytoplasm from the gametes
e. Zygote
i. Fertilized egg
ii. Diploid
D. The process of Meiosis
a. Meiosis I
i. Prophase I
1. Chromosomes stick together along
their length
2. Tetrad-four chromatids
ii. Metaphase I
1. Tetrads line up at the center of the
cell
iii. Anaphase I
1. Homologous chromosomes separate
iv. Telephase I
1. each pole has a haploid daughter cell
v. Cytokinesis I
1. Cytoplasm splits resulting in two
haploid daughter cells
b. Meiosis II
i. Each new haploid daughter cell goes
through Mitosis.
ii. Resulting in four haploid daughter cells
9.6 Meiosis increases genetic variation among
offspring
A. Crossing Over
a. The exchange of genetic material between
homologous chromosomes.
b. Occurs during prophase I
c. Segments of two chromatids can be exchanged
at one or more sites
B. Genetic Recombination
a. New combination of genetic information in a
gamete as a result of crossing over during
prophase I of meiosis.