Chapter 9: The Cellular Basis of Inheritance
Concept 9.1 All cells come from cells
I. Repair and Growth
A. The outermost layer of your skin is actually a layer of dead
cells
B. Underneath the outer layer is a layer of living cells that are
constantly reproducing and moving outward to replace the dead
cells that have been rubbed off
C. Another function of cell division is growth, from one fertilized
egg cell there are trillions of cells in your body
II. Reproduction
A. Cell production of new cells can result in _______________
________organisms, cell division also has an essential role in
the reproduction of __________ organisms
B. _____________________________________ is when an
organism inherits all of its genetic material from one parent
C. ______________________________________ is when an
organism inherits its genetic material from two parents
D. All multicellular organisms depend on cell division for growth
Concept 9.2 The Cell Cycle Multiplies Cells
I. Chromosomes and Cell Division
A. In eukaryotes, most of the genetic material is located within the
nucleus as a mass of very long fibers, made of DNA and
proteins called __________________________
B. When chromatin condenses it becomes visible as the compact
structure ________________________________
C. Before cell division occurs, a cell replicates all of its
chromosomes, the identical copy is called a sister __________
D. The sister chromatids are joined together in a region called the
_________________________
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II. The Cell Cycle
Cells that divide undergo an orderly sequence of events known as
the ______________________, which is from the “birth” of
the cell to the time it reproduces itself
Interphase
Accounts for about 90% of the cell cycle
Cell grows – ___________ phase (Gap)
DNA duplicates – ______________ (Synthesis)
Cell prepares to divide – _____________ phase
Mitotic Phase
Cell is actually dividing – _________________
Two processes:
_________- nucleus and chromosomes form “daughter cells”
________________________- cytoplasm is divided in two
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Concept 9.3 Cells Divide During the Mitotic Stage
I. The Mitosis Dance
During mitosis, the chromosomes movements are guided
by a football-shaped framework of microtubles called
the _______________________________
The spindle microtubles grow from two _______________,
the regions that contain the centrioles
There are five stages of mitosis
__________________ – The cell is making molecules
and organelles and has duplicated its DNA
______________________ – The chromatin fibers have
condensed into chromosomes and pair up with their
sister chromatids. The spindle forms, nuclear
envelope and nucleoli disappear
________________________ – All the chromosomes
gather in the middle of the cell
________________________ – Sister chromatids
separate from their partners
_________________________– Chromosomes reach
the poles of the spindle. The processes of prophase
are reversed.
_________________________ completes the process by
separating the cytoplasm into two daughter cells.
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Phases of Mitosis
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II. Cytokinesis in Animals and Plants
A. _______________ is the actual division of the cytoplasm
into two cells, typically occurring during telophase
B. In animal cells, the first indication of cytokinesis is an
______________________________ around the center
of the cell which eventually separates the two cells
C. In plants, a disk containing cell wall material called a
______________________ forms inside and grows
outward
D. Eventually the new piece of the cell wall divides the cell
in two
Concept 9.4 Cancer Cells Grow and Divide out of Control
I. Tumors and Cancer
A. An abnormal mass of normal cells is called a
___________________________________
B. Benign tumors can usually be surgically removed
depending on their location, plus benign tumors don’t
move through the body
C. _________________________ are masses of cells that
result from the production of cancer cells
D. _______________________ is caused by a severe
disruption of the mechanisms that control the cell cycle
E. The spread of cancer cells beyond their original site is
called ____________________
II. Cancer Treatment
A. When possible malignant tumors are removed by
______________________
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B. At the cellular level, _________________ therapy or
___________________ is used to stop the cancer cells
from dividing
C. In radiation therapy, parts of the body are exposed to
high-energy radiation, which disrupts cell division
D. Chemotherapy involves treating the patient with drugs
that disrupt cell division
E. Some drugs called antimitotic drugs interferes with
_____________________________
F. Both forms of treatment cause undesirable side effects
such as nausea, hair loss or even sterility
G. The government does not have a cure to cancer and is
not keeping it from the rest of us to keep population
numbers down.
Concept 9.5 Meiosis Functions in Sexual Reproduction
I. Homologous Chromosomes
A. ____________________________is the type of cell
division that produces four cells, each with half of the
number of chromosomes as the parent cell
B. Meiosis occurs in the sex organs, the testes in males and
ovaries in females
C. Almost all cells have the same number and types of
chromosomes
D. A display of all 46 chromosomes of an individual is
called a ____________________________
E. The two chromosomes of a matching pair that carries the
same sequence of genes controlling the same
characteristics are called
_________________________________________
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F. The 23rd pair of chromosomes which determine the
gender of the individual are called the
______________________________________
II. Diploid and Haploid Cells
A. ___________________cells are those cells that have
two homologous chromosomes for every set for a total
of 46 chromosomes 2n
B. ____________________, or sex cells, only have a single
set of chromosomes, one from each homologous pair
C. A cell that only has a single set of chromosomes is
called a ________________ cell
D. _________________________ occurs when the nucleus
of a haploid sperm cell fuses with a haploid egg cell
E. The result of fertilization is called a_____________
which is a diploid cell
III. The Process of Meiosis
A. If meiosis did not occur cells involved in fertilization
would produce new organisms having twice the number
of chromosomes of the previous generation
B. Meiosis Versus Mitosis
1. _________________ produces four new cells, each
with only one set of chromosomes, mitosis produces
two cells, each with the same number of
chromosomes as the parent cell
2. Meiosis involves the exchange of genetic material,
mitosis doesn’t
C. The Two Meiotic Divisions
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1. Meiosis consists of two distinct parts- meiosis I and
meiosis II
2. Meiosis I – _______________________ and their
sister chromatids separate
3. Meiosis II – Sister chromatids separate resulting in
a ______________________
D. The phases of Meiosis are as follows
 ________________ I
1. __________________ attach to the spindle
2. Sister chromatids in the tetrads exchange genetic
material
 ______________ I
1. Tetrads move to the middle of the cell and line up
 ______________ I
1. Homologous chromosomes separate and the sister
chromatids move to opposite ends of the cell
Meiosis I
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 Telophase I and Cytokinesis
1. The chromosomes arrive at the poles, the cell is
considered to be haploid because there is only one
set of chromosomes, even though each chromosome
consists of two sister chromatids
2. Cytokinesis divides the cytoplasm into two cells
 _____________________ II
1. A spindle forms and moves the chromosomes to
the middle of the cell
 _____________________ II
1. The chromosomes line up in the middle of the cell
 _____________________ II
1. The sister chromatids separate and move to opposite
poles
 _______________ II and Cytokinesis
1. The chromosomes arrive at the poles and
cytokinesis splits the cell one more time
Meiosis II
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Concept 9.6 Meiosis Increases Genetic Variation Among
Offspring
I. Assortment of Chromosomes
A. The way the chromosomes line up and separate during
metaphase I is a _____________________________
B. The assortment of chromosomes that end up in the
resulting cells occur randomly
C. The total number of combinations is equal to _________
where n=the haploid number of the cell. In humans
n=23 so 223 = over 8 million!!
Chromosome Assortment
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II. Crossing Over
________________________ is the exchange of genetic
information between homologous chromosomes
Crossing over adds to even more variation among offspring
When a chromosome contains a new combination of genes
from different parents it is called a
____________________________________________
Crossing Over
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III. Review: Comparison of Mitosis and Meiosis
A. Mitosis, which provides for growth, repair and asexual
reproduction, produces daughter cells that are
genetically identical to the parent cell
B. Meiosis, which takes place in the sex organs, yields
haploid daughter cells with only one set of homologous
chromosomes
C. In both mitosis and meiosis the chromosomes only
duplicate once, during interphase
D. Mitosis and meiosis both make it possible for cells to
inherit genetic information in the form of chromosome
copies
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