Transcript Slide 1

Cell Reproduction
Ch. 10 & 11
The Cell Cycle
1. All living things are composed of one or
more cells
2. Cells are an organisms basic unit of
structure and function
3. Cells come only from existing cells.
I. Why do cells divide?
A. Cells have a lifespan
red blood cells
less than 120 days
lining of sm intestine
1-2 days
white blood cells
10 hrs to decades
B. DNA Overload
C. Lower efficiency due to low surface area to
volume ratio
II. Chromosomes
A. DNA in a coiled, rod-shaped form that
occurs during cell division
B. Chromosome Structure
1. chromatin
a. the DNA and proteins in the nucleus
of a nondividing cell
b. thin, uncoiled strands (easier to read)
c. as a cell begins to divide, they form
2. Each chromosome consists of 2 identical
parts called chromatids
3. The point at which the chromatids are
attached is the centromere
a. during cell division the centromere
releases the chromatids allowing one sister
chromatid to go to each of the two daughter
C. Chromosome Numbers of Various Species
C. Chromosome Numbers of Various Species
and DNA
Humans – 46 chromosomes
1. Prokaryotes usually have only one
2. Sex Chromosomes
a. chromosomes that determine the sex of
an organism
b. humans
XX female
XY male
3. Autosomes
a. any chromosome that is not a sex
4. Homologous Chromosomes/Homologues
a. one of two members of a pair of
morphologically similar chromosomes
b. same size and shape
c. structurally different from other
chromosomes in the cell
5. Karyotype
a. a picture of an individual’s chromosomes
6. Diploid
a. cell that contains both homologous pairs
b. 2n
c. ie – humans 46
7. Haploid
a. a cell that contains only half of the
b. 1 n
c. ie – humans reproductive cells
– egg and sperm - 23
8. Polyploidy
a. cells with more than two copies of each
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8. Polyploidy
b. triploid – banana, apple, watermelon,
c. tetraploid – wheat, maize, cotton, potato,
d. hexaploid – chrysanthemum, wheat, oats
e. octaploid – strawberry dahlia, pansies,
Sugarcane -; tulips
Invasive Species - Asian carp
II. Cell Division
A. Cell Division in Prokaryotes
1. Binary Fission
a. the division of a prokaryotic cell into
two identical cells
Binary Fission
B. Cell Division in Eukaryotes
1. Mitosis
a. cell division in new cells with genetic
material that is identical to that of
the original cell
b. occurs in the reproduction of
unicellular organisms
c. occurs in the addition of cells to tissue
or organs in multicellular organisms
d. DNA and information stays the same
f. The Cell Cycle
1) the sequence of events from mitosis to
How Cells Divide website
1. Interphase
a. G1 phase
b. S phase
c. G2 phase
2. Mitosis
a. Prophase
b. Metaphase
c. Anaphase
d. Telophase
3. Cytokinesis
IV. Regulating the Cell Cycle
A. Controls on Cell Division
B. Cell Cycle Regulators
1. Cyclins
a. a family of proteins that regulate the
timing of the cell cycle in eukaryotic
2. Internal Regulators
a. allow cell cycle to continue only when
correct order of events is followed (ie –
DNA is replicated before chromosomes
are pulled apart)
3. External Regulators
a. growth regulators cause cells to
multiply rapidly when neighboring cells die
C. Uncontrolled Cell Growth
1. Cancer cells do not respond to the signals
that regulate cell growth
2. form tumors
V. Meiosis
A. the process of nuclear division that reduces
the number of chromosomes by half
B. 1n
C. egg and sperm cells
D. 2 nuclear divisions;
E. Phases of
1. Interphase
2. Meiosis I
a. Prophase I
b. Metaphase I
c. Anaphase I
d. Telophase I
3. Interkinesis
4. Meiosis II
a. Prophase II
b. Metaphase II
c. Anaphase II
d. Telophase II
5. Cytokinesis
F. Crossing Over
1. during Meiosis I the 4 homologous
chromosomes form a tetrad
2. the tetrad exchanges parts of their
Crossing Over
G. Formation of Egg and Sperm
1. gametes
a. sexual reproductive cells
b. egg and sperm
2. ootid
a. egg cell
b. gets all the
3. polar bodies
a. receive little
or no cytoplasm
and eventually
H. Asexual Reproduction
1. the production of offspring that does not
involve the union of gametes
2. 1 parent
3. no union of gametes
4. unicellular organisms
a. binary fission
b. mitotic division
5. Multicellular organisms
a. cloning
b. budding
6. Genetically identical to parents
Hydra budding -; strawberry
I. Sexual Reproduction
1. the production of offspring from the
exchange of genetic material
2. meiosis and union of gametes
3. offspring are genetically different from
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J. Linkage and Gene Maps
1. Gene Linkage
a. chromosomes are assorted
b. individual genes can be inherited
2. Gene Map
a. the further two genes were apart on a
chromosome the less likely they would be
inherited together
Gene Map