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Chapter 10 Notes
10–1
Cell Growth
A. Limits to Cell Growth
1. DNA “Overload”
2. Exchanging Materials
3. Ratio of Surface Area to Volume
4. Cell Division
Ratio of Surface Area to Volume in Cells
Cell Size
Surface Area (length x
width x 6)
Volume
(length x width x height)
Ratio of Surface Area to
Volume
10–2
Cell Division
A.
B.
C.
D.
Chromosomes
The Cell Cycle
Events of the Cell Cycle
Mitosis
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
E. Cytokinesis
Objective 1: Summarize the events that occur
during mitosis
 Homologous chromosome--a member of a
chromosome pair.
 similar in shape, size, and the genes they carry.
• Chromatid--one of a
pair of strands of DNA
that make up a
chromosome during
meiosis or mitosis.
Figure 10–4 The Cell Cycle
G1 phase
M phase
S phase
G2 phase
Interphase
 This is the non-reproducing stage of a cell’s life.
 It is the longest stage of a cell’s life
 Major events in interphase:
 Cells grow during interphase
 Chromosomes are duplicated about mid-way through
interphase to prepare for mitosis.
Interphase
Animal Cell
Plant Cell
Prophase
 Major events in prophase:
 Nucleoli disintegrates
 Chromatin coils up to form chromosomes
 Centrioles move to opposite poles of the cell
 Microtubules form spindle fibers between the centrioles
 The nucleus breaks down
Prophase
Animal Cell
Plant Cell
Metaphase
 Major events in metaphase:
 Chromosomes attach to the spindle fibers at the
centromere
 Chromosomes move to the equator of the cell
Metaphase
Animal Cell
Plant Cell
Anaphase
 Major events in anaphase:
 Centromeres split
 The two sister chromatids separate and move apart to
opposite poles of the cell
Anaphase
Animal Cell
Plant Cell
Telophase
 Major events in telophase:
 The nucleoli reappear
 The nucleus reforms
 Chromosomes uncoil and appear as a mass of chromatin
Cytokinesis
 Major Events:
 Happens at the same time as telophase
 In animals: cell membrane pinches in at the center
 In plants: a cell plate forms at the equator of the cell
 Daughter cells are formed
Telophase & Cytokinesis
Animal Cell
Plant Cell
Section 10-2
Figure
10–5 Mitosis and Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Centromere
Centriole
Chromosomes (paired
chromatids)
Interphase
Prophase
Centriole
Cytokinesis
Individual
Nuclear envelope
reforming
Go to
Section:
Spindle
Telophase chromosomes
Anaphase
Metaphase
Section 10-2
Figure
10–5 Mitosis and Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Centromere
Centriole
Chromosomes (paired
chromatids)
Interphase
Prophase
Centriole
Cytokinesis
Individual
Nuclear envelope
reforming
Go to
Section:
Spindle
Telophase chromosomes
Anaphase
Metaphase
Section 10-2
Figure
10–5 Mitosis and Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Centromere
Centriole
Chromosomes (paired
chromatids)
Interphase
Prophase
Centriole
Cytokinesis
Individual
Nuclear envelope
reforming
Go to
Section:
Spindle
Telophase chromosomes
Anaphase
Metaphase
Section 10-2
Figure
10–5 Mitosis and Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Centromere
Centriole
Chromosomes (paired
chromatids)
Interphase
Prophase
Centriole
Cytokinesis
Individual
Nuclear envelope
reforming
Go to
Section:
Spindle
Telophase chromosomes
Anaphase
Metaphase
Section 10-2
Figure
10–5 Mitosis and Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Centromere
Centriole
Chromosomes (paired
chromatids)
Interphase
Prophase
Centriole
Cytokinesis
Individual
Nuclear envelope
reforming
Go to
Section:
Spindle
Telophase chromosomes
Anaphase
Metaphase
Section 10-2
Figure
10–5 Mitosis and Cytokinesis
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Centromere
Centriole
Chromosomes (paired
chromatids)
Interphase
Prophase
Centriole
Cytokinesis
Individual
Nuclear envelope
reforming
Go to
Section:
Spindle
Telophase chromosomes
Anaphase
Metaphase
Meiosis
Meiosis--a form of cell division
that halves the number of
chromosomes when forming
reproductive cells.
Mitosis vs. Meiosis
2n
2n
2n
1n
2n
1n
1n
1n
1n
1n
Meiosis I
• Prophase I
– Chromosomes become visible
– Nuclear envelope breaks down
– Crossing-over occurs
• Metaphase I
– Pairs of homologous chromosomes
move to the equator of the cell
Meiosis I
• Anaphase I
– Homologous chromosomes move to
opposite poles of the cell
• Telophase I and Cytokinesis
– Chromosomes gather at the poles of the
cell
– Cytoplasm divides
Meiosis II
• Prophase II
– A new spindle forms around the
chromosomes
• Metaphase II
– Chromosomes line up at the equator
Meiosis II
• Anaphase II
– Centromeres divide
– Chromatids (now called chromosomes)
move to opposite poles of the cell.
• Telophase II and Cytokinesis
– Nuclear envelope forms around each set
of chromosomes
– Cytoplasm divides
Bivalent
Centromere
Chiasma (site of
crossing-over)
Mitosis vs. Meiosis
Close-up View
Prophase I
Meiosis
Bivalents align at the
metaphase plate
Prophase
Mitosis
2n = 4
Chromosomes align at the
metaphase plate
Metaphase I
Sister chromatids remain
together during anaphase I
X
X
N
X
X
N
N
Sister chromatids
separate during
anaphase
x
xx
x
Metaphase
Daughter Cells of meiosis I
No further chromosomal
replication; sister chromatids
separate during anaphase II
N
Daughter Cells of meiosis II
2N
2N
Daughter Cells
Objective 2: Relate crossing-over, independent
assortment, and random fertilization to genetic
variation.
 Independent assortment--the random
distribution of homologous
chromosomes.
 Crossing-over--the exchange of
reciprocal segments of DNA by
homologous chromosomes at the
beginning of meiosis.
 Fertilization is the random joining of 2
gametes.
Objective 3: Compare the formation of
gametes in male & female animals
 Spermatogenesis--the process by which sperm
are produced in male animals.
 Occurs in the testes
 Oogenesis--the process by which gametes are
produced in female animals.
 Occurs in the ovaries
Gamete Development
Diploid germ cell
Diploid germ cell
Spermatogenesis
Oogenesis
Sperm cell
Egg cell
Polar bodies
Meiosis in male & female animals
Sperm Formation
Egg Formation
Diploid germ cell
Meiosis I
Immature sperm cells
Secondary egg cell
First polar body
Undifferentiated egg cell
Meiosis II
Undifferentiated sperm cells
Sperm
Second polar bodies (all
3 will die)
Egg cell
(ovum)
Objective 4: Differentiate between
asexual and sexual reproduction
 asexual reproduction--a single parent passes
copies of all of its genes to each of its offspring
 There is no fusion of haploid cells
 The offspring is a clone of its parent
 sexual reproduction--two parents each form
haploid reproductive cells, which join to form
offspring.
Objective 5: Identify three types of
asexual reproduction
 Fission--separation of a parent into two or more
individuals of about equal size.
 Fragmentation--the body of an organism breaks
into several pieces.
 fragments develop into adults when missing parts are
regrown
 Budding--new individuals split off from existing
ones.
Objective 6: Evaluate the advantages and disadvantages of asexual
and sexual reproduction
Asexual Reproduction
 Advantages
 produce many
offspring in short
period of time
 don’t waste energy
making gametes or
looking for a mate
 Disadvantages
 little genetic variation
between individuals
Sexual Reproduction
 Advantages
 quickly produce
different combinations
of genes among
individuals
 Disadvantages
 produce fewer offspring
in longer periods of
time
 waste energy making
gametes & looking for a
mate