Transcript Ch 22 Cellular Reporduction

Standard Biology
Chapter 22
Cellular Reproduction
Section 22:1 Mitosis
Mitosis


One cell divides and
divides to form 3
trillion cells (you)
Process of cell
reproduction by which
2 new identical cells
are formed from one
parent cell
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Mitosis

Needed for growth,
repair, and
replacement of body
parts

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
Growth: new muscle
Repair: broken bone
need new bone cells
Replacement: new blood
cells when have loss of
blood
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Mitosis

All body cells are
formed by mitosis
(body cells are all cells
that are not sex cells)
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Different Cells Have Different Life
Span
Cell Type
Brain Cell
Red Blood Cell
Platelets
Stomach Lining
Liver Cells
Intestine Lining
Skin
Life Span
30-50 years
120 days
10 days
2 days
200 days
3 days
20 days
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Mitosis


Mitosis continues your
entire life
Cells go through
mitosis at different
rates, some are slow
and some are fast
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Cell Cycle


Most of the time cells are
not dividing, they are just
growing and doing their
job
Interphase: time between
mitosis when cells grow,
do their job and get ready
for mitosis by:
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Doubling chromosomes get
sister chromatids
Making more cell parts
(mitochondria…)
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Steps of Mitosis
Prophase
 Sister chromatids thicken so can be seen
 Nuclear membrane disappears
 Centrioles (animals only) move away from
each other
 Spindle fibers form between centrioles
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Prophase
a. Chromosome
(two sister
chromatids)
b. Centriole
c. Spindle fiber
d. Nuclear
membrane
(disintegrating)
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Prophase
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Steps of Mitosis
Metaphase
 Sister chromatids are hooked to spindle
fiber
 Sister chromatids are in center of cell
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Metaphase
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Metaphase
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Steps of Mitosis
Anaphase
 Sister chromatids are pulled apart
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Anaphase
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Anaphase
PLANT
ANIMAL
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Steps of Mitosis
Telophase
 Each chromatid forms a nucleus
 Nuclear membrane forms around the 2 new
nuclei
 Spindle fibers disappear
 Chromatids thin and can’t be seen
 Cell cytoplasm usually divides (cytokinesis)
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Telophase
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Telophase
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After Telophase the 2
new cells are in
interphase
Cytokinesis is the
division of the cell
contents forming two
new cells
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Results of Mitosis

Results of mitosis: get
2 new cells that are
genetically identical
(same chromosome)
but smaller in size
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Differences between mitosis in
plants and animals
1. Plants don’t have
centrioles, animals
cells do; both have
spindle fibers
Centrioles
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Differences between mitosis in
plants and animals
2. Plants have cell wall
so must add more cell
wall between new
cells not just pinch in
cytoplasm to divide it
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Standard Biology
Chapter 22
Cellular Reproduction
Section 22:2 Meiosis
Meiosis



Sex cells (eggs and
sperm) are produced
by a process different
from mitosis
Meiosis: cell divides
twice to form 4 new
cells each with ½ the
number of
chromosomes
Start with one body
cell end with 4 sex cells
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Meiosis

Interphase happens just like mitosis,
chromosomes are doubled
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Steps of Meiosis:
Meiosis I
Prophase I
 Sister chromatids shorten and thicken
 Nuclear membrane disappears
 Centrioles move to opposite ends of cell
 Spindle fibers form
 Two pair of sister chromatids (matching
chromosomes) come together; get tetrads;
exchange genetic material
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Steps of Meiosis:
Meiosis I
Prophase I
Homologous
Chromosomes
(tetrads)
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Steps of Meiosis:
Meiosis I
Metaphase I
 Tetrads in center of cell
 Spindle fibers attached to chromosomes
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Steps of Meiosis:
Meiosis I
Metaphase I
Tetrads
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Steps of Meiosis:
Meiosis I
Anaphase I
 A pair of sister chromatids gets pulled
away from the other pair of sister
chromatids
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Steps of Meiosis:
Meiosis I
Telophase I
 Cell divides
 Nuclear membrane DOES NOT
REFORM
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Steps of Meiosis:
Meiosis II
Prophase II and Metaphase II
 Spindle fibers attach to sister chromatids
 Sister chromatids are in middle of cell
Prophase II
Metaphase II
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Steps of Meiosis:
Meiosis II
Anaphase II and Telophase II
 Sister chromatids are pulled apart
 Nuclear membrane reforms
Anaphase II
Telophase II
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Result of Meiosis

Results of Meiosis:
end with 4 sex cells
that have ½ of the
chromosomes as
parent cell
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Sperm, Egg, and Fertilization
Comparison of Sperm and Egg
1.
2.
3.
4.
How Alike
sex cells
formed by meiosis
½ number of
chromosomes
humans develop at
puberty
1.
2.
3.
4.
5.
6.
How Different
egg larger than sperm
sperm has tail, can move
sperm form in male
testes
eggs form in female
ovary
only get 1 egg in meiosis
get 4 sperm in meiosis
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Sperm, Egg, and Fertilization
Formation of Polar Bodies
 Happens in meiosis to produce eggs
 Cell division is not equal, most of cytoplasm
goes to one cell
 Polar body is the cell formed with little
cytoplasm
 Polar bodies do not form eggs, they die
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Sperm, Egg, and Fertilization
Formation of Polar Bodies
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Sperm, Egg, and Fertilization
Fertilization
 Joining of sperm and egg
 Chromosomes come together and pair up
forming a new organism with the correct
number of chromosomes
 New organism has ½ chromosomes form
mother and ½ chromosomes from father
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Sperm, Egg, and Fertilization
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Standard Biology
Chapter 22
Cellular Reproduction
Section 22:3 Changes in the Rate of
Mitosis
Changes that Occur in the Human
Body with Age
Body System
Trait
20 Year
Old
1mm/
week
0.8 sec
70 Year
Old
0.6mm/
week
2.9 L/
min
7 of 24
words
recalled 42
Skin/Nails
Rate of fingernail
growth
Nervous
Reaction Time
Circulatory
Pumping action of 3.7 L/
heart
min
Memory
14 of 24
words
recalled
Nervous
0.95 sec
Changes that Occur in the Human
Body with Age
Body System
Trait
Respiratory
Lung volume
per breath
Muscular
% body fat
(male)
20 Year 70 Year
Old
Old
5.5 L/
3.0 L/
inhalation inhalation
15%
30%
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Aging
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Becoming older
All living things age
Loss of hair
Wrinkled skin
Bone calcium loss
Cells wear out faster than they are replaced or are
not replaced (mitosis slows down)
Muscle cells (including heart) are not replaced,
each cell can get bigger but no new cells
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Aging
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Cancer
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Healthy cells: regular
rate of mitosis
Cancer: too fast rate of
mitosis
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Shape of cell and nuclei
change
Abnormal cells crowd
out normal cells
Fig 22-11 p. 478
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Causes of Cancer
Environmental factors
 Chemicals: chewing
tobacco (mouth)
 Smoking tobacco
(lung)
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Causes of Cancer
Environmental factors
 Radiation: UV light
(skin)
 Viruses: (warts and
cervical cancer)
 Diet
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Causes of Cancer
Genetic Factors
 Runs in a family
 Locate the gene may
be able to prevent the
cancer

Many cancers thought
to be a combination of
environmental and
genetic factors
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