Download File

The Cell Cycle
The Cell Cycle
As you grow, you pass through different stages
in life. Your cells also pass through different
stages. The life cycle of a cell is called the cell
cycle.
The cell cycle BEGINS when the cell is formed
and ENDS when the cell divides and forms
new cells.
Before the cell divides, it must make a copy of
its deoxyribonucleic acid (DNA).
The Cell Cycle
As you know, DNA is the hereditary material
that controls all cell activities, including the
making of new cells.
The DNA of a cell is organized into structures
called chromosomes.
Why copy chromosomes?
To makes sure that each new cell will be an
exact copy of its parent cell.
Asexual Reproduction
A type of reproduction where a new
organism is produced from one parent
and has DNA identical to the parent
organism.
 Offspring produced from one parent
 There is no genetic variation!
(Hereditary information is identical
from parent to offspring)

http://thinktv.pbslearningmedia.org/resource/tdc02.
sci.life.stru.singlecell/single-celled-organisms/
Asexual Reproduction
Examples of organisms who reproduce asexually:
protists, bacteria, plants, fungi
(Some organisms can produce both asexually and sexually.)
http://thinktv.pbslearningmedia.org/resource/tdc02.sci.life.str
u.singlecell/single-celled-organisms/
Types of Asexual Reproduction:
Budding:
Organism that
produces a bud
that breaks
away to live on
its own.
Example: hydra
Types of Asexual Reproduction:
 Binary
Fission:
An organism whose
cells do not contain
a nucleus copy then
divide into two
identical organisms.
Example: bacteria
Types of Asexual Reproduction:
 Regeneration/Fragmentation:
-Regeneration uses cell division to
regrow body parts
-Fragmentation is when the body of
the parent breaks into pieces, each of
which grow into a new organism
Example:
planara,
starfish,
salamander
Types of Asexual Reproduction:
 Vegetative
Propagation:
New plants grow from
parts of the parent
plant (shoots or runners)
Example:
strawberry plant
Sexual Reproduction
Two sex cells, usually an egg and a
sperm, join to form a zygote, which
will develop into a new organism.
 Requires 2 parents
 Sexual reproduction results in a great
variety, or diversity, of offspring.

Sexual Reproduction
Examples of organisms who reproduce sexually:
(Some organisms can produce both asexually and sexually.)
Humans, animals, some plants
http://thinktv.pbslearningmedia.org/resource/tdc02.sci
.life.evo.redqueen/the-red-queen/
Intro to Mitosis
This is one type of cell division
(you learned about this in 6th grade, remember!?)
http://www.teachersdomain.org/resource/tdc02.sci.lif
e.stru.dnadivide/ (1:34)
Mitosis
It is the cell process in which the nucleus
divides to form two nuclei identical to
each other, and identical to the original
nucleus, in a series of steps.
Mitosis allows for growth and replaces
worn out or damaged cells.
Mitosis
From one cell, mitosis
produces 2 cells –
called daughter cells
Daughter cells are
identical to each
other and to the
original parent cell
Results of Mitosis
Division of nucleus- Nuclei are
identical to each other.
Same number & type of
chromosomes.
Mitosis
The nucleus divides in several
phases: IPMAT!
o
Interphase (technically not a phase)
o Prophase
o Metaphase
o Anaphase
o Telophase
Mitosis
Interphase
Technically not part
of mitosis.
A resting phase.
Mitosis
Prophase
Chromosomes
replicate and
nuclear membrane
disappears
Mitosis
Metaphase
Chromosomes line
up in pairs along
the equator –
middle of cell.
Mitosis
Anaphase

Chromosomes
divide.

Chromatids (half of
a chromosome
pair) separate and
move to opposite
ends of the cell.
Mitosis
Telophase
Nuclear membrane
forms.
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Video of Mitosis/Intro to Meiosis

http://www.schooltube.com/video/033a8b
81d8ac4b81b0b6/ (5:34)
Meiosis
Process by which the number of
chromosomes is reduced by half to form
sex cells.
A
human body cell has 46 chromosomes.
 Each
chromosome has a similar mate, so
human body cells have 23 pairs of
chromosomes.
 Sex cells have half the number of
chromosomes of a body cell, so they
have 23 chromosomes, one from each of
the 23 pairs.
Meiosis

Since Meiosis only needs half of the
number of chromosomes needed in
mitosis, there are 2 divisions of the
nucleus occur, Meiosis I and Meiosis II.
Meiosis II
 Results
in 4 cells
 Each with ½ their number of
original chromosomes
Meiosis I
Interphase
DNA is duplicated
Early
Prophase I
Prophase I
Chromosomes
replicate and nuclear
membrane
disappears
Late
Prophase I
Meiosis I
Metaphase I
 Copied chromatids /
chromosomes line up
in middle of cell
 Centromeres attach
to spindle fibers
Anaphase I
 Chromatid pairs
move to ends of
cell.
◦ They are NOT
pulled apart or
separated
Meiosis I
Telophase I
Cells pinch apart
 No further replication of hereditary material

There are now two cells. Both cells
have full sets of genetic material
(chromosomes)
Meiosis II
Prophase II
 Similar to mitosis
◦ Starts with TWO
cells instead of
one
◦ Spindle fibers
appear
Metaphase II
Duplicated
chromatid /
chromosomes line
up in middle of cell
 Spindle fibers attach
to centromeres

Meiosis II
Anaphase II
Chromatids separate
& move to ends of
cell
Telophase II
 Nuclear membranes
form at each end of
cell
 Cells divide
◦ There are now 4
cells!
Add the following words to your
Vocabulary glossary:
Asexual Reproduction
Sexual Reproduction
Mitosis
Meiosis
Exit Slip Directions:
1. Make a T-chart for Asexual and Sexual
reproduction
2. Then, add as many facts as you can under the
appropriate column.
3. Follow your teachers directions as to where to
turn this in.
Sexual
Asexual
Exit Slip Directions *
Place the following words/phrases in the correct column:
2 parents
1 parent
Identical offspring
Unique offspring
can adapt to changes
cannot adapt to changes
uses process of meiosis
uses process of mitosis
Sexual
Teacher note: print slide for easier use
Asexual