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Cell Cycle
Interphase, Mitosis, Cancer, and
Cell Size
© PicScience LLC 2011
What is
?
• cell divides and creates 2 identical daughter
cells; cell reproduction
Three types:
1. Prokaryotes – for
reproduction
2. Eukaryotes – for
growth and repair
3. Gametes – makes sex
cells
How do the types of division differ?
Diploid
cell
Prokaryotic division-cells
reproduce by binary
fission:
Cell’s genetic information
(chromosomes) is copied,
cell divides in two, each
cell is identical to parent
cell
S
S-phase
DNA
replication
Chromosome
segregation
gametes
Cytokinesis
+
zygote
Eukaryotic division-parent
cell makes copy of its
chromosomes before it
divides. Gametes made by
meiosis.
Let’s look more closely at
…
Cell Cycle—sequence of growth and division that a eukaryotic
cell undergoes
Two parts: 1) Interphase
2) Mitosis
Interphase—1st phase; busiest and most time consuming part
of cell cycle
1) Interphase
3 phases:G1 phase- cell growth, protein
G2
Mitosis
S
G1
production
S phase-chromosomes copied
(DNA synthesis), creates 2 sister
chromatids
G2 phase-cell prepares to divide,
new organelles form
2) Mitosis
• Mitosis-nucleus of cell divides to form 2 nuclei
▫ -ensures that each new cell will have a copy of
every chromosome
• Cytokinesis- division of cell cytoplasm, follows
mitosis
Mitosis
• 4 main phases:
▫
▫
▫
▫
Prophase
Metaphase
Anaphase
Telophase
Prophase
Metaphase
Anaphase
Telephase
Summary
G1
Interphase
S
G2
Cell
division
Prophase
Metaphase
Mitosis
Anaphase
Telephase
What happens if cells divide too much?
-uncontrolled dividing of cells form
failure to produce certain enzymes---controlled
by genes.
▫ Enzymes-organic catalysts that control the rate of
chemical reaction within the cell
Cancer
• Form masses of
cells called tumors
which deprive
normal cells of
nutrients
• Spread freely
because they lack
surface proteins
• Have abnormal
size, shape, and
abilities
Large cytoplasm
Single nucleus
Single nucleolus
Fine chromatin
Small cytoplasm
Multiple nuclei
Multiple and large nucleoli
Coarse chromatin
Cancer
• Invade tissues by
traveling through the
blood stream replacing
healthy cells
• 2nd leading cause of
death in U.S.
• Some causes of cancer:
environmental
influences
viruses
Cell Size
• Cells come in all sizes from very small to very
large
• Examples:
• nerve cell 1 micrometer (millionth of a meter)
• Ostrich yolk 8 cm in width
Why is cell size limited?
• 1.) the smaller the cell the easier and less time it takes for diffusion
of substances such as oxygen
to reach the mitochondria; site of
cellular respiration and production of ATP can occur
• 2.) cells DNA
also limits the size of the cell. If a cell
doesn’t have enough DNA to program its metabolism (all the
chemical reactions that occur in an organism) it cannot live.
Large cells often have more than one nucleus providing more
DNA.
• 3.) as cell size increases, volume increases much
faster than surface area
• See p. 202-203
= length ( ) X width (
sides
=
• Example:
A.
B.
C.
D.
x
x height ( )
1mm x 1mm x 6mm = 6 mm²
1cm x 1cm x 1cm = 1cm³
2mm x 2mm x 6mm =24mm²
2cm x 2cm x 2 cm = 8cm³
) X # of
Review
• 1.) Which of the following occurs during binary
fission?
• A.) two genetically identical cells are produced
• B.) a cell grows as large as it can
• C.) The nucleus of as cell divides into two nuclei
• D.) a cell develops a second cell membrane
Review
• 2.) In which phase of the eukaryotic cell cycle is
the genetic material duplicated?
• A.) G1 phase
• B.) S phase
• C.) G2 phase
• D.) M phase
Review
• 3.) Which 2 phases of the cell cycle make up cell
division?
• A.) telophase and cytokinesis
• B.) mitosis and cytokinesis
• C.) interphase and mitosis
• D.) cytokinesis and interphase
Review
•
•
•
•
•
4.) What happens in prophase?
A.) sister chromatids line up at center of the cell
B.) sister chromatids start to separate
C.) sister chromatids are formed
D.) the cell splits in two
Review
• 5.) What are masses of cancerous uncontrollable
cell growth called?
• A.) cysts
• B.) nodules
• C.) tumors
• D.) T cells
Review
•
•
•
•
•
6.) cancer spreads easily b/c they lack
A.) mitochondria
B.) cell membranes
C.) inhibitor growth genes
D.) surface proteins