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Cell Growth
10-1
GPS STANDARD
• SB1. Students will analyze the nature of
the relationships between structures and
functions in living cells.
• a. Explain the role of cell organelles for
both prokaryotic and eukaryotic cells,
including the cell membrane, in maintaining
homeostasis and cell reproduction.
I.
Cell Growth
• Unicellular Organisms- cell gets bigger
• Multicellular Organisms- cell divides into
more cells
– The cells of an adult are the same size as the
cells of the young. (Adults just have more
cells)
II. Limits to Cell Growth
• 1. DNA Overload
– As cells grow they don’t make more DNA so
there would be an information crisis
II. Limits to Cell Growth
• 2. Ratio of Surface Area to Volume
– Surface Area= l x w x # of sides
– Volume= l x w x h
II. Limits to Cell Growth
– The rate of exchange of food entering and
wastes leaving the cell depends on the surface
area of the cell membrane.
– The rate that food is used up and wastes are
produced depends on the cell’s volume.
– As the size of the cell increases, volume
increases faster than surface area and causes
problems for the cell- it can’t transport nutrients
and wastes across fast enough for the cell to
survive.
III. Cell Division
• Cells must divide before they get too big.
• The process by which a cell divides into
two new daughter cells is called Cell
Division.
IV. The Cell Cycle
• Cell Cycle- the series of events cells go
through as they grow and divide.
IV. The Cell Cycle
• A. Interphase: “the in-between phase”
– G1 phase- cells grow
– S phase- DNA replication and chromosome
duplication (it copies the DNA)
– G2 phase- prepares for mitosis by making
needed organelles.
IV. The Cell Cycle
• B. M phase (mitosis & cytokinesis)
– Mitosis- division of the nucleus
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1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
– Cytokinesis- division of the cytoplasm
– *the two newly formed daughter cells are
identical*
Cell Division
10-2
I. Chromosomes
• made of DNA and proteins
• Carry the genetic material
• Every organism has a specific number of
chromosomes.
– Daughter cells have the same number of
chromosomes as the parent cell
– Human cells have 46 chromosomes
• Usually chromosomes are not visible and it
is called chromatin. During cell division
the chromosomes are visible
• During cell division the chromosomes are
made up of two sister chromatids attached
at a centromere.
Chromosome Structure
II. Stages of the cell cycle
Interphase
– The longest phase of the cell cycle
– Includes G1, S, & G2 phases
– It is a period of growth, DNA
replication, and preparation for
mitosis.
– The nucleus is visible and
surrounded by a nuclear membrane.
• Mitosis- Division of the nucleus
• 1. Prophase
–
–
–
–
Nuclear membrane breaks down
Nucleolus disappears
Chromosomes coil up and become visible
Centrioles separate and mitotic spindle starts to
form
PROPHASE
• 2. Metaphase
– Chromosomes attach to the spindle fibers at the
centromeres
– Chromosomes line up in the middle of the cell
METAPHASE
• 3. Anaphase
– Sister chromatids begin to move toward
opposite sides of the cell
ANAPHASE
• 4. Telophase
– Two nuclear membranes start to reform
– Chromosomes start to uncoil
– Spindle breaks apart
TELOPHASE
• Cytokinesis- division of the cytoplasm
– In Plant Cells- a cell plate forms between the
two new daughter cells that will eventually turn
into a new cell wall to separate them.
– In Animal Cells- a furrow forms between the
two new cells and pinches the cell membrane
until two new cells form.
CYTOKINESIS-Splitting of the
cytoplasm.
Animal Cell
Reproduction
(Mitosis)
Plant Cell
Reproduction
(Mitosis)