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Cell Growth and Division
Why Cells Divide
1) DNA overload
Small cell – Information stored in DNA meets all the cell’s needs.
Huge cell -- Cell growth without limits leads to “_____________ crisis.”
The DNA can’t keep up with the cell’s need for proteins.
2) The cell volume becomes too ____________ for the surface area of the cell membrane to
manage.
Exchange of materials (wastes, nutrients, gases) occurs through the cell membrane.
The rate of exchange depends on the surface area of the cell.
The rate at which nutrients are used and waste products are produced depends on the
______________ of the cell.
Why Cells Divide
Ratio of surface area to volume
As a cell increases in size, __________ increases much more rapidly than surface area.
Ratio of surface area to volume decreases
Decrease in ratio causes _________________ for the cell
Cell Division
To avoid decreasing the ratio of surface area to volume, cells __________________ before they
become too large.
Each “daughter” cell has a greater ratio of surface area to volume than the “mother” cell.
Why Cells Divide
Although a giant cell will never threaten a city, cells do come in a wide variety of shapes and sizes.
Cell Reproduction
Cell ___________—all cells come from pre-existing cells.
____________________ is the process by which new cells are produced from pre-existing cells.
Each “daughter” cell gets an ______________ copy of the DNA and half of the cytoplasm and
organelles.
Cell Reproduction--Prokaryotes
In ___________________, cell division takes the form of BINARY FISSION
Bacteria have a single, circular DNA molecule with no proteins.
First, the DNA is _______________ (replicated)
Next, the cell splits into two equal, identical halves.
Cell Cycle and Mitosis
Genetic information that is passed from one generation to the next is carried by
_____________________.
Eukaryotic chromosomes are made up of ________ and __________.
Cells of every organism have a specific number of chromosomes.
Chromosomes
are ________ visible in most cells except during cell division.
the beginning of cell division, chromatin condenses into chromosomes.
Before cell division, each chromosome is _______________.
At
Each
chromosome consists of two identical _______” chromatids attached at a
_______________.
Chromosomes
Replicated chromosome
Consists of 2 sister __________________
Exact copies of each other
Connected by a _______________
Cell division ____________ chromatids.
Each new cell gets one copy of each chromatid.
The Cell Cycle
Eukaryotes undergo a life cycle known as the ______________________.
The Cell Cycle
The cell cycle is the series of events that cells go through as they __________ and divide
During the cell cycle a cell…
Grows
Prepares for ________________
Divides to form two daughter cells
The Cell Cycle
G1 –
S – chromosomes are replicated; ____________ is copied
G2 – organelles and molecules required for cell division are produced
M – mitosis and cytokinesis