Transcript Cell growth and Reproduction

Cell growth and
Reproduction
• Though there are exceptions
in cell size
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– nerve cells reaching 1 meter
– Ostrich egg measuring 8 cm
most cells are between 2200 nanometers (that’s too
small to see without a
microscope)
– Why are cells the size they
are?
Diffusion
What limits the cell size
• DNA
• Surface to volume
ratio
Cell Reproduction
• Remember the cell
theory? all cells --– Come from preexisting
http://www.cellsalive.com/howbig.htm cells
– Cell division results in
two IDENTICAL cells
– This way we can grow
and change and even
though our cells split we
are still the same person
Chromosomes
Chroma-colored
Stroma-body
• Contain DNA
• Become darkly colored
when stained
• Vanish after cell division
– They are the carriers
of the genetic
material that is
copied and passed
on generation to
generation
Structure of eukaryotic chromosomes
• Chromatin– long strands of DNA
wrapped around proteins
called histones
– Grouped together they
make up they form a
chromatin
– So things stay organized
during division they coil
up to form chromosomes
Structure of eukaryotic chromosomes
Chromosome Structure
Cell cycle
• the sequence of growth
and division of a cell
•
Can be divided into two periods
– Period of growth
– Period of division
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•
•
Most of the cells life is spent in
Interphase (PERIOD OF
GROWTH)
– Grows, carries on
metabolism, and the big
part
• CHROMOSOMES ARE
DUPLICATED
•
MITOSIS -Cell goes through a
series of steps to produce TWO
identical calls (period of
division)
Mitosis
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Web link
• http://www.biology.ar
izona.edu/cell_bio/a
ctivities/cell_cycle/c
ell_cycle.html
Root tip
http://bio.rutgers.edu/~gb101/lab2_mitosis/highmagroot1.html
Cytokinesis
• In cytokinesis the
cells cytoplasm
divides
• Is this a plant or
animal cell?
• Why?