Download Animal Cell Cycle - Montgomery`s Hedrick Life Science

Cell Cycles
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Reproduction can be asexual or sexual
Biologists measure success in living things by reproduction. That means making other living
things that have copies of the same DNA instructions, and are able to reproduce themselves. When one
living thing divides to make another identical living cell or another entire living thing, it is asexual
reproduction. When two parents produce a cell or new living thing, it is sexual reproduction.
Cell Cycles in Asexual Reproduction
For multicellular living things, success in life starts by growing from a single cell that is able
to make other living cell, tissues and organs with same DNA instructions. New cells are needed
continuously in multiple-celled living things as they grow, parts age and are damaged and mistakes occur. A
cell growing, then dividing to make two cells is a complete cell cycle. Not all cells divide.
Single celled living things are amazingly successful at growing and reproducing in every
possible situation. They are very simple, not having the many separate membrane-covered organelles that
animal and other eukaryotic cell have. Binary fission can occur very quickly in these simple cells, allowing
them to produce large numbers of identical cell copies, which can also produce more cells. Binary fission
also occurs in mitochondria and chloroplasts inside eukaryotic cells.
Cell Cycles
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Multicellular living things, including animals and plants, have eukaryotic cells with much
more complexity. They normally have their linear DNA arranged in several chromosomes in their nucleus. If
a cell divides, it must first make copies of all its organelles, and build more cell membrane and other
materials. All the DNA is also replicated, to make an identical copy of each chromosomes in the genome.
These copies separate, except at an area near the middle called the centromere. This gives sister chromatid
pairs the look of an X. These chromatid pairs are pulled into the center of the cell before it divides. When all
the pairs are lined up, the copies separate to opposite ends. Nuclear membranes form around each identical
group of duplicated chromosomes in the enlarged cell, The cell divides between the two nuclei, making two
identical sister cells.
Reproduction in single-celled eukaryotes is sometimes called binary fission. However, this is
different, because the chromosomes copies have to lined up and separated through mitosis. This ensures that
each cell gets a copy of each chromosomes.
Prokaryotic Cell Cycle: Binary Fission
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SKETCH THIS PROCESS ON ONE PAGE
Prokaryotic cell ready to divide
The single circular loop of DNA is loose in the cytoplasm inside
the cell membrane and outer cell wall of the prokaryotic parent
cell
DRAW and LABEL the chromosome, cell membrane, cell
wall, and ribosomes in the cytoplasm of the parent cell.
DNA replication and Cell Growth
The two strands of the single circular loop of DNA in each
prokaryotic cell are each copied through the process of DNA
replication. This results in two complete identical loops of
double-stranded DNA. As DNA is replicated, the cell produces
more non-membrane covered organelles like ribosomes and
other cell materials. The cell membrane and cell wall also grow
as the cell and lengthens.
DRAW and LABEL two identical loops of DNA separating
inside a longer version of the same cell.
DRAW and LABEL the two identical loops of DNA separated
towards opposite ends of the longer cell
Prokaryotic Cell Cycle: Binary Fission
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Fission
The cell membrane and cell wall begin to squeeze inwards as
the two identical chromosomes separate from each other away
from the center.
DRAW fission beginning
2 identical cells
The cell membrane and cell wall sqeezes inward until the two
cells are separated. Each cell has an identical chromosome
and a set of cell materials and organelles.
DRAW and LABEL the result of binary fission: two identical
daughter cells
Overview of the Eukaryotic Cell Cycle
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1st stage: Interphase (during the S part of cell cycle)
Each chromosome is replicated to make a pair of sister
chromatids
Organelles are copied
2nd stage: Mitosis (during the M part)
Sister chromatids are lined up in the middle of the cell and
separated into two identical nuclei
3rd stage: Cytokinesis (during the M part)
Parent cell is separated into two daughter cells, each with
identical sets of chromosomes that are also identical to the
parent genome
Animal Cell Cycle
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1st Stage: Interphase
1st stage: Interphase- beginning (sketch just the cell on the left)
DRAW an animal cell with a nuclear membrane containing 1 long pair of homologous
chromosomes (copies of each chromosome from the two parents) that are two different colors /
shading. Homologous chromosomes are similar, with the same DNA instructions, but some
differences, particularly between the X and Y chromosomes.
DRAW one 1 short pair of homologous chromosomes with two different colors / shading [4 unique
colors total] that have different instructions compared to the first homologous chromosome pair.
Include one pair of centrioles / centrosome (crossed tubes that make spindle fibers)
Animal Cell Cycle
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1st Stage: Interphase
1st stage: Interphase- end (sketch just the cell on the right)
DRAW the same animal cell after an identical copy of each chromosome has been made through
DNA replication. The nuclear membrane now contains a long pair of sister chromatids (identical
copies of the same chromosome) of identical color / shading AND another long pair of sister
chromatids (identical copies of the same chromosome) with the other color / shading AND 1 short
pair of sister chromatids of one color and 1 short pair of sister chromatids of the other color
DRAW two pairs of centrioles. These organelles were copied while the DNA in each chromosome
was replicated to make sister chromatid pairs
Animal Cell Cycle
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Prophase (2nd stage: mitosis 1)
2nd stage: Mitosis Prophase
The nuclear membrane has broken apart. Spindle fibers from the centrioles connect to the
centromere on each chromatid. Spindle fibers pull the chromatid pairs toward the center of the cell.
DRAW the chromatid pairs the SAME LENGTH and COLOR as is interphase as they move towards
the center of the cell.
DRAW spindle fibers connecting the centromere of each chromatid to the centriole pair on that
side.
Animal Cell Cycle
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Metaphase (mitosis 2)
2nd stage: Mitosis Metaphase
The chromatid pairs move along the spindle fibers into the middle of the cell. This ensures that
each half of the cell will get one copy of each chromosome, a chromatid from each pair. The cell
grows as organelles are copied, and more cell membrane is made.
DRAW the sister chromatid pairs lined up in the center of the cell. SHOW the spindle fibers and
centriole pairs
Animal Cell Cycle
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Anaphase (mitosis 3)
2nd stage: Mitosis Anaphase
Chromatid pairs split apart as each chromatid pulls itself along the spindle fiber towards the pair of
centrioles. They are now separate duplicated chromosomes. The cell continues to lengthen.
DRAW the sister chromatid pairs pulling themselves by their centromeres along the spindle
fibers towards the centriole pairs
Animal Cell Cycle
Telophase (mitosis 4)
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2nd stage: Mitosis Telophase
A nuclear membrane forms around each of the two sets of chromosomes in the cell. The cell has
enlarged. In animals, the cell membrane begins to pinch inwards between the two nuclei.
DRAW the 2 nuclear membranes enclosing the two groups of chromosomes.
CHECK that each nucleus has an exact copy of the two long homologous chromosomes and the
two short homologous chromosomes that were in the parent cell.
Animal Cell Cycle
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Cytokinesis (3rd stage: cell division)
3rd stage: Cytokinesis in animal cells
In animal cells, the cell membrane pinches inward until the two cells are separated. Each cell now
has an identical set of chromosomes in its nucleus and copies of all the organelles.
DRAW two daughter cells identical to the original parent cell which divided.
Cytokinesis in plant cells (3rd stage:
Cell Division)
Plant Cell Cycle
3rd stage: Cytokinesis in plant cells
In plant cells, the cell membrane cannot pinch inwards. The cell wall is stuck to the cell wall of next
cell over. The new cell membrane begins as a cell plate between the two nuclei. It grows from the
center out towards the cell membrane. The new cell wall between the two cells begins to grow in
between the two layers of cell membrane left behind as the cell plate grows outward. Cell division is
complete when the new cell membrane has merged with the original cell membrane to make
separate cells. Each cell now has an identical set of chromosomes in its nucleus and copies of all
the organelles, and will continue to grow next to its sister cell
DRAW two identical cells partially separated by a cell plate and new cell wall inside the cell plate