Biology 1115 Chapter 12
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Biology 1115 Chapter 12
The cell cycle
What best distinguishes living things from non living things?
The ability of organisms to
What is cell division?
reproduction of cells
What is the function of cell division? (2)
growth and repair
in a cell
What are chromosomes?
a structure carrying
(and protein), found in the
nucleus of a eukaryotic cell
How many chromosomes do humans have?
Define somatic cells.
, which have
chromosomes (2 sets of 23)
Define gametes. How many do humans have?
: sperm and eggs, which have
half as many chromosomes
as somatic cells
What is homologous? (2)
What is cell cycle?
the life of a cell from
to its own
What happens in preparation for cell division?
DNA is replicated
once copy of a duplicated chromosome
The part of a chromosome that
links sister chromatids
What does the cell cycle consist of? Briefly explain each.(2)
copying of chromosomes
in preparation for cell division (longest stage, cell spends most of its life here)
Mitotic (M) phase
Which stage is longest in cell division?
What are the five stages to mitosis?
When does cytokinesis get underway?
is well underway by
Which cytoskeleton component assists in the movement of chromosomes during cell division?
What is the mitotic spindle?
controls chromosome movement
What is centrosome?
microtubule organizing center
What happens in prophase? (2)
assembly of spindle microtubules
begins in the centrosome
forming two centrosomes that
migrate to opposite ends of the cell
, as spindle microtubules grow out of them
What is an aster and what is its function?
radial array of short microtubules
extends from each centrosome and
attaches to the plasma membrane
what are the 3 things that spindles include?
a structure of
attached to the
that links each
What happens in prometaphase?
spindle microtubules attach to the kinetochores
of chromosomes and begin to
move the chromosomes
What happens in interphase?
copying of chromosomes
in preparation for cell division
What happens in metaphase?
lined up at the metaphase plate
, the midway point between the spindle's two poles
What is the metaphase plate?
midway point between the spindle's two poles
What happens in anaphase?
sister chromatids separate
and move along the kinetochore microtubules toward
opposite ends of the cell
The microtubules shorten by___________ at their kinetochore ends.
What happens in telophase?
daughter nuclei for at opposite ends of the cell
Where does cytokinesis occur?
How does cytokinesis occur in animals?
occurs by a process known as
, forming a
How does cytokinesis occur in plants?
forms during cytokinesis
Why does the process of cytokinesis differ between plants and animals?
Because plant cell has
plant cell walls
Which organisms reproduce by binary fission?
(bacteria and archaea)
How do prokaryotes and eukaryotes differ with respect to their genetic material? (3)
has one piece of DNA
What is binary fission?
chromosome replicates (beginning at origin of replication) and the two daughter chromosomes
actively move apart
The eukaryotic cell is regulated by a _________________.
molecular control system
What are the 3 checkpoints in a cell cycle?
The ___________________ varies with the type of cell.
frequency of cell division
These cell cycle differences result from ______________________.
regulation at the molecular level
How is the cell cycle system regulated?
internal and external controls
For many cells what is the most important checkpoint?
What happens if a cell receives a go-ahead signal at the G1 checkpoint?
it will usually complete the S, G2 and M phases and divide.
what happens if a cell does not receive a go-ahead signal at the G1 checkpoint?
exit the cycle
, switching into a nondividing state called the
What is the order of phases in a cell cycle?
What is an example of an internal signal?
an example is that
not attached to spindle microtubules send a molecular signal that
What is an example of an external signal?
released by certain cells that
stimulate other cells to divide
give an example of a growth factor.
, which stimulates the
division of human fibroblast cells
What is cancer?
unregulated cell growth/division
_________ cells do not respond normally to the body's control mechanisms.
Cancer cells may not need growth factors to grow and divide, why? (3)
they make their
own growth factor
they may convey a
rowth factor's signal
without the presence of the growth factors
they may have an
abnormal cell cycle control system
A normal cell is converted to a cancerous cell by a process called ________________.
Cancer cell cause tumors, what are they?
masse of abnormal cells
within otherwise normal tissue
What benign tumor? (2)
a lump of abnormal cells that
remain at the original site
has not spread yet
What is malignant tumors?
lump of abnormal cells that have
invaded surrounding tissues
metastasize exporting cancer
cells to other parts of the body where they may form secondary tumors