Guided Reading ch 9.1
Cellular Growth
Cell Size Limitations
There are several factors that influence cell size.
The key factor that limits the _______________ of a cell is the ratio of its surface area to its volume. The
surface area of the cell refers to the area covered by the plasma ________________________.
The volume refers to the space taken by the __________________ __________ of the cell, including the
organelles in the cytoplasm and the __________________________.
In the diagram on page 244 the first cell has a surface to volume ratio of 6:1 but the second cell has a
ratio of 3:1. As the cell continues to _______________, the ratio of ___________________ to
___________________ will continue to decrease. This means the cell might have difficulty supplying
nutrients and expelling enough _________________ products.
By remaining ________________, cells have a higher ratio of surface area to volume and can sustain
themselves more easily.
Another task that can be managed more easily in a small cell than in a large cell is the
_________________ of substances. Recall the plasma membrane controls cellular transport because it is
selectively __________________________.
Once inside the cell substances move by ________________ or by motor proteins pulling them along
the cytoskeleton. Diffusion over large distances is _____________ and _______________________
because it relies on _____________________movement of molecules. Therefore, cells remain
______________ to maximize the ability of diffusion and motor proteins to transport nutrients and
waste products. Small cells maintain more ______________ transport systems.
The need for signaling ________________ to move throughout the cell also limits cell size. In other
words , cell size affects the ability of the cell to __________________________________ for cellular
function . If the cell becomes too _____________, it becomes almost impossible for cellular
communications, many of which involve movement of substances and signals to various organelles, to
take place efficiently.
The Cell Cycle
Once a cell reaches its ________________________, something must happen- either it will __________
growing or it will _______________. Most cells will eventually divide. Cell division not only prevents the
cell from becoming too large but it also is the way the cell ___________________ so that you
__________ and ____________certain injuries. Cells reproduce by a cycle of growing and dividing called
the _________________________. Each time a cell goes through one complete cycle it becomes
________ new cells. When the cell cycle is repeated continuously the result is a continuous production
of new cells.
There are ______________ main stages of the cell cycle.
Interphase is the stage during which the cell _____________, carries out cellular _____________, and
replicated, or makes copies of its _______________in preparation for the next stage of the cycle.
Interphase is divided into three substages: G1, S, and G2
Mitosis is the stage of the cell cycle during which the cell’s ______________ and nuclear material divide.
Mitosis is divided into _____________ substages: prophase, metaphase, anaphase, and telophase.
Cytokinesis occurs at the ____________of Mitosis, it is the method by which a cell’s
_________________ divides, creating a new cell.
The duration of the cell cycle varies, depending on the cell that is dividing. Some eukaryotic cells might
complete the cycle in as few as ________________minutes, while other cells might take up to one
______________ . For most normal, actively dividing animal cells, the cycle takes approximately
__________ hours.
The Stages of Interphase
During interphase the cell grow develops into a mature, functioning cell, duplicates its DNA and
prepares for division. Three stages:
The first stage of interphase is ___________ is the period immediately after a cell divides. During G1 a
cell is _______________, carrying out normal cell _________________, and preparing to replicate DNA.
Some cells, such as muscle and nerve cells, exit the cell cycle at this point and do not divide again.
The second stage of interphase, __________, is the period when a cell copies its ___________ in
preparation for cell division. ________________________ are the structures that contain the genetic
material that is passed from generation to generation of cells. ________________________ is the
relaxed form of DNA in the cell’s nucleus.
The third stage _________ follows the S stage and is the period when the cell prepares for the division
of its nucleus. A protein that makes _________________ for cell division is synthesized at this time. The
cell also takes _____________________ and makes sure it is ready to continue with mitosis.
The stages of Mitosis and Cytokinesis follow interphase. In ________________ the cell’s nuclear
material divides and separates into opposite ends of the cell. In ____________________ the cell divides
into two daughter cells with identical nuclei.
The cell cycle is the method by which eukaryotic cells reproduce themselves. Prokaryotic cells which you
have learned are simpler cells reproduce by a method called _______________ ________________.
Guided Reading ch 9.2 Mitosis and Cytokinesis
Page 249 Figure 9.6 draw in the stages of Mitosis in the table below include a detailed description of
what happens in each stage. Be sure to include all labels from the diagram.
Phase and illustration
Interphase
Prophase early
Prophase late
Metaphase
Anaphase
Telophase and Cytokinesis
Description
The Stages of Mitosis
ProphaseThe first stage of mitosis- the stage of mitosis during which a dividing cell spends the most time- is called
____________________. The cell’s chromatin tightens, or condenses into chromosomes. The
chromosomes are shaped like an X each half of the X is called a sister chromatid, that contain identical
copies of DNA. The structure at the center of the chromosome where the sister chromatids are attached
is called the centromere.
As prophase continues the ________________ disappears, and microtubule structures called spindle
fibers form in the cytoplasm. In animal cells structures called _________________________ migrate to
the ends or poles of the cell. The spindles apparatus is important in ___________________ and
____________________________ the chromosomes before cell division. Near the end of prophase the
nuclear envelope disappears. The spindle fibers are attached to the sister chromatids at the
___________________.
MetaphaseDuring the second stage of mitosis- _________________- the sister chromatids are pulled by the
spindles toward the center of the cell and line up in the middle, or equator of the cell. Metaphase is the
shortest of the phases.
AnaphaseThe chromatids are pulled apart during ___________________. The third stage of mitosis. The spindles
_______________________ and pull at the centromere. Sister chromatids separate simultaneously and
move the chromosomes toward the poles of the cell.
TelophaseThe last stage of mitosis is called ______________________. The stage during which the chromosomes
arrive at the poles of the cell and being to ________________. Two new nuclear
_______________________ begin to form and the nucleoli reappear. The _______________________
disassembles and some of the microtubules are recycled by the cell to build various parts of the
cytoskeleton. Mitosis is complete but the cell in not yet divided.
CytokinesisToward the end of mitosis the cell begins another process called _______________ that will divide the
cytoplasm. The result is two cells each identical. In animal cells cytokinesis is accomplished by
________________________ the cytoplasm forming what is called a cleavage furrow. In plant cells with
rigid cell walls a structure called a cell _______________ forms between the two nuclei. The cell plate
eventually fills in and becomes the new cell wall separating the two new daughter cells.