Download The Cell Cycle Virtual Lesson

Name _____________________ Date _______________ Period ______ # _____
The Cell Cycle Virtual Lesson
http://www.hippocampus.org/homeworkhelp/Biology/The%20Reproduction%20of%20Cells_The%20Cell%20Cycle%20&%20Mitosis%20Overview.html
1.
Cell division is required for the _____________ and _______________ of all
multicellular organisms. It is also used to replace and repair tissue and even for
reproduction in organisms (meiosis).
2.
Cell division is best described as a _____________ and goes through two major
phases _________________ (G1, S, and G2) and _______________ (M phase).
3.
In humans, cell division must _________________ and _____________ since it
occurs in spirts.
4.
What hormone in humans tells cells to rest or continue in the cell cycle?
5.
The part of the cell cycle where the cell is said to be in its “resting stage”
(interphase) is further divided into G1 ________________, G2 _______________, and S
______________________ in which proteins are synthesized and cell organelles are
duplicated in preparation for mitosis.
6.
Which part of interphase is responsible for chromosome duplication as DNA
synthesis occurs?
7.
Cell Cycle Regulation
If the cell at G1 checkpoint fails, it will exit the cell cycle and enter a nondividing resting state called _____________ (non-dividing). Nerve cell (neurons) never
reenter the cell cycle while cells found in organs such as the liver may remain here for
___________ and may reenter the cycle if the organ has been ___________ so that these
cells may be replenished.
If the proper _____________ are available, there are not too many cells already
cycling (density-dependent inhibition forces cells to leave the cycle), and growth factors
are present, then a cell may reenter the cell cycle at the end of G1 and begin the S phase.
Through recombinant DNA technology, scientists can make __________ in the
lab for use in patients who have a deficiency in this hormone to restore more normal
growth patterns.
8.
Why does a eukaryotic cell have to undergo mitosis?
9.
Eukaryotic chromosomes are made up of chromatin which consist of ______
wrapped around histone protein. In interphase the DNA is called chromatin and looks
like a ball of yarn. Early in mitosis, the chromatin condenses and forms chromosomes.
The two identical copies of the visible chromosomes are called ____________
chromatids and are linked at the centromere. Inside the centromere is a kinetochore
which will help make the mitotic spindle (spindle fibers). The mitotic spindle is
responsible for the __________ distribution of chromosomes to each of the daughter
cells. The _______________ is responsible for organizing the mitotic spindle.
Name _____________________ Date _______________ Period ______ # _____
10.
The four phases of mitosis (M) phase also known as “nuclear division” are
__________________(P), ________________(M), ___________________(A), and
_________________(T).
11.
___________________ (“cell splitting”) occurs after the stages of mitosis.
12.
Prophase (P): (Early) Chromatin condenses into _________________, the
______________ disappears, the ___________ fibers are formed. (Late) Spindle fibers
attach to chromosomes and the nuclear envelope disappears.
13.
Metaphase (M): Chromosomes line up on the ___________ __________
(middle). Sister chromatids separate.
15.
Anaphase (A): The poles move apart, lengthening of the cell occurs, and spindle
fibers ___________ pulling the sister chromatids away from each other to opposite poles.
16.
Telophase (T): A nuclear envelope forms around each set of chromosomes and
_____________ reappear. The __________ apparatus is disassembled.
17.
Cytokinesis is the division of the ____________. In animal cell cytokinesis a
contractile ring forms around the daughter cells which forms a ______________
_____________ which deepens until the cell is pinched into two new ________________
cells each with one nucleus and an identical sets of chromosomes. In plant cell
cytokinesis a _________ __________ is formed due to the extra outer layer- the cell wall.
18.
How much time does a cell spend in each phase of cell division?
Number of Cells
Field 1
Field 2
Field 3
Total
Percent
of Total
Cells
Counted
(%)
Interphase
Prophase
Metaphase
Anaphase
Telophase
Total
Cells
Counted
Highlight those items that were emphasized in summary section 5.
Time in
Each
Stage
(% x
1440
minutes)
I
P
M
A
T
C