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The Cell Cycle and
Control
1.
As you know cells are very small. We
need microscopes
__________ to help us see cells to
study them. There are reasons that cells
are small. Certain limitations keep a cell
__________________.
from
growing too large Instead of
continually growing, when a cell grows to
a certain size it _______
divides (reproduces).
Cell Size Limitations
2.
________-is
fast and efficient over short
Diffusion
distances, but becomes slow and
inefficient as distances become larger.
For example: A mitochondrion at the center
of a hypothetical cell with a diameter of
20 cm would have to wait months before
receiving molecules entering the cell!
3.
_____DNA DNA is responsible for coding for
proteins in our cells. The larger the cell
the more protein needs it would have.
The cell’s DNA could not keep up with
the protein needs of a large cell.
proteins
4. __________________________Surface area to volume ratio
As the
cell increases, the volume increases
much faster than the surface area. As
the cell increases it needs more
_________
_______ to
nutrients and has more wastes
excrete. This means it needs more
plasma membrane in which to release
wastes and diffuse nutrients.
Cell Reproduction-All cells come from
______________.
preexisting cells (Cell Theory)
5.
Scientists discovered that chromosomes
___________,
which contain DNA and proteins become
darkly colored when stained, are
responsible for passing genetic
information from one generation to
another. These chromosomes are
located inside the _______
nucleus and become
visible just before the cell divides.
6. Before a cell divides, the DNA is
unwound into _________
chromatin to carry out cell
functions.
The Cell Cycle
The cell cycle is the sequence of
growth and division of a cell.
_________________
8. Most of the cell's life is spent in the
period of growth called _________.
interphase
7.
9.
Following interphase, a cell enters
mitosis
its period of division called ______.
Mitosis is broken into four phases:
________, metaphase
_________, _________,
prophase
anaphase
and ________.
telophase After mitosis, a
short period called _________
cytokinesis
occurs in order to divide the
cytoplasm.
10. During
interphase the cell is in a
resting phase. It carries out
__________,
cell functions grows, copies its
DNA and makes new ________.
organelles
11.
Interphase is
divided into three
G1 phase
phases. ___
is the first growth
S
period of the cell, __
phase is the time to
copy DNA, and ___
G2
phase is the second
growth of the cell.
12.
Prophase- first phase of
mitosis
 Chromosomes become
visible

Chromosomes are
made of two sister
chromatids
_________ (B)
connected by a
__________
centromere (A)
 Centrioles move to
opposite poles of cell
 Spindle starts to form
 Nuclear membrane
breaks down
____________
13.
Metaphase

Chromosomes line up
along ______
equator of the cell
Spindle attaches to
centomeres
14.
Anaphase

Chromosomes
____________
divide
Chromatids
separate and move
sides
to opposite ______
of the cell
15.
Telophase

Chromosomes
unwind into
_________
chromatin
Nuclear membrane
forms around
chromatin
16.
Cytokinesis- is different in plant and
animal cells.
In animal cells, the plasma membrane
pinches
_______ in separating two new cells. This is
cleavage and the fold is called the
called _________
______________.
Cleavage
furrow
b. In plant cells, vesicles containing
cell
wall material line up in the center of the
______________
cell and fuse together forming a ________.
cell plate
The cell plate then connects with the existing
cell wall creating two new cells.
a.
17.
Label the cell cycle.
G1
B. S
C. G2
D. Metaphase
A.
Results of Mitosis
18.
When mitosis occurs, __________
unicellular
organisms remain unicellular-they have
simply multiplied. In __________
multicellular
organisms, cell division results in groups
of cells that work together as _______.
tissues
19.
Tissues form ______,
organs organs form
_____________,
organ systems and organ systems
form __________!
organisms
Control of the Cell Cycle
20.
Biologists believe that a series of
________
enzymes called cyclins control the cell’s
progress during the cell cycle. There are
enzymes that tell the cell when to start
mitosis as well as controlling it
throughout the phases.
21.
The production of these enzymes is done
by genes
_____. Genes are a segment of DNA
____
the controls the production of a protein.
22.
Cells can lose control of the cell cycle
and start dividing uncontrollably. The
results may be cancer
______.
Cancerous cells
Normal cells
Meiosis



There are two types of cells in your body:
cells
1) Somatic
___________—body
cells
2) _________—sex
cells (germ cells)
Gametes

Haploid
__________
cells cells have ½ the number of
chromosomes in a species. They are
designated by 1N or N. (Sex cells)

What is the haploid number for humans?
23
___


Diploid cells cells have the correct
__________
number of (paired) chromosomes for a
species. They are designated by 2N.
(Body or somatic cells).
What is the diploid number for humans?
46
___

The 2 chromosomes that make up a pair
are called homologous
__________ chromosomes.
Each _____________
sister chromatid in the pair has
information about the same ____.
gene The
combination they form together results in
a particular trait being expressed.

The process that forms new somatic
cells is _______.
mitosis

Human sex cells in the female are the
egg cells. In the male, they are the
____
______
sperm cells. Each has ___
23
chromosomes or the haploid number for
humans.

Female sex chromosomes are
represented by an ___
X and males are
represented by a ___.
Y Since
XX results
chromosomes are paired, _____
in a female offspring and _____
XY is male.


The cell division that forms new sex cells
is called _______.
Meiosis
haploid cells.
Meiosis produces ______

Meiosis is divided into two distinct parts:
________
Meiosis I and _________.
Meiosis II

Each ends with cell division.

Meiosis I consists of _________I,
Prophase
Metaphase _________I,
__________I,
Anaphase and
_________I.
Telophase

What happens immediately after
Telophase I? _________
Prophase II


Meiosis II consists of ________
Prophase II,
Metaphase
Anaphase II and
_________ II, _________
________
Telophase II. It occurs
immediately after ________.
Meiosis I No
replication of ______occurs
DNA
before
prophase II.

Asexual
_______ reproduction does not involve
the exchange of genetic material (DNA).
It can be accomplished by cellular
______
division. This reduces genetic _______
variation
because the resulting daughter cells are
_______.
identical

Bacteria reproduce by a mitotic division
called _______
Binary _______.
fission They have
circular _______
that copies itself and
DNA
then a new cell wall forms dividing the
cell.

Other types of asexual reproduction are:
Budding which is often used by fungi, and
_______,
________
Vegetative__________,
propagation which is used by
a lot of plants.

Sexual reproduction increases
_______variation
within a species
genetic
because it involves the exchange of
DNA
_____, which is the genetic material of a
species.

There are ____
four sperm produced in
meiosis of sperm cells, which is called
______________.
spermatogenesis Egg cells undergo
meiosis that is called _________.
oogenesis It
produces one
___ egg cell, which receives
most of the cytoplasm, and _____
three small
cells that are called polar
__________.
bodies

____________
Nondisjunction is when chromosomes do
not separate correctly and offspring end
up with one chromosome too many or
one too few. This causes birth defects.

When a gamete with an extra
chromosome is fertilized by a normal
gamete the result is called ________.
trisomy
Trisomy zygotes have an extra
st chromosome and they will develop
______________
21
into a baby with _______________.
Down syndrome

missing a chromosome
If a zygote is ________
the result is called monosomy
_________. This is
usually a lethal defect, but one result is
called _______________,
Turner syndrome Females will
have only one ___
X chromosome instead
of two.

When a whole extra set of chromosomes
___________
is present in the zygote the condition is
called ________.
polyploidy This is lethal to
animals, but is desired in plants.
Polyploidy leads to
larger flowers or fruit.
___________________.