Cell Cycle Notes by yurtgc548


									Chapter 10: Cell Cycle Notes
            Why Divide?
The cell theory states that:
     All cells come from other living cells.

1. Cells divide for the survival of the
   individual organism
2. Cells divide for the survival of the
   species (group of similar organisms)
  Cells divide for the survival of
    the individual organism
Cell division is used for growth,
   development, maintenance, and repair
   of the organism. This is carried out by:
   Mitosis- division of body cells to make
   more of the same kind of cell.
  – The parent cell is the original cell inside the
    organism that will divide.
  – The daughter cells are the two identical
    cells created when the parent cell divides.
  Cells divide for the survival of
          the species 
To reproduce more organisms that look
   similar to their parents:
   Sexual reproduction -two separate
   organisms produce egg and sperm that
   must combine or fuse together to
   produce offspring.
  – Meiosis process of making egg cells and
    sperm cells.
  – Fertilization the fusion of egg and sperm
    to produce a new organism.
  Cells divide for the survival of
          the species 
To reproduce more organisms that look
   similar to their parents:
   Asexual reproduction- offspring are
   produced by only one individual
  – Spores are produced by mold and other
    fungi that grow all by themselves into more
  – Binary fission is the process of a bacterium
    splitting in two new bacteria
Cell Cycle

Cell Cycle- is defined as the life of a cell
from the beginning of one interphase to
the beginning of the next interphase.
(with cell division in between)
– Step (1.) Interphase (G1,S & G2 phases)
– Step (2.) Cell Division
     –Mitosis-division of nucleus
     –Cytokinesis- division of cytoplasm
     Cell Cycle: Interphase
Step 1: Interphase – is the growth and
  development phase of the cell cycle.
  Three parts:
  (1.) Growth One or G1 phase
  (2.) Synthesis or S phase (make DNA)
  (3.) Growth Two or G2 phase
              G1 phase
initial growth phase of the cell.
 The cell grows and carries out its routine
This is the longest phase of interphase.
Many cells stop growing and get stuck in
this phase for the entire life of the organism
(Ex. Nerve cells).
 Other cells get stuck in G1 of interphase
until cell division is needed for growth or
      S phase (synthesis)
is when DNA replication occurs.
 After DNA replication the cell has two
complete copies of its DNA.
At this point, the cell is committed to
             G2 phase
the cell continues to grow and the final
preparations for cell division are made.

  Cell Cycle: Cell Division
Step 2: Cell Division: -the creation of two
daughter cells from one parent cell.
*Each daughter cell will have the same
number of chromosomes as the parent
Two Parts of Cell division:
       Mitosis and Cytokinesis
     Cell Division: Mitosis
Mitosis – “division of the
nucleus”. It is a synchronized
set of events that will separate
chromosomes, so that the two
nuclei formed will be identical.
 It is the beginning of cellular
– Prophase, Metaphase,
  Anaphase, & Telophase
                                   •   Mitosis Animation Simple
 Cell Division: Cytokinesis
Cytokinesis “division of the cell
cytoplasm”. It is the physical separation
of the cytoplasm into two new daughter
It is the end of cell division.
New cells pinch off from each other in
animal cells. In plants, a cell plate is
formed, because plants also have cell
walls to form.
  Slide # 5
1. Chromosome: coiled DNA
    structures within the nucleus
    containing genetic information
    that is passed on from generation
    to generation
2. Sister Chromatid: one of two
    identical “sister” parts of a
    duplicated chromosome-formed
    during S phase
3. Centromere (A): chromosome
    region that joins 2 sister
        Prophase: 1st Phase

1. DNA coils & becomes
2. Centrioles move to opposite
   ends of cell
3. Spindle fibers attach to
4. Nuclear membrane breaks

1. Spindle fibers push & pull
   chromosomes until they
   line up across center of
2. Centromere of each
   chromosome pair is
   attached to a spindle fiber

1. Spindle fibers shorten &
   paired chromatids separate
2. Spindle fibers pull
   separated chromosomes to
   opposite ends of the cell
3. Centromere of each pair
   divides; now have individual

1. Chromosomes begin to
   uncoil and decondense
2. Nuclear membrane
   reforms around each
   new set of chromosomes
1.  Cytokinesis is division of
    the cytoplasm
2. Distributes the organelles
   a. In animal cells, the cell
      membrane pinches in
   b. In plant cells, a cell
      plate forms across the
    What Phase Of the Cell Cycle Is It?

A                B            C

    Anaphase     Telophase    Cytokinesis

D                E            F

    Interphase   Metaphase   Prophase
is the caused by uncontrolled cellular
Typically, most cells don’t divide unless it
is for repair or maintenance.
 Cancerous cells keep dividing; crowding
out and stealing nutrients from healthy
Cancer “kills” when a mass of cancer cells
called a tumor interferes with the functions
of major organs.

The picture on the left shows a healthy right lung, and a small discolored left
lung. This indicates the presence of tumors, as seen in the picture on the right.

To top