The Cell Cycle by zujt6g

VIEWS: 14 PAGES: 34

									The Cell Cycle
  Molecular Biology
    Sumner HS
        Cell
 Reproduction/Division

The ability of organisms to reproduce their kind
is the one characteristic that best distinguishes
living things from nonliving.

The continuity of life is based on the
reproduction of cells, or cell division.
Cell Division Importance

Multicellular organisms depend on cell division
for

 Development from a fertilized cell

 Growth

 Repair or replacement of “bad” cells
            Big Growth

We start as one cell

We end up being made of trillions of cells

They don’t magically appear **Poof!**

The result of countless cycles of growth and
division of cells.
  Question to ponder...

What tasks does a cell need to do in order to
divide?

 Have a 2nd copy of DNA

 Have enough cytoplasm and organelles for a
 second cell
         The Cell Cycle


Cells go through predictable, controlled patterns
of growth or development and division.

Called the cell cycle
The Cell Cycle
         Big Picture

                       Cell 1

            Interpha
Cell 1         se/
             Mitosis
                       Cell 2
    Big Picture Cont’d1
                   Cell
         Interpha
            se/
          Mitosis
Cell 1              Cell 3



                    Cell 2
Cell 2   Interpha
            se/
          Mitosis
                    Cell 4
  Cell Cycle Major Phases
Interphase = period of
growth, DNA replication
and protein synthesis

Mitosis = cell division
               Interphase


Interphase can be
divided into
subphases

 G1 phase

 S phase

 G2 phase
               G1 Phase


Rapid growth

High
metabolic
activity

Making lots
of proteins
                     S Phase
DNA is copied
(replicated)

Cell has twice the
number of
normal
chromosomes.

Cell keeps
growing
                G2 Phase

More proteins made

Mitochondria & other
organelles replicate

Cell keeps growing
           Summarize



In your own words, summarize each of the
phases of interphase.
         Mitotic Phase
The Mitotic Phase has two major phases

Mitosis has four sub-phases

 Prophase

 Metaphase

 Anaphase

 Telophase

Cytokinesis
 New Note Instructions


For each of the phases of cell division...

....don’t write down the details I put up

Instead, prepare to summarize the main events
in about 10 words.
                Prophase
Chromosomes coil up and
become visible (twisted rubber
band)

Centriole begins to form spindle,
made from same material as
cytoskeleton.

Nuclear envelope and nucleolus
begin to disappear

Summarize!
               Metaphase
Chromosomes move to “equator” of
the cell

Each half of the chromosome is
attached to a spindle fiber at the
centromere.

Centromere is a protein that joins
the two “sister” chromatids, or
replicated chromosome pairs

Summarize!
            Anaphase


Sister chromatids are
pulled apart to opposite
ends of the cell.

Each chromatid is now a
separate chromosome.

Summarize!
           Telophase

Genetically identical
daughter nuclei form at
opposite ends of the cell

Nuclear envelope begins
to reappear.

Summarize!
               Cytokinesis

In animal cells,
cytokinesis occurs by a
process known as
cleavage, forming a
cleavage furrow.

A “string” of
cytoskeleton pinches
the cell in two

Summarize!
          Cytokinesis cont.



In plant cells, a cell plate
forms between the cells
after telophase.
Mitosis   results in
two identical cells called

daughter cells
Real Pictures: Early
     Prophase
Real Pictures: Late
    Prophase
Real Pictures: Metaphase
Real Pictures: Anaphase
Real Pictures: Early
    Telophase
Real Pictures: Late
   Telophase
Test Yourself
   Check Your Knowledge
        prophase, metaphase, anaphase and
 Identify
 telophase in these cells.

								
To top