After viewing this program you will be able to

Name the major phases of a cell’s life cycle.

Describe the primary characteristics involved in each phase of a cell’s life.

Cell Division:

The Formation of New Cells

Cell DivisionCell Division

In order for the total number of cells to increase and for an organism to grow, the cells must undergo cell division.

Parent and Daughter Parent and Daughter

CellsCells During cell division, one cell divides into two

cells. Each new cell, called a daughter cell is identical to the parent cell.

Parent Cell

DaughterCell

DaughterCell

Stages of DevelopmentStages of Development

The life cycle of a cell is divided into a series of stages or phases

Interphase Interphase

The phase in which the cell spends the majority of its life.

During this phase, the cell is performing its normal life functions.

InterphaseInterphase

Example

Red Blood Cells

carrying oxygen

InterphaseInterphase

The cell is also preparing for division by replicating its DNA and increasing its size.

The cells chromosomes appear in a tangled form known as chromatin.

Chromatin

MitosisMitosis

The actual process of cell division is divided into 4 steps or phases.

Prophase

Metaphase

Anaphase

Telophase

ProphaseProphase

Chromatin appears as rodlike bodies known as chromosomes in the nucleus.

Each chromosome has made a copy of itself.

ProphaseProphase

These chromosomes are called sister chromatids and are joined by a central part called a centromere.

ProphaseProphase

During this phase a spindle begins to form a “bridge” between opposite ends of the cell.

Near the end of this phase, the nuclear membrane and nucleolus also begin to disappear from view.

MetaphaseMetaphase

The chromosomes prepare for division by lining up along a center line of the cell, referred to as the equator.

They are attached to the spindles by their centromeres.

AnaphaseAnaphase

The chromosomes divide at the centromere and allows the sister chromatids to separate from one another.

TelophaseTelophase

The chromosomes reach the opposite ends of the cell.

The nuclear membrane and nucleolus begin to reappear.

Cytokinesis Cytokinesis The cytoplasm is pinched off and divided into two

nearly equal parts.

Each part contains a nucleus with identical chromosomes.

A new cell membrane and in plant cells, a cell wall also forms around the two new cells.

Interphase ReturnsInterphase ReturnsThe process of cell division is now over. Two

daughter cells have formed, each having the same number and kind of chromosomes as the original parent cell.

Parent Cell

DaughterCell

DaughterCell

46

46

46

Human cells with 46 chromosomes

Chromosome numberChromosome number

The number of chromosomes in any organism varies from species to species.

Organism Chromosome Number

Cat 38

Dog 78

Horse 64

InterphaseInterphase

In multicellular organisms such as humans, cell divisions take place millions of times as an organism grows and develops or replaces dead or injured cells.

The cell returns to the phase before cell division. It is busy performing its normal duties and making copies of DNA available for the next time it will divide.

Mitosis and Mitosis and CytokinesisCytokinesis

Although cell division is broken down into the steps previously discussed, it really occurs in a smooth, continuous process.

Double click to

watch as the

entire process

unfolds.

Quiz YourselfQuiz Yourselfclick on an answer to checkclick on an answer to check

1. The first stage of mitosis when chromosomes become visible is called..

A. anaphase

B. prophase

C. telophase

D. metaphase

Sorry, please review Sorry, please review Metaphase…...Metaphase…...

The chromosomes prepare for division by lining up along a center line of the cell, referred to as the equator.

They are attached to the spindles by their

centromeres. go

back

Sorry, please reviewSorry, please reviewTelophase...Telophase...

The chromosomes reach the opposite ends of the cell.

The nuclear membrane and nucleolus begin to reappear.

go back

Sorry, please reviewSorry, please reviewAnaphase...Anaphase...

The chromosomes divide at the centromere and allows the sister chromatids to separate from one another.

go back

CORRECT ANSWER CORRECT ANSWER !!!!

Next question

QuizQuizclick on the correct answerclick on the correct answer

2.Which of the following statements is NOT true about mitosis.

A. A single cell produces 2 identical daughter cells

B. The centromeres divide at Anaphase

C. Interphase is the shortest portion of a cell’s life cycle

CORRECT ANSWER CORRECT ANSWER !!!!

Next question

Oops, please review…Oops, please review…Parent/Daughter cells Parent/Daughter cells

go back

Parent Cell

DaughterCell

DaughterCell During cell

division, one cell divides into two cells. Each new cell, called a daughter cell is identical to the parent cell.

Oops, please reviewOops, please reviewAnaphase...Anaphase...

The chromosomes divide at the centromere and allows the sister chromatids to separate from one another.

go back

QuizQuizClick on the correct answerClick on the correct answer

3. During interphase, which of the following occur ?

A. The chromosomes appear as chromatin

B. The cell increases its size

C. The cell is performing its normal life functions

D. All of the above

CORRECT ANSWER CORRECT ANSWER !!!!

Next question

NICE TRY !!NICE TRY !!Review the other parts of InterphaseReview the other parts of Interphase

The cell is also preparing for division by replicating its DNA and increasing its size.

The cells chromosomes appear in a tangled form known as chromatin.

Chromatin

go back

NICE TRY !!NICE TRY !!Review the other parts of InterphaseReview the other parts of Interphase

go back

Example

Red Blood Cells

ËË carrying oxygen

QuizQuizClick on the correct answerClick on the correct answer

4. The four phases of mitosis occur in the following order…

A. metaphase, prophase, telophase, anaphase

B. prophase, metaphase, telophase, anaphase

C. anaphase, prophase, metaphase, telophase

D. prophase, metaphase, anaphase, telophase

CORRECT ANSWER CORRECT ANSWER !!!!

Good Job- Thanks for taking the time to review Cell Division Return to

tutorial

Uh oh, please reviewUh oh, please reviewMitosisMitosis

The actual process of Mitosis is divided into four steps or phases

Prophase

Metaphase

Anaphase

Telophase go back