The Cell Cycle and MitosisWhat is Mitosis? (Cell Division)1. Mitosis:

Asexual process where one cell (parentcell) splits into two identical daughter cellsthat each have a full set of chromosomes

• For example, 1 human skin cell with 46chromosomes divides into 2 skin cells with 46chromosomes each

Cell Division2. Continuous process = happens non-stop for

the entire life of the organism (except in certaincells, like nerves)

3. Daughter cells have same function,structure, and chromosomes number asparent cell (unless something goes wrongsuch as a mutation, which is a change inDNA).

Important Vocabulary Words Chromosomes- organized, coiled piece of DNA

containing an organismsʼ “genes”

can see them in individual cells during most of thecellʼs life cycle

chromosomes exits as stringy chromatin that iswrapped around histone proteins

Vocabulary Cont… Centromere- Button that holds the sister

chromatids together.

Centrioles- small, dark, cylindricalstructure that aid in celll division. (onlyfound in animal cells)

Vocabulary Words Karotypes- a

speciesʼ“chromosomesmap”

Is used toidentifypotentialproblems.

Why do cells divide?1. Replace worn or damaged cells (except

nerve cells)

2. Growth/development

3. Cells need to stay small (so they can be efficientin importing / exporting, and maintaininghomeostasis)

4. Asexual Reproduction

The Cell CycleAll cells “time” their division using the Cell

Cycle

The cell cycle is the sequence of growthand division of a cell.

The Cell Cycle Interphase

Mitosis - PMAT• Prophase• Metaphase• Anaphase• Telophase

The Cell Cycle Interphase, is where the cell spends the

majority of itʼs life. It is the busiest phase of the cell cycle

and is divided into 3 parts (G1, S, and G2).

DNA synthesisand replication

Centriolesreplicate; cellprepares for

divisionRapidgrowthandmetabolicactivityInterphase

The Cell Cycle

Mitosis begins after interphase is finished

Mitosis

Prophase: The first phase of mitosis

During prophase, the chromatin coils to formvisible chromosomes.

Spindle fibers

Disappearingnuclear envelope

Doubledchromosome

The two halves of the doubled structure arecalled sister chromatids.

Sisterchromatids

Prophase: The first phase of mitosis

Sister chromatids are held together by astructure called a centromere, which playsa role in chromosome movement duringmitosis.

CentromereCentromere is like aBUTTON that holdsthe chromatidstogether

Prophase: The first phase of mitosis

Metaphase: The second stage of mitosis

During metaphase, the chromosomes move tothe equator of the spindle.

Centromere

Sisterchromatids

Anaphase: The third phase of mitosis

During anaphase, the centromeres split andthe sister chromatids are pulled apart toopposite poles of the cell.

Telophase: The fourth phase of mitosis

During telophase, two distinct daughter cellsare formed. The cells separate as the cellcycle starts over, with the next interphase.

Nuclearenvelopereappears

Two daughter cells are formed

Cytokinesis Following telophase, the cellʼs cytoplasm

divides in a process called cytokinesis.

Cytokinesis differs between plants andanimals.

In animal cells: the plasma membranepinches in along the equator, forming acleavage furrow.

Cytokinesis

In plant cells: Thereʼs a tough cell wall, sothe plasma membrane does not pinch in.

A structure known as the cell plate is laiddown across the cellʼs equator.

A cell membrane forms around each cell,and new cell walls form on each side of thecell plate until separation is complete.

Results of Mitosis

When mitosis is complete

Unicellular organisms remain as single cells.

Multicellular organisms, cell growth andreproduction result in groups of cells thatwork together as tissue to perform aspecific function.

Results of Mitosis

Tissues organize in various combinations toform organs that perform more complex roleswithin the organism.

Multiple organs that work together form anorgan system.

What characteristic of life is this an example of??

Factors Effecting Cell Cycle Rate

1. Available Nutrients

2. Temperature

3. pH

4. Drugs and Chemotheraphy

The stringy structures in the cell nucleus thatcontain DNA are __________.

Question 1

D. chlorophylls

C. genes

B. chromosomes

A. centromeres

The answer is B.Chromosomes are the carriers of the geneticmaterial of the cell. A gene is a segment ofDNA that controls the production of a protein.

Look at the diagram and identify the stage ofmitosis that is depicted.

Question 2

D. telophase C. anaphase

B. metaphase A. prophase

Centromere

Sisterchromatids

The answer is B.Metaphase is the short second phase of mitosis,during which the chromosomes begin to line upon the equator of the spindle.

What is the process by which a cell's cytoplasmdivides?

Question 3

D. mitosis

C. meiosis

B. telekinesis

A. cytokinesis

The answer is A.Cytokinesis follows telophase and allows thetwo new cells to separate.

In multicellular organisms, groups of cells thatwork together to perform a specific function arecalled __________.

Question 4

D. cell cycles

C. tissues

B. organs A. organ systems

The answer is C.Tissues organize to form organs, which workwith other organs to form organ systems.