The Cell Cycle

The cell cycle is the regular sequence of growth and division that cells undergo. It contains three parts: interphase, mitosis, and cytokinesis

Chromosome Chromosomes, which contain DNA, are found inside the nucleus in the cell

Mitosis Mitosis consists of four phases, prophase, metaphase, anaphase, and telophase Mitosis is the process by which a cell’s nucleus divides to create a daughter cell that is genetically identical to the parent cell We call the original cell the parent cell and we call the new cell a daughter cell

When does Your Body Undergo Mitosis? Takes place when healing injured tissue Growth- zygote to adulthood Regular maintenance of the body

We all started off as a tiny, single cell. That cell then underwent a process called mitosis which then created another cell identical to it. Then that cell divided to create another, and so forth….

After fertilization occurs, mitosis begins

A baby slowly grows into an adult This is a result of mitosis…..

Interphase The first stage of the cell cycle It is the period before cell division During interphase three things happen: The cell grows to its mature size It makes a copy of its DNA and organelles It prepares for mitosis

Prophase The nuclear membrane begins to break down The chromatin in the nucleus begins to condense and coil, like fishing line around a ball Since DNA has replicated in interphase, each rod has doubled, each being an exact copy of the other Spindle fiber forms

Prophase

Metaphase The chromosomes line up across the center of the cell Each chromosome attaches to a spindle fiber at its centromere, which holds the chromatids together

Metaphase

Metaphase Chromosomes move along the spindle fibers and line up at the equator of the cell

Anaphase The centromeres split The two chromatids separate Each chromatid moves along the spindle fiber to opposite ends of the cell The cell stretches out

Anaphase Chromosomes begin to pull apart and move to opposite ends of the cell

Which phase am I? Anaphase!

Telophase The chromosomes begin to stretch out and lose their rod like structure This occurs in two regions at the ends of the cell A new nuclear membrane forms around each chromosome

Telophase

Which Phase am I ? Telophase!

The cell spends most of its time in interphase

Cytokinesis The cell membrane pinches in around the middle of the cell, eventually splitting in two Each daughter cell ends up with the same number of identical chromosomes and about half of the organelles and cytoplasm

Cytokinesis Division of the cytoplasm and organelles

Cytokinesis

Plant cell cytokinesis A plant cell does not divide in the same way as the animal cell because its cell wall is too rigid to squeeze together the way the animal cell does Instead a cell plate forms in the middle of the cell (made of sticky carbohydrate) The cell plate gradually develops into a cell membrane, then a cell wall develops

Plant Cell Cytokinesis

Note Check What are the three phases of the cell cycle? What are the four phases, in order, of mitosis? In which phase does DNA replicate? In your own words what it mitosis? Why are the daughter cells genetically identical to the parent cell in mitosis?

Cancer Any substance that is known to cause cancer is called a carcinogen Cancer can be caused by genetic factors, environmental factors, and /or a unhealthy diet Cancer occurs when a mutation occurs in the DNA The cell no longer follows the “check point rules”

Cancer Cancer cells can be thought of as bully cells, they don’t play by the rules They divide uncontrollably, invading the space of other cells so that they no longer can survive A tumor results from a mass of cells Benign tumors are good because they are localized and are easy to remove Malignant tumors spread throughout the body and are less easy to treat

What phase am I?

What phase am I in?

How about me?

And what phase am I in?