Ch. 9 Cellular Reproduction

Biology

Cellular Reproduction

Ms. Karen

Vocabulary

Individually copy the vocabulary below and its definition from the presentation in a binder paper sheet

1. Cell cycle

2. Chromosomes

3. Chromatin

4. Mitosis

1 Cell cycle

2 Interphase

Index

3 Binary fission

4 Mitosis

5 Cytokinesis

6 Thank you

Cell cycle

Once the cell reaches it’s size limit something must happen- either it will stop growing or it will divide. Most cells will eventually divide. Cell cycle is the cycle of growing and dividing.

The Cell Cycle

The Cell Cycle

Cell division is the way the cell reproduces.

Cellular reproduction allows you to grow and heal certain injuries.

Cell cycle is the cycle of growing and dividing.

Each time a cell goes through one completed cycle, it becomes two cells.

The Cell Cycle

There are 3 main stages of the cell cycle.

Cytokinesis

Interphase

Mitosis

Is the stage of the cell cycle during which the cell’s nucleus and nuclear material divide. Is divided into four substages.

Is the method by which a cell’s cytoplasm divides, creating a new cell.

Is the stage during which the cell grows, carries out cellular functions, and replicates, or makes copies of its DNA in preparation for the next stage. Is divided into 3 substages.

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The duration of cell cycle varies, depending on the cell that is dividing. Some eukaryotic cells might complete the cycle in as few as eight minutes, while other cells might take up to one year. For most animal cells, the cell cycle takes aprox. 12-24 hours

The stages of interphase

During interphase, the cell grows, develops into a mature, functional cell, duplicates its DNA, and prepares for division. Interphase is divided into 3 stages:

GAP 2 (G2)

Synthesis (S)

GAP 1 (G1)

GAP 1 (G1)

The first stage of interphase, G1, is the period immediately after a cell divides. During G1, a cell is growing, carrying out normal cell functions, and preparing to replicate DNA.

Chromosomes are structures that contain the genetic material that is passed from generation to generation of cells.

SYNTHESIS (S)

The second stage, S, is the period when a cell copies its DNA in preparation for cell division.

Chromatin is the relaxed form of DNA in the cell’s nucleus. This condenses to form chromosomes.

GAP 2 (G2)

The third stage, G2, is the period when the cell prepares for the division of its nucleus.

During this stage the cell also takes inventory and makes sure it is ready to continue with mitosis.

A protein that make microtubules for cell division is synthesized at this time.

The stages of mitosis and cytokinesis follow interphase.

cytokinesis

mitosis

The cell’s nuclear material divides and separates into opposite ends of the cell.

The cell divides into two daughter cells with identical nuclei.

Cell Cycle

• What happens when events occur in a cycle?

• Why can't cells continually grow larger and still survive?

Prokaryotic cell division

The cell cycle is the method by which eukaryotic cells reproduce.

Prokaryotic cells reproduce by a method called binary fission.

Mitosis & cytokinesis

MITOSIS

During mitosis, the cell’s replicated genetic material separates and the cell prepares to split into two cells

The key activity of mitosis is the accurate separation of the cell’s replicated DNA.

This enable the cell’s genetic information to pass into new cells intact, resulting in two daughter cells that are generally identical.

Stages of mitosis

PROPHASE

ANAPHASE

METAPHASE

TELOPHASE

Longest phase of mitosis. In this stage, the cell’s chromatin tightens, or condenses, into chromosomes.

Shortests stage of mitosis. Stage where chromosomes are pulled apart.

In this stage the chromosomes are pulled toward the center of the cell and they line up in the middle.

Last stage in which the chromosomes arrive at the poles of the cell.

PROPHASE

In this stage, the cell’s chromatin tightens, or condenses, into chromosomes. Also, the chromosomes are shaped like an X. At this point, each chromosome is a single structure that contains the genetic material that was replicated in interphase.

As prophase continues, the nucleolus seems to disappear. Microtubule structures called spindle fibers form in the cytoplasm, in ordert to form the spindle apparatus.

Near the end of prophase, the nuclear envelope seems to disappear. The spindle fibers attach to the sister chromatids of each chromosome on both sides of the centromere and then attach to opposite poles of the cell.

PROPHASE

1. Chromosomes are formed2. Spindle apparatus is formed 3. Nuclear envelope disappears

In this stage the chromosomes are pulled by motor proteins along the spindle apparatus toward the center of the cell and they line up in the middle, or equator, of the cell.

METAPHASE

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ANAPHASE

Microtubules of the spindle apparatus begin to shorten. This shortening pulls at the centromere of each sister chromatid, causing the chromosomes to separate into two identical chromosomes.

All of the sister chromatids separate simultaneously.

At the end of this phase, the microtubules, with the help of motor proteins, move the chromosomes toward the poles of the cell.

TELOPHASE

The chromosomes arrive at the poles of the cell and begin to decondense.Two new nuclear membranes begin to form and the nucleoli reappear. The spindle apparatus disassembles

Arrange the stages of mitosis to the image that they belong.

Anaphase

Interphase

Prophase

Cytokinesis

Telophase

Metapahse

Cytokinesis

This process begins at the end of mitosis and its function its to divide the cytoplasm. This results in two cells, each with identical nuclei.

CYTOKINESIS

Prokariotic cell

Animal cell

Plant cell

In plant cells we have a rigid cell wall covering the plasma membrane, for that reason, instead of pinching in half, a new structure called a cell plate forms between the 2 daughter nuclei. Cell walls then form on either side of the cell plate.

Divide by binary fissionWhen prokariotic DNA is duplicated, both copies attach to the plasma membrane. As the plasma membrane grows, the attached DNA molecules are pulled apart.

Cytokinesis is accomplished by using microfilaments to constrict, or pinch , the cytoplasm. The area where constriction occurs in called the furrow.

Mitosis

Why mitosis alone doesn't produce daughter cells? What is the process of cytokinesis?

Thank you!