unit 6 lesson 1 mitosis copyright © houghton mifflin harcourt publishing company

Unit 6 Lesson 1 Mitosis

Copyright © Houghton Mifflin Harcourt Publishing Company


Florida Benchmark


• SC.7.L.16.3 Compare and contrast the general processes of sexual reproduction requiring meiosis and asexual reproduction requiring mitosis.

Splitsville!


Why do cells divide?

• Cell division takes place for different reasons.

• Cell division is important for asexual reproduction, which involves only one parent organism.

• Most growth in a multicellular organism happens because cell division produces new cells.

• Cell division produces cells for repair.


What happens to genetic material during cell division?• The genetic material in cells is called DNA.

• In eukaryotic cells, DNA is found in the nucleus.

• A DNA molecule contains the information that determines the traits that a living thing inherits and needs to live.



What happens to genetic material during cell division?• During most of a cell’s life cycle, DNA is found in a

mass of loose strands called chromatin.

• Before cell division, DNA is duplicated.

• As cell division begins, the chromatin are compacted into visible structures called chromosomes.



What happens to genetic material during cell division?• A duplicated chromosome is made of two identical

structures called chromatids.



Around and Around


What are the stages of the cell cycle?

• The life cycle of a eukaryotic cell, called the cell cycle, can be divided into three stages: interphase, mitosis, and cytokinesis.



• Interphase is the stage in the cell cycle during which the cell is not dividing.

• The cell grows to about twice the size it was when it was first produced. It produces various organelles and engages in normal life activities.

• Changes that occur during interphase prepare a cell for division.




• In eukaryotic cells, mitosis is the part of the cell cycle during which the nucleus divides.

• Prokaryotes do not undergo mitosis because they do not have a nucleus.

• Mitosis results in two nuclei that are identical to the original nucleus.

• When mitosis is complete, the cell has two identical sets of chromosomes in two separate nuclei.




• Cytokinesis is the division of the parent cell’s cytoplasm.

• Cytokinesis starts during the last step of mitosis and eventually forms two complete cells.

• In plant cells, a cell plate forms during cytokinesis. The cell plate separates the cell into two new cells.



Phasing Out


What are the phases of mitosis?

• There are four phases of mitosis: prophase, metaphase, anaphase, and telophase.

• By the end of the four phases, the cell will have two identical nuclei.



• In prophase, the chromatin in the nucleus condense into chromosomes. The membrane around the nucleus breaks down.




• In metaphase, the chromosomes line up in the middle of the cell.




• In anaphase, each chromosome breaks up into two chromatids. They are pulled to opposite sides of the cell.




• In telophase, a new nuclear membrane forms around each group, and the chromosomes unwind into chromatin.

• After telophase, cytokinesis begins.




• After mitosis, cytokinesis results in two new cells, and the two new cells start the cell cycle again.



unit 6 lesson 1 mitosis copyright © houghton mifflin harcourt publishing company

Documents

cell division

cell cycle

mitosis slide

cell plate forms

mitosis results

step of mitosis

cells life cycle

eukaryotic cells