2.3 The Cell Cycle and Mitosis Take Cornell Notes on a separate sheet of paper

Which turtle has bigger cells? Think About It???? Which turtle has bigger cells?

Which turtle has bigger cells? Think About It???? Which turtle has bigger cells? NEITHER! They both have the same size cells.

Cell Division is Essential to Life Cell division is the only way single-celled organisms can reproduce. Multicellular organisms need cell division to grow and to replace dead or damaged cells. After growth stops, division remain important in normal cells. Some cells divide continuously like our skin and gut cells. Other cells have to divide to heal wounds like skin cuts or broken bones.

Why don’t cells continue to grow? There are two main reason why cells divide instead of continue to grow: The larger the cell becomes, the more demands the cell places on its DNA The cell has more trouble moving enough nutrients and wastes across the cell membrane.

DNA “Overload” Information that controls a cell’s function is stored in a molecule knows as DNA In eukaryotic cells, DNA is found in the nucleus

DNA “Overload” When a cell is small, the information stored in the DNA is able to meet all of the cell’s needs If a cell was too large an “information crisis” would occur and the cell would not function properly

Example: Small library in a large city

Exchanging Materials Food, water and nutrients enter the cell through its cell membrane Waste products leave in the same way

Exchanging Materials Example: Small streets in a big town

The stages of a cells life cycle is called. THE CELL CYCLE The stages of a cells life cycle is called THE CELL CYCLE. During the cell cycle the cell grows and divides producing 2 identical daughter cells. Does the cell spend most of it’s time in interphase or mitosis?

Interphase This is the beginning of the cell cycle Interphase This is the beginning of the cell cycle. It is subdivided into 3 phases: G1, S and G2. During interphase, the cell is preparing for division.

Interphase G1: The cell grows larger and the organelles are duplicated S: Exact copies of the DNA is made. This process is called DNA replication. G2: The DNA copies are checked for errors. Centrioles are produced.

Mitosis The process of cell division Mitosis follows interphase The 4 phases of mitosis can be remembered using the word: “PMAT” Prophase Metaphase Anaphase Telophase

The following slides will describe the 4 phases of Mitosis The following slides will describe the 4 phases of Mitosis. Draw and label the diagrams inside of the RED boxes into your notes.

Mitosis Prophase The chromatin condense into chromosomes. The centrioles begin to separate and spindle fibers form. The nuclear envelope breaks down. Centrioles

Mitosis Metaphase The chromosomes line up in the center of the cell The spindle fibers connect to the centromere

Anaphase The chromatid of each chromosome are pulled apart Mitosis Anaphase The chromatid of each chromosome are pulled apart Chromatid

Mitosis Telophase Chromosomes are separated into 2 identical sets at opposite ends of the cell. Chromatid loosen back into chromatin 2 new nuclear envelopes form

Cytokinesis The final step in the cell cycle Cytokinesis The final step in the cell cycle. The cytoplasm pinches in half. 2 identical daughter cells are produced.

2.3 The Cell Cycle and Mitosis At the end of your notes create new section for a “SUMMARY” Write a paragraph to summarize the cell cycle Mitosis

Copyright Pearson Prentice Hall Quiz The series of events that cells go through as they grow and divide is called the cell cycle. mitosis. interphase. cytokinesis. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Quiz The phase of mitosis during which the chromosomes line up across the center of the cell is prophase. metaphase. anaphase. telophase. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Quiz Cytokinesis usually occurs at the same time as telophase. after telophase. during interphase. during anaphase Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Quiz DNA replication takes place during the S phase of the cell cycle. G1 phase of the cell cycle. G2 phase of the cell cycle. M phase of the cell cycle. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Quiz During mitosis, “sister” chromatids separate from one another during telophase. interphase. anaphase. metaphase. Copyright Pearson Prentice Hall