KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions. The cell cycle has 4 main stages. The cell cycle is a regular

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1 Chapter 10

2 Chapter 10

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4 KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions. The cell cycle has 4 main stages. The cell cycle is a regular pattern of growth, DNA replication, and cell division.

5 Interphase Interphase is the longest phase in the cell cycle. During interphase, the cell carries out all its usual functions like respiration, enzyme production and growing There are three (3 ) stages of interphase: Gap 1 (G 1 ) DNA Synthesis (S) Gap 2 (G 2 )

6 The main stages of the cell cycle are gap 1, synthesis, gap 2, and mitosis. Gap 1 (G 1 ): cell growth, normal functions, replicate organelles DNA synthesis (S): copies DNA Gap 2 (G 2 ): additional growth Mitosis (M): includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis) Mitosis occurs only if the cell is large enough and the DNA is undamaged.

7 INTERPHASE G 1 S (DNA synthesis) G 2

8 G1 stage Cell Growth S stage DNA Replication: the genetic material (chromosomes) are replicated or copied. G2 stage Preparation for Mitosis

9 The rate of cell division varies with the need for those types of cells. Some cells are unlikely to divide (G 0 ).

10 G 1 checkpoint G 1 Control system S M G 2 M checkpoint G 2 checkpoint Within the cell cycle there are checkpoints where the cell cycle stops until a go-ahead signal is received

11 If a cell receives a go-ahead signal at the G 1 checkpoint, it will usually complete the S, G 2, and M phases and divide G 1 checkpoint G 0 G 1 G 1 (a) Cell receives a go-ahead signal. (b) Cell does not receive a go-ahead signal. If the cell does not receive the go-ahead signal, it will exit the cycle, switching into a nondividing state called the G 0 phase

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13 KEY CONCEPT Cells divide during mitosis and cytokinesis. Chromosomes condense at the start of mitosis.

14 Review of Chromatin DNA plus proteins is called chromatin. One half of a duplicated chromosome is a chromatid. Sister chromatids are held together at the centromere. Telomeres protect DNA and do not include genes. chromatid telomere centromere telomere Condensed, duplicated chromosome

15 Mitosis and cytokinesis produce two genetically identical daughter cells. Interphase prepares the cell to divide. During interphase, the DNA is duplicated. Mitosis divides the cell s nucleus in four phases. nucleus with DNA Parent cell centrioles spindle fibers centrosome

16 Centrioles (centrosomes) are microtubules that move cell structures during cell division

17 The SPINDLE FIBERS attach to the centromere and move the chromosomes and then pull the chromosomes apart

18 PROPHASE During prophase, chromosomes condense and spindle fibers form. The nuclear membrane disintegrates

19 METAPHASE During metaphase, chromosomes line up in the middle of the cell.

20 ANAPHASE During anaphase, sister chromatids separate to opposite sides of the cell.

21 TELOPHASE During telophase, the new nuclei form and chromosomes begin to uncoil.

22 Cytokinesis Cytokinesis differs in animal and plant cells. In animal cells, the membrane pinches closed: cleavage furrow. In plant cells, a cell plate forms.

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24 PREFIX Pro Meta Ana Telo MEANING Before Middle Away End Simple way to remember the order of mitosis: PMAT Prophase, Metaphase, Anaphase, Telophase

25 One cell with two of each chromosomes chromosomes divides to create two cells with two of each chromosome : the number of chromosomes per cell is conserved! 2 cells with identical genetic information and Cytoplasm, organelles etc.

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28 KEY CONCEPT Cell cycle regulation is necessary for healthy growth. Internal and external factors regulate cell division. External factors include physical and chemical signals. Growth factors are proteins that stimulate cell division. Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells.

29 Cell division is uncontrolled in cancer. Cancer cells form disorganized clumps called tumors. Benign tumors remain clustered and can be removed. Malignant tumors metastasize, or break away, and can form more tumors. normal cell cancer cell bloodstream

30 A TUMOR is a an abnormal mass of tissue. An abnormal mass of essentially normal cells is called a benign tumor.

31 Malignant tumors are masses of cells that result from the reproduction of cancer cells.

32 Cancer cells do not carry out necessary functions. Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

33 Carcinogens are substances known to promote cancer. Examples of carcinogens are tobacco smoke, Hepatitis B, and human papilloma viruses (HPV)

34 Standard cancer treatments typically kill both cancerous and healthy cells. 4 major types of treatment for cancer are surgery, radiation, chemotherapy, and biologic therapies