Name______________________________ Date_______ Period______ Chapter 9 The Life Cycles of Cells and Reproduction

Vocabulary Cell cycle Centromere Cleavage furrow Cytokinesis Interphase Metaphase plate Mitosis Sister chromatid Spindle Benign tumor Cancer Malignant tumor Metastasis Tumor Crossing over Diploid Egg Fertilization Gamete Haploid Homologous chromosome Meiosis Somatic cell Tetrad Zygote

Chapter 9 The Life Cycles of Cells & Reproduction WHY DO CELLS DIVIDE??? To reproduce. To grow bigger. To repair injuries. To become more efficient.

Lesson 9.1: The Cell Cycle and Mitosis Goals: Identify the phases of the cell cycle Discuss the activities of each phase of mitosis Compare the genetic makeup of cells before and after mitosis Compare reproduction in eukaryotic and prokaryotic cells

The Process of Cell Division The CELL CYCLE 2 Parts 1.Interphase 2.Mitotic Phase

1. Interphase – 3 stages –More than 90% of the life of a cell is spent in this phase – longest part of cell cycle –G1: cell growth, development, and protein production –S: “Synthesis”, DNA replication  chromosomes copied –G2: Organelles replicated (shortest) cell doubles in size Note: DNA exists as chromatin (no chromosomes yet)

Replicating DNA Original chromosome S phase

Stage 2: Mitosis Process of creating TWO identical nuclei Has FOUR Phases (PMAT) –Prophase (P) –Metaphase (M) –Anaphase (A) –Telophase (T)

Mitosis – Prophase –Longest phase of MITOSIS (50-60 % of total time required for mitosis) –Nuclear envelope starts to break down (disappears) –Chromosomes condense (become visible) – seen as sister chromatids (2 identical chromatids lying side by side) held together by centromeres –Centrioles/Centrosomes move to opposite poles –Spindle fibers grow from centrioles, attach at centromeres

Mitosis – Metaphase (hint “ M ”=middle) –Spindle fibers line up sister chromatids in the CENTER (MIDDLE) of the cell) – aka metaphase plate or equator

Mitosis - Anaphase (hint “ A ” = away) –Centromeres split – sister chromatids separate  individual chromosomes –Spindles move separated chromosomes to opposite sides of the cell (AWAY/APART)

Mitosis - Telophase –Nuclear envelope reforms around each new nuclei (2) –Spindle fibers break down –Mitosis is done –Cell membrane begins to pinch in the middle

Cytokinesis In animal cells - Cell membrane moves inward and pinches in the middle forming two identical cells “Cleavage Furrow” In plant cells – a cell plate (eventually becomes the cell wall) and cell membrane appear separating the 2 new cells There are now 2 identical cells – same DNA, etc.

Result Mitosis results in 2 IDENTICAL DAUGHTER Cells from 1 parent cell The DNA in each daughter cell is an EXACT copy of the parent

Prokaryotes and Binary Fission Prokaryotes do not have a nucleus, therefore they do not undergo mitosis Reproduce by binary fission Prokaryotic cell copies its DNA and doubles in size Copies of DNA separate and cell membrane pinches in resulting in two identical prokaryotic cells

Lesson 1 Review Please answer questions 1-6 on page 251 in your text book 1. _____ 2. _____ 3. _____ 4. _______________ 5. _______________ 6. _______________

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Lesson 9.2: What is Cancer? Goals: To define cancer To define benign tumors and malignant tumors To discuss how cancer spreads To identify certain methods to treat cancer

D. Uncontrolled Cell Growth 1. CANCER – physical condition in which a cell grows and divides too much 2.Cells have lost the ability to control their own rate of growth 3.Continue to divide until nutrient supply is exhausted (may invade other normal cell’s space, even if they bump into each other, and use up their nutrients)

Cancer Tumor – ball of cells NOT responding to signal molecules that control cell division –Benign – does not spread to healthy surrounding tissue – grows in only one area –Malignant – cancerous tumors which spread to and destroy healthy surround tissue Metastasis – spreading Causes –Genetic Defects Can be caused by lots of different factors (smoking, TANNING, radiation exposure, viral infections, defective genes…) Treatment Options: –surgery, radiation, chemotherapy

Lesson 2 Review Please answer questions 1-5 on page 253 in your text book 1. _____ 2. _____ 3. _____ 4. ___________________________ 5. ___________________________