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Cell Division Chapter 2 Section 3
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Cell Division The Regular sequence of growth and division that cells undergo is known as the_______________. The three main stages of the cell cycle are: Interphase Mitosis Cytokinesis Cell Cycle
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The Cell Cycle
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Interphase What three things occur during Interphase? The cell grows
The cell makes a copy of its DNA The cells prepares to divide into two cells.
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Replication of DNA What is replication?
The process by which the cell makes an exact copy of the DNA inside of the nucleus. Chromatin
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Cell Division The second stage of the cell cycle during which the cell's nucleus divides int two new nuclei is called ______________. Mitosis
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Mitosis Mitosis is divided into the following four phases: Prophase
Metaphase Anaphase Telophase
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Mitosis - Prophase ______________ condenses and coils – looks like rods. Chromatin
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Mitosis - Prophase Each doubled rod of condensed chromatin is called a _______________ and held together by a _______________. Each single strand of the chromosome is called a ____________. Chromosome Centromere Chromatid Chromatid Centromere Chromatid
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Mitosis - Prophase nuclear envelope The __________________ beaks down
Spindle fibers from a bridge (attached to the centrioles). Spindle fibers Nuclear envelope Centrioles
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Mitosis - Metaphase Spindle fibers ______________ line up across the center of the cell. Each chromosome attaches to a spindle fiber at its ___________ Chromosomes centromere Chromosome centriole
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Mitosis - Anaphase _____________ split. Two __________ separate.
Spindle fibers _____________ split. Two __________ separate. _____________ move to the opposite ends of the cell. Cell stretches out. Centromeres Chromatids Chromatids Separating chromatids centriole
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Mitosis - Telophase Cell membrane pinches inward ____________ unwind and lose their rod-like appearance New ______________ forms around each region of chromosomes Cell membrane starts to pinch inward. Chromosomes nuclear envelopes New nuclear membrane forms Chromosomes unwind
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Cell Division – Final Stage
The final stage of the cell cycle that follows mitosis is called _____________. _____________ are distributed between the two new cells, called daughter cells At the end of cytokinesis, new cells enter _____________ and the cycle begins again. cytokinesis organelles Interphase
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Cytokinesis in animal vs. plant cells
In animal cells: The _______________ squeezes together around the middle of the cell and the ___________ pinches into two new cells. In Plant cells A ___________ forms across the middle of the cell and develops into new cell membrane. Then new ____________ form around the cell membrane cell membrane cytoplasm cell plate cell walls
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Cytokinesis Plant Cell Animal Cell
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Mitosis Animation http://www.cellsalive.com/mitosis.htm
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Length of the cell cycle
Varies for different organisms. Can range from ____hours to ____ hours. Nerve, heart, and _______ cells never divide. They remain in interphase for as long as they live. Cancer cells divide rapidly. 2 22 brain
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DNA Structure DNA replication ensures that:
The replication process ensures that each new daughter cell will have a complete set of DNA which it needs to carry out all the cell’s activities.
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The Discovery of the Structure of DNA
James Watson and Fransis Crick Rosalind Franklin
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DNA Structure DNA looks like a twisted ladder and is often called a ________________. double helix
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DNA Structure The sides of the ladder are made up of molecules of ______________ called ______________ that are alternating with molecules of phosphate. sugar deoxyribose
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DNA Structure Ladder rungs are made up of a pair of molecules called nitrogen bases (containing nitrogen and other elements). The four nitrogen bases are: ____________________(A) ____________________(T) ____________________(G) ____________________(C) Adenine Thymine Guanine Cytosine
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DNA Structure How do the nitrogen bases pair up to make the rungs of the DNA ladder? ______________ pairs only with _______________ Adenine Thymine Cytosine Guanine
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Nitrogen Base Pairing
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DNA Replication DNA molecule unwinds and separates between the nitrogen bases on each rung. ____________________ that are floating in the nucleus pair up with each half (A with T and G with C) Two new DNA molecules are formed The order of nitrogen bases in each new DNA molecule will exactly match the order in the original DNA molecule. Nitrogen bases
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DNA Replication
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Cancer Cancer is a disease in which:
Cells grow and divide uncontrollably, damaging the parts of the body around them. Cancer can occur when something damages a portion of DNA in a chromosome. This damage causes a change in DNA called _____________. mutation
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Cancer Abnormal cells that develop uncontrollably may form a mass of abnormal cells which is called a _________________. Treatment for cancer include _____________, ________________ and or ____________________ tumor radiation surgery Drugs (chemotherapy)
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