Cell Division Chapter 2 Section 3

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

The Cell Cycle

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.

Replication of DNA What is replication? The process by which the cell makes an exact copy of the DNA inside of the nucleus. Chromatin

Cell Division The second stage of the cell cycle during which the cell's nucleus divides int two new nuclei is called ______________. Mitosis

Mitosis Mitosis is divided into the following four phases: Prophase Metaphase Anaphase Telophase

Mitosis - Prophase ______________ condenses and coils – looks like rods. Chromatin

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

Mitosis - Prophase nuclear envelope The __________________ beaks down Spindle fibers from a bridge (attached to the centrioles). Spindle fibers Nuclear envelope Centrioles

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

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

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

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

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

Cytokinesis Plant Cell Animal Cell

Mitosis Animation http://www.cellsalive.com/mitosis.htm http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html

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

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.

The Discovery of the Structure of DNA James Watson and Fransis Crick Rosalind Franklin

DNA Structure DNA looks like a twisted ladder and is often called a ________________. double helix

DNA Structure The sides of the ladder are made up of molecules of ______________ called ______________ that are alternating with molecules of phosphate. sugar deoxyribose

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

DNA Structure How do the nitrogen bases pair up to make the rungs of the DNA ladder? ______________ pairs only with _______________ Adenine Thymine Cytosine Guanine

Nitrogen Base Pairing

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

DNA Replication http://www.youtube.com/watch?v=hfZ8o9D1tus

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

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)