1. Cell Division Cause breaking up is hard to do

2. Mitosis Mitosis is the process of regular cell division resulting in two identical (or nearly identical) daughter cells. Between divisions the cell grows, builds internal structures and carries out life functions. This is called interphase. Near the end of Interphase, the cell must duplicate it’s DNA to prepare for division.

3. Interphase The period between divisions Growth 1 – cell grows and performs regular functions Synthesis phase -When the cell becomes too large it begins preparation to divide. It must first duplicate its chromosomes. This is called DNA replication. Growth 2 – cell experiences a short growth phase after Synthesis

4. Chromosomes In both Eukaryotes and Archaea, the DNA are in a double strand (like a twisted up ladder, what is called a double helix). This twisted strand is then wrapped tightly around protein units called histones. Chromosomes are very tiny, the DNA strand itself even more minute.

5. Microscope technology -light microscopes are limited to about 1500x because of the wavelength size of visible light, and how many light rays can be reflected off the surface of an object. So to view details of things like viruses and molecules such as DNA other technologies are used like x-ray diffraction, electron microscopes and the scanning tunneling micrograph. -Because X-rays have a much smaller wavelength than visible light, can be used to detect smaller objects.

6. Instruments used to view chromosomes Electron microscope Basically using a beam of electrons instead of light, electromagnets instead of lenses, can magnify images to 1-10 million (light microscope 1500-2000) Scanning tunneling micrograph By placing a slight charge on a thin metal needle and passing it near a sample the tiny voltage difference between the needle and individual atoms creates a current. By measuring the varying strength of the current gives us an “outline” of the atoms in the sample. (basically tracing around the atoms) this can be used to create images up to 50 billion magnification.

7. Pictures of chromosomes and DNA e microscopeSTM

8. Synthesis The DNA in each single chromosome is unwound from the histone proteins, unzipped to reveal the nitrogenous bases, a second strand is built on each parent strand and then the two strands are re-wound

9. More Synthesis Each chromosome replicates a copy of itself. The two (called a homologous pair) are connected near the center by a centromere.

10. Prophase Chromatin in the nucleus begins to condense and becomes visible in the light microscope as chromosomes. The nucleolus disappears (nuclear membrane is broken down). Centrioles begin moving to opposite ends of the cell and cytoskeletal fibers connect and extend from the centromeres to the centrioles, forming the mitotic spindle

11. prophase

12. Metaphase Spindle fibers align the chromosomes along the middle of the cell nucleus. This line is referred to as the metaphase plate. This organization helps to ensure that in the next phase, when the chromosomes are separated, each new nucleus will receive one copy of each chromosome.

13. metaphase

14. Anaphase The spindle fibers contract pulling the sister chromatids apart, and towards opposite poless

15. Anaphase

16. Telophase Chromatids arrive at opposite poles of cell, and new membranes form around the daughter nuclei. The chromosomes disperse and are no longer visible under the light microscope. The spindle fibers disperse, and cytokinesis or the partitioning of the cell may also begin during this stage.

17. Telophase

18. cytokinesis The cell divides down the center forming two new daughter cells. For plant cells a partition wall will be grown after.

19. http://www.youtube.com/watch?v=1cVZBV9t D-A http://www.youtube.com/watch?v=1cVZBV9t D-A http://www.youtube.com/watch?v=pOsAbTi9t Hw http://www.youtube.com/watch?v=pOsAbTi9t Hw

20. Assignment Try # 1-3 page 184 # 1,2 page 188 Note diagram pages 186/87