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Ch. 6 Notes Cell Reproduction & Mitosis

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  1. Ch. 6 NotesCell Reproduction & Mitosis By: Brianna Shields November 3, 2005

  2. DO NOW • Listen to this pod cast • Describe the benefit of bacterial gene sequencing

  3. Gamete Binary fission Gene Chromosome Chromatid Centromere Homologous chromosome Diploid Haploid Zygote Autosome Sex chromosome Karyotype Cell Cycle Interphase Mitosis Cytokinesis Cancer Spindle VOCAB NOTEBOOK-list the terms in your vocab notebook, leaving about 3-4 spaces between each term

  4. GOAL • Identify examples of cell division in eukaryotes and prokaryotes • Differentiate between a gene, a DNA molecule, a chromosome and a chromatid • Differentiate between homologous chromosomes, autosomes, and sex chromosomes • Compare haploid and diploid cells • Predict how changes in chromosome number or structure can affect development

  5. Gametes Organism’s reproductive cells (sperm, egg) Chromosomes

  6. Cell Division 1. Bacterial cell division 2. Eukaryotic division for growth and repair 3. Formation of gametes Chromosomes

  7. Role of DNA 1. Info. In DNA must be present in each cell after division 2. Stores info for which proteins to make and when 3. Directs cell activities 4. DNA gets copied and redistributed during division Chromosomes

  8. Prokaryotic cell division 1. Binary fission 2. Circular DNA attached to cell membrane 3. DNA copied 4. Cell divides by cinching inward through cell wall 5. Offspring identical to parent Chromosomes

  9. Eukaryotic cell division 1. GENES- segment of DNA encoding for a protein or RNA molecule Chromosomes

  10. Eukaryotic cell division 2. CHROMOSOME- coiled up string of DNA Chromosomes

  11. Eukaryotic cell division 3. CHROMATIDS- two exact copies of paired chromosomes Chromosomes

  12. Eukaryotic cell division 4. CENTROMERE- connects two sister chromatids in the middle Chromosomes

  13. Chromosomes 1. Humans= 23 pairs (46) of chromosomes Chromosomes

  14. Chromosomes 2. Homologous chromosomes- similar in size, shape and genetic content (chromatids that are connected) Chromosomes

  15. Chromosomes 3. One half of each chromosome pair comes from the mother and the other half from the father Chromosomes

  16. Diploid Cells Contain 2 sets of chromosomes Ex: somatic cells (body eells), no gametes In humans represented by (2n - 46) Chromosomes

  17. Haploid Cells Contain one set of chromosomes , such as gametes In humans represented by (n - 23) Chromosomes

  18. Zygote Fertilized diploid egg cell formed when two haploid gametes fuse Chromosomes

  19. Typical Number of Chromosomes Found in Common Organisms • Chromosome numbers in common species • Haploid and Diploid Chromosome Numbers

  20. Autosomes 22 of the chromosome pairs in humans, not directly involved in determining the gender of an individual Chromosomes

  21. Sex Chromosomes 1. One of the chromosome pairs containing genes that determine the sex of the individual X and Y XX - female XY- male Chromosomes

  22. Sex Chromosomes 2. The male determines the sex of the resulting offspring by absence or presence of Y chromosome Female can only donate an X Chromosomes

  23. Changes in chromosome number 1. Presence of all 46 chromosomes is essential for normal development and function 2. Humans missing one chromosome typically do not survive Chromosomes

  24. Changes in chromosome number 3. More than two copies of a chromosome - trisomy (improper development occurs) Chromosomes

  25. Karyotype Can detect abnormalities in chromosome number Photo of chromosomes arranged by size (in a dividing cell) Chromosomes

  26. Down Syndrome Extra copy of chromosome 21 Short stature, round face, upper eyelids cover inner corners of eyes, mental retardation Chromosomes

  27. Down Syndrome Risk of having a child with downs increases with mothers age Females are born with all the eggs they will ever have (no additional production) Any damage to eggs can accumulate over time Chromosomes

  28. Chromosomal Abnormalities

  29. Nondisjunction When chromosomes don’t separate properly when egg and sperm form One gamete ends up with both chromosomes, the other has none Trisomy results when abnormal gamete fuses with another Chromosomes

  30. Change in chromosome structure MUTATION - change in chromosome sturcture (4 TYPES) Chromosomes

  31. Change in chromosome structure 1. Deletion- piece of chromosome completely breaks off (often fatal) Chromosomes

  32. Change in chromosome structure 2. Duplication- chromosome fragment attaches to its homologue (doubles the info - 2 copies of a gene) Chromosomes

  33. Change in chromosome structure 3. Inversion- chromosome piece reattaches to original chromosome in reverse orientation Chromosomes

  34. Change in chromosome structure 4. Translocation- chromosome piece attaches to nonhomologous chromosome Chromosomes

  35. Assessment One • Summarize how prokaryotic cells divide by binary fission • Identify the point in a eukaryotic cell cycle at which DNA coils up to form chromosomes • Summarize the difference between a haploid cell and a diploid cell

  36. Cell Cycle Repeating sequence of growth and division in the life of an organism Cell Cycle

  37. Cell Cycle Interphase- (90% of the time)- made up of three phases G1 S G2 Cell Cycle

  38. Cell Cycle G1- First Growth Phase Rapid cell growth and development, routine functions Major part of cell life spent here Non-dividing cells remain here Muscle cells and nerve cells always here, cannot be replaced Cell Cycle

  39. Cell Cycle S- Synthesis phase DNA copied, end up with sister chromatid Cell Cycle

  40. Cell Cycle G2- Second Growth Phase Cell prepares nucleus to divide Microtubules assembled for moving chromosomes during mitosis Cell Cycle

  41. Cell Cycle Mitosis- nucleus divides into two Each nucleus ends up with same type and number of chromosomes Allows organisms to: Grow Replace damaged tissue Asexually reproduce Cell Cycle

  42. Cell Cycle Cytokinesis- cytoplasm divides in half Cell Cycle

  43. Control of the cell cycle 1. Cell growth checkpoint (G1) decides whether the cell will divide A. Cell must be healthy and large enough first B. Proteins will stimulate transition to S phase Cell Cycle

  44. Control of the cell cycle 1. Cell growth checkpoint (G1) decides whether the cell will divide C. If conditions are unfavorable or cells need a rest, growth will stop here D. Nerve and muscle cells remain here forever Cell Cycle

  45. Control of the cell cycle 2. DNA synthesis G2 checkpoint- DNA repair enzymes check the DNA replication A. Once past this point, proteins trigger mitosis Cell Cycle

  46. Control of the cell cycle Click here to view an animation of the cell cycle 3. Mitosis checkpoint- triggers end of mitosis Signals beginning or G1 phase again Cell Cycle