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CHAPTER 10 & 11.4

CHAPTER 10 & 11.4. MITOSIS & MEIOSIS. 10.1 CELL GROWTH, DIVISION & REPRODUCTION. GROWTH. What do you need to grow? What do your cells need to grow?. *AFFECTS OF CELL GROWTH. *More demands on DNA, more to control and regulate *More “required” materials crossing the cell membrane

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CHAPTER 10 & 11.4

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  1. CHAPTER 10 & 11.4 MITOSIS & MEIOSIS

  2. 10.1 CELL GROWTH, DIVISION & REPRODUCTION

  3. GROWTH What do you need to grow? What do your cells need to grow?

  4. *AFFECTS OF CELL GROWTH *More demands on DNA, more to control and regulate *More “required” materials crossing the cell membrane *More “waste” material crossing the cell membrane

  5. LMTS TO CELL SIZE • Larger cells place more demands on DNA • DNA overloads • results in an information crisis

  6. EXCHANGING MATERIALS • Rate of waste exchange depends on the surface area of the cell membrane • Rate at which O2 & food are used depends on cell volume

  7. Ratio of Surface Area to Volume • As the cell increases in size, the volume increases faster than the surface area (SA:V) • Traffic problems – Grid lock, cannot get rid of waste or move food around

  8. Measure each nucleus in 1 x 1 x 1 cell = 2 x 2 x 2 cell = 4 x 4 x 4 cell =

  9. CELL DIVISION & REPRODUCTION • Process of dividing into two daughter cells • 2 Types of reproduction • Asexual • Sexual

  10. ASEXUAL REPRODUCTION • Genetically identical offspring from a single parent

  11. SEXUAL REPRODUCTION • Offspring inherit genetic info from each of 2 parents; traits blended

  12. ASEXUAL VS SEXUAL REPRODUCTION • Asexual • Advantage – fast population increase • Disadvantage – no genetic variation • Sexual • Advantage – provides genetic variation • Disadvantage – use E to find a mate

  13. 10.2 THE PROCESS OF CELL DIVISION

  14. CELL DIVISION • Process of dividing into two daughter cells * Eukaryotic cells contain a nucleus and cytoplasm - Both must divide; 2 processes possible 1) Mitosis – div. of body cells 2) Meiosis – div. of reproductive cells Form sperm & egg

  15. CHROMOSOME STRUCTURE • Threadlike DNA & protein • Contains genetic info • Appear short and thick or “condensed” when cell is dividing * Very tightly coiled, compact

  16. PROKARYOTE VS EUKARYOTECHROMOSOMES • Prok – single, circle of DNA; chromosome floats ... • Euk – contain multiple, linear chromosomes; each organism has a different number • Humans have 46 & fruit flies have 8

  17. CHROMATIN • DNA and protein • Appears long and thin • “Relaxed” form present during time when cell is not dividing

  18. * ORGANIZATION LEVELS

  19. NUCLEIC ACIDS • Store & transmit genetic info • 2 types: • DNA (deoxyribonucleic acid) & RNA (ribonucleic acid) *DNA-Stores info, transmits info cell to cell *RNA-Transmits info w/in cell

  20. DNA rRNA tRNA tRNA mRNA

  21. CHROMATIDS • The 2 strands that make up a single chromosome; commonly called sister chromatids CENTROMERE • Holds the two sister chromatids together within a single chromosome

  22. *MORE ON CENTROMERE & CELL DIVISION *Centromere critical for cell division • Fibers attach and pull *DNA tightly coiled for cell division • Easier to separate into daughter cells

  23. CELL CYCLE - PROKARYOTES • Aka binary fission • Single circle of DNA is replicated • 2 circles attach at different pts • Cell divides between attachment pts

  24. CELL CYCLE - EUKARYOTES • Series of events that cells go through as they grow and divide • Growth: G1, S & G2 phases (Interphase) • Division: Mitosis & cytokinesis (M phase) • Mitosis w/ 4 parts prophase, metaphase, anaphase & telophase * M phase = div.of nucleus then cytoplasm

  25. CELL CYCLE

  26. G1 PHASE (Growth) • Cell is growing • Increases in size • Making new proteins *Cell grows to mature size

  27. S PHASE • DNA is copied

  28. G2 PHASE (Preparation) • Cell creates organelles & other materials needed for cell division * Preparation for mitosis

  29. *INTERPHASE G1 phase, S phase & G2 phase DNA is “relaxed” and being used Can see nucleus & nucleolus

  30. M PHASE • Cell division – division of nucleus & cytoplasm • Mitosis = division of nucleus • Produces 2 cells, each w/ same DNA as the parent cell • Cytokinesis = division of the cytoplasm • Result is formation of 2 daughter cells

  31. MITOSIS THINK PMAT!!!

  32. DIVIDING ONION ROOT TIP CELLS

  33. PROPHASE • Chromatin condenses (coils) into chromosomes • Nucleolus disappears • Nuclear membrane breaks down

  34. PROPHASE CONT’ • In animal cells: • Centrioles move to opposite poles of nucleus • See asters (microtubules extending in a fan-like pattern from the centrioles) • Spindle forms (microtubules that guide chromosomes)

  35. SPINDLE APPARATUS

  36. METAPHASE (MIDDLE) • Dyad chromosomes with 2 sister chromatids • Dyads line up across the middle of the cell (*Meet at midline) • Spindle fibers attach to centromere of each dyad

  37. ANAPHASE • Centromeres divide *Pulled away from midline 1st • Sister chromatids separate and move towards opposite poles of cell *Dyads (chromosomes) split

  38. TELOPHASE • Chromatids uncoil, forming chromatin • Nucleolus reappears • Nuclear membrane reappears • Spindle breaks down

  39. CYTOKINESIS • Cytoplasm divides into 2cells • Daughter cells – two new cells formed from one parent cell by cell division Each with: *Complete set of chromosomes *~ ½ parent cell cytoplasm *~ ½ parent cell organelles

  40. CYTOKINESIS • Animal cells • Cell membrane pinches inward * Cleavage furrow • Plant cells • Cell plate forms between daughter cells in middle area * Middle  outer edges

  41. 10.3 REGULATING THE CELL CYCLE

  42. * CELL CYCLE * Normal cell division is controlled *Cells grow only when • attached to a surface • touching other cells *Stop dividing if too crowded

  43. CONTROLS ON CELL DIVISION • Cyclins – family of proteins that control the cell cycle • Regulatory proteins – many! • Internal regulators • External regulators

  44. INTERNAL REGULATORS • Respond to events occurring inside cell • Ex. Several proteins ensure complete chromosome replication before starting the next step, mitosis EXTERNAL REGULATORS • Respond to events occurring outside cell • Ex. Growth factors either speed-up or slow down cell growth & division

  45. APOPSTASIS • Programmed cell death; key role in forming body structures • Ex. Embryonic fingers webbed; apopstasis  individual fingers During the early weeks of pregnancy, the child’s fingers and toes form in a “mitten” of skin. By the end of the second month of pregnancy, the extra skin dissolves, and the fingers and toes should separate. Syndactyly occurs when the fingers and toes do not fully separate during development.

  46. CANCER – UNCONTROLLED CELL GROWTH • Cancer cells do not respond to signals that control cell growth (forms tumor) • Tumor • Benign - does not invade ..... • Malignant – invades neighboring cells • Metastatic – Ca cells that travel to distant parts of body

  47. CAUSES (OF CANCER) • Defects in regulatory genes • Ex. p53 gene – normally slows cycle of cell division • Treatments include surgical removal, radiation & chemicals

  48. TUMOR FORMATION & METASTASIS DIAGRAM

  49. 11.4 MEIOSIS

  50. HOMOLOGS • Homologous chromosomes occur in pairs (homologs) • Each chromosome from the male parent has a corresponding chromosome from the female parent

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