THE CELL CYCLETHE CELL CYCLE

MitosisMitosis

Cellular Reproduction/DivisionCellular Reproduction/Division

THE CELL CYCLETHE CELL CYCLE 1. 1. The regular sequence of growth The regular sequence of growth

and division that cells undergoand division that cells undergo is is known as the cell cycle.known as the cell cycle.

2. The cell cycle is 2. The cell cycle is divided into 3 divided into 3 main stagesmain stages..

STAGE 1 – INTERPHASESTAGE 1 – INTERPHASE 3. When you look at 3. When you look at cellscells under a under a

microscopemicroscope, you mostly see them in a , you mostly see them in a non-non-reproducing statereproducing state..

4. The non-reproducing stage is called 4. The non-reproducing stage is called interphaseinterphase..

5. Interphase is 5. Interphase is the first stage of the cell the first stage of the cell cyclecycle..

STAGE 1 – INTERPHASESTAGE 1 – INTERPHASE 6. Interphase is the period6. Interphase is the period before cell before cell

division occursdivision occurs.. 7. During 7. During interphaseinterphase, the cell is using , the cell is using

energyenergy to carry out to carry out the basic cell the basic cell functionsfunctions..

8. At the same time, 8. At the same time, new cell parts such as new cell parts such as ribosomes and mitochondria are being ribosomes and mitochondria are being producedproduced..

INTERPHASE – GROWTHINTERPHASE – GROWTH 9. During the first part of interphase, 9. During the first part of interphase, the the

cell doubles in size and produces all the cell doubles in size and produces all the structures needed to carry out its structures needed to carry out its functionsfunctions..

10. The cell enlarges its 10. The cell enlarges its endoplasmic endoplasmic reticulumreticulum, makes new , makes new ribosomesribosomes, and , and produces produces enzymesenzymes..

INTERPHASE – GROWTHINTERPHASE – GROWTH 11. The 11. The mitochondriamitochondria makes copies of makes copies of

itself during the itself during the growthgrowth phase also. phase also. 12. During this time the cell will 12. During this time the cell will grow and grow and

reach its full size and structurereach its full size and structure..

INTERPHASE – DNA INTERPHASE – DNA REPLICATIONREPLICATION

13. 13. Once a cell has reached its mature Once a cell has reached its mature sizesize, the next part of interphase begins., the next part of interphase begins.

14. When the cell makes a copy of 14. When the cell makes a copy of the the DNA in its nucleusDNA in its nucleus it is called it is called replicationreplication..

INTERPHASE – DNA INTERPHASE – DNA REPLICATIONREPLICATION

15. DNA is found 15. DNA is found in the chromatin inside in the chromatin inside the cell’s nucleusthe cell’s nucleus..

16. DNA holds 16. DNA holds all the information that the all the information that the cell needs to carry out its functionscell needs to carry out its functions..

INTERPHASE – DNA INTERPHASE – DNA REPLICATIONREPLICATION

17. DNA replication is very important, 17. DNA replication is very important, because because each new cell that is produced each new cell that is produced must have a complete set of DNA in order must have a complete set of DNA in order to surviveto survive..

18. At the end of DNA replication, 18. At the end of DNA replication, the cell the cell contains two identical sets of DNAcontains two identical sets of DNA..

19. Once the DNA has been 19. Once the DNA has been replicatedreplicated, the , the cell will prepare to cell will prepare to dividedivide..

STAGE 2 – MITOSISSTAGE 2 – MITOSIS 20. Mitosis is 20. Mitosis is the stage during which the the stage during which the

cell’s nucleus divides into two new nucleicell’s nucleus divides into two new nuclei.. 21. During mitosis, one copy of 21. During mitosis, one copy of the DNAthe DNA is is

distributed into distributed into each of the two daughter each of the two daughter cellscells..

22. Mitosis is divided into 4 parts or 22. Mitosis is divided into 4 parts or phases: phases: prophase, metaphase, anaphase, prophase, metaphase, anaphase, and telophase (cytokinesis).and telophase (cytokinesis).

MITOSIS – PROPHASEMITOSIS – PROPHASE 23. During prophase, the 23. During prophase, the nuclear nuclear

membrane begins to break downmembrane begins to break down, and the , and the chromatin inside the nucleus is growing chromatin inside the nucleus is growing thicker and shorter.thicker and shorter.

24. The chromatin 24. The chromatin condenses and coilscondenses and coils, , like fishing line wrapping around a ball.like fishing line wrapping around a ball.

25. The condensed 25. The condensed chromatinchromatin begins to begins to look like look like tiny rodstiny rods..

26. Since the cell’s 26. Since the cell’s DNA has replicatedDNA has replicated each rod of chromatin has each rod of chromatin has doubleddoubled..

MITOSIS – PROPHASEMITOSIS – PROPHASE 27. Each of these 27. Each of these rods of chromatinrods of chromatin is an is an

exact copy of the otherexact copy of the other.. 28. These 28. These doubled rods of chromatindoubled rods of chromatin are are

now called now called chromosomeschromosomes.. 29. Each 29. Each individual strand or rod making individual strand or rod making

up the chromosomeup the chromosome is called a is called a chromatidchromatid.. 30. The structure holding the 30. The structure holding the chromatidschromatids

together is called a together is called a centromerecentromere..

MITOSIS – PROPHASEMITOSIS – PROPHASE 31. By this time the 31. By this time the nucleusnucleus has has

completely completely disappeareddisappeared.. 32. At the same time the 2 pairs of 32. At the same time the 2 pairs of

centriolescentrioles found in each cell begin to found in each cell begin to separate and go to opposite ends or poles separate and go to opposite ends or poles of the cellof the cell..

33. A structure called a 33. A structure called a microtubulemicrotubule then then forms forms between the pairs of centriolesbetween the pairs of centrioles..

MITOSIS - METAPHASEMITOSIS - METAPHASE 34. As metaphase begins the 34. As metaphase begins the

chromosomeschromosomes are scattered around the are scattered around the area that was once the area that was once the nucleusnucleus..

35. The 35. The chromosomeschromosomes then begin to then begin to line line up along the middle of cell known as the up along the middle of cell known as the equatorequator..

36. During 36. During metaphasemetaphase the the microtublesmicrotubles connecting the connecting the centriolescentrioles begin to get begin to get longer.longer.

MITOSIS – ANAPHASEMITOSIS – ANAPHASE 37. At the beginning of 37. At the beginning of anaphaseanaphase the the

centromerescentromeres split. split. 38. The 38. The two chromatidstwo chromatids that were once that were once

joined by the centromerejoined by the centromere begin to begin to separate and move apartseparate and move apart..

39. The 39. The two chromatidstwo chromatids that were once that were once joined are known as joined are known as sister chromatidssister chromatids..

MITOSIS – ANAPHASEMITOSIS – ANAPHASE 40. After 40. After separatingseparating, the , the sister chromatidssister chromatids

are pulled to the are pulled to the opposite polesopposite poles.. 41. At the end of anaphase, there is 41. At the end of anaphase, there is one one

set of single-stranded chromosomes at set of single-stranded chromosomes at each end of the celleach end of the cell..

MITOSIS – TELOPHASEMITOSIS – TELOPHASE 42. Telophase is the 42. Telophase is the final phase of mitosisfinal phase of mitosis, ,

when the cell begins to when the cell begins to divide in twodivide in two.. 43. The 43. The cell membranecell membrane begins to pinch begins to pinch

together at the center.together at the center. 44. This process is called 44. This process is called cytokinesiscytokinesis..

MITOSIS – TELOPHASEMITOSIS – TELOPHASE 45. During cytokinesis, the 45. During cytokinesis, the cytoplasm cytoplasm

divides and the organelles are divided into divides and the organelles are divided into the two sides of the cellthe two sides of the cell..

46. As the cell pinches in half, a 46. As the cell pinches in half, a nuclear nuclear membranemembrane forms from the forms from the endoplasmic endoplasmic reticulumreticulum on each end of the cell and on each end of the cell and encloses each set of chromosomesencloses each set of chromosomes..

MITOSIS – TELOPHASEMITOSIS – TELOPHASE 47. The chromosomes then 47. The chromosomes then join together join together

as one mass of chromatinas one mass of chromatin.. 48. At the conclusion of cytokinesis, 48. At the conclusion of cytokinesis, the the

cell membrane completely separates and cell membrane completely separates and forms two identical cellsforms two identical cells..

49. These identical cells are called 49. These identical cells are called daughter cellsdaughter cells..

LENGTH OF THE CELL LENGTH OF THE CELL CYCLECYCLE

50. The 50. The lengthlength of the cell cycle is of the cell cycle is different for different for each different type of each different type of cellcell..

51. The length of each 51. The length of each phasephase of the of the cell cycle is also determined by cell cycle is also determined by the the type of celltype of cell..

52. Some cells, such as those in bone 52. Some cells, such as those in bone marrow that form marrow that form red blood cellsred blood cells, , reproduce rapidly.reproduce rapidly.

LENGTH OF THE CELL LENGTH OF THE CELL CYCLECYCLE

53. The cell cycle for red blood cells 53. The cell cycle for red blood cells lasts less than 1 hourlasts less than 1 hour..

54. 54. Human liver cellsHuman liver cells divide only divide only when new cells are needed to help when new cells are needed to help repair a wound.repair a wound.

55. Some cells, such as 55. Some cells, such as brain cellsbrain cells, , never divide but remain in never divide but remain in interphaseinterphase their whole life.their whole life.

LENGTH OF THE CELL LENGTH OF THE CELL CYCLECYCLE

56. It is estimated that 56. It is estimated that 25 million 25 million cell cell divisions occur every divisions occur every second in the second in the adult human bodyadult human body..