1. How Cells Reproduce
Chapter 9

2. Reproduction
Parents produce a new generation of cells or multicelled individuals like themselves
Parents must provide daughter cells with:
hereditary instructions
encoded in DNA
enough metabolic machinery to start up their own operation

3. Division Mechanisms Eukaryotic organisms Mitosis Meiosis
Prokaryotic organisms
Prokaryotic fission

4. Roles of Mitosis Multicelled organisms Growth Cell replacement
Repair damaged tissue
Some protistans, fungi, plants, animals
Asexual reproduction

5. Henrietta’s Immortal Cells
Impacts, Issues Video
Henrietta’s Immortal Cells
Growing Body Parts
Growing Body Parts II
NY Times

6. Chromosome A DNA molecule & attached proteins
Duplicated in preparation for mitosis
one chromosome (unduplicated)
one chromatid
two sister
chromatids
one chromatid
one chromosome (duplicated)

7. Chromosome Number Sum total of chromosomes in a cell Somatic cells
Chromosome number is diploid (2n)
Two of each type of chromosome
Gametes
Chromosome number is haploid (n)
One of each chromosome type

8. Human Chromosome Number
Diploid chromosome number (2n) = 46
Two sets of 23 chromosomes each
One set from father
One set from mother
Mitosis produces cells with 46 chromosomes--two of each type

9. 1 2 3 4 5
Chromosome Number 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
XX (or XY)

10. Maintaining Chromosome Number
chromosome (unduplicated) in
cell at interphase
Maintaining Chromosome Number
same chromosome (duplicated) in interphase prior to mitosis
mitosis, cytoplasmic division
chromosome (unduplicated)
in daughter cell
at interphase

11. Organization of Chromosomes
Chromosome structural organization

12. multiple levels of coiling of DNA and proteins
Chromosome
centromere
(constricted region)
multiple levels of coiling of DNA and proteins
fiber
beads on a string
DNA double helix
core of histone
nucleosome

13. The Cell Cycle
The cell cycle

14. The Cell Cycle interphase G1 S telophase anaphase Mitosis metaphase
prophase G2

15. Phases of the Cell Cycle
The cell cycle consists of
Mitotic (M) phase, including mitosis and cytokinesis
Interphase, including cell growth and copying of chromosomes in preparation for cell division
© 2014 Pearson Education, Inc. 15

16. Interphase (about 90% of the cell cycle) can be divided into subphases
G1 phase (“first gap”)
S phase (“synthesis”)
G2 phase (“second gap”)
The cell grows during all three phases, but chromosomes are duplicated only during the S phase 16

17. Interphase Usually longest part of the cycle Cell increases in mass
Number of cytoplasmic components doubles
DNA is duplicated

18. Control of the Cycle
For many cells, the G1 checkpoint seems to be the most important
If a cell receives a go-ahead signal at the G1 checkpoint, it will usually complete the S, G2, and M phases and divide
If the cell does not receive the go-ahead signal, it will exit the cycle, switching into a non-dividing state called the G0 phase
Cancer involves a loss of control over the cycle, malfunction of the “brakes”

19. Stopping the Cycle Some cells normally stop in interphase
Neurons in human brain
Arrested cells do not divide
Adverse conditions can stop cycle
Nutrient-deprived amoebas get stuck in interphase

20. Mitosis Period of nuclear division 5 stages: Prophase Pro-metaphase
Anaphase
Telophase
Usually followed by cytoplasmic division

21. Early Prophase - Mitosis Begins
Duplicated chromosomes begin to condense

22. Late Prophase New microtubules are assembled
One centriole pair is moved toward opposite pole of spindle
Nuclear envelope starts to break up

23. Transition to Metaphase
Spindle forms
Spindle microtubules become attached to the two sister chromatids of each chromosome

24. Metaphase All chromosomes are lined up at the spindle equator
Chromosomes are maximally condensed

25. The Spindle Apparatus Consists of two distinct sets of microtubules
Each set extends from one of the cell poles
Two sets overlap at spindle equator
Moves chromosomes during mitosis

26. Anaphase Sister chromatids of each chromosome are pulled apart
Once separated, each chromatid is a chromosome

27. Spindle Apparatus one of the condensed chromosomes spindle equator
one spindle pole
one of the condensed chromosomes
spindle equator
microtubules organized
as a spindle apparatus
one spindle pole

28. Telophase Chromosomes decondense
Two nuclear membranes form, one around each set of unduplicated chromosomes

29. Results of Mitosis Two daughter nuclei
Each with same chromosome number as parent cell
Chromosomes in unduplicated form

30. Mitosis
Mitosis Jingle
Mitosis Step by Step

31. Cytoplasmic Division
Usually occurs between late anaphase and end of telophase
Two mechanisms
Cleavage (animals)
Cell plate formation (plants)

32. Cell Plate Formation
Cytoplasmic division

33. Animal Cell Division
The contractions continue and cut the cell in two.
Band of microfilaments at the former spindle equator contracts.
Mitosis is over, and the spindle is now disassembling.

34. Cell Plate Formation former spindle equator vesicles converging

35. Mitotic Control Kinases enzymes
help to induce cell death or stop the cell cycle
Growth factors
promote transcription of genes that have roles in body’s growth
initiates mitosis
Checkpoint genes

36. Tumors
Sometimes a checkpoint gene mutates and control over cell division is lost.
Cells uncontrollable division forms an abnormal mass called a tumor.
Neoplasms

37. Loss of Cell Cycle Controls in Cancer Cells
Cancer cells do not respond to signals that normally regulate the cell cycle
Cancer cells may not need growth factors to grow and divide
They may make their own growth factor
They may convey a growth factor’s signal without the presence of the growth factor
They may have an abnormal cell cycle control system 37

38. A normal cell is converted to a cancerous cell by a process called transformation
Cancer cells that are not eliminated by the immune system form tumors, masses of abnormal cells within otherwise normal tissue
If abnormal cells remain only at the original site, the lump is called a benign tumor
Malignant tumors invade surrounding tissues and can metastasize, exporting cancer cells to other parts of the body, where they may form additional tumors
© 2014 Pearson Education, Inc. 38

39. Radio Wave Continuation
Cancer
Cancer and Metastasis
Radio Wave Treatment
Radio Wave Continuation

40. Cancer benign tumor malignant tumor
1 Cancer cells slip of out their home tissue
2 The metastasizing cells
become attached to the wall
of a blood or lymph vessel.
They secrete digestive
enzymes onto it. Then they
cross the wall at the breach.
3 Cancer cells creep or
tumble along inside blood
vessels, then leave the
bloodstream the same way
they got in. They start new
tumors in new tissues.

41. Cancer

42. Cancer

43. Cancer