1. CHAPTER 8 The Cellular Basis of Reproduction and Inheritance
Modules 8.1 – 8.3

2. Parents
Reproduction
Inheritance
Cell Cycle
Cell Division
Life cycle
Daughter

3. Parents
Asexual
Reproduction
Inheritance
Mitosis
Cell
Division
Cell Cycle
Sexual
Meiosis
Daughter

4. 8.1 Like begets like, more or less
Some organisms make exact copies of themselves, asexual reproduction

5. 8.2 Cells arise only from preexisting cells
All cells come from cells
Cellular reproduction is called cell division
Cell division allows an embryo to develop into an adult
It also ensures the continuity of life from one generation to the next

6. 8.3 Prokaryotes reproduce by binary fission
Prokaryotic cells divide asexually
These cells possess a single chromosome, containing genes
The chromosome is replicated
The cell then divides into two cells, a process called binary fission
Prokaryotic chromosomes
Figure 8.3B

7. Binary fission of a prokaryotic cell
Plasma membrane
Prokaryotic chromosome
Cell wall
Duplication of chromosome and separation of copies
Continued growth of the cell and movement of copies
Division into two cells
Figure 8.3A

8. THE EUKARYOTIC CELL CYCLE AND MITOSIS
8.4 The large, complex chromosomes of eukaryotes duplicate with each cell division
A eukaryotic cell has many more genes than a prokaryotic cell
The genes are grouped into multiple chromosomes, found in the nucleus
The chromosomes of this plant cell are stained dark purple
Figure 8.4A

9. Chromosome distribution to daughter cells
When the cell divides, the sister chromatids separate
Chromosome duplication
Two daughter cells are produced
Each has a complete and identical set of chromosomes
Sister chromatids
Centromere
Chromosome distribution to daughter cells
Figure 8.4C

10. 8.5 The cell cycle multiplies cells
The cell cycle consists of two major phases:
Interphase, where chromosomes duplicate and cell parts are made
The mitotic phase, when cell division occurs
Figure 8.5

11. 8.6 Cell division is a continuum of dynamic changes
Eukaryotic cell division consists of two stages:
Mitosis
Cytokinesis

12. Centrosomes (with centriole pairs) Early mitotic spindle Centrosome
INTERPHASE
PROPHASE
Centrosomes (with centriole pairs)
Early mitotic spindle
Centrosome
Fragments of nuclear envelope
Kinetochore
Chromatin
Centrosome
Spindle microtubules
Nucleolus
Nuclear envelope
Plasma membrane
Chromosome, consisting of two sister chromatids
Figure 8.6

13. TELOPHASE AND CYTOKINESIS
METAPHASE
ANAPHASE
TELOPHASE AND CYTOKINESIS
Cleavage furrow
Nucleolus forming
Metaphase plate
Nuclear envelope forming
Spindle
Daughter chromosomes
Figure 8.6 (continued)

14. 8.7 Cytokinesis differs for plant and animal cells
In animals, cytokinesis occurs by cleavage
This process pinches the cell apart
Cleavage furrow
Cleavage furrow
Contracting ring of microfilaments
Figure 8.7A
Daughter cells

15. In plants, a membranous cell plate splits the cell in two
Cell plate forming
Wall of parent cell
Daughter nucleus
In plants, a membranous cell plate splits the cell in two
Cell wall
New cell wall
Vesicles containing cell wall material
Cell plate
Daughter cells
Figure 8.7B

16. 8.9 Growth factors signal the cell cycle control system
Proteins within the cell control the cell cycle
Signals affecting critical checkpoints determine whether the cell will go through a complete cycle and divide
G1 checkpoint
Control system
M checkpoint
G2 checkpoint
Figure 8.9A

17. Cancer cells have abnormal cell cycles
8.10 Connection: Growing out of control, cancer cells produce malignant tumors
Cancer cells have abnormal cell cycles
They divide excessively and can form abnormal masses called tumors
Radiation and chemotherapy are effective as cancer treatments because they interfere with cell division

18. Malignant tumors can invade other tissues and may kill the organism
Lymph vessels
Tumor
Glandular tissue
Metastasis 1
A tumor grows from a single cancer cell. 2
Cancer cells invade neighboring tissue. 3
Cancer cells spread through lymph and blood vessels to other parts of the body.
Figure 8.10

19. Parents
Asexual
Reproduction
Inheritance
Mitosis
Cell
Division
Cell Cycle
Sexual
Meiosis
Daughter

20. 8.12 Chromosomes are matched in homologous pairs
MEIOSIS AND CROSSING OVER
8.12 Chromosomes are matched in homologous pairs
Somatic cells of each species contain a specific number of chromosomes
Human cells have 46, making up 23 pairs of homologous chromosomes
Chromosomes
Centromere
Sister chromatids
Figure 8.12

21. Multicellular diploid adults (2n = 46) Mitosis and development
The human life cycle
Haploid gametes (n = 23)
Egg cell
Sperm cell
MEIOSIS
FERTILIZATION
Diploid zygote (2n = 46)
Multicellular diploid adults (2n = 46)
Mitosis and development
Figure 8.13

22. MEIOSIS I: Homologous chromosomes separate
INTERPHASE
PROPHASE I
METAPHASE I
ANAPHASE I
Spindle attached to homologous chromosomes
Centrosomes (with centriole pairs)
Sites of crossing over
Metaphase plate
Sister chromatids remain attached
Spindle
Nuclear envelope
Chromatin
Sister chromatids
Tetrad
Centromere
Homologous chromosomes separate
Figure 8.14, part 1

23. MEIOSIS II: Sister chromatids separate
TELOPHASE I AND CYTOKINESIS
TELOPHASE II AND CYTOKINESIS
PROPHASE II
METAPHASE II
ANAPHASE II
Cleavage furrow
Sister chromatids separate
Haploid daughter cells forming
Figure 8.14, part 2

24. PARENT CELL (before chromosome replication) Site of crossing over
MITOSIS
MEIOSIS
PARENT CELL (before chromosome replication)
Site of crossing over
MEIOSIS I
PROPHASE
PROPHASE I
Tetrad formed by synapsis of
homologous chromosomes
Duplicated chromosome (two sister chromatids)
Chromosome replication
Chromosome replication
2n = 4
Chromosomes align at the metaphase plate
Tetrads align at the metaphase plate
METAPHASE
METAPHASE I
ANAPHASE I
TELOPHASE I
ANAPHASE TELOPHASE
Sister chromatids separate during anaphase
Homologous chromosomes separate during anaphase I; sister chromatids remain together
Haploid n = 2
Daughter cells of meiosis I 2n 2n
No further chromosomal replication; sister chromatids separate during anaphase II
MEIOSIS II
Daughter cells of mitosis n n n n
Daughter cells of meiosis II
Figure 8.15

25. Two equally probable arrangements of chromosomes at metaphase I
Meiosis produces genetic variations : Independent orientation of chromosomes
POSSIBILITY 1
POSSIBILITY 2
Two equally probable arrangements of chromosomes at metaphase I
Metaphase II
Gametes
Combination 1
Combination 2
Combination 3
Combination 4
Figure 8.16

26. C E C E C E c e c e c e Coat-color genes Eye-color genes Brown Black
White
Pink
Tetrad in parent cell (homologous pair of duplicated chromosomes)
Chromosomes of the four gametes
Figure 8.17A, B

27. Crossing over during prophase I of meiosis
Tetrad
Chaisma
Centromere
Figure 8.18A

28. How crossing over leads to genetic recombination
Coat-color genes
Eye-color genes
How crossing over leads to genetic recombination
Tetrad (homologous pair of chromosomes in synapsis) 1
Breakage of homologous chromatids 2
Joining of homologous chromatids
Chiasma
Separation of homologous chromosomes at anaphase I 3
Separation of chromatids at anaphase II and completion of meiosis 4
Parental type of chromosome
Recombinant chromosome
Recombinant chromosome
Parental type of chromosome
Figure 8.18B
Gametes of four genetic types

29. ALTERATIONS OF CHROMOSOME NUMBER AND STRUCTURE
8.19 A karyotype is a photographic inventory of an individual’s chromosomes
To study human chromosomes microscopically, researchers stain and display them as a karyotype
A karyotype usually shows 22 pairs of autosomes and one pair of sex chromosomes

30. Preparation of a karyotype
Fixative
Packed red
And white
blood cells
Hypotonic solution
Blood culture
Stain
White
Blood cells
Centrifuge 3 2 1
Fluid
Centromere
Sister chromatids
Pair of homologous chromosomes 4 5
Figure 8.19

31. 8.20 Connection: An extra copy of chromosome 21 causes Down syndrome
This karyotype shows three number 21 chromosomes
An extra copy of chromosome 21 causes Down syndrome
Figure 8.20A, B

32. The chance of having a Down syndrome child goes up with maternal age
Figure 8.20C

33. 8.21 Accidents during meiosis can alter chromosome number
Abnormal chromosome count is a result of nondisjunction
Either homologous pairs fail to separate during meiosis I
Nondisjunction in meiosis I
Normal meiosis II
Gametes
n + 1
n + 1
n – 1
n – 1
Number of chromosomes
Figure 8.21A

34. Or sister chromatids fail to separate during meiosis II
Normal meiosis I
Nondisjunction in meiosis II
Gametes
n + 1
n – 1 n n
Number of chromosomes
Figure 8.21B

35. Fertilization after nondisjunction in the mother results in a zygote with an extra chromosome
Egg cell
n + 1
Zygote 2n + 1
Sperm cell
n (normal)
Figure 8.21C

36. 8.22 Connection: Abnormal numbers of sex chromosomes do not usually affect survival
Nondisjunction can also produce gametes with extra or missing sex chromosomes
Unusual numbers of sex chromosomes upset the genetic balance less than an unusual number of autosomes

37. Table 8.22

38. A man with Klinefelter syndrome has an extra X chromosome
Poor beard growth
Breast development
Under- developed testes
Figure 8.22A

39. A woman with Turner syndrome lacks an X chromosome
Characteristic facial features
Web of skin
Constriction of aorta
Poor breast development
Under- developed
ovaries
Figure 8.22B

40. 8.23 Connection: Alterations of chromosome structure can cause birth defects and cancer
Chromosome breakage can lead to rearrangements that can produce genetic disorders or cancer
Four types of rearrangement are deletion, duplication, inversion, and translocation

41. Homologous chromosomes
Deletion
Duplication
Homologous chromosomes
Inversion
Reciprocal translocation
Nonhomologous chromosomes
Figure 8.23A, B

42. Chromosomal changes in a somatic cell can cause cancer
A chromosomal translocation in the bone marrow is associated with chronic myelogenous leukemia
Chromosome 9
Reciprocal translocation
Chromosome 22
“Philadelphia chromosome”
Activated cancer-causing gene
Figure 8.23C

43. Parents
Asexual
Reproduction
Inheritance
Mitosis
Cell
Division
Cell Cycle
Sexual
Meiosis
Daughter