1. Chapter 8 Cellular Reproduction: Cells from Cells
General Biology
CM Lamberty

2. Biology and Society Rain Forest Rescue Pollination of near extinction
Endangered species of plants that normally reproduce sexually can by propagated by asexual reproduction.
Cell division is at the heart of organismal reproduction, whether by sexual or asexual means

3. Figure 8.00a

4. What Cellular Reproduction Accomplishes
When a cell undergoes reproduction, or cell division,
Before a parent cell splits into two
During cell division, each daughter cell receives one set of chromosomes.

5. FUNCTIONS OF CELL DIVISION
Cell Replacement
Growth via Cell Division
Colorized TEM LM
Human kidney cell
Early human embryo
Figure 8.1a

6. FUNCTIONS OF CELL DIVISION Asexual ReproductionLM
Amoeba
Sea stars
African Violet
Figure 8.1b

7. What Cellular Reproduction Accomplishes
In asexual reproduction:
Some multicellular organisms, such as sea stars, can grow new individuals from fragmented pieces.
Growing a new plant from a clipping is another example of asexual reproduction.
In asexual reproduction,
Mitosis is the type of cell division responsible for:
Sexual reproduction requires fertilization of an egg by a sperm using a special type of cell division called meisois

8. Cell Cycle and Mitosis In a eukaryotic cell:
Most genes are located on chromosomes in the cell nucleus
A few genes are found in DNA in mitochondria and chloroplasts

9. Eukaryotic Chromosomes
Each eukaryotic chromosome contains one very long DNA molecule, typically bearing 1000s of genes
The number of chromosomes in a eukaryotic cell depends on the species

10. Number of chromosomes in body cells Species Indian muntjac deer 6
Koala 16
Opossum 22
Giraffe 30
Mouse 40
Human 46
Duck-billed platypus 54
Buffalo 60
Dog 78
Red viscacha rat
102
Figure 8.2

11. Eukaryotic Chromosomes
Are made of chromatin, a combination of DNA and protein molecules
Are not visible in a cell until cell divisions occurs
Chromosomes

12. Eukaryotic Chromosomes
THE DNA in a cell is packed into an elaborate, multilevel system of coiling and folding

13. DNA double helix Histones “Beads on a string” Nucleosome
TEM
Nucleosome
Tight helical fiber
Looped domains
Duplicated chromosomes
(sister chromatids)
TEM
Centromere
Figure 8.4

14. Eukaryotic Chromosomes
Before a cell divides, it duplicates all of its chromosomes, resulting
Sister chromatids are joined together
When the cell divides,
Once separated, each chromatid is

15. Chromosome duplication Sister chromatids Chromosome distribution to
daughter cells
Figure 8.5

16. The Cell Cycle A cell cycle is the orderly sequence of events
The cell cycle consists of two district phases:
Most of the cell cycle is spent in interphase
During interphase, a cell:

18. The Cell Cycle
The mitotic (M) phase includes two overlapping processes:
Mitosis, in which the nucleus and its contents divide evenly into two daughter nuclei
Cytokinesis, in which the cytoplasm is divided in two

19. Mitosis and Cytokinesis
During mitosis the mitotic spindle,
Spindle microtubules grow from
Mitosis consists of four distinct phases:

20. (with centriole pairs) Early mitotic spindle Fragments of
INTERPHASE
PROPHASE
Centrosomes
(with centriole pairs)
Early mitotic
spindle
Fragments of
nuclear envelope
Centrosome
Chromatin
Centromere
Nuclear
envelope
Plasma
membrane
Chromosome, consisting
of two sister chromatids
Spindle
microtubules LM
Figure 8.7.a

21. Nuclear envelope forming Cleavage furrow Spindle Daughter chromosomes
METAPHASE
ANAPHASE
TELOPHASE AND CYTOKINESIS
Nuclear
envelope
forming
Cleavage
furrow
Spindle
Daughter
chromosomes
Figure 8.7b

22. Mitosis and Cytokinesis
Cytokinesis typically:

25. Cancer Cells: growing out of control
Normal plant and animal cells have a cell cycle control system that consists of specialized proteins, which send “stop” and “go-ahead” signals at certain key points during the cell cycle.
What is cancer?
Cancer cells can form tumors
The spread of cancer cells beyond their original site of origin is
Malignant tumors can
A person with a malignant tumor is said to have cancer

26. Cancer Cells: growing out of control

27. Cancer Treatment
Cancer treatment can involve:

28. Cancer Prevention and Survival
Certain behaviors can decrease the risk of cancer:

29. Meiosis, the Basis of Sexual Reproduction
Uses meiosis
Uses fertilization
Produces offspring that contain a unique combination of genes from the parents.

30. Homologous Chromosomes
Different individuals of a single
A human somatic cell
A karyotype is an image
Homologous chromosomes are
Humans have:

32. Gametes and the Life Cycle of Sexual Organisms
The life cycle of a multicellular organism is the sequence of stages
Humans are diploid organisms in which
In humans a haploid sperm fuses with a haploid egg during
Sexual life cycles involve an alternation
Meiosis produces

37. The Process of Meiosis
In meiosis

40. Review: Comparing Mitosis and Meiosis
In mitosis and meiosis, the chromosomes duplicate only once, during the preceding interphase.
The number of cell divisions varies:
All the events unique to meiosis occur during meiosis I

42. The Origin of Genetic Variation
Offspring of sexual reproduction
Independent Assortment of chromosomes
When aligned during metaphase I of meiosis,
Every chromosome pair orients
For any species the to total number of chromosome combinations that can appear in the gametes due to independent assortment is
2n where n is the haploid number

46. Random Fertilization
A human egg cell is fertilized randomly by one sperm,

47. Crossing Over
In crossing over:
Genetic recombination,

53. When Meiosis goes Awry What happens when errors occur in meiosis?
How Accidents during Meiosis can alter chromosomes
In nondisjunction,
Nondisjunction can occur
If nondisjunction occurs, and a normal sperm fertilizes an egg with an extra chromosome,
If the organism survives,

57. When Meiosis goes Awry

59. Down Syndrome: An Extra Chromosome 21
Is also called trisomy 21
Is a condition in which an individual has an extra chromosome 21
Affects about one out of every 700 children

60. Down Syndrome: An Extra Chromosome 21
The incidence of Down Syndrome increases with the age of the mother.

61. Abnormal Numbers of Sex Chromosomes
Nondisjunction can also affect the sex chromosomes.

62. Evolution Connection: The Advantage of Sex
Asexual reproduction conveys an evolutionary advantage when plants are
Sexual reproduction may convey an evolutionary advantage by: