1. The Control of Gene Expression
Chapter 11
The Control of Gene Expression

2. To Clone or Not to Clone?
A clone is an individual created by asexual reproduction
And thus is genetically identical to a single parent

3. Cloning has many benefits But evokes just as many concerns
Cloning has many benefits
But evokes just as many concerns

4. Gene Regulation-the turning on and off of genes
11.1 Proteins interacting with DNA turn prokaryotic genes on or off in response to environmental changes.
Gene Regulation-the turning on and off of genes
Can help organisms respond to environmental changes.
Gene expression-the process by which genetic information flows from genes to proteins; from genotype to phenotype.

5. 11.2 Differentiation yields a variety of cell types, each expressing a different combination of genes
In multicellular eukaryotes
Cells become specialized as a zygote develops into a mature organism

6. Different types of cells
Different types of cells
Make different proteins because different combinations of genes are active in each type
Figure 11.2
Muscle cell
Pancreas cells
Blood cells

7. Cell division in culture
11.3 Differentiated cells may retain all of their genetic potential
Most differentiated cells
Retain a complete set of genes
Regeneration-the regrowth of lost body parts
Root of carrot plant
Single cell
Root cells cultured in nutrient medium
Cell division in culture
Figure 11.3
Plantlet
Adult Plant

8. Two cell populations in adult
11.5 In female mammals, one X chromosome is inactive in each cell
An extreme example of DNA packing in interphase cells
Is X chromosome inactivation in the cells of female mammals
Early embryo
Two cell populations in adult
Cell division and random X chromosome inactivation
Orange fur
X chromosomes
Active X
Inactive X
Inactive X
Allele for orange fur
Black fur
Active X
Allele for black fur
Figure 11.5

9. 11.10 Nuclear transplantation can be used to clone animals
ANIMAL CLONING
11.10 Nuclear transplantation can be used to clone animals
Nucleus from donor cell
Donor cell
Implant blastocyst in surrogate mother
Clone of donor is born
(reproductive cloning)
Remove nucleus from egg cell
Add somatic cell
from adult donor
Grow in culture to produce an
early embryo (blastocyst)
Remove embryonic stem cells from blastocyst and grow in culture
Induce stem cells to form specialized cells (therapeutic cloning)
Figure 11.10

10. CONNECTION
11.11 Reproductive cloning has valuable applications, but human reproductive cloning raises ethical issues
Reproductive cloning of nonhuman mammals
Is useful in research, agriculture, and medicine
Figure 11.11

11. Critics point out that there are many obstacles
Both practical and ethical, to human cloning

12. CONNECTION
11.12 Therapeutic cloning can produce stem cells with great medical potential
Like embryonic stem cells, adult stem cells
Can perpetuate themselves in culture and give rise to differentiated cells
Blood cells
Adult stem cells in bone
marrow
Nerve cells
Cultured embryonic stem cells
Heart muscle cells
Different culture conditions
Different types of differentiated cells
Figure 11.12

13. Unlike embryonic stem cells
Adult stem cells normally give rise to only a limited range of cell types

14. THE GENETIC BASIS OF CANCER
11.16 Cancer results from mutations in genes that control cell division
Cancer cells, which divide uncontrollably
Result from mutations in genes whose protein products affect the cell cycle

15. Proto-Oncogenes
A mutation can change a proto-oncogene (a normal gene that promotes cell division)
Into an oncogene, which causes cells to divide excessively
Proto-oncogene DNA
Mutation within the gene
Multiple copies of the gene
Gene moved to new DNA locus, under new controls
Oncogene
New promoter
Hyperactive growth- stimulating protein in normal amount
Normal growth- stimulating protein in excess
Normal growth- stimulating protein in excess
Figure 11.16A

16. Tumor-Suppressor Genes
Tumor-Suppressor Genes
Mutations that inactivate tumor suppressor genes
Have similar effects as oncogenes
Tumor-suppressor gene
Mutated tumor-suppressor gene
Normal growth- inhibiting protein
Defective, nonfunctioning protein
Cell division under control
Cell division not under control
Figure 11.16B

17. 11.18 Multiple genetic changes underlie the development of cancer
11.18 Multiple genetic changes underlie the development of cancer
Cancers result from a series of genetic changes in a cell lineage

18. Colon cancer Develops in a stepwise fashion
Colon cancer
Develops in a stepwise fashion
Colon wall 1 2 3
Cellular changes:
Increased cell division
Growth of polyp
Growth of malignant tumor (carcinoma)
DNA changes:
Oncogene activated
Tumor-suppressor gene inactivated
Second tumor- suppressor gene inactivated
Figure 11.18A

19. Accumulation of mutations Can lead to cancer
Accumulation of mutations
Can lead to cancer
Chromosomes 1 2 3 4
mutation
mutations
mutations
mutations
Normal cell
Malignant cell
Figure 11.18B

20. 11.20 Avoiding carcinogens can reduce the risk of cancer
CONNECTION
11.20 Avoiding carcinogens can reduce the risk of cancer
Reducing exposure to carcinogens (which induce cancer-causing mutations)
And making other lifestyle choices can help reduce cancer risk

21. Cancer in the United States
Cancer in the United States
Table 11.20