Chapter Eleven: How Genes are Controlled

Questions:

1. What are some disadvantages of cloning?
2. What does RNA interference accomplish?
3. What are homeotic genes?

Answers:

1. Cloning does not increase genetic diversity.  And cloned animals may face health problems related to abnormal gene regulation.  
2. It prevents expression of a gene by interfering with translation of its RNA product, involves binding of small, complementary RNAs to mRNA molecules and leads to degradation of mRNA or inhibition of translation.
3. Homeotic genes are master control genes that determine the anatomy of the body, specifying structures that will develop in each segment.

Key Terms:
Gene Expression- the overall process of information flow from genes to proteins.
Operon- a group of genes under coordinated control in bacteria. 
Repressor- can bind and block RNA polymerase action. 
Regulatory Gene- codes for a repressor protein.
Activators- enhance RNA polymerase binding to the promoter.
Transcription factors- promote RNA polymerase binding to the promoter.
Silencers-repressors that inhibit transcription.
Signal transduction pathway- a series of molecular changes that converts a signal at the cell's surface to a response within the cell.
Reproductive cloning- used to produce animals with desirable traits.
Adult stem cells- can produce many but not all types of cells.


Important Facts:

1. Eukaryotic chromosomes undergo multiple levels of folding and coiling, called DNA packing.  DNA packing can prevent transcription.  
2. Control of gene expression occurs with breakdown of mRNA, initiation of translation, protein activation, and protein breakdown.
3. Nuclear transplantation is the replacing of the nucleus of an egg or zygote with a nucleus from an adult somatic cell.
4. Cloned animals can show differences from their parent due to the variety of influences during development. 
5. Carcinogens are cancer-causing agents that damage DNA and promote cell division.

Relevant Video:
http://www.youtube.com/watch?v=FVuAwBGw_pQ

Diagram-