The Structure ; Function of DNA

I. How and Why Genes are Regulated? A. Gene Expression in Differentiated Cells 1. What does it mean to say that the cells in your body are differentiated?

It means that the cells in the body are specialized to do certain tasks with some genes in a cell turned off and some genes in the cell turned on.

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2. The great differences among cell types is due to the selective expression of its genes. Define gene expression.

Gene expression is the overall process by which genes information flows from genes to proteins that is for a genotype to a phenotype.

B. Gene Regulation in Prokaryotes 3.Why is gene regulation a simpler process in prokaryotes than multicellular eukaryotes? (2 reasons)

Because prokaryotes are single cells and do not require elaborate regulation of gene expression as multicellular eukaryotes and prokaryotes do not have cell specialization in multicellular eukaryotes.

4.Why would a bacterium able to regulate its genes have a selective advantage over one lacking this ability?

The regulation of its genes (turn on and off) allows bacteria cells to conserve resources and energy not having to make things from scratch in its environment.

C. Gene Regulation in Eukaryotic Cells

5. Explain what the following analogy means. Your cells use “DNA packing” in the same way we might pack up a box of unneeded items in the attic for long-term storage.

The analogy means that cells use DNA packing for the long-term inactivation of genes just like a storage unit.

6.What is X-chromosome inactivation?

When one of the X-chromosome in each somatic cell is highly compacted and is almost completely inactive.

7.The initiation of Transcription is the most important stage of gene regulation in eukaryotes.

8. True or false? Your cells will use most of their genes during their lifetime. False

9.Only the genes necessary for each cell’s specialized Structure and function will be transcribed.

10.Explain alternative RNA splicing.

A type of regulation at the RNA processing level where different mRNA molecules are produced from the same primary transcript depending on which RNA segments are treated as exons or introns.

11. How might the rate of mRNA breakdown in the cytoplasm be utilized as a means of gene regulation?

After they bind to complementary sequences in molecules they trigger a breakdown of their target mRNA and block translation.

12.Give an example of a post-translational method of gene regulation.

The cutting of the hormone insulin into to shorter chains to activate it.

13. Plant and animals are complex organisms having many different tissue types and organ systems. Gene expression needs to be regulated at both at the molecular and organismal level to maintain homeostasis (i.e., if you are getting low on oxygen, how does your brain “know” this and then coordinate various organs and tissues to correct the problem?) How can one part of the body control gene expression in another part of the body?

One part of the body can control gene expression in another by the use of cell to cell signaling.

14. Master control genes called homeotic genes regulate sets of other genes that determine what body parts will develop in what locations.

II. Cloning Plants ; Animals

1. Why is it easier to clone plants than animals? Because plants have less of a complex genetic makeup than an animal.

2. What is the difference between cloning and regeneration? Cloning is a copy of an organism while regeneration is the re-growth of an organism.

3. What sorts of health problems do cloned animals tend to have? Obesity, pneumonia, liver failure, and premature death

4. True or false? Reproductive cloning in mammals is 30-40% successful. False 5. Briefly describe how reproductive cloning is accomplished. The putting of the blastocyst into the uterus of a surrogate mother.

6. What is the difference between reproductive and therapeutic cloning?

Reproductive cloning is used to produce organisms while therapeutic are for stem cells.

7. What is the difference between totipotent and pluripotent cells?

Totipotency is the ability of all living cells potentially to regenerate whole new individuals eg cloning while Pluripotency is the potential of a cell to develop into more than one type of mature cell, depending on environment.

8. How are embryonic stem cells obtained? From the blastocysts of an embryo 9. Which type of stem cells have been used to successfully treat human patients? Umbilical cords stem cells were used to cure krabbes disease and leukemia 10. Where are adult stem cells normally obtained? (2 tissues) Bone marrow and heart muscle cells

III. The Genetic Basis of Cancer

1. a. Name two types of genes normally found in our DNA that play a role in the development of cancer.

Proto-oncogene , BRCA1, and carcinogens

b.How can the above genes contribute to cancer?

They mutate or change the structure of the cell to form cancer.

2. Give two reasons why cancer is more likely to occur as we age.

The longer we live the better chance there is for a cell to make a mistake while dividing and as we get older the higher the chance the cell has to be damaged by carcinogens and collect mutations.

3. What is the most deadly type of cancer? Lung cancer