ANSWERS TO REVIEW QUESTIONS

1. Transcription and translation must be controlled so that the appropriate amounts of proteins are present for specific cell types.

2. Epigenetic changes are chemical modifications of DNA that alter gene expression but do not change the DNA base sequence. An example would be methylation. They may be passed on to daughter cells.

3. Epigenetic information determines how and when genes are accessed and transcribed. DNA encodes the information that specifies the sequence of amino acids in a protein.

4. Answers vary depending on cell types. One example would be: Neurons, Osteocytes and Melanocytes.

5. A mutation in the promoter can alter rate and ease of transcription and therefore affect protein levels.

6. Oxygen level

7. Progenitor cells in the pancreas divide to give rise to daughter cells that differentiate as either exocrine or endocrine cells.

8. Histones are proteins, so genes encode them. Yet histones control which genes are transcribed, and under what conditions.

9. Chromatin remodeling silences transcription. MicroRNA blocks translation.

10. Acetylation

11. They bind target mRNAs by complementary base pairing. They are cleaved from pri-miRNAs and processed into mature microRNAs.

12. Bidirectional transcription, alternative splicing, alternative processing

13. Pre-mRNA transcripts that contain introns and exons must be processed to produce mature mRNA for a specific cell type or function. By regulating which exons are retained and spliced, exon shuffling generates more than one mature mRNA and therefore different proteins.

14. Genes come in pieces. Genes can move. The same sequence of DNA can encode more than one protein because of alternate splicing.

15. Several answers are possible. Examples might be: introns interrupt genes. Exons from different genes can contribute to the same protein. An intron on one strand may be an exon on the other.

ANSWERS TO APPLIED QUESTIONS

1. Adds – i.e. acetylase

2. Parts of the protein-encoding genes mix and match. The genes contain many large introns.

3. Chromatin remodeling factors have been shown to affect transcription, chromosome stability, DNA repair, and cell cycle control. Because Chd1 is a DNAbinding protein involved in chromatin remodeling, mutations in Chd1 can interfere with the proper functioning of the chromosome in several ways leading to pleotropic affects.

4. 3

5. Mutation in the APP promoter increases transcription which causes amyloid beta peptide overexpression. In trisomy 21, gene triplication leads to the accumulation.

6. Individualized diagnosis and therapy through pharmacogenetics.

7. The promoter for the adjacent gene activates the aromatase gene.

8. Gene expression patterns and the alleles differ. The man has mutations in oncogenes or tumor suppressor genes and those that control blood pressure. The woman has wild type alleles of these genes.

9. Gene expression profiling of blowfly larva to give a more precise indication of age