Chapter Eleven
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 is methylation. Epigenetic changes 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. Neurons secrete neurotransmitters, melanocytes produce and release pigment molecules,
and fibroblasts secrete abundant collagen and elastin.
5. Oxygen level
6. Progenitor cells in the pancreas divide to give rise to daughter cells that differentiate as
either exocrine or endocrine cells.
7. A mutation in the promoter can alter rate and ease of transcription and thereby affect protein
levels.
8. Histones are proteins, so genes encode them. Yet histones control which genes are
transcribed, and under what conditions.
9. Patterns of acetyl, phosphate, and methyl groups binding.
10. Methyl groups bind to histones and DNA.
11. Chromatin remodeling silences transcription. MicroRNA blocks translation.
12. An algorithm is necessary because two patterns are at play: a microRNA may bind multiple,
different mRNAs, and a single mRNA may have many different microRNAs bind to it.
13. Bidirectional transcription, alternative splicing, alternative processing
14. Pre-mRNA transcripts that contain introns and exons are processed to produce mature
mRNA in a specific cell type. By regulating which exons are retained and spliced, exon
shuffling generates more than one mature mRNA and therefore different proteins.
15. Genes come in pieces. Genes can move. The same sequence of DNA can encode more
than one protein because of alternate splicing.
16. Introns
17. A third are only in primates, and many are transcribed only in the brain, the organ that most
distinguishes humans from other apes.
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without the prior written consent of McGraw-Hill Education.
ANSWERS TO APPLIED QUESTIONS
1. Insulin-like growth factor and growth hormone build muscle. EPO produces more red blood
cells, increasing oxygen-carrying capacity. VEGF and FGF improve blood supply by making
more capillaries.
2. Fetal hemoglobin could be made in a postnatal person.
3. The microRNA pattern could indicate patients for whom more aggressive initial therapy
would be beneficial.
4. Adds (acetylase)
5. Parts of the protein-encoding genes mix and match. The genes contain many large introns.
6. 3
7. Gene expression changes alter levels of the protein and not their amino acid sequences, as
mutations do.
ANSWERS TO WEB ACTIVITIES
1. Gene expression profiles can subtype a cancer and identify which drugs are likely to work,
and which are likely to produce severe adverse effects in individuals. Prognosis is also
possible.
2. a. mRNA types and levels b. The data can be compared to gene expression profiles of
sick people, such as those with cancers of the affected tissues.
3. This question refers to Table 11.1 in the 10th edition. Alpha-thalassemia undermethylates
chromatin. ICF syndrome undermethylates DNA repeats. Rett syndrome fails to remove
acetyls from histones on a gene (DLX5) expressed in the brain. Rubinstein-Taybi syndrome
adds acetyls to certain histones, causing inappropriate transcription of some genes.
FORENSICS FOCUS
1. Gene expression profiling of blowfly larva to give a more precise indication of age.
ANSWERS TO CASE STUDIES AND RESEARCH RESULTS
1. Different transcription factors activate different sets of genes.
2. TIGD7 function unknown. UQCRH cellular energetics. PSMA6 part of proteasome; protein
refolding. WDR12 exact function unknown but involved in cell cycle, signal transduction,
apoptosis. TFB2M is a transcription factor. USP15 is involved with ubiquitin; getting rid of
misfolded proteins.
b. Limitations: small sample sizes. Which other factors affected transcription?
Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution
without the prior written consent of McGraw-Hill Education.
3. The open configuration of chromatin may indicate exactly where oncogenes are being
overexpressed, so these areas might serve as targets for the development of new cancer
drugs.
Copyright © 2015 McGraw-Hill Education. All rights reserved. No reproduction or distribution
without the prior written consent of McGraw-Hill Education.