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# 7.4: Regulation of Gene Expression

Difficulty Level: At Grade Created by: CK-12

## Lesson 7.4: True or False

Name___________________ Class______________ Date________

Write true if the statement is true or false if the statement is false.

_____ 1. In your body, different types of cells have different genes.

_____ 2. Using a gene to make a protein is called protein expression.

_____ 3. A regulatory element is located on the DNA.

_____ 4. An operon is a region of prokaryotic DNA.

_____ 5. lacX, lacY, lacZ, and lacA are genes for the four proteins needed to digest lactose.

_____ 6. Essentially, regulatory proteins must turn “on” certain genes in particular cells.

_____ 7. In prokaryotic cells, RNA polymerase binds to the operator.

_____ 8. Repressors promote transcription by enhancing the interaction of RNA polymerase with the promoter.

_____ 9. The ATAT box is a regulatory element that is part of the promoter of most eukaryotic genes.

_____ 10. Because of a mutation, it is possible for a fly to have legs growing out of its head.

_____ 11. Mutations in some regulatory genes can cause cancer.

_____ 12. In eukaryotic gene regulation, regulatory proteins must bind to the regulatory elements before RNA polymerase binds to the promoter.

_____ 13. In the lac operon, when lactose is absent, the repressor protein does not bind to the operator.

_____ 14. Homeobox genes code for regulatory proteins that switch on whole series of major developmental genes.

_____ 15. In your body, different types of cells use different genes.

Name___________________ Class______________ Date________

Read these passages from the text and answer the questions that follow.

Eukaryotic Gene Regulation

In eukaryotic cells, the start of transcription is one of the most complicated parts of gene regulation. There may be many regulatory proteins and regulatory elements involved. Regulation may also involve enhancers. Enhancers are distant regions of DNA that can loop back to interact with a gene’s promoter.

The TATA Box

Different types of cells have unique patterns of regulatory elements that result in only the necessary genes being transcribed. That’s why a skin cell and nerve cell, for example, are so different from each other. However, some patterns of regulatory elements are common to all genes, regardless of the cells in which they occur. An example is the TATA box. This is a regulatory element that is part of the promoter of most eukaryotic genes. A number of regulatory proteins bind to the TATA box, forming a multi-protein complex. It is only when all of the appropriate proteins are bound to the TATA box that RNA polymerase recognizes the complex and binds to the promoter. Once RNA polymerase binds, transcription begins.

Regulation During Development

The regulation of gene expression is extremely important during the development of an organism. Regulatory proteins must turn on certain genes in particular cells at just the right time so the organism develops normal organs and organ systems. Homeobox genes are an example of genes that regulate development. They code for regulatory proteins that switch on whole series of major developmental genes. In insects, homeobox genes called hox genes ensure that body parts such as limbs develop in the correct place.

Questions

1. List three factors involved in eukaryotic gene regulation.

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2. Describe the TATA box and its role.

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3. Where does RNA polymerase bind to the DNA? What happens next?

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4. What is a homeobox gene?

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5. What is an enhancer?

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## Lesson 7.4: Multiple Choice

Name___________________ Class______________ Date________

Circle the letter of the correct choice.

1. Using a gene to make a protein is called
1. protein expression.
2. gene expression.
3. gene regulation.
4. protein synthesis.
2. Gene expression is regulated
1. to ensure that all cells make the same proteins.
2. to ensure that the correct proteins are made from the right genes.
3. to ensure that the correct proteins are made in the cells in which they are needed.
4. to ensure that all cells only use some genes.
3. Which of the following statements concerning the lac operon is correct?
1. When lactose is present, the repressor protein binds to the operator.
2. When lactose is absent, a repressor protein binds to the operator.
3. When lactose is absent, a repressor protein binds to the promoter.
4. When lactose is present, the repressor protein binds to the promoter.
4. Gene regulation during development involves
1. homeobox genes.
2. proto-oncogenes and tumor-suppressor genes.
3. the lac operon.
4. all of the above
5. Which three factors are involved in eukaryotic gene regulation?
1. regulatory proteins, regulatory elements, and activators
2. regulatory proteins, operator, and promoter
3. regulatory proteins, regulatory elements, and RNA polymerase
4. regulatory proteins, regulatory elements, and enhancers
6. Which of the following statements is correct? (1) Activators promote transcription by enhancing the interaction of RNA polymerase with the promoter. (2) Repressors promote transcription by enhancing the progress of RNA polymerase along the DNA strand. (3) Repressors prevent transcription by impeding the progress of RNA polymerase along the DNA strand. (4) Activators prevent transcription by impeding the interaction of RNA polymerase with the promoter.
1. 1 and 3
2. 2 and 4
3. 1 only
4. All 4 statements are correct.
7. Which statement best describes the TATA box?
1. The TATA box is a regulatory element that is part of the promoter of most prokaryotic genes.
2. The TATA box is a regulatory element that is part of the promoter of most eukaryotic genes.
3. The TATA box is a regulatory protein that binds to the promoter of most eukaryotic genes.
4. The TATA box is a regulatory protein that binds to the promoter of most prokaryotic genes.
8. Which of the following statements is correct?
1. Regulatory proteins bind to regulatory elements, which are located near promoters.
2. Regulatory elements bind to regulatory proteins, which are located near promoters.
3. Regulatory proteins bind to regulatory elements, which are also known as operons.
4. Regulatory proteins bind to regulatory elements, which are located near enahncers.

## Lesson 7.4: Vocabulary I

Name___________________ Class______________ Date________

Match the vocabulary word with the proper definition.

Definitions

_____ 1. using a gene to make a protein

_____ 2. regulatory region of DNA located near the promoter

_____ 3. a region of prokaryotic DNA that consists of one or more genes that encode the proteins needed for a specific function and their regulatory regions

_____ 4. when inactivated leads to tumor formation and cancer

_____ 5. enzyme that transcribes DNA to mRNA

_____ 6. code for regulatory proteins that switch on whole series of major developmental genes

_____ 7. protein that binds to regulatory region on DNA

_____ 8. a regulatory element that is part of the promoter of most eukaryotic genes

_____ 9. promotes transcription by enhancing the interaction of RNA polymerase with the promoter.

_____ 10. region of a gene where RNA polymerase binds

_____ 11. gene for a regulatory protein that controls the cell cycle

_____ 12. consists of a promoter, an operator, and three genes that encode the enzymes needed to digest lactose

Terms

a. activator

b. gene expression

c. homeobox genes

d. lac operon

e. operon

f. promoter

g. proto-oncogene

h. regulatory element

i. regulatory protein

j. RNA polymerase

k. TATA box

l. tumor-suppressor gene

## Lesson 7.4: Vocabulary II

Name___________________ Class______________ Date________

Fill in the blank with the appropriate term.

1. The ____________ is a region of an operon where regulatory proteins bind.

2. Transcription is partly controlled by ____________ proteins.

3. Using a gene to make a protein is called ____________ expression.

4. RNA ____________ is the enzyme that transcribes DNA to mRNA.

5. The ____________ box is a regulatory element that is part of the promoter of most eukaryotic genes.

6. Regulatory proteins bind to regions of DNA, called regulatory ____________.

7. Gene expression is regulated to ensure that the correct ____________ are made.

8. Mutations in tumor-suppressor genes can cause ____________.

9. Homeobox genes regulate ____________.

10. Activators ____________ transcription.

11. Repressors ____________ transcription.

12. An ____________ is a region of DNA that consists of one or more genes that encode the proteins needed for a specific function.

## Lesson 7.4: Critical Writing

Name___________________ Class______________ Date________

Thoroughly answer the question below. Use appropriate academic vocabulary and clear and complete sentences.

Describe gene regulation in the lac operon.

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Date Created:
Feb 23, 2012