Concept explainers
Genes that are expressed at all times at relatively constant levels are known as _____ genes.
- inducible
- repressible
- positive
- constitutive
- protein-encoding
Introduction:
Genes are functional units of DNA. Genes carry the hereditary information and pass it from one generation to the next. The availability of genes depends on the location and environment of the cell.
Answer to Problem 1TY
The correct answer is constitutive genes.
Explanation of Solution
Explanation/justification for the correct answer:
Constitutive genes are transcribed continuously in the cell at the constant level like the housekeeping genes transcribe important proteins (actin, GAPDH). These genes are required by all the cells for proper functioning and maintenance of cell.
The explanation for the incorrect answer:
Option A is incorrect.
Inducible genes are expressed in the cell when inducer binds to co-repressor. Inducer presence depends upon the concentration of certain substances in the cell. Thus, this is not the correct answer.
Option B is incorrect.
Repressible genes are expressed only in the presence of co-repressor. Thus, these genes are activated during specific times in the cell. Hence, the option is correct.
Option C is incorrect.
Genes which positively affect the transcription of genes are known as positive genes. Positive genes are not required by each cell. Thus, the option is not correct.
Option E is incorrect.
Protein coding is the process in which the DNA sequence is transcribed into a stretch of a polypeptide. The polypeptide produced through the process may or may not be continuously produced in the cell. Thus, it is incorrect.
The correct answer is d.
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Chapter 12 Solutions
Principles of Biology
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