Question

What is a hormone-response element? a. a receptor for a steroid hormone b. a receptor for a polypeptide hormone c. a segment of DNA where a hormone-receptor complex binds d. an enzyme that is activated in response to hormone binding and produces a second messenger

Short answer

c. a segment of DNA where a hormone-receptor complex binds.

Step-by-step solution

Define hormone-response element:

A hormone-response element is a specific sequence of DNA that can be recognized and bound by hormone-receptor complexes. These elements are typically located in the regulatory regions of target genes, and their binding by hormone-receptor complexes leads to the activation or repression of those genes. Now, let's analyze each of the given options:

Option A:

A receptor for a steroid hormone. This option is incorrect because it describes the hormone receptor and not the hormone-response element itself.

Option B:

A receptor for a polypeptide hormone. Similar to option A, this option is also incorrect because it describes a hormone receptor rather than the hormone-response element.

Option C:

A segment of DNA where a hormone-receptor complex binds. This option correctly describes a hormone-response element, as previously defined.

Option D:

An enzyme that is activated in response to hormone binding and produces a second messenger. This option is incorrect because it describes a secondary process related to hormone signaling, but does not define the hormone-response element. So, based on our analysis, the correct answer is:

Answer:

c. a segment of DNA where a hormone-receptor complex binds.

Key concepts

Gene Regulation

Gene regulation refers to the complex control of gene expression in a cell’s environment. It is a crucial process that determines when and where specific genes are turned on or off. This regulation ensures that the right genes are expressed at the right times, enabling cells to respond to external signals, such as hormones.
One way gene regulation occurs is through hormone-response elements found in DNA. These elements act like switches. By allowing hormone-receptor complexes to bind, they help control the activation or repression of target genes.
Understanding gene regulation is essential in fields such as biotechnology and medicine. It helps scientists comprehend how various factors influence gene expression, leading to advancements in disease treatments and genetic engineering.

DNA Binding

DNA binding involves specific proteins interacting with DNA sequences to regulate genetic activity. Some of the most significant proteins involved in this process are transcription factors and hormone-receptor complexes.
These proteins recognize particular sequences in DNA, like hormone-response elements, and bind to them. This binding is critical because it can either stimulate or repress the transcription of genes.

• Transcription factors are proteins that help turn specific genes on or off by binding to nearby DNA.
• Hormone-receptor complexes, often involved in the body's response to signaling molecules, bind to DNA to modulate gene activity, leading to physiological changes.

By understanding how DNA-binding proteins work, researchers can manipulate gene expression, opening doors to numerous scientific advancements.

Hormone-Receptor Complex

A hormone-receptor complex forms when a specific hormone binds to its receptor. This complex plays a vital role in signaling cascades within cells, directly influencing gene regulation.
Once formed, the complex travels through the cell and binds to hormone-response elements in the DNA. This binding activates or represses target genes depending on the hormone and cell type involved.

• Steroid hormones, for instance, diffuse through cell membranes to directly bind and form complexes with intracellular receptors.
• These complexes can then influence transcription by attaching to hormone-response elements on the DNA.

The hormone-receptor complex’s ability to affect gene expression is fundamental to processes like metabolism, development, and immune responses.