Problem 12 - Campbell Biology

Question

\begin{equation} \begin{array}{l}{\text { The frog on the left }} \\ {\text { was injected with }} \\ {\text { MSH, causing a change }} \\ {\text { in skin color within }} \\ {\text { minutes due to a }} \\ {\text { rapid redistribution of }}\end{array} \end{equation}\begin{equation} \begin{array}{l}{\text { pigment granules in }} \\ {\text { specialized skin cells. }} \\ {\text { Using what you know }} \\ {\text { about neuroendocrine }} \\ {\text { signaling, explain }} \\ {\text { how a frog could use }} \\ {\text { MSH to match its skin }} \\ {\text { coloration to that of its }} \\ {\text { surroundings. }}\end{array} \end{equation}

Step-by-Step Solution

Answer

MSH causes pigment granules to redistribute in the frog’s skin, enabling it to change color and match its surroundings via neuroendocrine signaling.

Step 1 - Understanding MSH

MSH stands for Melanocyte-Stimulating Hormone. It is a hormone involved in the process of pigmentation in animals. MSH stimulates the production and release of melanin by melanocytes in the skin and hair.

Step 2 - Understanding Neuroendocrine Signaling

Neuroendocrine signaling involves the interaction between the nervous system and the endocrine system. This allows for the regulation of many physiological processes through the release of hormones that are then distributed across the body.

Step 3 - Pigment Granules Distribution

In the context of the frog, MSH causes pigment granules within melanophores to rapidly redistribute. This redistribution can increase the dispersion of melanin, causing the skin to darken.

Step 4 - Matching Surroundings

A frog releases MSH in response to environmental cues received through sensory organs. For example, when a frog is in a darker environment, MSH is released, causing pigment granules to disperse and darken its skin, allowing it to blend with its surroundings to avoid predators.

Key Concepts

Melanocyte-Stimulating Hormone (MSH)

Melanocyte-Stimulating Hormone (MSH) plays a crucial role in pigmentation. It is responsible for stimulating melanocytes, the cells that produce melanin, the pigment that determines color in skin and hair. When MSH binds to receptors on melanocytes, it activates a signal transduction pathway that increases the production of melanin. This enhancement in melanin production leads to a noticeable darkening in the skin or hair. In frogs, the release of MSH can quickly lead to a change in skin color in response to various environmental factors.

Pigment Granules Redistribution

Pigment granules, or melanosomes, are specialized subcellular structures that store melanin. The redistribution of these granules within skin cells is key to color change. In the presence of MSH, pigment granules in frog melanophores (skin cells containing melanin) disperse throughout the cell, leading to a darker skin tone. This has two major benefits for the frog: helping it blend into its environment to avoid predators and regulating body temperature by absorbing more or less sunlight.

Environmental Adaptation in Frogs

Frogs are excellent at adapting to their environments. This adaptability is partly due to their ability to change skin color using MSH. When environmental signals such as changes in light intensity or background color are detected, the frog's sensory system sends signals to release MSH. This hormone then causes pigment granules to redistribute in the melanophores, allowing the frog's skin to darken or lighten. This rapid adaptation helps them avoid predators and regulate their body temperature, which is vital for their survival in varied habitats.