Problem 7 - Campbell Biology

Question

Application/Analysis Cells transplanted from the neural tube of a frog embryo to the ventral part of another embryo develop into nervous system tissues. This result indicates that the transplanted cells were (A) totipotent. \(\quad\) (C) differentiated. (B) determined. \(\quad\) (D) mesenchymal.

Step-by-Step Solution

Answer

B) determined

Step 1: Understand the key concept

Identify what it means for cells to develop into nervous system tissues. This implies the cells have a specific developmental fate.

Step 2: Define the terms

Totipotent cells can develop into any cell type. Differentiated cells have already become a specific cell type. Mesenchymal cells are often involved in forming structures like muscle and bone. Determined cells have a specific fate, but may not have yet shown outward signs of differentiation.

Step 3: Connect the concept to the terms

Since the transplanted cells develop into nervous system tissues regardless of their new environment, they must have been committed to that fate. This is indicative of determination.

Step 4: Eliminate incorrect options

The result does not indicate the cells are totipotent (since they do not develop into any cell type), differentiated (since they are not in their final form yet), or mesenchymal (which relates more to other tissues).

Step 5: Choose the correct answer

Given the analysis, the correct term is determined.

Key Concepts

Cell Fate

When we talk about cell fate, we are discussing what a cell is destined to become. Early in development, cells go through a process where they become committed to develop in a certain way. Cell fate becomes progressively restricted as development proceeds. Initially, cells have the potential to become many different types. As they receive signals and interact with their environment, they start following a more defined path.

Totipotent Cells

Totipotent cells are the ultimate all-rounders in early development. These are cells that have the potential to develop into any cell type within an organism. This includes all the various specialized cells of the body as well as the extraembryonic tissues like the placenta. This totipotent capability is usually limited to the very early stages of development. For example, in humans, a fertilized egg and the cells from the first few divisions are totipotent. They can form any type of cell needed for complete organismal development.

Differentiation

Differentiation is the process through which cells become specialized. After a cell's fate has been determined, it undergoes a series of changes to acquire the structures and functions characteristic of its specific type. This is a crucial part of development. Various factors including genetic signals and environmental conditions guide this process. For instance, a cell from the neural tube knows to become a nerve cell while another might become a muscle cell. The specific set of instructions a cell follows decides its ultimate form and function.

Mesenchymal Cells

Mesenchymal cells have a particular role in the body. These cells are multipotent stromal cells that can differentiate into a variety of cell types such as bone cells (osteoblasts), cartilage cells (chondrocytes), muscle cells (myocytes), and fat cells (adipocytes). They are usually found in the connective tissues. Mesenchymal cells play a key role in developing tissues like muscle, bone, and tendons but are not typically involved in the nervous system. This makes them quite distinct from cells that form neural tissues.