Question 1

What is the term for the phenomenon in which a gene plays a role in the development of several different, apparently unrelated functions?

Accepted Answer

Pleiotropy is the term used to describe the phenomenon in which a gene plays a role in the development of several different, apparently unrelated functions. This is commonly observed in genetics where a single gene can have multiple effects on an organism's phenotype. Redundancy refers to the duplication of genes with a similar function, multipotency refers to the ability of stem cells to differentiate into multiple cell types, and neurogenesis refers to the formation of new neurons in the brain. None of these terms specifically describe the phenomenon of a gene affecting multiple unrelated functions.

Question 2

Because noggin, chordin, and follistatin all play a role in neural plate differentiation, there is _______ of gene effects.

Accepted Answer

The fact that multiple genes (noggin, chordin, and follistatin) are involved in the same neural plate differentiation process suggests redundancy, as multiple pathways are able to accomplish the same outcome.

Question 3

The tangled threads of chromosomes that are in the process of separating are called

Accepted Answer

The process of separating chromosomes during cell division is called mitosis. The tangled threads of chromosomes that are visible during this process are called mitotic figures. Therefore, choice B is the best answer. Choices A, C, and D are not related to this process.

Question 4

In neural tube development, a neuroblast may divide _______ to produce two neuroblasts.

Accepted Answer

In neural tube development, a neuroblast can divide symmetrically to produce two neuroblasts, ensuring the expansion of the neuroblast population before differentiation into neurons or glial cells.

Question 5

In the developing neural tube, mitosis occurs almost exclusively near the

Accepted Answer

Mitosis in the developing neural tube primarily occurs in the ventricular zone, which is the region of the neural tube closest to the central canal where neural stem cells divide and differentiate into various types of neurons and glial cells. The meninges and pia mater are membranes that surround and protect the brain and spinal cord, but they do not play a role in cell division in the neural tube. Rhombomeres are transverse segments of the developing hindbrain, and while they are important for patterning and differentiation of the neural tube, they do not directly participate in cell division.

Question 6

Astrocytes can be distinguished from neurons because only astrocytes express

Accepted Answer

Glia fibrillary acid protein (GFAP) is a specific protein expressed by astrocytes, while neurons do not express this protein. This allows astrocytes to be distinguished from neurons. The other options listed are not specific to astrocytes and can be found in other cell types as well.

Question 7

In the developing cerebral cortex, the _______ is the layer of postmitotic cells that expands to form cortical layers II-IV.

Accepted Answer

The cortical plate is the layer of postmitotic cells that expands to form cortical layers II-IV in the developing cerebral cortex. The molecular layer, ventricular zone, and intermediate zone are other important layers in the development of the cerebral cortex, but they do not expand to form cortical layers II-IV.

Question 8

In the cerebral cortex, the layer of cells that populate the region just above, but not lining, the ventricular surface is referred to as the

Accepted Answer

The subventricular zone is the layer of cells located just above the ventricular zone in the developing cerebral cortex.

Question 9

In the cerebral cortex, how does cell division in the ventricular zone differ from that in the subventricular zone?

Accepted Answer

The answer of In the cerebral cortex, how does cell...

Question 10

Which molecule, used to determine the birthdate of a cell, is especially useful because immunohistochemistry can be applied to identify it safely and efficiently?

Accepted Answer

BrDU (Bromodeoxyuridine) is a synthetic nucleoside analog of thymidine that is commonly used to label newly synthesized DNA in proliferating cells. It can be incorporated into DNA during S-phase and its presence can be detected by immunohistochemistry. Therefore, BrDU is useful for determining the birthdate of a cell, and it can be identified safely and efficiently with immunohistochemistry. Thymidine is also used as a nucleoside analog to label newly synthesized DNA, but it cannot be detected with immunohistochemistry. Fos (a protein) and GFAP (a glial cell-specific protein) are not molecules used to determine the birthdate of a cell.

Question 11

Immunohistochemistry is the process of using _______ to visualize a particular molecule.

Accepted Answer

Immunohistochemistry (IHC) involves using antibodies to bind to specific antigens in tissue samples, allowing for visualization of the targeted molecule. Epitopes are specific regions on the antigen that the antibody binds to. Autoradiography involves the use of radioactive materials to visualize molecules and thymidine is a nucleoside used in DNA synthesis, not for visualization in IHC.

Question 12

In the developing neural tube, migrating postmitotic cells shinny outward on _______ toward their destination.

Accepted Answer

Migrating postmitotic cells in the developing neural tube use radial glia as a scaffold to move towards their destination.

Question 13

Neurons that develop from the ganglionic eminences migrate _______ along glia and become _______.

Accepted Answer

Neurons that develop from the ganglionic eminences migrate tangentially along glia and become basal ganglia.

Question 14

Researchers injected a DNA marker into rhesus monkeys at different prenatal stages of development, let them grow up, and then looked at the neocortex neurons. They found that, depending on when during development they injected their DNA marker, the labeled neurons would be located in a different layer of the cortex with the most recently labeled ones located in layer II. What do these results suggest?

Accepted Answer

The results suggest that cortical neurons settle in an inside-out manner, with neurons first populating layer VI and then migrating towards the outer layers, with the most recently labeled neurons located in layer II. This is consistent with the current understanding of cortical development in mammals.

Question 15

In adults, newly born interneurons in the olfactory bulb arise from cells in the

Accepted Answer

Newly born interneurons in the olfactory bulb are produced from neural stem cells located in the subventricular zone adjacent to the lateral ventricles in the brain.

Question 16

If BrDU-stained neurons are found in the dentate gyrus, from where did they originate?

Accepted Answer

BrDU is commonly used to label dividing cells. The dentate gyrus is part of the hippocampus and is known to have a high rate of neurogenesis, the generation of new neurons. The subgranular zone is the location of the neural stem cells that give rise to new neurons in the dentate gyrus. Therefore, the BrDU-stained neurons likely originated from the subgranular zone.

Question 17

In neural crest cell migration, cells that stop just short of the somites will develop into neurons of the

Accepted Answer

Neural crest cells that stop just short of the somites will develop into neurons of the dorsal root ganglia.

Question 18

Neural crest cells from the thoracic and lumbar regions will form the

Accepted Answer

Neural crest cells from the thoracic and lumbar regions will form the sympathetic ganglia.

Question 19

In order to migrate to their destinations, neural crest cells must move though the _______ by secreting _______.

Accepted Answer

The basal lamina, a layer of extracellular matrix, separates the neural crest cells from their destinations. In order to migrate through the basal lamina, the neural crest cells must secrete metalloproteases to break down the matrix and create a path for their migration. Cell adhesion molecules play a role in cell-to-cell interaction and do not facilitate the movement through the basal lamina. The subventricular zone is not relevant to neural crest cell migration.

Question 20

What repels migrating neural crest cells?

Accepted Answer

Ephrins are known to repel migrating neural crest cells and guide them to their proper destination during development. Anterior somites actually attract neural crest cells, while fibronectin and metalloproteases do not have a significant effect on neural crest cell migration.

Quiz 3: Neurogenesis and Migration