Question 1

Differentiation is the process whereby a cell's determined state is expressed.

Accepted Answer

Differentiation is the process by which a cell's determined state is expressed, meaning it undergoes a specific pathway of development to become a specific cell type.

Question 2

During development, many genes act in such a way as to decrease the number of alternative developmental pathways that a cell can follow. Usually there are two alternative developmental paths for a cell to follow. What is the term given to genes that act in this fashion?

Accepted Answer

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Question 3

A homeobox gene is one that produces a group of repetitive base sequences such as a VNTR.

Accepted Answer

A homeobox gene is actually a gene that contains a specific DNA sequence called a homeobox, which encodes a protein domain called the homeodomain. This domain is involved in the regulation of gene expression during embryonic development. It is not related to VNTRs or repetitive base sequences.

Question 4

Do Hox gene clusters exist in humans? If so, how many are known to exist?

Accepted Answer

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Question 5

It is presently believed that the asymmetric distribution of substances in the egg, positioned by the mother, is responsible for establishing the determined state. Which general term describes such molecular positioning?

Accepted Answer

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Question 6

Give a brief definition of a homeobox.

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Question 7

What significant conclusion has the classic work on the eyeless and Pax6 genes provided in terms of developmental mechanisms?

Accepted Answer

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Question 8

Drosophila and Arabidopsis use different sets of nonhomologous master regulatory genes to establish the body axis and specify the identity of structures along such an axis.

Accepted Answer

Drosophila and Arabidopsis are two different organisms with different body plans and genetic makeup. As such, they use different sets of nonhomologous master regulatory genes to establish their body axes and specify identity along the axis.

Question 9

In Drosophila, maternal-effect genes are influential in determining the anterior-posterior organization of the developing embryo.

Accepted Answer

Maternal-effect genes in Drosophila, such as bicoid and nanos, play a critical role in establishing the anterior-posterior axis of the embryo.

Question 10

A gene that specifies the fate of a particular anatomical segment in Drosophila is called a(n) ________.

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Question 11

The bicoid gene of Drosophila generates embryos with two posterior regions. What is the likely aspect of embryonic development that the bicoid gene probably controls?

Accepted Answer

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Question 12

What is the general order of genes involved in determining early Drosophila development?

Accepted Answer

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Question 13

Mutations in the selector genes sometimes form structures in the wrong segment, transforming the antenna of a fly into a leg, for example. What are such mutations called?

Accepted Answer

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Question 14

Molecular/structural orientations (gradients) in an egg are thought to play a significant role in development. What is the origin of such gradients? What evidence indicates that the maternal genotype is involved in providing such gradients?

Accepted Answer

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Question 15

Which class of genes controls the developmental identity of segments along the anterior-posterior axis?

Accepted Answer

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Question 16

From a human developmental standpoint, what is the significance of Hox genes?

Accepted Answer

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Question 17

Genetic involvement in development appears to be achieved, at least in part, by variable gene activity.

Accepted Answer

Genetic involvement in development is achieved through variable gene activity, which means that different genes are activated or repressed at different stages of development to orchestrate the formation and differentiation of cells and tissues. This process is regulated by various factors, such as epigenetic modifications, transcription factors, and signaling molecules, and can be influenced by environmental cues, such as nutrition and stress. Therefore, genetic activity is not fixed or predetermined, but rather dynamic and responsive to internal and external signals.

Question 18

What is the significance of the homeodomain?

Accepted Answer

The answer of What is the significance of the homeodomain?...

Question 19

Segmentation genes, such as the pair-rule class, are inherited through mitochondrial DNA in Drosophila.

Accepted Answer

Segmentation genes are inherited through nuclear DNA in Drosophila, not mitochondrial DNA. Mitochondrial DNA is maternally inherited and is responsible for energy production in cells. Segmentation genes are a group of genes responsible for patterning the body segments during embryonic development. They are located on nuclear DNA, which is inherited from both parents.

Question 20

Determination is the process whereby a cell's eventual developmental fate is set.

Accepted Answer

Determination is the process that determines a cell's eventual fate. This is different from differentiation, which is the process whereby a cell undergoes morphological and functional changes to become a specialized cell type.

Quiz 18: Developmental Genetics