Question

A. A mutation in the Dorsal gene that causes the Dorsal protein to bind with high affinity to all of the DNA binding sites for dorsal (remember normally there are low and high affinity sites in front of different genes that allow the effect of a gradient to proceed at the molecular level).

1)What will happen to the particular molecule,

2) what would happen at the cell(s) level, and

3) what would happen at the level of the whole body (if it is a developmental mutant, what would happen if the embryo continued to develop to the adult stage with that mutation)?

D. A single amino acid change in the Bax channel in the human hair follicle stem cells.The mutation causes these channels to randomly open at a regular interval.

1)What will happen to the particular molecule,

2) what would happen at the cell(s) level, and

3) what would happen at the level of the whole body (if it is a developmental mutant, what would happen if the embryo continued to develop to the adult stage with that mutation)?

C. A somatic mutation in the voltage gated sodium channels in the motor neuron that innervates (attaches to) the pinky muscle fibers. The mutation lengthens (2X as long) the “chain” of the cytoplasmic “ball” for these channels.

1)What will happen to the particular molecule,

2) what would happen at the cell(s) level, and

3) what would happen at the level of the whole body (if it is a developmental mutant, what would happen if the embryo continued to develop to the adult stage with that mutation)?

Answer 1

A.

1. if the dorsal gene is mutated, then the dorsal protein distribution will be affected. A deformed larva will be produced having only dorsal cells.

2. dorsal gene produces dorsal protein which acts upon the nuclei present in the ventral side of the egg. In the nucleus, the dorsal binds to the specific DNA sites that either activates of supresses the process of transcription. Due to the mutation in dorsal gene, the dorsal protein so formed is also deformed one and it will not enter into the nucleus and the transcription does not takes place. thus all the cells of an embryo will behave as dorsal cells.

3. the dorsal protein helps in forming the mesodermal sells which will develop into body muscles, fat bodies and gonads. . it also regulates the gastrulation process in flies. Due to mutation in dorsal gene, the embryonal cells will not be able to differentiate as mesoderm, mesectoderm, neurogenic, ectoderm, epidermis and amnioserosa. Thus organ formation will not takes place properly.

B.

1. if one amino acid of bax protein is mutated then its action on mitochondria will also gets altered. the bax protein regulates the opening of the mitochondrial voltage dependent anion channels and alters the membrane potential and causes the release of cytochrome c which regulates cell death.

2. these bax proteins are regulating the apoptosis by inhibiting or inducing cell death. if it is getting mutated then the cell death cycle will also change. it may also lead to cancer.

3. the mutation of bax gene can be well seen in the body. as it will lead to the cancer like melanoma cancer, breast cancer etc. In some cases, it may also lead to auto- immunity where the antibodies are not able to differentiate self and non- self tissues. in worst cases, it may also lead to a mental disorder called as schizophrenia.

C.

1. The somatic mutation in the voltage gated sodium channels in the motor neuron will not allow the proper inflow of sodium ions into the motor neuron and thus depolarsation of the membrane will not occur, so no action potential and no response.

2. As the somatic mutation in the voltage gated sodium channels in the motor neuron will not allow the sodium ions to come inside the motor neuron. the polarity of the membrane will not change. so the impulses will not move to the next part within the axonal membrane.

3. since the membrane polarity is not changing due to mutation,  the muscles will also not respond to the stimulus. The muscle will take the stimulus via sensory neurons and give to motor neurons for the response of the stimulus. but since the voltage gated sodium channels in the motor neuron are mutated, there is no chance of response exhibited by the motor neuron as the membrane polarity is not changing and nerve impulses are not moving forward in the axonal membrane.