Posted: November 18th, 2021
1. (1 point) Evaluate the following lac operon partial diploids. Indicate whether the production of functional β-galactosidase from lacZ and of permease from lacY is “inducible”, “constitutive”, “absent” or “noninducible” for each partial diplod
a. F’ I+-p+o+Z+Y+ X F- I+p+o+Z-Y-
b. F’ I+-p+ocZ+Y- X F- I+p+o+Z-Y+ c. F’ I+-p+ocZ-Y+ X F- Isp+o+Z+Y+
2~3 Describe the effects on attenuation and on tryptophan synthesis of the following mutations of the two tryptophan codons (UGGUGG) in the attenuator region of operon.
2. (1 point) The tryptophan codons are mutated to UAGUGG. 3. (1 point) The tryptophan codons are mutated to UUGUUG.
4. (1 point) What would be the phenotype of a null mutation in the CRP protein gene in the regulation of Lac operon and why?
5. (1point) What would be the phenotype of a “constitutively expressed” mutation in the CRP protein gene in the regulation of Lac operon (i.e. CRP proteins are always highly expressed) and why?
6. (2 points) A repressible operon system, like the trp operon, contains three genes, G, Z, and W. Operon genes are synthesized when the end product of the operon synthesis pathway is absent, but there is no synthesis when the end product is present. One of these genes is an operator, one is a regulatory protein, and the other is a structural enzyme involved in synthesis of the end product. In the table below, “+” indicates that the enzyme is synthesized by the operon, and “-“ means that no enzyme synthesis occurs. Use this information to determine which gene corresponds to each operon function.
G+Z+W+ ￼ ￼ +
G-Z+W+ ￼ ￼ + G+Z-W+ ￼ ￼ – G+Z+W- ￼ ￼ ￼ ￼ ￼ + G-Z+W+/G+Z-W- ￼ ￼ ￼ ￼ ￼ + G+Z-W+/G-Z+W- ￼ ￼ ￼ ￼ ￼ + G-Z-W-/G+Z+W+ ￼ ￼ ￼ ￼ ￼ + G+Z+W-/G-Z-W+ ￼ ￼ ￼ ￼ ￼ +
7. (1 point) Gene A is maternally imprinted (silenced) while Gene B is paternally imprinted when imprinted silencing occurs. A Mom with Genes A and B imprinted and a Dad with an imprinted Gene A have a daughter and a son. The children then marry individuals known not to be silenced for either gene. What is the imprint status of the daughter and son respectively? If each marriage results in the birth of a daughter and a son, what would you expect the imprint status of genes A and B to be for the grandchildren?
8 ~ 9. On a rare occasion, human can be born with a condition known as “uniparental disomy”. This happens when an individual inherited both copies of a chromosome from one parent but no copies from the other parent. For example, abnormal sperm that lacks chromosome 15 can fertilize an egg that contains two copies of chromosome 15. This is known as maternal uniparental disomy 15. Alternatively, there are cases of paternal disomy 15 (an abnormal sperm with two copies of chromosome 15 fertilizes an egg with no copies).
8. (1 point) If a female is born with paternal disomy 15, would you expect her to be normal or have Angelman syndrome (AS) or have Prader-Willi syndrome (PWS)? And explain why?
9. (1point) Would you expect her to produce normal offspring or offspring affected with AS or PWS?
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