Question

In: Biology

questions 1-4? 1. Use the following diagram of the lac I gene and lac operon. Where would...

questions 1-4?

1.

Use the following diagram of the lac I gene and lac operon. Where would the lac repressor be bound in a (nonmutant) E. coli cell that is growing in no glucose and high lactose?

(I = lac repressor gene; Z, Y, A = lac operon structural genes; P = lac promoter; O = lac operator)

		The repressor would not be bound
		P
		I
		P and O
		O

2.

Euchromatin is associated with more loose and open organization of DNA and genes in these regions are more likely to be active and transcribed.

		False
		True

3.

There are mutations to the lac operon that allow beta galactosidase to be expressed constitutively even when lactose is absent. Which of the lac genotypes below would enable for this constitutive expression?

		I+ P+ Oc Z+ Y+ A+
		I+ P- O+ Z+ Y+ A+
		Is P+ O+ Z+ Y+ A+
		I+ P+ O+ Z- Y+ A+
		I+ P+ O+ Z+ Y+ A+

4.

If a typical somatic cell has 14 chromosomes, how many chromosomes are expected in each gamete of that organism?

		14
		56
		28
		7
		23

Expert Solution

Q.1. Where would the lac repressor be bound in a (nonmutant) E. coli cell that is growing in no glucose and high lactose

Answer- The repressor would not be bound

(Note: lactose is inducible operon. When lactose is absent then the repressor protein will bound to the operator site to prevent the transcription. In the presence of lactose, the repressor will bound to the inducer (lactose) and hence, cannot bind to the operator so, transcription proceeds)

Q.2. Euchromatin is associated with more loose and open organization of DNA and genes in these regions are more likely to be active and transcribed.

True.

During Giemsa staining process euchromatin show faint stain while heterochromatin is darkly stained. Heterochromatin is tightly coiled with the protein part (darkly stained) and contains gene-poor regions. While euchromatin is loosely packed (light stained ) and contains gene-rich regions. As euchromatin is loosely arranged, so the DNA of the euchromatin is accessible for the enzymes responsible for the transcription process. therefor, euchromatin contains genes.

Q.3. There are mutations to the lac operon that allow beta galactosidase to be expressed constitutively even when lactose is absent. Which of the lac genotypes below would enable for this constitutive expression?

Answer- I+ P+ Oc Z+ Y+ A+

(In this mutant, the operator has a constitutive mutation, therefore no repressor can boun to the operator in any condition. If the repressor is failed to bind to the operator, then the transcription will always proceed and beta-galactosidase will be expressed constitutively weather the lactose is present or absent).

Q.4. If a typical somatic cell has 14 chromosomes, how many chromosomes are expected in each gamete of that organism?

The gametes are produced by meiotic cell division. Meiosis is also called reduction division as the chromosome numbers become half in the products.

So if the somatic cell contain 14 chromosomes then the gametes will contain the half number of the somatic chromosomes.

Answer: 7.

gladiator answered 2 years ago

Predict the level of gene expression of the lac operon in the following situations: (WT- normal...

Predict the level of gene expression of the lac operon in the following situations: (WT- normal function, Mut- loss of function mutation) (please type so answer is easier to read) No lactose, WT repressor Lactose, WT repressor No lactose, Mut repressor Lactose, Mut repressor

Predict the level of gene expression of the lac operon, as well as the status of...

Predict the level of gene expression of the lac operon, as well as the status of the lac repressor and the CAP protein, when bacterial growth media contains the following sugars: a) no lactose or glucose, b) lactose but no glucose, c) glucose but no lactose, d) both lactose and glucose.

Describe the likely effect on gene expression of a mutation in the lac operon: a) that...

Describe the likely effect on gene expression of a mutation in the lac operon: a) that delegate the operator b) that mutates the lacI gene inactivating the repressor c) that the promoter mutates in the -10 region

1. For the lac operon, explain what would happen and why regarding expression of the operon...

1. For the lac operon, explain what would happen and why regarding expression of the operon in each of the following scenarios. Be sure to include both positive and negative regulation in your explanation. a.) lactose is present, glucose is absent b.) lactose is absent, glucose is present c.) both lactose and glucose are present d.) lactose is present, glucose is absent, but there is a mutation to the sequence in the CAP site

Explain what are gene regulatory operons,with lac operon and tryptophan operon examples by drawing figures for...

Explain what are gene regulatory operons,with lac operon and tryptophan operon examples by drawing figures for each?

1.)A.)The lac operon is inducible by the presence of lactose. Loss-of-function mutations in the lacI gene,...

1.)A.)The lac operon is inducible by the presence of lactose. Loss-of-function mutations in the lacI gene, which encodes the lac repressor (pick all that apply): A.)slow down the isomerization of lactose into allolactose B.)decrease the amount of permease activity in the cell in the presence of lactose. C.)prevent loss-of-function lacZ mutations from making the lac operon uninducible D.)are recessive to wild type B.)Mutations that eliminate the lacO operator site (pick all that apply): A.)slow down the isomerization of lactose into...

Explain how gene regulation occurs using the lac operon as an example.

Explain how gene regulation occurs using the lac operon as an example

A)How is the lac operon regulated if the bacteria is put into an environment where there...

A)How is the lac operon regulated if the bacteria is put into an environment where there is excess amount of lactose and glucose at the same time. (10 pts) B)From the previous question, how would the outcome change if the glucose and lactose amounts are very low? (10 pts) C)Where would the lac repressor be bound in E. Coli bacteria that is growing in low glucose and high lactose? (7pts)

How is the lac operon regulated if the bacteria is put into an environment where there...

How is the lac operon regulated if the bacteria is put into an environment where there is excess amount of lactose and glucose at the same time. (10 pts) 7) From the previous question, how would the outcome change if the glucose and lactose amounts are very low? (10 pts)