Lactose (or rather, its derivative allolactose) can lift the Lac Repressor protein from the Operator site...
Lactose (or rather, its derivative allolactose) can lift the Lac Repressor protein from the Operator site in DNA, thus allowing for expression of the genes coded by the Lac Operon.
However, lactose cannot cross the bacterial cell membrane without the help of the Permease protein channel, which is coded by the lacY gene in the Lac Operon.
So, it appears that we have a case of "what's first, the chicken or the egg?" - how can lactose enter the cell and allow the expression of the lacY gene, if the Lac Y gene needs to be expressed for lactose to enter the cell ?
Using your own 150 or fewer words, how could you explain this apparent conundrum?
Homework Answers
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Lactose (or rather, its derivative allolactose) can
lift the Lac Repressor protein from the Operator site...
The lac operon contains three genes: lacZ, lacY, and lacA for β‑galactosidase, galactoside permease, and thiogalactoside transacetylase, respectively.
The lac operon contains three genes: lacZ, lacY, and lacA for β‑galactosidase, galactoside permease, and thiogalactoside transacetylase, respectively. The operon also contains a promoter site and an operator site. The regulatory gene includes the I gene for the Lac repressor protein and a promoter for that gene.The lac operon undergoes negative regulation. In the normal condition, the Lac repressor protein is active. Allolactose, an isomer of lactose, is the signal molecule that binds to the Lac repressor. Determine which events...
for 1-5 define those The Lac operon is an inducible set of genes found in bacteria...
for
1-5 define those
The Lac operon is an inducible set of genes found in bacteria cells that helps the bacteria to metabolize the disaccharide lactose. When it is turned on it produces proteins that pump lactose into the bacteria cell and break it down into glucose and galactose, which can then be used by the bacteria as a source of energy The two figures below show the Lac Operon along with the lacl gene (which regulates the Lac operon...
In this problem you will explore how to solve problems involving partial diploid lac operon bacterial...
In this problem you will explore how to solve problems involving partial diploid lac operon bacterial strains. Bacterial strains that are "partially diploid" have two copies of the lac operon because they aquired a plasmid carrying just the lac operon region. One copy of the lac operon region is on the recipient's bacterial chromosome, and the other copy is on the P plasmid that was introduced into the cell by conjugation. Partial diploid genotypes are written with the P segment...
3. The CAP activator protein and the Lac repressor both control the Lac operon (see Figure...
3. The CAP activator protein and the Lac repressor both control the Lac operon (see Figure 28-14). Fill out the table below with No expression, Low/Medium expression, or High expression to summarize when the Lac operon will be expressed in each of the three E. coli strains in the table. An example has been done for you. RNA polymerase- binding site (promoter) CAP binding site start site for RNA synthesis operator Lacz gene -80 -40 14080 nucleotide pairs Figure 08-14...
Background: Several genetic regions are needed for lactose metabolism: P(promoter), O(operator), lacZ(b-galactosidase gene), lacY(permease gene), lacA(transacetylase...
Background: Several genetic regions are needed for lactose
metabolism: P(promoter), O(operator), lacZ(b-galactosidase gene),
lacY(permease gene), lacA(transacetylase gene) and lacI(repressor
gene). Strains can be defined as having + - c or s copies: + refers
to the functional version, - refers to a defect version, c refers
to a constitutively active version and s refers to a superrepressor
version. Each strain may or may not have an extra-chromosomal
plasmid containing the genes indicated. TA=transacetylase
it would be very helpful if you...
Yet, all the cells in your body contain the same genes (and same alleles). The difference...
Yet, all the cells in your body contain the same
genes (and same alleles). The difference across cell types
is that genes get selectively expressed (turned on or off)
based on the proteins needed for cellular function given their
environment.
Select which statement explains the reason why hair does not
normally grow on your muscle cells.
a.
Muscle cells have the gene for keratin, but do not express
it
b.
Muscle cells do not have the gene for keratin and...
A) An Operon is:? 1- A gene that affect another gene transcription. 2. A gene coding...
A) An Operon is:? 1- A gene that affect another gene transcription. 2. A gene coding for a metabolic pathway. 3. A protein that blockgene expression. 4. A set of genes under the control of one promoter. B )- In bacteria the Lac Operon genes code for proteins that break down.? 1- Arabinose 2- Lactose 3- Galactose 4- Glucose C )mRNA processing involves removal of .......? 1- Introns 2- The poly-A tail 3- The 5' cap 4- Exons D )...
What happens to the expression of the Lac gene of E. coli if the following conditions...
What happens to the expression of the Lac gene of E. coli if the following conditions occur? For each condition below, mark an X in the column labelled Activated or Repressed, then explain why you chose that answer. Please assume the glucose levels are low in the cell. The first row is done for you. Activated a Repressed b Explain your answer Repressor, Lactose, and RNA polymerase are all present in abundance X Repressor binds to lactose so it can...
For Questions 4-18, consider the mutations described in the left-hand column below. Identify whether the Lac operon will be ON or OFF in each of the environments listed across the top. The expression...
For Questions 4-18, consider the mutations described in the left-hand column below. Identify whether the Lac operon will be ON or OFF in each of the environments listed across the top. The expression of the normal (wild type) operon is given. Note that "ON" and "OFF" refer to whether the operon is expressed at high levels (ON) or basal//low/no levels (OFF). (Hint: mutations render the indicated site inactive while leaving the remaining part of the operon or protein functional.) Note...
3. (2 points) In the nematode roundworm, Caenorhabditis elegans, the LIN-14 protein controls the timing of...
3. (2 points) In the nematode roundworm, Caenorhabditis elegans, the LIN-14 protein controls the timing of certain cell divisions during development. LIN-14 protein levels are normally high in early development but decrease in the later stages. In a lin-4 mutant, the level of LIN-14 protein stays high throughout development, changing the pattern of cell divisions in the animal and producing defects in the shape of the animal. The lin-4 gene encodes a microRNA that binds to a sequence in the...
for
1-5 define those
The Lac operon is an inducible set of genes found in bacteria cells that helps the bacteria to metabolize the disaccharide lactose. When it is turned on it produces proteins that pump lactose into the bacteria cell and break it down into glucose and galactose, which can then be used by the bacteria as a source of energy The two figures below show the Lac Operon along with the lacl gene (which regulates the Lac operon...
In this problem you will explore how to solve problems involving partial diploid lac operon bacterial strains. Bacterial strains that are "partially diploid" have two copies of the lac operon because they aquired a plasmid carrying just the lac operon region. One copy of the lac operon region is on the recipient's bacterial chromosome, and the other copy is on the P plasmid that was introduced into the cell by conjugation. Partial diploid genotypes are written with the P segment...
3. The CAP activator protein and the Lac repressor both control the Lac operon (see Figure 28-14). Fill out the table below with No expression, Low/Medium expression, or High expression to summarize when the Lac operon will be expressed in each of the three E. coli strains in the table. An example has been done for you. RNA polymerase- binding site (promoter) CAP binding site start site for RNA synthesis operator Lacz gene -80 -40 14080 nucleotide pairs Figure 08-14...
Background: Several genetic regions are needed for lactose
metabolism: P(promoter), O(operator), lacZ(b-galactosidase gene),
lacY(permease gene), lacA(transacetylase gene) and lacI(repressor
gene). Strains can be defined as having + - c or s copies: + refers
to the functional version, - refers to a defect version, c refers
to a constitutively active version and s refers to a superrepressor
version. Each strain may or may not have an extra-chromosomal
plasmid containing the genes indicated. TA=transacetylase
it would be very helpful if you...
Yet, all the cells in your body contain the same
genes (and same alleles). The difference across cell types
is that genes get selectively expressed (turned on or off)
based on the proteins needed for cellular function given their
environment.
Select which statement explains the reason why hair does not
normally grow on your muscle cells.
a.
Muscle cells have the gene for keratin, but do not express
it
b.
Muscle cells do not have the gene for keratin and...
For Questions 4-18, consider the mutations described in the left-hand column below. Identify whether the Lac operon will be ON or OFF in each of the environments listed across the top. The expression of the normal (wild type) operon is given. Note that "ON" and "OFF" refer to whether the operon is expressed at high levels (ON) or basal//low/no levels (OFF). (Hint: mutations render the indicated site inactive while leaving the remaining part of the operon or protein functional.) Note...
3. (2 points) In the nematode roundworm, Caenorhabditis elegans, the LIN-14 protein controls the timing of certain cell divisions during development. LIN-14 protein levels are normally high in early development but decrease in the later stages. In a lin-4 mutant, the level of LIN-14 protein stays high throughout development, changing the pattern of cell divisions in the animal and producing defects in the shape of the animal. The lin-4 gene encodes a microRNA that binds to a sequence in the...
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