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LuckyWell [14K]
3 years ago
13

During exercise, sensory receptors detect changes in oxygen and carbon dioxide levels in the blood. This information is then sen

t to the brain's medulla, which causes the heart to beat faster and increases the rate of breathing. Exercising also causes the nervous system to signal the pancreas and thyroid gland to release hormones which regulate metabolism. Which statement is best demonstrated by this scenario? A. Hormones act as signal molecules between all body systems. B. Increased heart rate and blood flow decrease oxygen supply. C. Exercise is important for the body to function properly. D. Nerves transmit and respond to every major system in the body.
Biology
1 answer:
ratelena [41]3 years ago
8 0

Answer:

Exercise is very important for the body to function properly.

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According to PET scan results, what do cocaine addicts process less efficiently?
BabaBlast [244]
Positron Emission Tomography scan of the brain of cocaine addicts showed that the drug affects how the brain use glucose. Cocaine users' brain cannot use glucose efficiently and there are also reduced metabolic activity in other areas of the brain.
3 0
3 years ago
Describe the probable effects on gene expression in the lac operon of each mutation: a. Mutation in the lac operator that delete
Stella [2.4K]

Answer:

a. Reduces represor binding.

b. Constitutive expression of the operon.

c. Stronger promoter if it is more similar to the consensus sequence. Weaker promoter if less similar.

Explanation:

The lac operon is an operon required for lactose transport and metabolism in enteric bacteria such as <em>Escherichia coli</em>. <u>It is regulated by glucose and lactose availability</u> and consists of the following structural genes:

  • Lac z gene: encodes the enzyme β-galactosidase, which catalyzes the hydrolysis reaction of lactose into glucose and galactose.
  • Gene lac y: encodes the protein galactoside permease involved in the transport of lactose into the bacterium.
  • Lac a gene: encodes the enzyme thiogalactoside transferase, which catalyzes the transfer of the acetyl group of acetyl coenzyme A to 6-OH of a thiogalactoside acceptor. This gene is not related to lactose metabolism.
  • Promoter: region of DNA recognized by RNA polymerase for transcription.
  • Operator: region of DNA located between the promoter and the beginning of the structural genes, which is recognized by the repressor protein Lac I.
  • Repressor gene (lac I): encodes the Lac I repressor protein, which recognizes the operator region, where it binds. It prevents the transcription of genes under the control of this promoter but stimulates the binding of RNA polymerase. When the repressor is absent (in the presence of inducer which in this case will be lactose or IPTG), RNA polymerase will begin transcription.

The lac operon is under a type of negative regulation, where genes can always be transcribed, except when the Lac I repressor protein is bound to the operon region, for which it has a high affinity. In this case, the promoter of the lac I gene is constitutive, so the Lac I protein is permanently expressed and remains bound in tetramer form to the operon region, preventing the transcription of structural genes.

Since lactose is the inducer of the operon, it is able to bind to the Lac I repressor protein and generate a conformational change that decreases its affinity for the operon region. Thus, the operon region is left free, <u>RNA polymerase can freely transcribe the structural genes and β-galactosidase can degrade lactose to glucose plus galactose</u>. <u>In the absence of lactose, the Lac I repressor protein maintains its high affinity for the operator region, preventing RNA polymerase from transcribing the structural genes</u>. In this way, the system remains closed with consequent energy savings for the bacterium.

As a final clarification, actually the true inducing molecule of the lac operon is called allolactose, an isomer of lactose obtained by a transglycosylation occasionally carried out by β-galactosidase.

a. When there is a mutation in the lac operator that deletes most of the operator, then the repressor Lac I can no longer bind and RNA polymerase will begin transcription.

b. When there is a mutation in the Lac I gene that eliminates the binding of repressor to operator, then this protein can not produce the repression so there would be a constitutive expression of the operon.

c. Since the promoter us a region of DNA recognized by RNA polymerase for transcription, if there is a mutation here it will generate a stronger promoter in the case that this part is similar to a consensus sequence (the most commonly encountered nucleotides found at a certain location). In the case that it is less similar, then it will generate a weaker promoter.

7 0
3 years ago
Benjamina started her walk from the front door of her ground floor apartment. She walked 6 meters to the corner of the building
gizmo_the_mogwai [7]
According to given information,
Distance = 6 + 10 = 16 m
Displacement = 4 m

So, Distance - Displacement = 16 - 4 = 12 m

So, your final answer is 12 m.

Hope this helps!
6 0
3 years ago
Read 2 more answers
A red blood cell is placed in a hypertonic solution. This means the concentration of solutes in the solution is __________ than
Viktor [21]

Answer:

1. Higher

2.Contract

Explanation:

If an animal cell is kept in a hypertonic solution, water will move from higher water potential to lower that is from the intracellular fluid into the solution resulting in the contraction of the cell

7 0
3 years ago
What is the definition of energy
Aleksandr [31]
The ability to do work.
7 0
3 years ago
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