Are viruses alive? The scientific debate continues. Viruses exhibit some characteristics of life, but others are missing.

if you were to watch an individual neurotransmitter molecule just after it was released what would happen to it

Olenka [21]

Neurotransmitter leaves the presynaptic cell by exocytosis. It is released in the synaptic space, and moves to the postsynaptic membrane to meet its receptor. When binding occurs, it triggers a response in the new cell.

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Every neuron forms connections with another cell.

When a presynaptic cell sends information, a neurotransmitter is released.

After the exocytosis event, this chemical substance travels through the synaptic space forward to the other cell. Once there, it binds to its receptors in the postsynaptic membrane.

When the joining occurs, the receptor acquires a channel shape. This change allows the ion transference that will make possible the modification of the action potential.

This binding produces the excitatory postsynaptic potential -depolarization-.

A new action potential initiates in the postsynaptic cell and spreads to the rest of the membrane, depolarizing it.

If the communication between cells needs to stop, the neurotransmitter will be taken out from the synaptic space instead of binding to its receptor.

There are two mechanisms by which the neurotransmitter can be eliminated: by deactivation or reuptake.

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6 0

2 years ago

Homologous chromosomes migrate to opposite poles during _____.

Drupady [299]

They migrate during Anaphase :)

4 0

3 years ago

When farmers leave plant stalks in the field to reduce soil erosion, it is called ____. a. contour farming c. no-till farming b.

aleksklad [387]

Answer:

Option (C)

Explanation:

In no-till farming method, the farmer usually uses a no-till planter with the help of which they make a narrow type of trench that is sufficient enough for the seed to be grown in rows. The residue of the cover crop is allowed to place on the surface of the soil by not plowing, as a result of which the soil is protected from getting eroded and losing of moisture content. This improves soil quality.

This method helps in increasing the water content that percolates down into the soil, holding the organic matter and recycling of nutrient matters. It also expands the growth and population of microbes in the soil, which provides more nutrients to the soil and increases the fertility of the soil.

Thus, when a farmer leaves plant stalks in the field to reduce soil erosion, then it is known as no-till farming.

Hence, the correct answer is option (C).

5 0

3 years ago

Read 2 more answers

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 Escherichia coli. It is regulated by glucose and lactose availability 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, RNA polymerase can freely transcribe the structural genes and β-galactosidase can degrade lactose to glucose plus galactose. 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. 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

2 years ago

Five ounces of beef strip steak would count as ____ ounce equivalent of the protein foods.

Andrews [41]

The 5 ounces of beef strip steak would count as 5-ounce equivalents in the Protein Foods Group.

Al the foods made from poultry, meat, seafood, peas and beans, eggs, processed soy products, seeds, and nuts are regarded as the component of the Protein Foods Group.

Steak, like any other animal product, is a rich source of protein. A 5 oz serving of steak gives 38 grams of protein, more than 6 times of the amount in one egg. The proteins help in repairing muscles and other tissues and also helps in building muscles.

5 0

3 years ago