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UNO [17]
3 years ago
13

Which of the following best describes an aspect of a membrane's molecular structure that causes it to be selectively permeable?

Biology
1 answer:
atroni [7]3 years ago
3 0

Answer:

<u>d. Transport proteins within the membrane serve as a tunnel for molecules to enter the cell. </u>

<u />

Explanation:

Solutes are typically moved across the cell through either passive or active transport. The cells, surrounded by a bilipid layer or plasma membrane is amphiphlic- its polar, hydrophilic lipid heads face outwards, while their non-polar hydrophobic lipid tails face inwards towards each other.

While lipid-soluble molecules move across the layer easily, it is also difficult for charged and also large molecules to move across its surface, into the cell. Transmembrane channels, <u>embedded within the membrane</u>, help to maintain selective permeability as transport proteins, pores and gated channels. Simple diffusion happens as a method of passive transport in cells through plasma membranes.

The solutes travel through the plasma membrane in the process of diffusion from regions of high concentration to regions of low concentration; this occurs without the use of energy. <u>Molecules moving against their concentration require active transport mechanism to cross the membrane</u>.

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A 21-year-old female was lost in the woods for several hours. The ambient temperature is 25 degrees Fahrenheit. She is lethargic
Annette [7]

The female should be gently wrapped with dry blankets due to exposure of temperature of about 25 degrees Fahrenheit.

Explanation:

Prolonged exposure to extreme heat or cold conditions can impair the body’s temperature control system.  

In the above case the patient is exposed to extreme cold condition in a wood with a freezing temperature of 25 degrees Fahrenheit (-3 degrees Celsius) which leads to hypothermia and frostbite.

Extreme cold conditions can freeze the tissue layers of the parts of the skin exposed like those of the face, hands and feet especially. Due to this the skin becomes white (even grayish yellow or blue) and waxy, cold and numb, and the outer surface may become hard and blistered. There will also be extreme pain, stinging and tingling sensation in the exposed areas.  

These changes are mainly due to impaired blood circulation and hypothermia. Hypothermia which is lowering of body temperature causes confusion and lethargy.

The first-aid given for frostbite primarily includes warming the body. The affected person’s body should be covered with warm and dry blankets gently and loosely and any wet clothes should be removed.  

So when the body is warmed, the body temperature also will increase and correct the hypothermic symptoms like lethargy and confusion.

5 0
3 years ago
There are only about 40 different tRNAs in a cell even though 61 codons code for amino acids. This discrepancy can be attributed
bogdanovich [222]

Answer:

The correct answer is - wobble; the curvature of the anticodon loop; inosine.

Explanation:

The wobble phenomenon or hypothesis tells that why there are multiple codons are present for a single amino acid. 20  amino acids are coded by 61 codons. It states that tRNA can identify and attach to more than one amino acid due to the curvature of the anticodon loop.

The curvature of the anticodon loop is that the base at the 1st position on the anticodon to binding but the less-precise base pairs that can arise between the 3rd base of the codon. The inosine is the nucleoside that presents in a position in the curvature of the anticodon loop and its position responsible for wobble as well.

3 0
3 years ago
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There are number of endemic species, because island isolation promotes allopatric speciation and the latter occurs when species become separated from each other to the level that prevents genetic recombination.  
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aleksley [76]
<span> Some of the important features of a prokaryotic cell is that it contains a plasma membrane, ribosomes, and genetic material (DNA) that is not bound by a membrane. Therefore, prokaryotic cells lack a nuclear membrane. </span>
4 0
3 years ago
Read 2 more answers
He association of two or more polypeptides in a multimeric protein is known as the:
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He association of two or more polypeptides in a multimeric protein is known as the <span>Quaternary structure.</span>
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