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Phantasy [73]
3 years ago
14

A unique substance composed of atoms having the same atomic number

Biology
1 answer:
Darina [25.2K]3 years ago
6 0

Answer:

Element

Explanation:

An element is made up of a single type of atom, that is, it’s a substance made up of atoms that have the same number of protons in the nucleus, this number is known as the atomic number of the element. An atom is the smallest particle of an element that retains its properties.Each element is made up of atoms with the same chemical properties such as reactivity, ionization potential. Chemical elements are identified by names given in antiquity, derived from some property of them, from the name of their discoverer, from the place of discovery. In nature there are 92 elements that can be presented (at 1 atm of pressure and 25 ºC) as solid: iron, lead; liquid: bromine, mercury or gas: chlorine, oxygen.

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3 years ago
HURRY PLEASE I NEED A PARAGRAPH. Describe how cell membranes are selectively permeable.
Simora [160]

Explanation:

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4 0
3 years ago
The interaction between DNA and histone proteins (forming nucleosomes) plays a key role in the regulation of gene expression in
ladessa [460]

Answer:

A. The chromatin near cis-regulatory sequences will be more closed and there will be less transcription.

Explanation:

In the presence of histones, the cis-regulatory sequences of DNA like promoter, enhancers etc. are not exposed. The function of the histone acetyltransferases (HATS) is to cause chromosome decondensation i.e. removal of histones from the DNA so that transcription of the DNA could occur. Histone acetyltransferases (HATS) cause acetylation of lysine amino acid of the histone proteins. Acetyl group is negatively charged so the acetylation of histone proteins leads to the removal of their positive charge which ultimately leads to the decrease in the interaction between N terminal of histones and negatively charged phosphate group of the DNA molecule. As soon as histones are removed from the DNA where cis-regulatory sequences are located, the DNA becomes accessible for transcription.

But here a drug has been added which blocks the activity of histone acetyltransferases (HATS) in cancer cells. So it is quite evident that in these cells, histones will not get removed from the cis-regulatory sequences of DNA so the DNA will be more closer or tightly packed as a result of which  less transcription will occur.

7 0
3 years ago
Help please, this is for a test and I would like to double check my answer with someone
ehidna [41]

Answer:

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Explanation:

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5 0
2 years ago
Describe the genetic makeup of the offsprings of asexual reproduction.
WARRIOR [948]

Answer:

They are genetically identical to the parents and only differ if a genetic mutation occurs.

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The greater the genetic variation, the better change that an individual in the population have a favorable gene that can help survival.  Genetic variation is an important force in evolution as it allows natural selection to increase or decrease frequency of alleles already in the population.

Explanation:

6 0
2 years ago
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