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Svetach [21]
3 years ago
11

Why is the resting membrane potential (Vm) approximately - 70 mV for most cells? Most cells contain a large concentration of Cl-

making them negatively charged. The large concentration of proteins in the interstitial space draws Na+ out of the cell making it negatively charged. Most membranes are 10 times more permeable to Na+ than to K+. Most membranes are 40 times more permeable to K+ than to Na+.
Biology
1 answer:
Yuki888 [10]3 years ago
7 0

Answer:

Option (4).

Explanation:

Cell membrane potential may be defined as the difference in the electric potential between inside and outside of the cell. This potential is important for the action potential.

The resting membrane potential of the cell is -70mV. This membrane potential is maintained by the potassium ions of the cell. The cell membrane are almost 40 times more permeable to potassium ions than sodium ions and makes the cell membrane potential negative.

Thus, the correct answer is option (4).

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The miller and urey abiotic synthesis experiment (and subsequent, similar experiments) showed that __________.
Murljashka [212]
<span>simple organic molecules can form spontaneously under conditions like those thought to prevail early in Earth's history</span>
4 0
3 years ago
Which of the following best explains how the expression of a eukaryotic gene encoding a protein wil differ if the gene is expres
Ivan

Answer: c. The protein will be made but will not function, because prokaryotes cannot remove introns.

Explanation:

Eukaryotic cells are cells that have membrane-surrounded organelles, such as a nucleus which is an organelle that stores the DNA, the genetic material. On the other hand, prokaryotic cells do not have a nucleus, and the genetic material is a single molecule, usually circular and closed and double-stranded, which is located in a sector of the cell known as the nucleoid (meaning "similar to the nucleus"), which does not imply the presence of a nuclear membrane.

<u>A gene is a unit of information at a DNA locus that codes for a protein. To synthesize that protein, DNA must be transcribed into messenger RNA (mRNA), and that mRNA is read by ribosomes in a process called translation or protein synthesis</u>. The difference between protein synthesis in prokaryotic and eukaryotic cells is that in prokaryotes, transcription and translation take place directly in the cytoplasm since there is no nucleus. In eukaryotes, transcription takes place inside the nucleus, to generate mRNA. This mRNA molecule is then directed to the cytoplasm where translation happens.

a. In prokaryotic cells, ribosomes are produced in the cytoplasm, whereas in eukaryotic cells they are generated in the nucleolus within the cell nucleus. So they both have ribosomes and they are used to make proteins, then this option is true.

b. RNA polymerase initiates transcription of all different types of RNA (mRNa, ribosomal RNA and transfer RNA). However, there are three RNA polymerase variations, each one translate a different type of gene. But, prokaryotic RNA polymerase can translate eukaryotic genes. Then this option is not true.

c. Prokaryotic cells don't  have introns because those cells do not perform a post-transcriptional RNA modifications, only done by eukaryotic cells. One of the modifications is the excision of introns in RNA. An intron is a region of DNA that is part of the primary RNA transcript, but unlike exons, they are removed from the mature transcript prior to translation. <u>So, this remotion does not happen in prokaryotes because they just don't have introns</u>. Also, in prokaryotic cells. the translation and transcription machinery is coupled. So, the transcription and translation occurs simultaneously, there will be no remotion of introns then the protein will be synthesized differently, since the reading frame is changed. Remember that each codon (set of three nucleotides) codes for an amino acid. So if the gene sequence is different because certain sections of the gene have not been removed, the protein will be different, and probably it will not function. This option explains how the expression of an eukaryotic gene encoding a protein will differ if the gene is expressed in prokaryotic cells.

d. The genetic code is the set of rules that defines how a sequence of nucleotides in RNA is translated into a sequence of amino acids in a protein. This code is common to all living organisms, although there are small variations, and it has a unique origin and is universal.  So, the code defines the relationship between each sequence of three nucleotides, called a codon, and each amino acid.  The sequence of genetic material is composed of four distinct nitrogenous bases, which are represented by letters in the genetic code:

  • Adenine (A)
  • Thymine (T)
  • Guanine (G)
  • Cytosine (C)
  • Uracil (U), only in RNA (instead of T)

So, the genetic code is the same for eukaryotes and prokaryotes. So this option is not true.

7 0
3 years ago
Science 7.   Grade 7.
Murrr4er [49]
Question 2: Because the offspring most often will look like it's parents.
7 0
3 years ago
Which best describes independent assortment?
bekas [8.4K]

Answer:

In metaphase 1, chromosomes from the mother and father line up randomly along the middle of the cell.

Explanation:

In diploid (2n) organisms, the homologous chromosomes are the two copies of each chromosome, where one of these homologs is the chromosome from the mother, while the second one is from the father. During metaphase I, the homologous pairs of chromosomes pair together at the middle of the cell. The law of independent assortment, also known as or Mendel's Second Law, states that homologous chromosomes line up in random orientations at the metaphase plate during this period (metaphase I).

5 0
3 years ago
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Thinking about the safety of yourself and your fellow classmates. Does the school have adequate safety measures in place? Is the
s344n2d4d5 [400]

Answer:

Yes it does for example the science room has the materials to be safe during school.No because there is still the covi going on and some students aren't taking it seriously.One concerne that I have is that if they need help with their studies their should be tutoring

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3 years ago
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