<span>Facilitated diffusion
Diffusion
occurs because of the movement of molecules from the region of higher
concentration to the region of lower concentration. This movement of
molecules occurs due to a thermal motion. Diffusion normally occurs
between two compartments having difference in concentration. In case of
fluid it moves from the region of higher concentration to the region of
concentration until a balance is reached. The process of diffusion is
very important for the humans as well. The oxygen that humans breathe in
gets diffused with the blood.<span> </span></span>
Answer:
2 cells meet and the number of chromosomes becomes equivalent to the somatic cell.
Explanation:
In meiosis crossing over occurs and the number of chromosomes divided or remain half as compared to a somatic cell which is called Haploid (n). When two haploid cell meets than diploid (2n) cell formed which further transforms into a zygote. So, the purpose of meiosis is the cross over which creates genetic variation among individuals and reduced the number of chromosomes into the half. Because if the number of chromosomes remains the same as (2n) and (2n) meets and becomes 4n. Which is the wrong pattern so nature keeps this balance in a unique manner that (n) and (n) meets and form (2n).
Diagram found elsewhere attached
Answer:
Clockwise from bottom
3. formation of mRNA in the nucleus
6. secretion of hormone by tissue
4. initiation of DNA replication because of a signal given by the hormone
2. synthesis of protein molecule by mRNA and tRNA
1. secretion of protein by the cell
5. binding of the hormone molecule with its receptor of the cell
Explanation:
The tissue in the top left releases a hormone. For example, a steroid hormone such as estrogen, which can impact gene expression at the level of transcription. This hormone then travels to a different cell to carry out its function. The hormone is able to enter the cell and binds receptors which recognise it. In this case, these receptors are present in the nuclear envelope. When the hormone has bound the receptor, it initiates a signalling cascade that the cell responds to.
In this case, the effect of the signal from the hormone is to initiate DNA replication. This is a common effect of hormones such as growth factors that signal the cells to proliferate.
The initiation of the signalling can also affect how genes are expressed. In this case, an mRNA is produced in the nucleus, which is created as a result of transcription. This mRNA molecule then moves to the cytoplasm, where it becomes translated into a polypeptide sequence at a ribosome, with the help from transfer RNAs (tRNAs).
This polypeptide forms a mature protein by progressive folding and potential modifications, and is released by the cell to perform its functions.
DNA helicase is the enzyme that unwinds the DNA double helix by breaking the hydrogen bonds down the center of the strand. It begins at a site called the origin of replication, and it creates a replication fork by separating the two sides of the parental DNA.
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Nitrogen is a naturally occurring element that is essential for growth and reproduction in both plants and animals. It is found in amino acids that make up proteins, in nucleic acids, that comprise the hereditary material and life's blueprint for all cells, and in many other organic and inorganic compounds.
