The the polymerase causes the strands of DNA to separate temporarily, and the enzyme synthesizes a strand of messenger RNA (mRNA) to using the the sequence of bases on one strand of DNA (the coding strand) to create a complementary strand of mRNA.īy complementary we mean that the base sequence on mRNA has bases that are the complementary pairs of those on DNA. Additional transcription factors then bind, and an enzyme called RNA polymerase II then binds to the complex. Instead, the single bacterial chromosome is in the cytoplasm in an area sometimes referred to as the "nucleoid." The production of cellular proteins requires two major processes.įirst, cellular signals reaching the nucleus cause the TATA-binding protein to the starting point of a particular gene. In eukaryotes chromosomes are located in the cell nucleus, but prokaryotes (bacteria) have a more primitive cellular structure, and they do not have a true nucleus. Humans have 23 pairs of chromosomes, which carry our entire genome. As noted above, the genetic code is contained in chromosomes which are gigantic molecules of DNA complexed with proteins and wound into a compact structure. The sequence of bases in DNA can be thought of as the "letters" that provide the basis for the genetic code for all of the proteins synthesized by our bodies, and these, in turn, provide the basis for the structure of all of our cells, all of our enzymes, and all of our inherited traits and characteristics. However, about 100 genes are transcribed into "ribosomal RNAs" and "transfer RNAs" that also play a vital role in the synthesis of proteins, which will be described shortly. Most of the genes are transcribed into "messenger RNAs" (mRNA) that provide a template that is used to translate the code into specific proteins. " Altogether our 23 pairs of chromosomes with their 3 billion base pairs carry the code for 20,000-25,000 genes. " The segments of DNA that contain genes (referred to as "coding areas ") take up only 3-5% of our DNA the rest of the DNA consists of " non-coding areas. Each chromosome contains thousands of " genes. Altogether our 46 chromosomes contain about 6 billion nucleotides, i.e., 3 billion base pairs. Each of our cells has a complete set of our 46 chromosomes, i.e., our entire genome.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |