Transcription

• Transcription occurs in the nucleus and is the synthesis of DNA in a complimentary single mRNA strands with the intention of copying the opposite strand's genetic code in the 5' to 3' direction
• RNA polymerase binds to a section of DNA (gene) and unwind. It picks one template strand (antisense strand) to use as a complimentary template for the free RNA nucleotides to bind to, with covalent bonds forming between their sugar phosphates to create a continuous chain that is released when the RNA polymerase reaches the end of the selected gene
• Hydrogen bonding and complimentary base pairing ensures stability in the genetic code processes and prevents mutations in the gene expressed
• The stability of DNA can be threatened by free radicals, chemicals, cigarette smoke, exposure to UV or exposure to nuclear radiation
• DNA sequence has no effect on gene expression- only the sequence of the specific genes transcribed and translated can affect the genotype- even, the cell is very selective about what genes it activates and lets itself show- not all genes are expressed and they can be switched off or repressed according to its relevance to that specific cell's functionality
• DNA is a good data storage because it can hold long sequences of bases arranged in any order and still be stable and accurately copied
• Genetic codes are universal with 4 common bases (uracil/thymine, adenine, cytosine, guanine) with codons being groups of gene triplets for which there are 64 possible combination (4^3)
• The Template strand used as a complimentary base for transcripted mRNA is the antisense strand
• The non-template strand is identical to the transcripted mRNA strand (with Thymine instead of Uracil) and is called the sense strand
• The first stage of transcription, initiation, happens upon RNA polymerase binding to the promoter region on the DNA's left.
• The second stage of transcription, elongation, is the simple process of adding complimentary RNA bases to the DNA template strand then unwinding them
• The third and last stage of transcription, termination, is reached upon the RNA polymerase enzyme detecting the terminator region on the template DNA strand that prompts the enzyme to release/"drop off" the copied gene and let DNA supercoil again
• Transcription is an essential step in gene expressions
• In Transcription, upon RNA polymerase binding to a promotor region, it helps link free RNA nucleotides together based on complimentary base pairing with a template ("anti-sense") strand of DNA, adding to the 3' end of the growing RNA strand. Adenine in the DNA molecule pairs to Uracil in RNA instead of Thymine and this process is regulated by transcription factors.
• Transcription is an essential process in gene expression
• RNA nucleotides linked together to form a strand/chain; RNA strand assembled on DNA template/antisense strand/copy made of sense strand; RNA polymerase carries out transcription/links RNA nucleotides; uncoiling/separation of DNA strands; 5′ end of nucleotides linked to 3′ end of (growing RNA) strand; complementary base pairing (is the basis of copying the base sequence); uracil instead of thymine in RNA; starts at/RNA polymerase binds to a promoter; regulated by transcription factors/DNA binding proteins/nucleosomes.