[1] Chargaff developed the Chargaff’s rules, which explains a peculiar regularity in the ratios of nitrogen bases. (Number of adenines = Number of thymines, Number of guanines = Number of cytosines)
[2] DNA grows from 5’-3’. Each DNA strand has a 5' end where a phosphate group resides and a 3’ end where the hydroxyl group of the deoxyribose sugar is found.
[3] DNA consists of two antiparallel strands of nucleotides. Adenine is always paired with thymine by double hydrogen bonds and guanine is always paired with cytosine by triple hydrogen bonds.
[4] Watson and Crick suggested that when a DNA molecule replicates, each of the daughter molecules will have on old strand and one newly made strand. This model is known as semiconservative replication.
[5] During DNA replication, the leading strand is continuously synthesized towards the replication fork while the lagging strand is synthesized in short fragments called Okazaki fragments.
[6] During transcription, mRNA is synthesized from the template strand of DNA. Transcription begins at 5’TATA3’, which is located in the promoter region, and terminates when a terminator sequence (AAUAA) is transcribed.
[7] Modified guanine nucleoside triphosphate is added to the start of the pre-mRNA, also known as 5’ cap. The 3’ end capped by 200 adenine ribonucleotides, also known as ploy-A-tail.
[8] Introns, noncoding segments in the pre-mRNA, are spliced out by spliceosome, which consists of proteins, snRNP and snRNA.
[9] tRNA functions as the delivery system of amino acids to ribosomes as proteins are synthesized. The molecule has a cloverleaf structure, carrying an anticodon and amino acid covalently boud to the 3’ end.
[10] RNA translation is always initiated with the start codon, 5’AUG3’ and terminates with stop codon.
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