Nucleic Acids PDF

🧬 Nucleic acids Nucleic acids are polymers specialized for the storage, transmission, and use of genetic information. two types of nucleic acids—DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) Monomers: nucleotides...

🧬 Nucleic acids Nucleic acids are polymers specialized for the storage, transmission, and use of genetic information. two types of nucleic acids—DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) Monomers: nucleotides Transmit hereditary information Determine what proteins a cell manufactures A nucleotide has three components: a nitrogen-containing (nitrogenous) base, Pyrimidine - a sixmembered single-ring structure Purine - fused double-ring structure a pentose sugar, ( are a type of monosaccharide that contain five carbon atoms in their molecular structure) deoxyribose - DNA Nucleic acids 1  ribose - RNA (differs by the absence of one oxygen atom) one to three phosphate groups Nucleosides - molecules consisting of a pentose sugar and a nitrogenous base— but no phosphate group Nucleoside monophosphates - nucleotides that make up nucleic acids contain just one phosphate group Nucleic acids 2  Transesterification - is a chemical reaction that involves the exchange of the alkoxy group of an ester with the alkoxy group of an alcohol. BETWEEN the 3′ — OH on the sugar of the existing chain and the alpha (first) phosphate of the incoming nucleoside triphosphate Nucleic acids 3  Nucleotides join together through phosphodiester linkages between the 5' and 3' carbon atoms to form nucleic acids. The 3' -OH of the sugar group forms a bond with one of the negatively charged oxygens of the phosphate group attached to the 5' carbon of another sugar. When the two nucleotides join, they release a small molecule called pyrophosphate (which is made of two phosphate groups). This release of pyrophosphate gives off energy, which helps the reaction happen. Nucleic acids 4  💡 An ester bond (or ester linkage) is a type of covalent bond formed between an alcohol and a carboxylic acid Oligonucleotides (relatively short, with about 20 nucleotide monomers) include RNA molecules that function as “primers” to begin the duplication of DNA; RNA molecules that regulate the expression of genes; and synthetic DNA molecules used for amplifying and analyzing other, longer nucleotide sequences. Polynucleotides, more commonly referred to as nucleic acids, include DNA and some RNA. Polynucleotides can be very long, and indeed are the longest polymers in the living world. Some DNA molecules in plants and animals contain hundreds of millions of nucleotides. Base pairing occurs in both DNA and RNA Nucleic acids 5  RNA include uracil (U) instead of thymine. principle of complementary base pairing DNA RNA thymine and adenine pair A-U (T-A) C-G cytosine and guanine pair (C-G) held together primarily by hydrogen bonds This attraction is not as strong as a covalent bond Nucleic acids 6  RNA Even though RNA is generally single-stranded, base pairing can occur between different regions of the molecule. Complementary base pairing can also take place between ribonucleotides in RNA and deoxyribonucleotides in DNA. 💡 Adenine in an RNA strand can pair either with uracil (in another RNA strand) or with thymine (in a DNA strand). Simularly adenine in DNA can pair either with thymine (in the complementary DNA strand) or with uracil (in RNA). Nucleic acids 7  DNA Two separate polynucleotide strands of the same length held together by hydrogen bonds between base pairs. - t twists into a double helix. The key differences among DNA molecules are their different nucleotide base sequences. Nucleic acids 8  DNA carries information and is expressed through RNA DNA transmits information in two ways: DNA can be reproduced exactly. This process, called DNA replication, is done by polymerization using an existing strand as a base-pairing template. Certain DNA sequences can be copied into RNA, in a process called transcription. The nucleotide sequence in the RNA can then be used to specify a sequence of amino acids in a polypeptide chain, in the process called translation. The overall process of transcription and translation is called gene expression. Nucleic acids 9  3′-AGTCGT-5′ - RNA with the sequence 5′-UCAGCA-3′ 1. DNA replication and transcription depend on the base-pairing properties of nucleic acids Nucleic acids 10  2.. The entire DNA molecule is replicated. The complete set of DNA in a living organism is called its genome. However, not all of the information in the genome is needed at all times and in all tissues, and only small sections of the DNA are transcribed into RNA molecules (Figure 4.7B). The sequences of DNA that are transcribed into RNA are called genes. 💡 Each somatic cell of your body normally has 23 pairs of chromosomes The X bears about 1,600 genes with varied functions. But the Y has hardly any genes; maybe 50, and only 27 of these are in the male-specific part of the Y. Nucleic acids 11