Nucleic Acids -Evs

Nucleic Acids

The central dogma of molecular biology.

Types Of Nucleic acidsIn eukaryotic cells nucleic acids are either:Deoxyribose nucleic acids (DNA)Ribose nucleic acids (RNA)Messenger RNA (mRNA)Transfer RNA (tRNA)Ribosomal RNA (tRNA)

The nucleus contains the cells DNA (genome)RNA is synthesized in the nucleus and exported to the cytoplasmNucleusCytoplasm

Nucleotide StructureDespite the complexity and diversity of life the structure of DNA is dependent on only 4 different nucleotidesDiversity is dependent on the nucleotide sequenceAll nucleotides are 2 ring structures composed of:5-carbon sugar : b-D-ribose (RNA)b-D-deoxyribose (DNA)Base PurinePyrimidinePhosphate group A nucleotide WITHOUT a phosphate group is a NUCLEOSIDE

Nucleotide Structure - 1SugarsRiboseDeoxyriboseGeneric Ribose StructureN.B. Carbons are given numberings as a prime

Nucleotide Structure - 2Bases - PurinesAdenineGuanineAG

Nucleotide Structure - 3Bases - PyrimidinesThymineCytosine

Nucleotide Structure - 4Bases - PyrimidinesUracilThymine is found ONLY in DNA.In RNA, thymine is replaced by uracilUracil and Thymine are structurally similar

Nucleotide Structure - 4Phosphate GroupsPhosphate groups are what makes a nucleoside a nucleotidePhosphate groups are essential for nucleotide polymerizationBasic structure:

Nucleotide Structure - 4Phosphate GroupsNumber of phosphate groups determines nomenclatureMonophosphatee.g. AMPDiphosphatee.g. ADPFree = inorganic phosphate (Pi)Free = Pyro- phosphate (PPi)

Triphosphatee.g. ATPNucleotide Structure - 4Phosphate Groups

Nucleotide Structure - 4Base-Sugar-PO42- Monophosphate

Nucleotides arelinked byphosphodiesterbonds

Bases form a specific hydrogen bond patternDNA is double stranded

Watson and Crick

The strands of DNA are antiparallel

The strands are complimentary

There are Hydrogen bond forces

There are base stacking interactions

There are 10 base pairs per turn

Chargoffs rule

Properties of a DNA double helix

DNA is a Double-Helix

RNase P M1 RNATranscription of a DNA molecule results in a mRNA molecule that is single-stranded.

RNA molecules do not have a regular structure like DNA.

Structures of RNA molecules are complex and unique.

RNA molecules can base pair with complementary DNA or RNA sequences.

G pairs with C, A pairs with U, and G pairs with U.bulgeinternal loophairpin

Nucleic Acid StructureBase PairingRNA is [usually] single strandedBase pairing can occur in RNA but is usually within the same strand

In eukaryotes,genes contain exons (coding regions) and introns (non-coding regions).

Prokaryotic genes do not contain introns.

Functions of Functions of Nucleotides and Nucleic Acids

Nucleotide FunctionBuilding blocks for DNA and RNAIntracellular source of energy - Adenosine triphosphate (ATP)Second messengers - Involved in intracellular signaling (e.g. cyclic adenosine monophosphate [cAMP])Intracellular signaling switches (e.g. G-proteins)

*The nucleus contains the cells DNA, which makes up the genome.The nucleus is surrounded by a nuclear envelope, two membrane bilayersMolecules come into and out of the nucleus through nuclear poresThe inside of the nucleus is called the nucleoplasm.Chromatin is the name given to DNA complexed with proteins (histones)The nucleolus is a region where the DNA is concentrated for replication**FIGURE 8-4b Deoxyribonucleotides and ribonucleotides of nucleic acids. All nucleotides are shown in their free form at pH 7.0. The nucleotide units of DNA (a) are usually symbolized as A, G, T, and C, sometimes as dA, dG, dT, and dC; those of RNA (b) as A, G, U, and C. In their free form the deoxyribonucleotides are commonly abbreviated dAMP, dGMP, dTMP, and dCMP; the ribonucleotides, AMP, GMP, UMP, and CMP. For each nucleotide, the more common name is followed by the complete name in parentheses. All abbreviations assume that the phosphate group is at the 5 position. The nucleoside portion of each molecule is shaded in pink. In this and the following illustrations, the ring carbons are not shown.*FIGURE 8-4a Deoxyribonucleotides and ribonucleotides of nucleic acids. All nucleotides are shown in their free form at pH 7.0. The nucleotide units of DNA (a) are usually symbolized as A, G, T, and C, sometimes as dA, dG, dT, and dC; those of RNA (b) as A, G, U, and C. In their free form the deoxyribonucleotides are commonly abbreviated dAMP, dGMP, dTMP, and dCMP; the ribonucleotides, AMP, GMP, UMP, and CMP. For each nucleotide, the more common name is followed by the complete name in parentheses. All abbreviations assume that the phosphate group is at the 5 position. The nucleoside portion of each molecule is shaded in pink. In this and the following illustrations, the ring carbons are not shown.*******"Dictionary" of amino acid code words in mRNAs. The codons are written in the 53 direction. The third base of each codon (in bold type) plays a lesser role in specifying an amino acid than the first two. The three termination codons are shaded in pink, the initiation codon AUG in green. All the amino acids except methionine and tryptophan have more than one codon. In most cases, codons that specify the same amino acid differ only at the third base.*