DNA: The Hereditary Material Lecture Notes PDF

DNA: The Hereditary Material Composition BIOL 111 Nucleic acid is composed of a long polymer of nucleotides. Each nucleotide comprises a nitrogenous base, a phosphate group, and a sugar molecule. Nitrogenous base comes in two types: purines (adenine and guanine) and pyrimidines (thymine, cytosine, a...

DNA: The Hereditary Material Composition BIOL 111 Nucleic acid is composed of a long polymer of nucleotides. Each nucleotide comprises a nitrogenous base, a phosphate group, and a sugar molecule. Nitrogenous base comes in two types: purines (adenine and guanine) and pyrimidines (thymine, cytosine, and uracil) Two types of nucleic acid: DNA and RNA. DNA is found mainly in the nucleus and a small part in the mitochondria. RNA is found in the cytoplasm and the nucleus. Both contain the purine bases adenine, guanine, and the pyrimidine base cytosine, but DNA has thymine, and RNA has uracil. DNA: The Hereditary Material BIOL 111 BIOL 111 Composition SUGARS NITROGENOUS BASES 5' end Pyrimidines 5'C Deoxyribose (in DNA) Ribose (in RNA) (c) Nucleoside components 3'C Nucleoside Nitrogenous base DNA Cytosine (C) 5'C Thymine (T, in DNA) Uracil (U, in RNA) mRNA Phosphate group 5'C 3'C Purines 3'C Sugar (pentose) NUCLEUS (b) Nucleotide CYTOPLASM 3' end mRNA (a) Polynucleotide, or nucleic acid Adenine (A) Ribosome Guanine (G) Polypeptide DNA: The Hereditary Material Structure BIOL 111 BIOL 111 DNA molecule comprises two polynucleotide strands arranged as a double helix. The two strands have opposite orientations in which the 5’ end of one strand is opposite the 3’end of the other. The two strands are held together by hydrogen bonds between the nitrogenous bases. DNA: The Hereditary Material Structure BIOL 111 Chromosome Structure BIOL 111 In the nucleus, DNA is packaged into chromosomes. DNA undergoes several levels of coiling and folding to form the chromosomes. The first level of folding requires histone proteins. Other proteins are involved in this process. In humans, Somatic cells have 23 pairs (46 individuals) of chromosomes. Germline cells have 23 individual chromosomes. Chromosome Structure BIOL 111 Chromosome Structure BIOL 111 Types of DNA Sequences In the cell, DNA is categorized into: Nuclear DNA Coding regions (genes) Non-coding regions (extragenic DNA) Mitochondrial DNA Types of DNA Sequences Nuclear DNA Linear chromosomes Mitochondrial DNA circular Types of DNA Sequences Nuclear DNA  3X109 base pair of DNA  Contains ~ 20,000 (~2% of the genome)  Diploid in somatic cells  Diploid: two copies Mitochondrial DNA  16,600 base pair of DNA  Contains 37 genes  Polyploid in a mitochondrion  Polyploid: multiple copies Types of DNA Sequences Nuclear DNA