Genetic Material BISC120 PDF

What is responsible for all this diversity? Genetic Material BISC120 Learning Objectives 1. Recall the organization of genetic material in the cell and how it is organized and distributed during mitosis. 2. Be familiar with DNAs structural components and their function. Genetic Material and E...

What is responsible for all this diversity? Genetic Material BISC120 Learning Objectives 1. Recall the organization of genetic material in the cell and how it is organized and distributed during mitosis. 2. Be familiar with DNAs structural components and their function. Genetic Material and Expression Figure 6.1b Genetic Material in the Cell Figure 12.3 Genetic Material in the Cell • All the DNA in a cell constitutes the cell’s genome • A genome can consist of a single DNA molecule (prokaryotes) or multiple DNA molecules (eukaryotes) • DNA molecules are packaged into chromosomes in cells • The DNA molecule of a chromosome carries several hundred to a few thousand genes Figure 12.3 Phases of the Cell Cycle Figure 12.6 Cell division, amirite? Continuity of life is based on the reproduction of cells, or cell division Figure 12.2 Why does genetic material become visible during division? Figure 12.3 Organization of Genetic Material During Cell Division In preparation for cell division, DNA is replicated and the chromosomes condense Image source: National Human Genome Research Institute Organization of Genetic Material During Cell Division • Each duplicated chromosome has two sister chromatids (joined copies of the original chromosome), attached along their lengths by cohesins • The centromere is the narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached Figure 12.4 Organization of Genetic Material During Cell Division • During cell division, the two sister chromatids of each duplicated chromosome separate and move into two nuclei • Once separate, the chromatids are called chromosomes. Figure 12.5 Organization of Genetic Material During Cell Division • Eukaryotic cell division consists of • mitosis, the division of the genetic material in the nucleus • cytokinesis, the division of the cytoplasm • Gametes are produced by a variation of cell division called meiosis (next week) • Meiosis yields non-identical daughter cells that have half as many chromosomes as the parent cell. Figure 12.5 How does DNA replication transmit genetic information? Figure 16.1b Learning Objectives 1. Recall the organization of genetic material in the cell and how it is organized and distributed during mitosis. 2. Be familiar with DNAs structural components and their function. Components of DNA • DNA is a polymer of nucleotides, each consisting of a nitrogenous base, a sugar, and a phosphate group Figure 16.5 Figure 5.1a Components of DNA • DNA is a polymer of nucleotides, each consisting of a nitrogenous base, a sugar, and a phosphate group • The nitrogenous bases can be adenine (A), thymine (T), guanine (G), or cytosine (C) • The composition and arrangement of nucleotides varies from one individual to the next • Almost like an individual code Figure 16.5 Structure of DNA • It was discovered that the number of adenine (A) and Thymine (T) bases are always equal to each other, and the number of Guanine (G) and Cytosine (C) bases are always equal to each other. Figure 16.5 Figure 16.6 Structural Model of DNA • Maurice Wilkins and Rosalind Franklin used a technique called X-ray crystallography to study molecular structure • Franklin produced a picture of the DNA molecule using this technique • Franklin’s images enabled James Watson and Francis Crick to deduce that DNA was helical • The pattern in the photo suggested that the DNA molecule was made up of two strands, forming a double helix History of Controversy https://sciencehistory.org/education/scientific-biographies/james-watson-francis-crick-maurice-wilkins-and-rosalind-franklin/ Double Helix • DNA molecules are made up of two strands, forming a double helix • Two outer sugar-phosphate backbones rotate around paired nitrogenous bases in the molecule’s interior. • Backbones are antiparallel (subunits run in opposite directions). Figure 16.07ba Nucleotide Pairing • Adenine (A) paired only with thymine (T), and guanine (G) paired only with cytosine (C) • Therefore, in any organism the amount of A = T, and the amount of G = C Figure 16.9 What if thymine and cytosine traded places? labxchange.org 5′ end 3′ end DNA nucleotide Sugar-phosphate backbone 3′ end Figure 16.07ab 5′ end @microbiologistlablife