Part I-A: DNA and Genome Structure PDF

PART I-A 1. Structure of DNA molecule 2. Structure of viral, bacterial and eukaryotic genomes 1. STRUCTURE OF DNA MOLECULE Draw one nucleotide in your notebook Label parts as well as 3’ and 5’ ends (RNA only) (DNA only)  1 Which is the 5’ end? 2 DNA has...

PART I-A 1. Structure of DNA molecule 2. Structure of viral, bacterial and eukaryotic genomes 1. STRUCTURE OF DNA MOLECULE Draw one nucleotide in your notebook Label parts as well as 3’ and 5’ ends (RNA only) (DNA only)  1 Which is the 5’ end? 2 DNA has a major and minor groove. B-DNA has 10 pb per turn. 2. STRUCTURE OF VIRAL, BACTERIAL AND EUKARYOTIC GENOMES Viral Genomes Capsid Linear, dsDNA Bacterial Genomes (E. coli) Bacterial Genomes (E. coli)  Eukaryotic Genomes dsDNA housed in nucleus and mitochondria (chloroplast) histones and non-histone proteins  Eukaryotic Genomes Genes with introns NOTE: both are dsDNA.  Eukaryotic Genomes Abundant repetitive DNA Non- Genes repetitive DNA sequences (46.06%) Pseudogenes Mini- and Microsatellites Telomeres Nuclear Human Tandem Micro- Genome repeats satellites Minisatellites (7.47%) Satellites Centromeres Repetitive DNA sequences Class I Interspersed repeats (53.94%) repeats Class II (42.35%) repeats RNA genes Other (4.12%) Composite elements Eukaryotic Genomes Diploid  Eukaryotic Genomes Chromatin: DNA + protein Histones H1, 2 x [H2A, H2B, H3, H4] Positive charge Non-histone chromosomal proteins Scaffold proteins Kinetochore Telosome -or- shelterin When H1 is attached, it is called a chromatosome  Eukaryotic Genomes Heterochromatin vs Euchromatin Light bands (~90%): Euchromatin Open chromatin (relaxed DNA) Gene rich / Transcriptionally active Histones are heavily acetylated Loose H1 association Dark bands (~10%): Heterochromatin Closed chromatin Gene poor Remains condensed during interphase Tight H1 association Condensation of chromatin (eukaryotes) Transcriptionally active genes  Eukaryotic Genomes Chromosome territories and TADs TAD = ~ 1 Mb (several hundred Kb – 2 Mb) Changes in chromatin conformation and gene expression (eukaryotes) Epigenetics Epigenetics Non-sequence changes to the DNA molecule that impact gene expression: DNA methylation Histone Modification Nucleosome positioning Behaviors and the environment can impact our epigenome  Histone modification Histone modifications include: Acetylation Phosphorylation Methylation Ubiquitination DNA methylation: CpG Chromatin remodeling complexes can: Move nucleosomes Chemically alter histone tails Change type of histone An example on how to summarize information to study Also happens to be Q12 of the Study Guide Feature Virus E coli Eukaryotes DNA or RNA? DNA or RNA dsDNA dsDNA ss or ds? ss or ds Location of Inside capsid Cytoplasm (nucleoid region) Nucleus genome Relative size of 4 Kb – 2 Mb 100 Kb – 15 Mb 8 Mb – 900 Gb genome Chromosome Linear or circular Circular Nuclear genome: Linear structure mtDNA, cpDNA: Circular Ploidy 1n 1n 2n Presence of no no yes introns Presence of no very little abundant repetitive DNA Genome Histones, scaffold proteins, Nucleoprotein. NAPs + topoisomerases help kinetochore, telosome. associated Histones in some DNA viruses. achieve negative supercoiling. Chromatin (euchromatin, proteins heterochromatin) Most DNA viruses are Plasmids. Other? monopartite, most RNA viruses Most have a single Highly dynamic condensation are multipartite. chromosome. THANK YOU