Chapter 11 An Introduction to Human Genome Forensic

Chapter 11: An Introduction to Human Genome Forensic Biology by Richard Li

Structure & Properties A linear polynucleotide consisting of four types of monomeric nucleotides Each nucleotide contains: Deoxyribose, a Nitrogenous base, and a Phosphate group Four bases: Adenine (A) Cytosine (C) Guanine (G) Thymine (T) Forensic Biology by Richard Li 2

Structure & Properties The Double Helix Watson & Crick B-Form of DNA- right handed turns and two grooves that spiral (major & minor) Stabilized by chemical interactions A always pairs with T C always pairs with G Forensic Biology by Richard Li 3

Structure & Properties Denaturation Melting curve Melting Temperature Renaturation (reannealing) Euchromatin Heterochromatin Forensic Biology by Richard Li 4

Structure & Properties Human Chromosomes Short arm (p) & Long arm (q) Centromeres- DNA sequences found near the point of attachment of mitotic or meiotic spindle fibers Telomeres- ends of chromosomes Forensic Biology by Richard Li 5

Human Chromosomes Gametes- spermatozoa and ova ▪ Haploid ▪ 22 autosomes + 1 sex chromosome Somatic Cells- most other cells except reproductive ▪ Diploid ▪ Two copies of each autosome + 2 sex chromosomes= 46 Forensic Biology by Richard Li 6

Human Nuclear Genome Human genome one set of 23 chromosomes Contains biological information to perform biological functions Nuclear and Mitochondrial Genomes 3. 2 billion base pairs 30, 000 – 40, 000 genes ▪ Encode information for the synthesis of proteins Human Genome Project (1990)▪ 2. 6 billion base pairs (80%) completed Forensic Biology by Richard Li 7

Human Nuclear Genome Intergenic Non-coding Sequences 60% of human genome sequence Repetitive DNA ▪ Genome-wide (interspersed repeats) ▪ SINEs, LTR ▪ Tandemly repeated DNA ▪ ▪ Repeat units that are placed next to each other in an array Satellite DNA Minisatellites Microsatellites Forensic Biology by Richard Li 8

Human DNA Polymorphisms Differences between individual genomes Sequence polymorphism Length polymorphism DNA markers Genetic mapping Forensic DNA profiling Forensic Biology by Richard Li 9

Human DNA Polymorphisms Majority are Single-nucleotide polymorphisms (SNP) Alleles Homozygous Heterozygous Genotype- combination of alleles at any given locus DNA profile Forensic Biology by Richard Li 10