DNA Structure and Function PDF

Course Outline 1. Introduction to Biotechnology 2. Fundamental principles of biotechnology 3. Genetic Engineering Techniques 4. Omics sciences 5. Biotechnology Applications Biotechnology Fundamental Principles...

Course Outline 1. Introduction to Biotechnology 2. Fundamental principles of biotechnology 3. Genetic Engineering Techniques 4. Omics sciences 5. Biotechnology Applications Biotechnology Fundamental Principles of Biotechnology Biotechnology  Deoxyribonucleic acid - DNA 1953 - At King’s College London, Rosalind Franklin obtained images of DNA using X-ray crystallography. Franklin’s images allowed James Watson and Francis Crick to create their famous two-strand, or double-helix, model. Deoxyribonucleic acid is a molecule composed of 2 chains that coil around each other to form a double helix. Nucleotide Biotechnology Biotechnology  Watson-Crick Model of DNA The DNA structure consists of: A. Right-handed double helix B. The hydrophilic backbone of alternating deoxyribose and phosphate groups faces outwards and interacts with H2O C. The purine and pyrimidine bases, which are hydrophobic and relatively insoluble in water, stacked inside the double helix stabilized by hydrophobic interactions and perpendicular to the long axis Biotechnology  Watson-Crick Model of DNA D. Base pairing occurs in which a nucleobase in one strand is paired in the same plane with a base on the other strand due to hydrogen bond interactions. § Purine pairs with a pyrimidine - A pair with T - C pair with G Biotechnology  Watson-Crick Model of DNA A and G are long (double-ring purines) C and T are short (single-ring pyrimidines) Need one long and one short nucleotide per pair C-G has three hydrogen bonds A-T has two hydrogen bonds Biotechnology  Watson-Crick Model of DNA F. The DNA strands interact in an antiparallel orientation with the sequences being complementary to one another 5’-ATGCTA-3’ 3’-TACGAT-5’ G. The stacked bases are 3.4 Å apart H. The base pairing of the two strands creates a major groove and a minor groove on the surface of the duplex I. Each turn of the helix (measured from one minor groove to the next minor groove) § Includes 10.5 base pairs stacked § Covers 36 Å Biotechnology Biotechnology What is Gene and Genome? Biotechnology  Gene and Genome Genes are stretches of information in the sequence that encodes for a particular function (usually a particular protein, but sometimes also an RNA sequence) About 20,000 genes in humans Typically, 1000s of nucleotides long Genes can be expressed (use to make proteins) or repressed (not used) Regions of DNA are divided into coding and non-coding segments Over 50% of human DNA is non-coding Biotechnology Biotechnology  Genes are organized in the large-scale structure of the DNA in the nucleus The complete set of genes or genetic material present in a cell or organism à Genome Biotechnology  In bacteria, genome usually circular The genome in eukaryotes is organized into chromosomes Each chromosome is a separate DNA molecule Human cells contain 46 chromosomes (23 each from mother and father) Chromosomes are extended and replicated during interphase portion of the cell cycle → extended allows for gene expression Chromosomes are condensed, visible with light during cell division (M phase) DNA wraps around protein “spools” to form nucleosomes Nucleosomes are made of histone proteins Biotechnology Biotechnology