* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Pierce chapter 10
DNA paternity testing wikipedia , lookup
Zinc finger nuclease wikipedia , lookup
DNA sequencing wikipedia , lookup
Mitochondrial DNA wikipedia , lookup
Epigenetics in learning and memory wikipedia , lookup
History of RNA biology wikipedia , lookup
Comparative genomic hybridization wikipedia , lookup
DNA methylation wikipedia , lookup
Epigenetics wikipedia , lookup
Human genome wikipedia , lookup
Genomic library wikipedia , lookup
Holliday junction wikipedia , lookup
Designer baby wikipedia , lookup
DNA profiling wikipedia , lookup
Nucleic acid tertiary structure wikipedia , lookup
No-SCAR (Scarless Cas9 Assisted Recombineering) Genome Editing wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Nutriepigenomics wikipedia , lookup
SNP genotyping wikipedia , lookup
Cancer epigenetics wikipedia , lookup
DNA polymerase wikipedia , lookup
DNA damage theory of aging wikipedia , lookup
Genetic engineering wikipedia , lookup
Gel electrophoresis of nucleic acids wikipedia , lookup
Genealogical DNA test wikipedia , lookup
United Kingdom National DNA Database wikipedia , lookup
Microsatellite wikipedia , lookup
Molecular cloning wikipedia , lookup
Cell-free fetal DNA wikipedia , lookup
DNA nanotechnology wikipedia , lookup
DNA vaccination wikipedia , lookup
Bisulfite sequencing wikipedia , lookup
Microevolution wikipedia , lookup
Point mutation wikipedia , lookup
Vectors in gene therapy wikipedia , lookup
Epigenomics wikipedia , lookup
Primary transcript wikipedia , lookup
Extrachromosomal DNA wikipedia , lookup
DNA supercoil wikipedia , lookup
Non-coding DNA wikipedia , lookup
Cre-Lox recombination wikipedia , lookup
Helitron (biology) wikipedia , lookup
Therapeutic gene modulation wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Nucleic acid double helix wikipedia , lookup
History of genetic engineering wikipedia , lookup
Chapter 10 – DNA: The Chemical Nature of the Gene Early DNA studies • Johann Friedrich Meischer – late 1800s – Studied pus (contains white blood cells) – Isolated nuclear material • Slightly acidic, high phosphorous content • Consisted of DNA and protein – Called in “nuclein” – later renamed nucleic acid • By late 1800s – Chromatin thought to be genetic material, but protein or DNA? Early DNA studies • Tetranucleotide theory – DNA made up of 4 different nucleotides in equal amounts • Nucleotide – pentose sugar, phosphate group, nitrogenous base – Under this assumption, DNA doesn’t have the variety needed for genetic material • Protein composed of 20 different amino acids; complex structures • Erwin Chargaff 1940s – Base composition of DNA among different species had great variety, but consistent within a single species – Adenine amount roughly equals thymine amount; guanine amount roughly equals cytosine amount Fred Griffith 1928 • Worked with different strains of the bacteria Streptococcus pneumoniae • Transformation – bacteria acquired genetic information from dead strain which permanently changed bacteria Oswald Avery published 1944 • Based on Griffith’s findings • What was transforming principle – protein, RNA, or DNA? • Conclusion: when DNA is degraded, no transformation occurs; DNA genetic material Alfred Hershey and Martha Chase 1952 • DNA or protein genetic material? • Conclusion: phage injects DNA, not protein, into bacteria; DNA genetic material Maurice Wilkins and Rosalind Franklin early 1950s • Worked independently on X ray crystallography • Diffraction pattern gives information on molecular structure James Watson and Francis Crick • Published paper detailing DNA structure in 1953 – Based on published data and unreleased information • 1962 won Nobel prize along with Maurice Wilkins Heinz Fraenkel Conrat and Bea Singer 1956 • RNA can serve as genetic material in viruses • Created hybrid virsuses; progeny particles were of RNA type Nucleotide structure • Pentose (5 carbon) sugar – 1′ to 5′ “′” refers to carbon in sugar (not base) – RNA – ribose • -OH at 2′ carbon • Less stable – DNA – deoxyribose • -H at 2′ carbon • Phosphate group – Phosphorous and 4 oxygen – Negatively charged – Attached to 5′ carbon Nucleotide structure • Nitrogenous base – Covalently bonded to 1′ carbon – Purine • Double-ringed; six- and five-sided rings • Adenine • Guanine – Pyrimidine • Single-ringed; six-sided ring • Cytosine • Thymine (DNA only) • Uracil (RNA only) Nucleotide structure • Nucleoside – Base + sugar • Nucleotide – Nucleoside + phosphate Polynucleotide strands • Nucleotides covalently bonded – phosphodiester bonds – Phosphate group of one nucleotide bound to 3′C of previous sugar • Backbone consists of alternating phosphates and sugars – Always has one 5′ end (phosphate) and one 3′ end (sugar –OH) DNA double helix • 2 antiparallel strands with bases in interior • Bases held together by hydrogen bonds – 2 between A and T; 3 between G and C • Complementary base pairing; complementary strands • B-DNA Helices – Watson and Crick model – Shape when plenty of water is present – Right hand/clockwise turn; approx 10 bases per turn • A-DNA – Form when less water is present; no proof of existence under physiological conditions – Shorter and wider than B form – Right hand/clockwise turn; approx 11 bases per turn • Z-DNA – Left hand/counterclockwise turn – Approx 12 bases per turn – Found in portions with specific base pair sequences (alternating G and C) – Possible role in transcription regulation? Genetic implications • Watson and Crick indicated structure revealed mode of replication – H bonds break and each strand serves as a template for new strand due to complementary base pairing • Central dogma – Replication • DNA from DNA – Transcription • RNA from DNA – Translation • Polypeptide/protein from mRNA Special structures • Sequences with a single strand of nucleotides may be complementary and pair – forming doublestranded regions • Hairpin – Region of complementary bases form base; loop formed by unpaired bases in the middle • Stem – No loop of hairpin Special structures • Cruciform – Double-stranded – Hairpins form on both strands due to palindrome sequences • Complex structures can form within a single strand DNA methylation • Addition of methyl groups to certain bases • Bacteria is frequently methylated – Restriction endonucleases cleave unmethylated sequences • Amount of methylation varies among organisms – Yeast – 0% – Animals – 5% – Plants – approx 50% • Methylation in eukaryotic cells is associated with gene expression – Methylated sequences are low/no transcription Bends in DNA • Series of 4 or more A-T base pairs cause DNA to bend – Affects ability of proteins to bind to DNA’ affects transcription • SRY gene – Produces SRY protein • Binds to certain DNA sequences; bends DNA – Facilitates binding of transcription proteins; activates genes for male traits