Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Zinc finger nuclease wikipedia , lookup
DNA repair protein XRCC4 wikipedia , lookup
DNA sequencing wikipedia , lookup
Homologous recombination wikipedia , lookup
DNA profiling wikipedia , lookup
DNA replication wikipedia , lookup
DNA polymerase wikipedia , lookup
Microsatellite wikipedia , lookup
United Kingdom National DNA Database wikipedia , lookup
DNA: The Genetic Material CHAPTER 12 SECTION 1 Discovery of the Genetic Material Genetic information is carried on the chromosomes in eukaryotic cells Two main components of chromosomes are DNA and protein Which macromolecules—nucleic acid (DNA) or proteins—was the source of genetic information Fredrick Griffith (1928) Studied two strains of bacteria Streptococcus pneumoniae, which causes pneumonia. One strain that causes pneumonia is called the smooth (S) strain. The other is called the rough (R) strain. He found that one strain could be transformed, or changed into the other form. He injected the strains into lab mice and discovered that the R strain had changed into the S strain which caused the death of the mice When the S bacteria was killed, DNA was released. Some of the R bacteria incorporated this DNA into their cells and this changed the bacteria in S bacteria DNA Structure Nucleotides are the subunits of nucleic acids and consists of a five-carbon sugar, a phosphate group, and a nitrogenous base. The two nucleic acids found in living are DNA and RNA. DNA nucleotides contain the sugar deoxyribose, a phosphate and of four nitrogenous bases: Adenine (A), guanine (G), cytosine (C) and thymine (T) RNA contains the sugar ribose, a phosphate, and of four nitrogenous bases: adenine, guanine, cytosine and uracil Adenine and Guanine are double-ringed bases called purine bases Thymine, cytosine and uracil are single-ringed bases called pyrimidine bases The structure question Rosalind Franklin used x-ray diffraction data to help determine the structure of DNA DNA is a double helix, or twisted ladder shape, formed by two strands of nucleotides twisted around each other Watson and Crick Used Franklin’s data to determine the width of the helix and the spacing of the bases. Together they built a model of the double helix and discovered 3 important features: Two outside strands consist of alternating deoxyribose and phosphate Cytosine and quanine bases pair to each other by three hydrogen bonds Thymine and adenine bases pair to each other by two hydrogen bonds Top, a GC base pair with three hydrogen bonds. Bottom, an AT base pair with two hydrogen bonds. Non-covalent hydrogen bonds between the pairs are shown as dashed lines. Chromosome Structure Eukaryotic DNA is organized into individual chromosomes. The length of a human chromosome ranges from 51 million to 245 million base pairs. If a DNA strand 140 million nucleotides long was laid out in a straight line, it would be about 5 cm long. In order to fit into the nucleus of a eukaryotic cell, the DNA tightly coils around a group of beadlike proteins called histones The phosphate groups in DNA create a negative charge, which attracts the DNA to the positively charged histone proteins and forms a nucleosome The nucleosomes than group together into chromatin fibers, which super-coil to make up the DNA structure recognized as a chromosome