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Structure & Function of DNA. DNA and RNA are nucleic acids that consist of long chains of nucleotides. The nucleotides have three parts; Phosphate Nitrogen Sugar base. DNA forms a double helix. In DNA there are four different nucleotides, each with a different nitrogen base.
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DNA and RNA are nucleic acids that consist of long chains of nucleotides • The nucleotides have three parts; • Phosphate • Nitrogen Sugar • base
In DNA there are four different nucleotides, each with a different nitrogen base. Adenine always binds with Thymine Guanine always binds with Cytosine This pattern is called complementary base pairing In RNA thymine is replaced by uracil
The process of rewriting the instructions from a DNA molecule to an RNA molecule is called transcription Transcription is based on complementary base pairing
The process of assembling a protein from the instructions in messenger RNA is called translation
Translation is based on the Genetic Code, which is the same for all organisms
Three consecutive nucleotides (nitrogen bases) of a mRNA molecule are called a codon Each codon is the instructions to add one specific amino acid to the protein
The Genetic Code is the list of all possible codons and the amino acid each one codes for There are 20 amino acids and 64 codons
Sickle cell disease is caused by a mutation in only one nucleotide of the DNA
Sickle cell disease (sickle cell anemia) is caused by an abnormal type of hemoglobin called hemoglobin S. • Hemoglobin is a protein inside red blood cells that carries oxygen. • Hemoglobin S changes the shape of red blood cells, especially when the cells are exposed to low oxygen levels. • The red blood cells become shaped like crescents or sickles.
The fragile, sickle-shaped cells deliver less oxygen to the body's tissues. • They can also get stuck more easily in small blood vessels, and break into pieces that interrupt healthy blood flow. • Sickle cell anemia is inherited from both parents. If you inherit the hemoglobin S gene from one parent and normal hemoglobin (A) from your other parent, you will have sickle cell trait. • People with sickle cell trait do not have the symptoms of sickle cell anemia.
Genetic Transformation • Host Organism = Escherichia coli (E. coli) • Bacteria contain one large chromosome and one or more small, circular pieces of DNA calledplasmids that often contain genes for traits that increase the chance of survival. • Bacteria can transfer plasmids back & forth in nature, and share these beneficial genes.
Human cell Isolate DNAfrom twosources 1 Bacterial cell DNA Cut bothDNAs 2 Plasmid DNAfragments Gene V Othergenes Gene V Mix the DNAs and join them together 3 Recombinant DNA plasmids Bacteria take up recombinant plasmids 4 Recombinant bacteria Clone the bacteria 5 Bacterial clones Find the clone with gene V 6 Grow bacteria and isolate protein V 7 Figure 12.9 Protein V
Genetic Transformation • The jellyfish, Aequorea victoria, has a gene that produces a Green Fluorescent Protein or GFP that glows green. • GFP has been inserted into a plasmid called pGLO. • We will attempt to genetically transform the • E. coli so that they will glow green.
pGLO Plasmid • The pGLO plasmid contains; • Green Fluorescent Protein gene • Beta-lactamase gene • Beta-lactamase is a protein secreted • by bacteria that inactivates ampicillin • 3. Previously contained genes that make digestive enzymes to breakdown the sugar arabinose
Gene Regulation System • The genes to produce these arabinose-digesting enzymes are only turned on when arabinose is present. • When arabinose runs out or is absent the genes are turned off and do not make the enzymes. • This is a Gene Regulation System
Gene Regulation System • When the pGLO plasmid is produced, the gene for GFP replaces some of the genes for the arabinose-digesting enzymes. • So, when arabinose is present the GFP gene is turned on and GFP is produced. • When arabinose is absent the GFP gene is turned off and no GFP is produced.
