1. What must DNA do? 1.Replicate to be passed on to the next generation 2.Store information 3.Undergo mutations to provide genetic diversity

2. DNA structure: A review Double-stranded helix Composed of repeating nucleotides (made of a pentose sugar, phosphate and a nitrogenous base) Sugar and phosphate make up the backbone while the bases make up the “rungs” of the ladder Bases have complementary pairing with cytosine (C) pairs with guanine (G) and adenine (A) pairs with thymine (T)

3. DNA structure

4. How does DNA replicate? The two strands unwind by breaking the H bonds Complementary nucleotides are added to each strand by DNA polymerase Each new double-stranded helix is made of one new strand and one old strand (semiconservative replication) The sequence of bases makes each individual unique

5. DNA replication

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7. RNA structure and function Single-stranded Composed of repeating nucleotides Sugar-phosphate backbone Bases are A, C, G and uracil (U) Three types of RNA –Ribosomal (rRNA): joins with proteins to form ribosomes –Messenger (mRNA): carries genetic information from DNA to the ribosomes –Transfer (tRNA): transfers amino acids to a ribosome where they are added to a forming protein

8. RNA structure

9. Sum It Up!!! Make a Venn Diagram in your notes to compare and contrast DNA and RNA.

10. Comparing DNA and RNA Similarities: –Are nucleic acids –Are made of nucleotides –Have sugar-phosphate backbones –Are found in the nucleus Differences: –DNA is double stranded while RNA is single stranded –DNA has T while RNA has U –RNA is also found in the cytoplasm as well as the nucleus while DNA is not

11. Proteins: A review Composed of subunits of amino acids Sequence of amino acids determines the shape of the protein Synthesized at the ribosomes Important for diverse functions in the body including hormones, enzymes and transport Can denature causing a loss of function

12. Proteins: A review of structure

13. 2 steps of gene expression 1.Transcription – DNA is read to make a mRNA in the nucleus of our cells 2.Translation – Reading the mRNA to make a protein in the cytoplasm

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15. Overview of transcription and translation Bio

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17. The genetic code Made of 4 bases Bases act as a code for amino acids in translation Every 3 bases on the mRNA is called a codon that codes for a particular amino acid in translation

18. What did we learn from the human genome project (HGP)? Humans consist of about 3 billion bases and 25,000 genes Human genome sequenced in 2003 There are many polymorphisms or small regions of DNA that vary among individuals were identified Genome size is not correlated with the number of genes or complexity of the organisms

19. What is the next step in the HGP? Functional genomics Understanding how the 25,000 genes function Understanding the function of gene deserts (82 regions that make up 3% of the genome lacking identifiable genes) Comparative genomics Help understand how species have evolved Comparing genomes may help identify base sequences that cause human illness Help in our understanding of gene regulation

20. How can we modify a person’s genome? Gene therapy - insertion of genetic material into human cells to treat a disorder –Ex vivo therapy – cells are removed for a person altered and then returned to the patient –In vivo therapy – a gene is directly inserted into an individual through a vector (e.g. viruses) or directly injected to replace mutated genes or to restore normal controls over gene activity Gene therapy has been most successful in treating cancer

21. Ex vivo gene therapy

22. DNA technology terms Genetic engineering – altering DNA in bacteria, viruses, plants and animal cells through recombinant DNA techonology Recombinant DNA – contains DNA from 2 or more different sources Transgenic organisms – organisms that have a foreign gene inserted into them Biotechnology – using natural biological systems to create a product or to achieve an end desired by humans