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DNA, Genes and Genetics

DNA, Genes and Genetics. What is DNA?. - DNA Stands for D eoxyribo N ucleic A cid -DNA is the hereditary material inherited from past generations -The vast majority ( >99%) of your DNA is in the nucleus of your cells. DNA Structure.

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DNA, Genes and Genetics

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  1. DNA, Genes and Genetics

  2. What is DNA? -DNA Stands for DeoxyriboNucleic Acid -DNA is the hereditary material inherited from past generations -The vast majority ( >99%) of your DNA is in the nucleus of your cells

  3. DNA Structure -DNA’s structure is known as a double helix. (Think of a twisted ladder) -The helix is composed of two strands -The sides of the ladder (red in the picture) are composed of alternating deoxyribose sugar and phosphate molecules -The rungs of the ladder are composed of nucleotides held together by hydrogen bonds

  4. Nucleotides Adenine and guanine are known as purines Cytosine and thymine are known as pyrimidines A always binds to TC always binds to G

  5. Watson and Crick Francis Crick James Watson • “Discovered” the structure of DNA in 1953 • Used the knowledge of many other scientists to determine the structure • Awarded the Nobel prize in 1962 for DNA’s structure*

  6. What are Genes? Genes are segments of DNA responsible for the production of a functional protein. Every person has two copies of each gene,one inherited from each parent. Genes are responsible for your traits! Ex. widow’s peak, skin tone, etc Environment can be a factor in traits as well*

  7. Chromosomes • Chromosomes are compact molecules of DNA • A human set of chromosomes contains 23 pairs • 23rd pair are your sex chromosomes • Karyotype

  8. Sex chromosome abnormalities • XXX – Triple X syndrome (1 in 1000) -little to no effect • XXY – Klinefelters syndrome (1 in 1000) -often infertile, taller, slight reading/ learning impairment, increased breast tissueXYY – XYY syndrome (1 in 1000) -increased growth velocity -severe acne? -slight developmental delays (reading and writing)

  9. So how we get from DNA to Protein?

  10. Transcription • DNA is copied into messenger RNA (mRNA) by an enzyme called RNA polymerase in the nucleus • RNA is identical to DNA except Thymine (nucleotide) is replaced by Uracil • RNA is single stranded

  11. Transcription

  12. Translation • mRNA is then exported to the cytoplasm and processed further by other enzymes to remove the “junk” DNA called introns • The final mRNA is transported to ribosomeswhere translation occurs. • Ribosomes read the mRNA in multiples of 3 nucleotides called codons • For example: 5’ AUGCCCUCAGAG3’

  13. Codon Table AUG (Methionine) -required to START translation AUG, AUA, and GUA -causes the protein to STOP being translated

  14. Translation • Each codon signals the cell to retrieve and add an amino acid to a growing chain of amino acids using transfer RNA (tRNA).

  15. AA sequence = Protein! • Once the entire mRNA sequence is read and translated into amino acids the chain of AA’s is released • This chain of AA’s folds and contorts into a structure called its tertiary structure* Finally a functional protein!

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