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DNA Structure and Protein Synthesis for Beginners

Explore the basics of genetics, from the composition of DNA to protein synthesis. Learn about DNA replication, transcription, translation, and the genetic code. Discover how genes work in this easy-to-understand guide.

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DNA Structure and Protein Synthesis for Beginners

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  1. How Genes Work

  2. Structure of DNA • DNA is composed of subunits – nucleotides • Three parts • Deoxyribose (5-carbon sugar) • Phosphate group • Nitrogen base – 2 major types • Purines (adenine (A) and guanine (G)) • Pyrimidines (cytosine (C) and thymine (T))

  3. Structure of DNA • DNA is a twisted ladder • Sides of ladder • Deoxyribose • Phosphate • Rungs (inside) of ladder • Nitrogen base • Bases in the middle of the DNA match up using Chargaff’s base pairing rules • A=T • C=G

  4. DNA replication • Replication – process of copying DNA • Strands are complementary • Process of replication – complex, requires several enzymes • Preserves the sequence of bases • Mutagens – causes mutations

  5. Protein synthesis (building proteins) • DNA  RNA  protein • RNA is chemically similar to DNA • Two exceptions • Ribose (an additional oxygen atom) • Thymine is replaced by uracil (U) • Occurs in three forms • Transcription uses messenger RNA (mRNA) • mRNA copies the nucleotides • tRNA • rRNA

  6. Protein synthesis (building proteins) • Two stages • Transcription – copying of genetic information • RNA polymerase “unwinds” DNA • Base pairing take place (A=U, C=G) • There is NO thymine (T) in RNA • Creates mRNA (messenger RNA) in the nucleus • mRNA enters cytoplasm • Finds ribosomes

  7. Protein synthesis (building proteins) • Two stages (con’t) • Translation • rRNA (ribosomal) translate mRNA codons into anticodons (more base-pairing) • A=U • C=G • tRNA (transfer) brings amino acids to ribosomes

  8. The Genetic Code • Codon – three nucleotides in mRNA specify a particular amino acid • Order of bases determines order of amino acids • Order of amino acids determines structure and function of protein • 64 possible codons, 20 amino acids, 3 “stop” codons

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