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Understanding DNA Structure, Replication, Transcription, Translation, and Mutation Processes

This guide explores crucial aspects of DNA, including its structure as a double helix made of nucleotides with specific base pairing rules. Learn about DNA replication, where enzymes like DNA polymerase ensure accurate copying. Discover transcription, which converts DNA to mRNA, and translation, where mRNA is transformed into proteins through codons. We also cover gene expression regulation via promoters and operators, the importance of mRNA processing, and types of mutations like point mutations and frameshift mutations, emphasizing their roles in genetic variations.

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Understanding DNA Structure, Replication, Transcription, Translation, and Mutation Processes

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Presentation Transcript

  1. Unit 6 DNA

  2. Griffith Experiment

  3. DNA Structure • DNA is a polymer made of monomers called nucleotides • Each nucleotide is made of: • A phosphate group • Deoxyribose (sugar) • Nitrogen containing base

  4. DNA Structure • DNA is in the shape of a double helix • Each nucleotide is paired

  5. Types of Nucleotides • C – Cytosine Pyrimidines • T – Thymine • A – Adenine Purines • G – Guanine

  6. Base-Pairing Rules • Nucleotides always pair in the same way • Thymine (T) always pairs with Adenine (A) • Cytosine (C) always pairs with Guanine (G) • Ex. TTACGTAG AATGCATC

  7. DNA Replication • Replication is a process by which DNA is copied • Occurs during the S stage of the cell cycle

  8. DNA Replication • Enzymes are responsible for splitting and copying DNA • DNA polymerase- enzyme that binds DNA strands together

  9. DNA _________ Replication • Steps of Replication: • DNA strand is unzipped • Free nucleotides bind to each template strand • Two identical DNA strands are formed

  10. DNA Transcription • Transcription is the process of copying a sequence of DNA into a message called RNA • RNA is a temporary copy of DNA • Three types of RNA: • mRNA- message • rRNA- forms part of ribosomes • tRNA- transfers amino acids to help make proteins

  11. DNA Transcription Transcription Animation • Steps of transcription: • Gene is recognized, DNA unwinds • RNA strand binds to template strand - GC, TA, AU (not T) • Completed RNA strand separates

  12. DNA Translation • Translation- process converts, mRNA message into a polypeptide • Polypeptides make up proteins • Codon- 3 nucleotide sequence that codes for an amino acid

  13. DNA Translation

  14. Steps of Translation The start mRNA codon attracts a complimentary tRNAanticodon Each amino acid is added to the next tRNA Process continues until a stop codon is reached. Protein is then released

  15. Gene Expression • Genes can make a lot of protein, little, or none • Transcription is controlled by promoters and operators • Promoter- DNA segment that allows a gene to be transcribed • Operator- DNA segment turns a gene “on” or “off”

  16. Gene Expression • Operon- • region of DNA that includes a promoter, operator and genes that code for certain proteins

  17. mRNA Processing • Sometimes pieces of mRNA are not needed • Introns are removed • A cap and tail are added • Molecule joins together

  18. Mutations • mutation- change in an organism’s DNA • Single gene mutations usually occur in replication • Mutations affecting a group of genes happen in meiosis

  19. Mutations • Types of mutations: • Point mutation- one nucleotide is substituted for another • Frameshift mutation • Insertion- addition of a nucleotide • Deletion- removal of a nucleotide • Gene duplication • Gene translocation

  20. Point mutation Gene duplication Frameshift Translocation

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