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Molecular Genetics

Molecular Genetics. DNA. Deoxyribonucleic acid A double stranded helix that is made of nucleotides Stores our genetic information Can never leave the nucleus. A DNA nucleotide. There are four different bases that make up DNA DNA has four complementary bases Cytosine – guanine

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Molecular Genetics

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  1. Molecular Genetics

  2. DNA • Deoxyribonucleic acid • A double stranded helix that is made of nucleotides • Stores our genetic information • Can never leave the nucleus

  3. A DNA nucleotide • There are four different bases that make up DNA • DNA has four complementary bases • Cytosine – guanine • Adenine - thymine

  4. DNA – the double helix Strong covalent bonds • Theses nucleotides join together to make the double stranded DNA. • Watson and Crick were the two scientists who discovered the DNA molecule Weak hydrogen bonds

  5. DNA Replication • Making another copy of DNA • Happens before the cell divides • S phase of Interphase • Happens in the nucleus

  6. Steps of replication • Unzip DNA • DNA helicase enzyme 2. Add complementary nucleotides • DNA polymerase enzyme 3. Zip up the new strands of DNA • DNA ligase enzyme

  7. DNA replication is semi conservative - each new strand is half old/half new

  8. How does DNA give us our traits? • Gene • piece of DNA that codes for 1 protein • The types of proteins that are made give us our characteristics • But DNA cannot leave the nucleus, and proteins are made in ribosomes! • So…

  9. RNA saves the day! • Ribonucleic acid • Cytosine – guanine • Adenine – uracil • Single stranded • Can leave the nucleus and enter the ribosome

  10. Types of RNA ribosomal RNA rRNA messanger RNA mRNA Transfer RNA tRNA

  11. Protein synthesis happens in two steps • Transcription • Making messenger RNA (mRNA) • Happens in the nucleus • Translation • Using mRNA, tRNA, and rRNA to make proteins • Happens in the ribosome

  12. Transcription DNA unzips new complementary RNA bases create an mRNA strand

  13. TranslationtRNAs put the correct amino acid sequence together to build a protein

  14. Codons and protein • Three bases (triplet code)on mRNA are called a codon and code for one amino acid.

  15. Mutation • A change in the sequence of bases of DNA • A change in the base sequence could lead to the wrong protein being made • There are two types of mutations • Point mutation– a single base is changed • AAT CGG ATA GTA • ATT CGG ATA GTA • Frameshift mutation – a base is added or deleted • AAT CGG ATA GTA • AAT CGT GAT AGT A • Which type of mutation is the most harmful?

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