Mutations Cells can make mistakes when replicating Or

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Mutations • Cells can make mistakes when replicating – Or transcribing • Repair mechanisms

Mutations • Cells can make mistakes when replicating – Or transcribing • Repair mechanisms fix these mistakes – Similar to spell check • A permanent change occurs in a cells DNA mutations

Types of Mutations • Point mutation/Substitution - change in 1 base pair – Wrong

Types of Mutations • Point mutation/Substitution - change in 1 base pair – Wrong amino acid – change codon to a stop codon (translation stops early) – Proteins cannot function properly

Frameshift Mutations Shift the codons 1. Insertions – additions of a nucleotide 2. Deletion

Frameshift Mutations Shift the codons 1. Insertions – additions of a nucleotide 2. Deletion – loss of a nucleotide 3. Duplication – repeating sequences of codons

Protein Folding and Stability • Change of 1 amino acid can lead to change

Protein Folding and Stability • Change of 1 amino acid can lead to change in folding and stability of protein – Sickle cell disease – one amino acid change = change in structure of hemoglobin

Causes of Mutations • Some can be spontaneous • DNA Polymerase can add an

Causes of Mutations • Some can be spontaneous • DNA Polymerase can add an incorrect nucleotide – 1/100, 000 – Proofreading reduces it to 1/1, 000, 000 • Chemicals and radiation can damage DNA

Mutagens • Def. – substance that cause mutations • Change chemical structure of bases

Mutagens • Def. – substance that cause mutations • Change chemical structure of bases – Bond with wrong bases • Create imposter bases

Mutagens • Radiation – creates high energy electrons which (escape) and break bonds •

Mutagens • Radiation – creates high energy electrons which (escape) and break bonds • UV – less energy, cause bonds to break and form with other bases/bonds

Somatic vs. Gamete Mutations • Somatic (body) cells – each mutation gets passed to

Somatic vs. Gamete Mutations • Somatic (body) cells – each mutation gets passed to the daughter cell – Not to offspring • Gamete (sex) cells – passed to offspring (children) and will be present in every cell

What happens if… DNA sequence is AACGTGACT m. RNA = U U G C

What happens if… DNA sequence is AACGTGACT m. RNA = U U G C A C U G A A. A. = LEU – HIS - STOP

Now a mutation occurs DNA sequence is GACGTGACT m. RNA = C U G

Now a mutation occurs DNA sequence is GACGTGACT m. RNA = C U G C A C U G A A. A. = LEU – HIS - STOP NO CHANGE IN AMINO ACID SEQUENCE!!!! NEUTRAL MUTATION

• https: //www. ted. com/talks/james_watson_o n_how_he_discovered_dna#t-15617

• https: //www. ted. com/talks/james_watson_o n_how_he_discovered_dna#t-15617

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