One Gene One Polypeptide SBI 4 UI 5
One Gene – One Polypeptide SBI 4 UI – 5. 1
Gregor Mendel • Grew pea plants • Certain “factors” responsible for patterns of inheritance – Today: “factors” known as genes • Genes direct the production of proteins – Proteins determine phenotype and drive cellular processes
Garrod’s Hypothesis • British physician • Certain illnesses recur in some families • Determined that certain chemicals were present in people with a specific disease • Hypothesized that enzymes are under hereditary control – Error in hereditary material = enzyme error
Guess Who?
Beadle & Tatum • Experimented with red bread mould – Healthy Neurospora crassa can synthesize all the complex amino acids and vitamins – Defective strains cannot • Mutations caused changes in specific enzymes involved in metabolic pathways
One Gene – One Enzyme • Concluded that a gene acts by directing the production of only one enzyme • They proposed the one gene – one enzyme hypothesis
Vernon Ingram • Studied hemoglobin protein in people with sickle cell anemia • Substitution of a single amino acid led to a change in the structure of hemoglobin • He linked hereditary abnormality to a single amino acid alteration
One Gene – One Polypeptide • We know that genes code for enzymes and proteins
To Do • Section 5. 1 – Understanding Concepts #1 -3
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