1. One Gene – One Polypeptide
SBI 4UI – 5.1

2. 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

3. 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

4. Guess Who?

5. 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

6. 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

8. 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

9. One Gene – One Polypeptide
We know that genes code for enzymes and proteins

10. To Do
Section 5.1
Understanding Concepts #1-3