Lecture 5 - the chemical nature of the gene

Question 1

evidence that genes are located on chromosomes

Answer 1

1902

Question 2

what are genes made of process

Answer 2

nucleus was extracted from a bacterial cell, they found a polymer of nitrogenous bases and phosphates, surrounded by proteins.

Question 3

arguments in favor of genes being made of protein

Answer 3

protein has a complex structure, that would be sufficient enough to carry genetic information - 20 different amino acids.
DNA only has four bases.

Question 4

arguments in favor of genes being made of dna

Answer 4

the amount of DNA doubles right before mitosis, and halves right after mitosis.
gametes have half the amount of dna, and fertilisation doubles it again.

Question 5

griffiths experiments

Answer 5

griffiths experiments consisted of treateing mice with two strains of bacteria ; a virulent S strain and a none virulent R strain.

On treating the mice with the S strain, the mice were killed and the bacteria showed up in their blood.
treatment of the r strain , the mice lived and none showed in the blood. treating the mice with a killed s strain presented the same result.
however when treated with both the r strain and the killed s strain, the micen was still killed.
this was a result of bacterial transformation.

Question 6

transformation

Answer 6

the uptake of dna fragments into a bacteria from the surrounding environment

Question 7

transduction

Answer 7

the uptake of dna into a bacteria using a bacteriophage.

Question 8

an example of horizontal gene transfer

Answer 8

some bacterial cells transfer genes that code for antibiotic resistance to other genes.

Question 9

how was it proved that the transforming substance was DNA?

Answer 9

a soluble cell extract of the killed s strain was prepared, tested its ability to transform type r strain into type s strain.