Meselson and Stahl’s experiment

Question 1

What was used in Meselson and Stahl’s experiment?

Answer 1

Bacteria cells with grow and divide in optimal conditions

Question 2

How is DNA formed?

Answer 2

The DNA is formed from molecules in their food

Question 3

What was the procedure?

Answer 3

There were 2 forms of nitrogen in the food 14N (light) and 15N (heavy) and if they are grown for long in 15N, the DNA will contain 15N in the bases. The nitrogen supply can be radio-labelled and the DNA can be extracted and centrifuged so DNA with 15N is heavier and collects near the botttom

Question 4

What is the effect of radio-labelled nitrogen?

Answer 4

Scientists can see where the DNA has collected in the centrifuge tube

Question 5

What types of DNA is produced?

Answer 5

Bacteria grown in 15N are transferred into 14N and each old strand of DNA, is a template for the new strands so all of DNA contains 1 strand of 15N and one strand of 14N

Question 6

What is the function of the sequence of bases?

Answer 6

Information storage which forms the code to build proteins

Question 7

What is the function of long DNA molecules?

Answer 7

Large amounts of information can be stored

Question 8

What is the function of the base pairing rule?

Answer 8

Complementary strands can be replicated

Question 9

What is the function of the double helix?

Answer 9

It gives the molecule stability

Question 10

What is the function of hydrogen bonds?

Answer 10

They allow the 2 strands to easily seperate for copying/reading info

Question 11

What do codons code for?

Answer 11

A specific amino acid

Question 12

What do genes code for?

Answer 12

A sequence of amino acids in a polypeptide so the primary structure