DNA

Question 1

What is the structure of DNA?

Answer 1

double helix = 2 polynucleotide strands wound round eachother joined by hydrogen bonds between the bases

Question 2

How many hydrogen bonds between A and T ?

Answer 2

two

Question 3

How many hydrogen bonds between G and C ?

Answer 3

three

Question 4

Who discovered the structure of DNA?

Answer 4

James and Watson and Francis Crick in 1953

Question 5

What is the structure of a DNA nucleotide?

Answer 5

pentose sugar = called deoxyribose which has 5 carbon atoms
phosphate group = negatively charged
organic nitrogen base - have two groups
1.) single ring bases - cystosine (C) and thymine (T) - pyrimidines
2.) double ring bases - adenine (A) and guanine (G) - purines

Question 6

What is the structure of a DNA polynucleotide?

Answer 6

• many nucleotides joined together via a condensation reaction between the phosphate group of one nucleotide and the sugar of another creating a phosphodiester bong - stronger than covalent to ensure that the genetic code is not broken
• has a sugar phosphate backbone - the strong covalent bonds between the sugar and phosphate groups that hold the polymer together

Question 7

What is the function of DNA?

Answer 7

• stores your genetic info (instructions needed to grow + develop)
• passes on genetic info from cell to cell
• codes for the sequence of amino acids int he primary structure of a protein which in turn determines the final 3D structure and function of a protein

Question 8

How does the structure of DNA relate to its function?

Answer 8

• very stable due to sugar phosphate backbone (covalent bonds) + double helix
• weak hydrogen bonds –> strands can separate during DNA replication and protein synthesis
• double stranded so replication can occur using one strand as a template (semi-conservative replication)
• phosphodiester backbone protects more chemically reactive bases inside helix
• large molecule so it can carry lots of genetic info