unit 1 KA1 - structure of DNA

Question 1

describe the structure of DNA

Answer 1

• nucleotides (deoxyribose sugar, phosphate and a base)
• sugar-phosphate backbone
• base pairing (A-T/G-C) by hydrogen bonds
• double stranded anti-parallel structure
• deoxyribose and phosphate at 3’ and 5’ ends of each strand respectively, forming a double helix

Question 2

what forms the genetic code

Answer 2

the base sequence of DNA

Question 3

describe prokaryotes

Answer 3

• cells with a single, circular chromosome and smaller circular plasmids

Question 4

describe eukaryotes

Answer 4

• they all have linear chromosomes in the nucleus which are tightly coiled and packaged with associated proteins
• they also contain circular chromosomes in their mitochondria and chloroplasts

Question 5

why is yeast a special example of a eukaryote

Answer 5

it also has plasmids

Question 6

what are the associated proteins in eukaryotes called

Answer 6

histone proteins