DNA Structure

Question 1

what is chargaff’s discovery

Answer 1

• there is significant DNA variation between species, thus DNA could be the genetic material

Question 2

what is chargaff’s rules

Answer 2

a = t
g= c
the composition of DNA varies between species

Question 3

what does the DNA structure look like

Answer 3

• a double stranded molecule with particular features

Question 4

what are the components of DNA

Answer 4

• bases
• phosphates
• deoxyribose sugar
• the single unit building blocks of the macromolecule DNA are nucleotides

Question 5

how are polynucleotides formed

Answer 5

• nucleotide monomers are joined together with PHOSPHODIESTER BONDS tp form polynucleotide = nucleic acid

Question 6

which direction does the DNA (and RNA) strands synthesis in

Answer 6

5’ –> 3’

Question 7

how are phosphodiester bonds formed

Answer 7

the hydroxyl group on the 3rd carbon of one nucleotide reacts with the phosphate group attached to the 5th carbon on another nucleotide

Question 8

are the 2 strands antiparallel or parallel

Answer 8

antiparallel

Question 9

what do 2 antiparallel DNA strands form

Answer 9

• a double stranded helix

Question 10

what is the Watson-cricks model of the DNA structure

Answer 10

• DNA has a double-stranded helical structure
• the sugar phosphate backbone is on the outside
• the base are on the inside
• stabilized by hydrogen bonds
• the 2 polynucleotide strands are oriented in opposite directions

Question 11

what does it mean that it is a semi-conservative model of replication

Answer 11

• means that each DNA strand of the double helix is used as a template strand for the synthesis of 2 new strands

Question 12

why does your cell replicate its DNA

Answer 12

• your body needs to make more cells:

- for: different growth stages, pregnancy, repair of injury