Lecture 7-9

Question 1

Topic 7

Answer 1

DNA STRUCTURE

Question 2

Properties of DNa

Answer 2

1. must allow for accurate replication : required
2. Must contain information: instructions to code whole collection of protein expressed in particular organisms
3. Must be able to change ( rarely) : genetic materials is stable enough to be reliable ( to encode an organism’s protein ), but on occasion, can change to result in hereditary changes/ mutation.

Question 3

DNA structure

Answer 3

• building block that compose of diff elements
  1. Purine double ring structure ex adeninin and thymine
  2. Pyramidine( base) has single ring structure. Ex cytosine and thymine

Question 4

DNA structure- based pairings

Answer 4

A+G= T+C
1. same amount of purine and Pyramidine
2. Same amount of A and T; same amount of Gand C
3. A and T isn’t necessary equal to Gand C some organisms has more GC in genome as it’s more stable but has higher tuberculosis

Question 5

DNA double helix

Answer 5

• Always pyrimidine pair with
  Complementary bases A pairs with T and G pairs with C
• nucleotides consisting of phosphate, sugar , and base
• two sugar phosphate backbone are held together by antiparallel oriented opposite. 5”-3” , 3”-5”
• A==T two hydrogen bonds in between
• G===C, three hydrogen bond between. More stable need energy to break apart

Question 6

DNA synthesis in the 5”-3” direction

Answer 6

• replication catalyzed by DNA polymerase
• phosphate produces energy that help drive DNA synthesis

Question 7

DNA is semi- discontinuous

Answer 7

1. Primase synthesis short RNA primers using DNA as template.
2. DNA polymerase 111 synthesis DNA at 3”of RNA.
3. DNA polymerase 1 removes primer and fills the gap
4. Ligase: connect DNA fragments

• type of bond catalyzed by dna is phosphodiester bond