3 - Synthesis and Modification of DNA Flashcards
1
Q
chemical synthesis process
A
- deprotection of nucleophile (usually hydroxyl)
- base coupling
- capping (optional) - acetylation is done to prevent further chain extension
- oxidation
- cheap process
- synthesized in a 3’ to 5’ direction
2
Q
biological synthesis process
A
- DNA is made by DNA polymerase
- synthesized in a 5’ to 3’ direction
- no replication without primer
3
Q
DNA error checking
A
- strands dissociate bc they are not complementary
- moves to 3’ to 5’ exonuclease site
4
Q
primase
A
synthesized a small piece of RNA
5
Q
DNA polymerase
A
replicate DNA
6
Q
RNA primer
A
- needed for replication
- destroyed by 5’ to 3’ exonuclease act
7
Q
ligase
A
joins the Okazaki fragments by repairing damage from destruction of RNA primer
8
Q
telomeres
A
- “buffer zones”
- repeats of TTAGGG sequences
- when telomeres get too short, cell undergoes apoptosis
9
Q
apoptosis
A
cell death
10
Q
DNA methylation
A
DNA covalently modified with methyl groups
11
Q
histone modification
A
- tails that attach to proteins
- alter the activity of DNA
12
Q
CpG island
A
region of DNA with many cytosine-P-guanine
13
Q
epigenetic modification
A
- information affects gene expression but not encoded within sequence
- example is methylation of CpG (very common)
14
Q
DNA attack from the inside
A
- depurination (Gs and As)
- oxidation by ROS
- deamination (amine to carbonyl)
15
Q
deamination problems
A
if deamination results in a thymine molecule, there is no way for the cell to know its a mutation
