DNA Flashcards
What is DNA make up of?
A phosphate group
Pentose sugar 2-deoxyribose
base
Why is the phosphate group an ion?
One of the oxygens has a negative charge
What are the 4 different bases ?
Adenine
Thymine
Cytosine
Guanine
What is a polynucleotide chain?
Nucleotides joined together
What is the sugar-phosphate backbone?
Covalent bonds form between the phosphate group of one nucleotide and the sugar of another
What type of reaction forms a sugar-phosphate backbone?
Condensation polymerisation releasing a molecule of water
What type of bond forms between a phosphate and sugar in a sugar-phosphate backbone?
Phosphodiester bond
How many polynucleotide strands join to make DNA?
2
What is the double helix structure of DNA?
2 polynucleotide strands spiralled together and held together by hydrogen bonds between the bases
Which base pairs with A?
T
Which base pairs with T?
A
Which base pairs with C?
G
Which base pairs with G?
C
How many hydrogen bonds form between A and T?
2
How many hydrogen bonds form between C and G?
3
How does complimentary base pairing work?
A hydrogen bond forms between a partially positive hydrogen atom and a die pour of electrons on a nearby oxygen or nitrogen.
They have to be the right distance apart
What parts of adenine bond with which parts of thymine?
Adenine N = H thymine
Adenine H = O thymine
What parts of guanine bond to which parts on cytosine/
Guanine H = O cytosine
Guanine H = N cytosine
Guanine O = H cytosine
What is the formula of cisplatin?
[PtCl2(NH3)2]
What shape is cisplatin?
Square planar
How does cisplatin work as an anticancer drug?
1) Nitrogen atom on guanine base in DNA forms a co-ordinate bond with cisplatin’s platinum ion, replaces one of the chloride ion ligands
2) A second nitrogen atom from a nearby guanine molecule can bond to the platinum and replace the second chloride ion
3) The presence of the cisplatin complex is bound to the DNA strands causes the strands to kink and this means the DNA strands cant unwind and the strand can be copied properly
What are the adverse effects of using cisplatin?
- Hair loss
- Suppress the immune system
- causes kidney damage
Why are there adverse effects of cisplatin?
Cisplatin binds to DNA in normal cells as well as cancer cells
How can the effects of using cisplatin be lessened?
Giving very low dosages
Target the tumour directly
Even though there are negative effects of cisplatin, why is it still used?
The positive long term effects outweigh the negative short-term effects
