DNA is a polymer of four different
Nucleotides
Key Terms
DNA is a polymer of four different
Nucleotides
What 3 components is each nucleotide made up of
phosphate ion
pentose sugar (2-deoxyribose)
base
What are the 4 bases in DNA
Adenine, guanine, cytosine and thymine
What does formation of nucleotides involve
Condensation reactions
Nucleotides: what does the phosphate ion bond to and what is eliminated
Phosphate ion bonds to deoxyribose and water is eliminated
Nucleotides: what does the organise base bond to and what is eliminated
Deoxyribose and water is eliminated
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| Term | Definition |
|---|---|
DNA is a polymer of four different | Nucleotides |
What 3 components is each nucleotide made up of |
|
What are the 4 bases in DNA | Adenine, guanine, cytosine and thymine |
What does formation of nucleotides involve | Condensation reactions |
Nucleotides: what does the phosphate ion bond to and what is eliminated | Phosphate ion bonds to deoxyribose and water is eliminated |
Nucleotides: what does the organise base bond to and what is eliminated | Deoxyribose and water is eliminated |
What are polynucleotides | Condensation polymers of nucleotides |
How are phosphodiester bonds formed | The phosphate group of one nucleotide joins to the sugar of another nucleotide |
What back bone does a polynucleotide have | To the sugars |
Single strand of DNA | Polynucleotide |
What does DNA exist as | Two polynucleotide standards in the form of a double helix |
DNA structure: what are the two strands held together by | H bonds between pairs of bases |
How many h bonds form between A and T | 2 |
How many h bonds form between cytosine and guanine | 3 |
Why does the H bonding between base pairs lead to a double helix with complementary strands |
|
Why are other base pair combinations not possible | They wouldn’t place atoms at the correct distance or in correct alignment to H bond properly |
Genetic code: what does a sequence of bases in certain sections of DNA hold the code for | The amino acid sequence of certain proteins |
Genetic code: when do the two strands of the double helix separate | When the DNA is transcribed to make an mRNA template for protein synthesis/replicated during cell division |
Genetic code: whu does strand separation occur without breaking the polynucleotide chain | Because the H bonds between the strands are weaker than the covalent bonds between nucleotides |
What is cisplatin a complex of | Platinum (II) |
How to remember structure of cisplatin | Cis means 2 Cl groups and 2 NH3 groups are together |
What effect does cisplatin have when it binds to DNA | Blocks DNA replication and transcription and triggers programmed cell death |
Mechanism for hydrolysis of cisplatin | [PtCl2(NH3)2] <> [PtCl(H2O)(NH3)2]+ + Cl- |
Second step in mechanism of action of cisplatin | Ligand substitution reaction occurs between a nitrogen atom in a guanine base and the platinum ion |
Third step in mechanism of action of cisplatin | Second nitrogen atom from a nearby guanine bonds to the platinum by replacing the chloride ligand |
Fourth step in mechanism of action of cisplatin | Cisplatin complex causes DNA double helix to kink Means DNA can’t unwind and can’t be copied coorectly. Damage to DNA triggers apoptosis |
Why does cisplatin have side effects | It binds to DNA in normal cells as well as cancer wells |
What do patients having chemotherapy also experience |
|
How can the side effects of chemotherapy be reduced | By using the lowest possible dose of cisplatin and by targeting delivery of the drug directly to the cancer cells in |