Nucleotides and Phosphodiester Bonds (Part 2) Flashcards
What are nucleotides?
Nucleotides are the monomers from which DNA and RNA polymers are built
What are monomers and polymers?
Monomers = Small subunits, that combine to make a polymer.
Polymers = large molecule made from many repeating subunits, known as monomers.
What is the nucleotide structure?
Nucleotide structure includes:
1. a pentose sugar
2. a nitrogen-containing organic base
3. a phosphate group
What are the components of a DNA nucleotide?
- a deoxyribose sugar
- a phosphate group
- one of four nitrogenous bases:
- adenine (A)
- cytosine (C)
- guanine (G)
- thymine (T)
What are the components of an RNA nucleotide?
- a ribose sugar
- a phosphate group
- one of four nitrogenous bases:
- adenine (A)
- cytosine (C)
- guanine (G)
- uracil (U)
Draw what an RNA nucleotide looks like.
Draw what a DNA nucleotide looks like.
What are the two structural forms of the nitrogenous base mo9lecules in DNA and RNA?
purines
pyrimidines
What is a purine, and give the two examples?
Adenine and guanine are purines: they have a double ring structure
What is a pyrimidines, and give the three examples?
Cytosine, thymine and uracil are pyrimidines: they have a single ring structure
What is a pentose sugar?
contains 5 carbon atoms
Where is deoxyribose sugar found?
DNA
Where is Ribose sugar found?
RNA
What is the difference between deoxyribose and ribose, in terms of structure?
Deoxyribose contains one fewer oxygen atom that ribose
- In ribose carbon 2 has an OH group, while in deoxyribose carbon 2 has an H group.
What type of polymers are DNA and RNA?
DNA and RNA are polymers (polynucleotides), meaning that they are made up of many nucleotides joined together in long chains
How are nucleotides joined together, and what parts does it occur between?
Separate nucleotides are joined together via condensation reactions
- These condensation reactions occur between the phosphate group of one nucleotide and the pentose sugar of the next nucleotide
How is a phosphodiester bond formed?
A condensation reaction between two nucleotides forms a phosphodiester bond
- It is called a phosphodiester bond because it consists of a phosphate group and two ester bonds
What is a sugar-phosphate backbone?
The chain of alternating phosphate groups and pentose sugars produced as a result of many phosphodiester bonds is known as the sugar-phosphate backbone (of the DNA or RNA molecule)
What bonds allow polynucleotides to be synthesised?
As the synthesis of polynucleotides requires the formation of phosphodiester bonds, the same is true for the reverse process: the breakdown of polynucleotides requires the breakage of phosphodiester bonds
