Nucleic Acids And Nucleotides Flashcards
What are the three parts of a nucleotide
A Penrose sugar
A base (sometimes called a nitrogenous base as they contain nitrogen)
A negatively charged phosphate group
What are the elements that are found in nucleotides
Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus
Draw a nucleotide in its simple form with the symbols for the carbons
DRAW IT
What are nucleotides used to make
Both DNA and RNA
What is a difference between the nucleotides of DNA and RNA
In DNA the pentose sugar is deoxyribose whereas in RNA the pentose sugar is ribose
What are the 4 different bases that are found in DNA
Thymine, Adenine, Guanine and Cytosine
Which two bases are purines and why
Adenine and Guanine both have a double ring structure so they are purines
Which two bases are pyramidines and why
Thymine and cytosine have a single ring structure - these bases are called pyramidines
What is a difference in the bases that are in DNA and RNA
RNA similarly contains adenine, guanine and cytosine. However, it doesn’t contain the base thymine and instead contains the base uracil.
What is the bond that forms between nucleotides and between what parts of the nucleotide
A bond forms between the phosphate group on the 5’ carbon on one nucleotide and the hydroxyl group on carbon 3 of the pentose sugar of another nucleotide
What is the bond that forms between two nucleotides called
It is called a phosphodiester bond
What is it called when two nucleotides and bonded together and when more than two nucleotides are bonded together
Two - dinucleotide
More than two - Polynucleotide
What type of reaction is the reaction that form the phosphodiester bond
It is a condensation reaction as water is released
How can the phosphodiester bond be broken
It can be broken by adding back water - this is called a hydrolysis reaction
How do polynucleotides form
They form as the nucleotides continue to be added by forming phosphodiester bonds
What are both DNA and RNA
They are both polynucleotides
What does DNA consist of
It consists of two polynucleotide strands with the sugar-phosphate backbone on the outside with the bases in the centre.
What are the two polynucleotides held together by
They are held together by hydrogen bonds that form between the bases on opposite strands.
What are the bases on one strand in terms of the other strand
The bases on one strand are complementary to the bases on the other strand
What are the different complementary bases pairs
Guanine and cytosine
Thymine and adenine
What is a rule for the base pairs and what does it mean for DNA
A purine on one strand will always pair with a pyramidine on the other strand. It means that the distance between the sugar phosphate backbone is constant all down the DNA molecule.
What are the two polynucleotides in relation to each other
They are anti parallel which means that they run in opposite directions.
What does antiparallel mean in terms of the phosphate groups, carbon and the hydroxyl group
On one side the top the phosphate group is attached to carbon 5 of the deoxyribose sugar and at the bottom is the hydroxyl group attached to carbon 3. Whereas on the other strand the phosphate attached to carbon 5 is at the bottom and the hydroxyl group attached to carbon 3 is at the top.
What do the different base pairs form
They form different numbers of hydrogen bonds
How many hydrogen bonds does guanine and cytosine form
It forms 3 hydrogen bonds
How many hydrogen bonds does adenine and thymine form
2 hydrogen bonds
Because of complementary base pairing what occurs in terms of ratio
The ratio/proportion of guanine and cytosine is the same and the proportion of adenine/thymine is also the same.
What do the polynucleotide strands of DNA do
They twist around each other to form a double helix.
What does a double helix consist of
A sugar phosphate backbone on the outside and base pairs in the centre
What are the first 3 differences between DNA and RNA
DNA contains deoxyribose whereas RNA contains ribose
DNA contains the base thymine whereas RNA contains uracil
DNA is found in chromosomes in the nucleus whereas RNA is found in the cytoplasm
What are the last two differences between DNA and RNA
DNA is an extremely long molecule whereas RNA is a relatively short molecule.
DNA consists of two polynucleotide strands in a double helix RNA consists of one polynucleotide strand
What is uracil and how many bonds does it form
It is also a pyramidine and forms two hydrogen bonds with adenine.
How do RNA nucleotides form polymers
Through the formation of phosphodiester bonds in condensation reactions
What is RNA’s role
It plays an essential role in the transfer of genetic information from DNA to proteins.
What happens to RNA after protein synthesis
RNA molecules degrade in the cytoplasm and its phosphodiester bonds are hydrolysed and the nucleotides are released and reused.
