- Module 2 - Nucleic acids Flashcards
What are nucleotides?
Monomers that form the basis of the nucleic acids DNA and RNA.
What elements do all nucleotides contain?
C, H, N, O and P
What is the difference between the structure of the pentose sugar in DNA and RNA.
DNA - deoxyribose pentose sugar.
RNA - Ribose
What are the bases found in RNA and DNA
DNA - ATCG
RNA - AUCG
What bases are purines? What does this mean?
Adenine and Guanine are purines, they have the larger bases and have double carbon ring structures.
What bases are pyrimidines? What does this mean?
Thymine and Cytosine (and uracil).
Pyrimidines are the smaller bases and have single ring carbon structures.
How is a nuleotide formed?
The phosphoric acid and the nuecleoside combine and a molecule of water is formed (condensation) in a phosphodiester bond between and OH group on the acid and a OH group on carbon 5 of the sugar.
How are polynucleotides formed?
Nucleotides join together. They join up between the phosphate group of one nucleotide and the sugar of another nucleotide via a condensation reaction forming a phosphodiester bond.
What are the 5’ and 3’ ends of polynucleotides?
Every polynucleotide has a 5’ (5 prime) and a 3’ (3 prime) end.
At the 5’ end C5 of the pentose sugar is nearest the end, at the 3’ end C3 is nearest the end.
How can polynucleotides be broken down?
They can be broken down into nucleotides by hydrolysis reactions.
What is the basic structure of DNA?
Two polynucleotide strands joined together to form a double helix shape. The two strands are held together by hydrogen bonds between the bases.
What does it mean by ‘the strands of DNA run anti-parallel to one another’?
They run in opposite directions.
How many hydrogen bonds are A and T linked by? What about C and G?
A and T are linked by 2.
C and G are linked by 3.
What is the name of the protein that allows DNA to be packed up tightly?
Histones.
Why must DNA be tightly coiled and packaged?
To fit into the nucleus.
What is ATP made up of?
A sugar (ribose), a base (adenine) and three phosphate groups.
How is ATP broken down?
The bonds between the phosphate groups are unstable which means they are easily broken (in a hydrolysis reaction).
ATP —> ADP + Pi
What is the addition of an inorganic phosphate group to a molecule like ADP called?
Phosphorylation. This requires free energy.
ADP + Pi —> ATP
How is ATP suited for energy transfer?
Small and soluble - moves in and out of cells easily.
Releases small amounts of energy - prevents wasted energy
Has an unstable phosphate bond (which is easily broken)
Easily reformed