51 WJEC Biology AS Level - Study And Revision Guide - Neil Roberts (1.5 Nucleic Acids And Their Functions) Flashcards
What are DNA and RNA made up of?
Both DNA and RNA are made up of monomers called nucleotides.
What does each nucleotide contain?
Each nucleotide contains
- a phosphate group
- a nitrogen-containing organic base
- a pentose (5-carbon) sugar
either ribose (RNA) or deoxyribose (DNA)
How many groups of organic bases are there?
There are two groups of organic bases
- pyrimidines (single ring)
- purines (double ring).
What are the nitrogenous bases found in DNA and RNA?
Four nitrogenous bases found in DNA -
- Guanine (purine)
- Adenine (purine)
- Cytosine (pyrimidine)
- Thymine (pyrimidine in DNA)
- Uracil (pyrimidine in RNA)
What is adenosine triphosphate?
Adenosine triphosphate is also a nucleotide
It has a ribose sugar joined to the adenine base,
with three phosphate groups attached.
Describe the reaction that breaks down ATP.
When the high-energy bond between the second and third phosphate group is broken via hydrolysis by the enzyme ATPase -
- 30.6 kJ of energy is released for use in the cell
- Adenosine diphosphate is formed.
This reaction is reversible.
It requires energy from respiration of glucose to reform the bond.
ATP →→→ ADP+ Pi + 30.6kJ energy
(Pi = inorganic phosphate)
What is important to remember when spelling the various nucleotides.
Candidates often write
- thiamine instead of thymine
- cysteine instead of cytosine.
Thiamine is a vitamin
Cysteine is an amino acid
What is important to remember when spelling ATP?
It is NOT adenine triphosphate.
How much ATP do we have in our cells?
How much ATP do we use everyday?
What is the implication?
We have a total of 5g of ATP in our cells
We use up 50kg every day.
This means that this reversible reaction must occur over 10,000 times a day because we cannot store it.
Draw a diagram of a nucleotide.
Draw a diagram of ATP
Draw a diagram of ADP