2.1.3 Nucleotides and Nucleic Acids Flashcards
1
Q
What is DNA?
A
Deoxyribonucleic acid
2
Q
What is the structure of DNA?
A
- A polymer made up of repeating units called nucleotides
- Each nucleotide consists of a common sugar, a phosphate group and one of four bases (either A, T, C or G)
- There is complementary base pairing where A and T pair up and C and G pair up
- Antiparallal
3
Q
What does antiparallel mean?
A
- Chains are running in opposite directions
- One runs in the 5’3’ direction and the other in the 3’5’ direction
4
Q
What is the structure of a DNA nucleotide?
A
- Contains deoxyribose sugar
- H on carbon 2
- Nitrogenous base can be either A, T, C or G
5
Q
What is the structure of an RNA nucleotide?
A
- Contains ribose sugar
- OH on carbon 2
- Nitrogenous base can be either A, U, C or G
6
Q
What are purines?
A
- Contain 2 carbon-nitrogen rings
- A and C
7
Q
What are pyrimidines?
A
- Contain 1 carbon-nitrogen ring
- T and C
- A purine base will always pair with a pyrimidine base
8
Q
What are the differences between RNA and DNA?
A
- RNA contains ribose and DNA contains deoxyribose
- RNA contains uracil and DNA contains thymine
- RNA is single stranded and DNA is double stranded
9
Q
How are polynucleotides formed?
A
- Phosphodiester bond
- Between the phosphate group of one nucleotide and the deoxyribose sugar of the next
- Catalysed by DNA polymerase
10
Q
How do two single polynucleotide strands join together to make a double helix?
A
- Hydrogen bonding between base pairs
- Complementary base pairing is A-T and C-G
- There are 2 hydrogen bonds between A and T and three hydrogen bonds between C and G
- Two antiparallel polynucleotide strands twist to form a double helix
11
Q
What is ATP?
A
- Adenosine triphosphate
- Chemical energy needed to fuel biological activities
- Must be produced continually
- Energyi food molecules is transferred to molecules of ATP by respiration
12
Q
What is the structure of ATP?
A
- Contains adenine, ribose and 3 phosphates
- The phosphates are joined by a phosphoanhydride bond
- Adding a phosphate group is called phosphorylation
13
Q
How is ATP formed?
A
- Made when adenosine diphosphate (ADP) is bonded to a third inorganic phosphate (Pi) using the energy released from glucose
- With ATP synthase enzyme
14
Q
What is the role of ATP?
A
- Stores most of the energy in the third bond of the molecule in small manageable amounts
- Energy is released when that bond is broken
15
Q
How is energy released from ATP?
A
- Phosphoanhydride bond between the second and third phosphate is hydrolysed
- By ATPase enzyme
- Forms ADP and inorganic phosphate
