2.1 - 2.4 Nucleic acids Flashcards
What are the 2 types of nucleic acid?
Deoxyribonucleic Acid (DNA)
Ribonucleic Acid (RNA)
Describe the structure of a DNA nucleotide
- Phosphate
- Deoxyribose sugar
- Nitrogenous base
Name the 4 DNA bases
Adenine
Thymine
Guanine
Cytosine
Describe the structure of an RNA nucleotide
- Phosphate
- Ribose sugar
- Nitrogenous base
Name the 4 RNA bases
Adenine
Uracil
Guanine
Cytosine
What is the structure of DNA?
- Double helix
- Anti-parallel nucleotide strands
- Complementary base pairing
- Phosphodiester bond between the 5’ carbon of one nucleotide and the 3’ carbon of another
- Hydrogen bonding holding DNA strands together
Name the complimentary base pairs
Adenine - Thymine
Cytosine - Guanine
What is the function of DNA?
- Store genetic information
- Allow protein synthesis
- Allows genetic info to pass from cell to cell and generation to generation
Describe the process of DNA replication
- DNA Helicase unszips the two strands by breaking the hydrogen bonds between the complementary base pairs. This allows each strand to act as a template.
- Free DNA nucleotides align with their complementary base pair on the exposed strands. They attach via hydrogen bonds (A with T, C with G)
- DNA Polymerase joins adjacent nucleoides together in a condensation reaction. This forms a phosphodiester bond between nucleotides.
- Each DNA molecule now has one new strand and one original strand. Therefore this process is called semi-conservative replication.
Describe how DNA’s sugar-phosphate backbone contributes to its function
Provides strength/stability to molecule
Describe how DNA’s length contributes to its function
Long so can store lots of information
Describe how DNA’s helical structure contributes to its function
Compact
Describe how DNA having a sequence of bases contributes to its function
Allows for very accurate replication
Describe how DNA’s double stranded structure contributes to its function
Both strands can act as templates during DNA replication
Describe how DNA’s relatively weak hydrogen bonds contribute to its function
Allows strands to be easily separated for replication or protein synthesis
Describe the structure of ATP
- 3 phosphate groups
- Ribose sugar
- Adenine base
Give the word and symbol equation illustrating how ATP stores energy
ATP + H₂O ⇌ ADP + Pi + E
ATP + water ⇌ ADP + inorganic phosphate + energy
Name the enzyme which converts:
ATP + H₂O → ADP + Pi + E
ATP hydrolase
Name the enzyme which converts:
ATP + H₂O ← ADP + Pi + E
ATP synthase
What are the two main roles of ATP?
- Providing energy for energy-requiring reactions
- Phosphorylation of molecules (inorganic phosphate can be transferred to other molecules)
Give examples of ATP providing energy for energy-requiring reactions
- Muscle contraction
- Active transport
- Metabolic processes
- Endo/exocytosis
Why is energy stored as ATP?
- Only one hydrolysis reaction required so energy can be released quickly
- Releases small, manageable amounts of energy
Why can cells not store ATP?
- It is too reactive
- Instead, energy-demanding cells have more mitochondria
Explain why water is a solvent
Partially + and - charges of water attract the charges on other molecules, causing them to separate (dissolve)
Explain why water being a solvent is of biological significance
Metabolic reactions inside living organisms can only happen when the reactants are dissolved in water
Explain why water has a high specific heat capacity
Can absorb large amounts of heat before it changes temp, due to h-bonds
Explain why water having a high specific heat capacity is of biological importance
Large bodies of water have a stable temperature (important for habitats)
Explain why water has a relatively large latent heat of vaporisation
Some molecules of water have enough kinetic energy to evaporate. These molecules take energy with them so the water cools down.
Explain why water having a relatively large latent heat of vaporisation is of biological importance
Provides a cooling effect via evaporation i.e sweating
Explain why water has strong cohesion between molecules
Due to their polarity, water molecules attract each other and form hydrogen bonds
Explain why water having strong cohesion between molecules is of biological importance
Supports column of water moving up the xylem in transpiration stream.
Surface tension can support small organisms on top of the water.
Describe the function of hydrogen ions (H+)
Control pH
Describe the function of iron ions (Fe2+)
A component of haemaglobin
Describe the function of sodium ions (Na+)
Transport of glucose and amino acids
Describe the function of phosphate ions
Component of DNA and ATP
