Nucleic Acids Flashcards
What are the two important information-carrying molecules in living cells?
DNA and RNA
What is the primary function of DNA in living cells?
Holds genetic information
How does mRNA function in relation to DNA?
Transfers genetic information from DNA to the ribosomes
What are ribosomes formed from?
RNA and proteins
What are DNA and RNA classified as?
Polynucleotides
What are the components of a DNA nucleotide?
Deoxyribose, a phosphate group, and one of the organic bases adenine, thymine, cytosine or guanine
What are the components of an RNA nucleotide?
Ribose, a phosphate group, and one of the organic bases adenine, uracil, cytosine or guanine
What type of bond is formed between two nucleotides?
A phosphodiester bond
What structure does a DNA molecule have?
A double helix with two polynucleotide chains
How are the polynucleotide chains in DNA held together?
By hydrogen bonds between specific complementary base pairs
What is the structure of an RNA molecule?
A relatively short polynucleotide chain
Why did many scientists doubt that DNA carried the genetic code?
Because of the relative simplicity of DNA
What does semi-conservative replication of DNA ensure?
Genetic continuity between generations of cells
What is the first step in the semi-conservative replication of DNA?
Unwinding of the double helix
What happens during the breakage of hydrogen bonds in DNA replication?
Hydrogen bonds between complementary bases in the polynucleotide strands are broken
What is the role of DNA helicase in DNA replication?
To unwind DNA and break its hydrogen bonds
What occurs after the unwinding of DNA during replication?
Attraction of new DNA nucleotides to exposed bases on template strands and base pairing
What is the role of DNA polymerase in DNA replication?
To catalyse the condensation reaction that joins adjacent nucleotides
What is ATP classified as?
A nucleotide derivative
What are the components of a single molecule of ATP?
A molecule of ribose, a molecule of adenine, and three phosphate groups
What enzyme catalyses the hydrolysis of ATP
ATP hydrolase
What can the hydrolysis of ATP be coupled to?
Energy-requiring reactions within cells
What happens to the inorganic phosphate released during the hydrolysis of ATP?
It can be used to phosphorylate other compounds, often making them more reactive
What enzyme catalyses the reaction that resynthesises ATP during photosynthesis or respiration
ATP synthase
How is ATP resynthesised?
By the condensation of ADP and Pi
What are the key processes involved in the semi-conservative replication of DNA?
- unwinding of the double helix
- breakage of hydrogen bonds between complementary bases
- role of DNA helicase in unwinding DNA
- attraction of new DNA nucleotides to exposed bases
- role of DNA polymerase in joining adjacent nucleotides
What are the main functions (4) of ATP in cellular processes?
- provides energy for cellular reactions
- coupled to energy-requiring reactions
- phosphorylates other compounds to increase reactivity
- resynthesised from ADP and Pi by ATP synthase
What are the 5 properties of water?
- metabolite
- solvent
- high specific heat capacity
- large latent heat of vaporisation
- cohesion
How is water a metabolite?
- used in hydrolysis reactions
- formed in condensation reactions
How is water a solvent?
Dissolves ions and polar molecules and transports them
Why has water got a high specific heat capacity?
Buffers changes in temperature
Why has water got a large latent heat of vaporisation?
Provides a cooling effect
Why is water cohesive?
Due to its hydrogen bonding, water has large cohesive forces which allow it to be pulled up through a tube, such as a xylem vessel
