Nucleic Acids Flashcards
What does DNA stand for?
Deoxyribonucleic acid
What does RNA stand for?
Ribonucleic acid
Monomer of nucleic acids is…
… nucleotides
What makes up a nucleotide?
Phosphate, pentose sugar and nitrogenous base
What types of pentose sugar are there?
Deoxyribose (in DNA) and ribose (in RNA)
What are the types of nitrogenous bases?
Adenine, thymine (DNA only), cytosine, guanine and uracil (RNA only)
What are pyramidines?
Single ring structures eg. Cytosine, thymine and uracil
What are purines?
Double ring structures eg. Adenine and guanine
Describe the structure of RNA
Single stranded polynucleotide chain that is relatively short. Pentose sugar is always ribose and nitrogenous bases either A, G, C or U
What are the types of RNA?
mRNA (messenger), rRNA (ribosomal) and tRNA (transfer)
Describe structure of DNA
Double helix structure made of 2 polynucleotides, extremely long molecules. Pentose sugar always deoxyribose. Nitrogenous bases either A, T, C, or G
How are the 2 polypeptide chains in DNA held together?
Hydrogen bonding between nitrogenous bases
How are the nucleotides held together?
3,5 phosphodiester bonds, forming the sugar-phosphate backbone
Describe the complimentary base pairings
T/U with A (2 hydrogen bonds) and C with G (3 hydrogen bonds)
How is DNA adapted for its function?
Very stable structure so can pass through generations with rare mutations. 2 strands are held together by H bonds (weak individually) allowing strands to be separated in DNA replication. Extremely large molecule so carries a huge amount of genetic information. Function of gene depends on base sequence. Complimentary base pairs means DNA is replicated accurately.
Why is DNA stable?
Phosphodiester backbone protects the bases inside double helix. Many H bonds are strong together
Describe semi-conservative replication
DNA helix add (enzyme) unwinds molecule and breaks H bonds between complimentary base pairs.
Bases are exposed when strands separate allowing each strand to act as a template.
Free activated nucleotides found in nucleoplasm form H bonds to complimentary bases.
DNA polymerase joins adjacent nucleotides by forming phosphodiester bonds and rewinds molecule.
This forms 2 identical DNA molecules each with 1 original strand and 1 new strand
What does ATP stand for?
Adenosine triphosphate
What is ATP made of?
3 phosphate groups, ribose and adenine
How is ATP a source of energy?
Energy stored in ATP is released by breaking off the third phosphate
What does ADP stand for?
Adenosine diphosphate (one phosphate broken off)
What does ATP hydrolase do?
Hydrolyses ATP into ADP and Pi (inorganic phosphate)
What does ATP synthase do?
Condenses ADP and Pi into ATP
What are the processes that synthesise ATP?
Oxidative phosphorylation, photophosphorylation and substrate-level phosphorylation
Describe the properties of ATP
Releases energy is small amounts rapidly. One single bond broken so energy source not store. Always readily available. Very water soluble (therefore transportable) but cannot cross plasma membranes as it is polar, so requires protein carries to cross membrane.
Describe the roles of ATP
Metabolic processes, movement, active transport, secretion of products from cells and activation of molecules
