Nucleic Acids, H2O + ATP Flashcards
Describe how the structure of DNA relates to its function.
- sugar-phosphate so strength and stability
- large so can store a lot of information
- helix so compact
- double stranded for semi-conservative replication
- hydrogen bonds for strand separation
- many weak hydrogen bonds so stable
Describe structure of DNA.
- polymer of nucleotides
- each nucleotide formed from deoxyribose
- phosphodiester bonds
- double helix held by hydrogen bonds
- between adenine/thymine, cytosine/guanine
Describe semi-conservative replication.
- DNA helicase breaks hydrogen bonds
- strands separates between complimentary base pairs
- each strand acts as a template
- free nucleotides attach
- complementary base pairing due to H bonds (A-T, C-G)
- DNA polymerase joins nucleotides forming phosphodiester bonds by condensation reaction
- one old strand and one new strand
Describe how phosphodiester bonds form between two nucleotides.
- condensation reaction
- between phosphate and deoxyribose
- catalysed by DNA polymerase
Describe how the separation of strands occurs.
- DNA helicase
- breaks hydrogen bonds between base pairs
Describe the role of DNA polymerase in semi-conservative.
- joins nucleotides
- catalyses condensation reaction
- formation of phosphodiester bonds
Two scientists who proposed chemical structure of DNA.
Crick and Watson
Features of DNA that allow for semi-conservative replication.
- weak hydrogen bonds between complimentary base pairs can be unzipped
- two strands act as templates
- complimentary base pairing for accurate replication
Compare mRNA and DNA
similarities =
- phosphodiester bonds
- made up of nucleotides
differences =
- DNA has deoxyribose, mRNA ribose
- DNA thymine, mRNA uracil
- DNA longer, mRNA shorter
- DNA double stranded, mRNA single
- DNA hydrogen bonds, mRNA no hydrogen bonds
Give two ways ATP is a suitable energy source.
- little energy lost as heat
- releases energy instantaneously
- phosphorylates other compounds making them more reactive
- rapidly re-synthesised
- not lost from cells
Describe how an enzyme can be phosphorylated.
- attachment of inorganic phosphate
- hydrolysis of ATP
Properties that make water important for organisms.
- metabolite in condensation
- a solvent so reactions can occur
- high heat capacity so buffers change in temp
- large latent heat so cooling effect
- cohesion so supports columns of water
- cohesion so produces surface tension supporting organisms
State and explain the property of water that helps to prevent temperature increase in a cell.
- high specific heat capacity
- buffers changes in temperature
Give two properties of water that are important in cytoplasm of cell.
- polar molecule
- acts as a universal solvent
Role of iron ions in cells.
- haemoglobin binds with oxygen
