DNA, ATP, Water & inorganic ions Flashcards
Describe how structure of DNA is relayed to its function
- Sugar-phosphate (backbone)/double stranded/helix so provides strength/stability /protects bases/protects hydrogen bonds;
- Long/large molecule so can store lots of information;
- Helix/coiled so compact;
- Base sequence allows information to be stored/ base sequence codes for amino acids/protein;
- Double stranded so replication can occur semi-conservatively/ strands can act as templates;
- Complementary base pairing / A-T and G-C so accurate replication/identical copies can be made;
- (Weak) hydrogen bonds for replication/ unzipping/strand separation;
- Many weak hydrogen bonds so stable/strong molecule;
Describe Semi-conservative replication
- Strands separate / H-bonds break;
- DNA helicase
- each strand act(s) as template(s);
- (Free) nucleotides attach to exposed 5.in a complementary manner A-T C-G
- DNA polymerase joins nucleotides (between phosphate and deoxyribose) forming phosphodiester bonds by condensation; in 5’3’ direction
- new DNA molecules contain one old strand and one new strand;
Describe the role of DNA polymerase in the semi-conservative replication of DNA.
- Joins (adjacent DNA) nucleotides;
- (Catalyses) condensation (reactions);
- (Catalyses formation of) phosphodiester bonds (between adjacent nucleotides);
Name the two scientists who proposed models of the chemical structure of DNA and of DNA replication.
Crick and Watson;
Give two features of DNA and explain how each one is important in the semi-conservative replication of DNA.
- Weak / easily broken hydrogen bonds between bases allow two strands to separate / unzip;
- Two strands, so both can act as templates;
- Complementary base pairing allows accurate replication;
ATP is an energy source used in many cell processes. Give two ways in which ATP is a suitable energy source for cells to use.
- Releases relatively small amount of energy/ little energy is lost as heat;
- Releases energy instantaneously;
- Phosphorylates other compounds, making them more reactive;
- Can be rapidly re-synthesised;
- Is not lost from/ does not leave cells;
Describe how an enzyme can be phosphorylated.
Attachment/association of (inorganic) phosphate (to the enzyme);
* 2. (Released from) hydrolysis of ATP OR (Released from) ATP to ADP + Pi;
Explain five properties that make water important for organisms.
- A metabolite in condensation/hydrolysis/ photosynthesis/respiration; 2. A solvent so (metabolic) reactions can occur OR A solvent so allowing transport of substances;
- High heat capacity so buffers changes in temperature;
- Large latent heat of vaporisation so provides a cooling effect (through evaporation);
- Cohesion (between water molecules) so supports columns of water (in plants);
- Cohesion (between water molecules) so produces surface tension supporting (small) organisms;
Describe the roles of iron ions, sodium ions, and phosphate ions in cells. Iron ions
IRON IONS
1. Haemoglobin binds/associates with oxygen OR Haemoglobin transports/loads oxygen;
SODIUM IONS
- Co-transport of glucose/amino acids (into cells);
- (Because) sodium moved out by active transport/Na – K pump;
- Creates a sodium concentration/diffusion gradient;
- Affects osmosis/water potential;
PHOSPHATE IONS
6. Affects osmosis/water potential;
7. Joins nucleotides/in phosphodiester bond/in backbone of DNA/RNA/in nucleotides;
8. Used in/to produce ATP;
9. Phosphorylates other compounds (usually) making them more reactive;
10. Hydrophilic/water soluble part of phospholipid bilayer/membrane
Describe the structure of DNA
Polymer of nucleotides;
Accept ‘Polynucleotide’
Accept for ‘phosphate’, phosphoric acid
Each nucleotide formed from deoxyribose, a phosphate (group) and an organic/nitrogenous base;
Phosphodiester bonds (between nucleotides);
Double helix/2 strands held by hydrogen bonds;
(Hydrogen bonds/pairing) between adenine, thymine and cytosine, guanine;
