Zusammenfassung der Ressource
Nucleic Acids, ATP, and Water
- DNA and RNA are polymers of Nucleotides
- DNA
- The pentose sugar in DNA nucleotide is deoxyribose
- Each have the same sugar and phosphate group
- Bases can differ
- A , T, C, G
- Used to store genetic information
- RNA
- Similar structure to DNA
- Used to transfer genetic information from the DNA to the ribosomes
- RNA contains Ribose sugar
- also contains phosphate group
- and bases, A, C, U, G
- Type of biological molecule
- Containing pentose sugar, organic base, phosphate group
- Nucleotides joined together to form polynucleotides
- joined via condensation reactions
- Forming a phosphodiester bond between phosphate group and a sugar of another nucleotide
- Chain of sugar, phosphate called sugar-phosphate backbone
- DNA is made of two polynucleotides in a double-helix structure
- DNA polynucleotides joined by hydrogen bonding between bases
- Bases only join to one to another - complementary base pairing
- A -- T
- Equal base pairs in a molecule
- C --- G
- The two polynucleotides run antiparallel and twist to form helix
- RNA is a relatively short polynucleotide chain
- Made from single chain
- DNA Replication
- Replicates by Semi-Conserative replication
- Half of the strands, in each new DNA molecule, are from the original DNA
- Maintains genetic continuity between cell generations
- Enzyme DNA helicase breaks hydrogen bonds between complementary base pairs
- Makes the DNA helix unwind to form two single strands
- These two new strands act as a template for a new strand.
- Complementary base pairing means that free DNA nucleotides are attracted to the exposed bases
- Condensation reactions join the new strands together
- Catalysed by DNA Polymerase
- Moves in opposite ways along antiparallel DNA strand
- Each end of DNA molecule is different
- 3' and 5' run antiparallel - run side by side but in opposite directions
- Active site of DNA polymerase complementary to original 3' end
- New nucleotides only start on the 3' end of the orignal strand
- Meaning if antiparallel forms the 5' end of new strand at the 3' end of the orginal strand
- New strand made in the 5' to 3' direction
- DNA polymerase starts at the 3' end and moves 3' to 5' direction on the original strand
- Two DNA polymerases working on one orginal DNA double-helix move in opposite directions to each other
- Hydrogen bonds reform between the original and new bases
- Each new DNA molecule contains a original strand and a new strand
- Unique Properties of Water
- Functions or water to living organisms
- Metabolic processes
- E.g. condensation / hydrolysis reactions
- Water is a metabolite
- Used as a solvent
- Substances can dissolve in it
- Most reactions take place in solution - cytoplasm
- Temperature Control
- Takes a lot of energy to evaporate water - breaking hydrogen bonds between water
- Used to cool down organisms without losing too much water
- High specific heat capacity
- Resists rapid temperature changes
- Cohesive
- Stick together - helpful in water transportation in plants
- Cohesion - attaction between molecules of the same type
- Structure of Water
- Polar molecule, partially negative oxygen and 2 partially positive hydrogens
- Charged ions in water will be completely surronded by water (dissolved)
- Positive ions will attract negative oxygen
- Negative ions attract positive hydrogen
- Water requires special channel proteins to move through membranes
- Aquaporins allow polar water to diffuse
- ATP
- Cells get energy from glucose in respiration
- Energy can't be used directly from glucose
- Use energy to form ATP
- ATP used to release energy
- Made from the nuleotide base adenine
- ribose sugar and 3 phosphate
- Energy stored in bonds between the phosphate groups
- Hydrolysis reaction
- phosphate bond broken
- A lot of energy released
- ATP can be resynthesised using products in condensation reaction
- Immediate source of energy
- ATP can diffuse to parts of the cell that need energy