CHEMICAL ELEMENTS AND WATER
Polar - Positive charge (has charge)
Non-polar - Negative charge (no charge)
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Main elements in organic molecules:
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Carbon
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Hydrogen
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Oxygen
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Nitrogen
Hydrogen
Ions are used in:
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Active transport
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Photosynthesis
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Cell Respiration
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The pH of a solution is the measure of the activity of dissolved H+ ions.
High H+ = Acidic Solutions (1-6 pH)
Low H+ = Basic Solutions (8-14 pH)
Chemiosmosis
Oxygen
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Electron acceptor in aerobic respiration
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Oxidation of ATP (adenine tri-phosphate) in mitochondria
Phosphorous
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Essential for phospho-lipid bilayer
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Active component of ATP
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Backbone of DNA
Sodium and Potassium
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POTASSIUM: Nerve impulses, osmosis, cation in cell cytoplasm
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SODIUM: Nerve impulses, cation in blood plasma
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Concentration gradient of these two ions in blood plasma and cell cytoplasm allows sodium-potassium pump to work.
Nitrogen
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Production of amino acids (many long chains of amino acids make proteins) [AMINE GROUP - NH2)
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Chlorophyll in chloroplast also contains nitrogen
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Nitrogen cycles
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Exists in different forms e.g.:
Calcium
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Essential mineral
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Structure of bones and teeth, exoskeletons (CaCO3)
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Blood clotting
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Ions are essential for synaptic transmission and muscle contraction
Iron
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Important micro-nutrient
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Oxygen-binding component of hemoglobin
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Used to make chlorophyll, takes part in photosynthesis (usually a limiting factor in plant productivity)
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Facilitates movement of electrons in cell
Sulphur
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Found in some amino acids
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A reactant for chemosynthetic bacteria found in deep sea vents
WATER
- Medium of all chemical reactions on a cellular level
- Polar molecule (capacity to carry charge)
*Hydrogen is partially positive
*Oxygen is negative
This leads to oxygen in water to become partially negative.
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Hydrogen bonds are the temporary attractions formed between polar molecules.
Cohesive - Water molecules are able to stick to other water molecules.
Adhesive - Water molecules are able to stick to other surfaces.
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CAPILLARY ACTION - Water will move up xylem against gravity
SURFACE TENSION - Strong enough to support insects and cause drops to form.
WATER HAS A HIGH SPECIFIC HEAT CAPACITY
- Needs a lot of energy for temperature change in water (hydrogen bonds)
- Water is a good coolant (removes heat through evaporation)
- Slow heating/cooling of water is ideal for organisms to live in
WILL DISSOLVE POLAR SOLUTES EASILY
- Most metabolic reactions dissolved and happen in water