Cellular Water Properties

• Water is crucial in living organisms and has unique properties.

Water in Cells

• All living things consist of one or more cells.
• Cytoplasm exists in all cells.
• Cytoplasm consists of cytosol (a gel-like substance), organelles (like mitochondria), macromolecules, and ions.
• Cytosol is the liquid component of the cytoplasm that surrounds intracellular organelles.
• Cytoplasm includes all contents of a cell, excluding the nucleus, including all organelles and the cytosol.
• Cytosol consists of approximately 70 to 80% water and is colorless.
• Cellular metabolism occurs inside cytosol.
• Photosynthesis and other cellular processes require water.

Water Around Cells

• Tissue exists as a group of cells with a similar function.
• Connective tissue components include cellular and non-cellular elements.
• Blood is a connective tissue.
• Blood composition: 45% red/white blood cells and 55% blood plasma.
• Blood plasma consists of approximately 92% water.

Water in Living Things

• The human body is approximately 60-70% water.
• Water is critical for living organisms.
• Water in the brain is 75%.
• Water in the blood is 83%.
• Water in the heart is 79%.
• Water in the bones is 22%.
• Water in muscles 75%.
• Water in the liver is 86%.
• Water in the kidneys is 83%.
• Different living things consist of approximately 60-95% water.
• Life evolved originally in a marine (water) environment.
• First came macromolecules, then organelles, then came cells.
• Hydrothermal vents exist on the deep ocean floor with water and nutrients but no light.

Chemical Structure of Water

• The Chemical formula for water is H₂O.
• Hydrogen and oxygen are held together with covalent bonds.
• Water molecules are polar.
• Oxygen attracts electrons more strongly than hydrogen in a covalent bond between oxygen and hydrogen (H-O).
• Hydrogen and oxygen form covalent bonds.
• Hydrogen (H+) has a slightly positive charge, while oxygen (O-) has a slightly negative charge.
• Electronegativity is the measure of an atom's ability to attract shared electrons to itself.
• Water's polarity contributes to its properties of attraction.
• Molecules of water attract one another, establishing bonds of hydrogen.
• Water attracts or is attracted to other polar molecules (like itself!) and ions.
• Hydrophilic substances interact or dissolve in water; hydro = water, -philic = loving.

Sodium Chloride with Water

• Salt is made up of sodium chloride.
• The chemical formula is NaCl.
• The positive portion of water molecules (hydrogen+) attracts the negative chloride ions (Cl-).
• The negative portion of water molecules (oxygen-) attracts the positive sodium ions (Na+).
• NaCl + cytosol = negative chloride ions + positive sodium ions + cytosol.

Importance of Ions

• Ions in cellular processes are highly relevant.
• A decrease of chloride ions (Cl-) in the egg's cytosol changes the electronegativity of the cytosol from negative to positive.
• Before fertilization cells have a Negative Resting Potential.
• After Fertilization cells exibit Fast Polyspermy Block

Properties of Water

• These will be covered separately: Water's States (Gas, Liquid, and Solid), Water's High Heat Capacity, Water's Heat of Vaporization, Water's Solvent Properties, Water's Cohesive and Adhesive Properties.

Water's States: Gas, Liquid, Solid

• Liquid water: hydrogen bonds constantly form and break as the water molecules slide past each other.
• Gas water: Water molecules' higher energy causes hydrogen bonds to break completely allowing them to escape into the air (steam or water vapor) when the water boils, as the heat rises.
• Solid water: Water temperature reduces and freezes the water molecules, which then form into a crystalline structure that is maintained by hydrogen bonding.
• Solid water has a lower density is in its solid form because the water molecules orient themselves so they push further apart as hydrogen bonds orient as they freeze.
• Ice floats at the surface of liquid water.
• When ice crystals form upon freezing, they rupture the delicate cell membrane and proteins that are essential for living cells to function.
• Ice crystals can be difficult to form by adding a solution (glycerol) that binds with the hydrogen bonds of water (until -37.8C).

Water's High Heat Capacity

• Water's high heat capacity is due to hydrogen bonding among its molecules.
• Water holds a lot of heat without its temperature rising, but a small amount of water is super strong when it comes to heat.
• Water takes a long time to heat and cool.
• Blood plasma consists mostly of water.
• Plasma disperses and save's heat
• A 1°C rise in body temperature requires a 10–12.5% increase in metabolic rate.
• Febrile consists of the fever response, and the Water's heat capacity

Water's Solvent Properties

• Water is a polar molecule with slightly positive and slightly negative charges.
• Ions and molecules that are polar can dissolve in water easily because it's a great solvent.
• Ions and polar molecules creates hydrogen bonds, surrounding the particle with water molecules (sphere of hydration).
• Water molecules are slightly positive and negative charges because water is a polar molecules

Water's Cohesive and Adhesive Properties

• Cohesion water molecules are attracted to one another because hydrogen bonds.
• Cohesion allows for surface tension.
• Surface tension is a substance's capacity to not rupture under tension or stress.
• Attraction can be stronger than water's forces of cohesion, especially if water is exposed to surfaces that are charged such as tubes that are capillary.
• Glass (or silicon dioxide) naturally carries negative charges on its surface.
• Cohesive Forces consist of Water transport from the roots to the leaves.
• Adhesive forces consist of a “pull" on the water column.

Water’s Cohesive and Adhesion Properties in Living Things

• Water is transported from roots to leaves because of the water vessels.
• Adhesive forces are created when water molecules evaporate on the plant.

Explore the role of water in cells, blood, and plant transport. Understand water's solvent properties, cohesion, and adhesion. Review the chemical composition and percentage of water in the human body.