Lecture 3 Bio 110

Water Content in Humans

The percentage of water composition in humans, which is $55-60\%$

Water as a Transport Medium

A transport mechanism in organisms where blood is $\frac{1}{2}$ water

Temperature Buffer

The ability of water to resist temperature change, acting as a buffer for organisms and ecosystems

Polar Covalent Bonds in Water

Covalent bonds in which oxygen is more electronegative than hydrogen, causing partial charges and making water polar

Hydrogen Bonds

Electrostatic attractions between a partially positive hydrogen atom and a partially negative atom on another molecule

Hydrogen Bond Requirements

The requirement of both a hydrogen donor and a hydrogen acceptor to form a bond

Hydrogen Bonding Capacity of Water

The capacity of one water molecule to form $4$ hydrogen bonds

Hydrophilic

Water loving; refers to polar molecules that are soluble in water

Hydrophobic

Water fearing; refers to nonpolar molecules that are insoluble in water

Amphipathic

Having both hydrophilic and hydrophobic characteristics

Brønsted-Lowry Acid

A substance that donates protons ($H^+$/hydrogen ions) when placed in an aqueous solution

Brønsted-Lowry Base

A substance that accepts protons ($H^+$) out of water when placed in an aqueous solution

pH

The negative log of $H^+$ concentration in solution ($mol/L$), expressed as $-\log[H^+]$

pH Scale

A scale running from $0$ (acidic, where $[H^+] > [OH^-]$) to $7$ (neutral, where $[H^+] = [OH^-]$) to $14$ (basic, where $[H^+] < [OH^-]$)

Logarithmic pH Scale

The principle that a $1$ unit change in pH corresponds to a $10$ fold change in $H^+$ concentration