Biochemist ry Unit 5

Biochemistry life chemistry It’s all about theyou eat, and the & that we obtain from eating them!! It’s all about the foods you eat, and the molecules & energy that we obtain from eating them!!

One of the most importan t molecule s in living systems! One of the most importan t molecule s in living systems! WATER

Lets discuss how this molecule is formed…

WATER is an example of a molecule that is covalently bonded

covalently bonded = sharing electrons

What is a covalent bond? Electrons are shared among two or more atomsElectrons are shared among two or more atoms

Do you remember the ionic bond? Electrons are either given or taken among two or more atoms Their opposite charges, bring them together

Lets Practice a few covalent bonds:

e- spend more time around the oxygen e- spend less time around the hydrogens

e- spend more time around the oxygen e- spend less time around the hydrogens

CREATES a POLAR molecule Two “poles” (ends) Opposite charges

Properties of Water that contribute to its importants for life: Cohesion 1) Cohesion *Water attracted to other water molecules

Properties of Water that contribute to its importants for life: Cohesion 1) Cohesion * Water attracted to other water molecules b/c of a hydrogen bond!!

The Hydrogen bond: * Water attracted to Water b/c of a hydrogen bond!!

Properties of Water that contribute to its importants for life: Cohesion 1) Cohesion *Water attracted to other water molecules

… results in Surface Tension … results in Surface Tension -` *Cohesion of water molecules to eachother at the surface of the body of water. Difficult to stretch or break surface Properties of Water that contribute to its importants for life:

… results in Surface Tension … results in Surface Tension - *Cohesion of water molecules to eachother at the surface of the body of water. Properties of Water that contribute to its importants for life:

… results in Surface Tension … results in Surface Tension - Properties of Water that contribute to its importants for life:

Adhesion - 2) Adhesion - water attracted to other surfaces makes water “sticky”

WHAT is going on here?

Properties of Water that contribute to its importants for life: Adhesion - 2) Adhesion - water attracted to other surfaces makes water “sticky”

This is a sea bird that died as a result of an oil spill… This is a sea bird that died as a result of an oil spill… Explain why??? (use: “H-bond”, “polar”, “surface tension” in your answer) Explain why??? (use: “H-bond”, “polar”, “surface tension” in your answer)

Adhesion + Cohesion… results in capillarity Adhesion + Cohesion… results in capillarity - *molecules moving against gravity (upward). Think of a plant… from root to leaf

Specific Heat of water is high 3) Specific Heat of water is high - amount of heat needed to raise or lower temp by 1 o C - takes “a lot” of heat for water Properties of Water that contribute to its importants for life:

Specific Heat 3) Specific Heat = (high) - takes “a lot” for water b/c the thermal energy is absorbed in the H- bonds BEFORE it increases motion of the water molecule Properties of Water that contribute to its importants for life:

Specific Heat Specific Heat = (high for water) - water does not heat up or cool down as fast as other substances Properties of Water that contribute to its importants for life:

WHY does water heat up slower than the metal pan??? Ever try to touch the pan (before the water boils??)

H- bonds in water have to break before the water can heat no H-bonds in the metal Ever try to touch a pan of water (before the water boils??)

… results in temperature moderation … results in temperature moderation - *A body of water will change temperature less when it absorbs or looses a given amount of heat than another substance Takes a lot of heat to raise the temp.

“THANK goodness for that!”

As water cools night) & reforms H-bonds…

Heat is given off (b/c it is leaving the water) coast does not cool off as fast as mainland

… results in temperature moderation … results in temperature moderation - *When water cools, it FORMS H- bonds. This release of energy (heat) Less drop in temp during same amount of time

… results in: is high for water … results in: heat of vaporization is high for water : causes evaporative cooling Keeps you from overheating Properties of Water that contribute to its importants for life:

WHY SWEAT?

Less dense as a solid than liquid 4) Less dense as a solid than liquid Properties of Water that contribute to its importants for life: - Oceans and Lakes do not freeze from bottom up b/c ice floats

5) Water is versatile Solvent Properties of Water that contribute to its importants for life: R E ACID H + BASE L U E OH -