Properties of water

Water in the world Water makes up 70% of the

Earth’s surface

As it turns out, water accounts for 70% of a cell’s mass!

Water helps to maintain homeostasis within a cell/organism.

What are the properties of water that make it so useful to living organisms?

Properties of Water 1. Water is a polar molecule

2. Water is the “universal solvent”

3. Pure water has a neutral pH of 7

4. Water is both adhesive and cohesive

5. Solid water is less dense than liquid water

Properties of Water 1. Water is a polar molecule

2. Water is the “universal solvent”

3. Pure water has a neutral pH of 7

4. Water is both adhesive and cohesive

5. Solid water is less dense than liquid water

Water is a polar molecule A water molecule has an overall

positive charge

This makes it great for bonding!

Water molecules form hydrogen bonds easily with other water molecules

A water molecule is held together with covalent bonds

Electrons are shared, but they are shared unevenly

Properties of Water 1. Water is a polar molecule

2. Water is the “universal solvent”

3. Pure water has a neutral pH of 7

4. Water is both adhesive and cohesive

5. Solid water is less dense than liquid water

Water is the “universal solvent” Mixture: a combination of two or more substances in

which each substance retains its individual properties

Different from a reaction! No new product is created.

Heterogeneous mixture: components remain distinct

Salads! Sand and water!

Homogeneous mixture: mixture has a uniform composition

Salt water! Iced tea!

Water is the “universal solvent”

Solvent: the substance that does the dissolving in a mixture.

Solute: the substance that is dissolved in a mixture.

Example – powdered lemonade

Water is the solvent

The lemonade is the solute

Water is the “universal solvent” Water is able to

dissolve many substances, making it very useful!

Properties of Water 1. Water is a polar molecule

2. Water is the “universal solvent”

3. Pure water has a neutral pH of 7

4. Water is both adhesive and cohesive

5. Solid water is less dense than liquid water

Water has a neutral pH Acids: substances that release hydrogen ions (H+)

when dissolved in water

pH of less than 7

Bases: substance that release hydroxide ions (OH-) when dissolved in water

pH greater than 7

Water has a neutral pH Pure water has a pH of 7!

Good for carrying out biological processes and allows us to maintain homeostasis

Properties of Water 1. Water is a polar molecule

2. Water is the “universal solvent”

3. Pure water has a neutral pH of 7

4. Water is both adhesive and cohesive

5. Solid water is less dense than liquid water

Water is both adhesive and cohesive Remember, water is polar and is therefore good for

bonding!

Cohesion: water’s ability to form hydrogen bonds with other water molecules (water = water).

Creates a high surface tension

Droplets, bugs and leaves!

Adhesion: water’s ability to form hydrogen bonds with molecules other than water (water = something else).

Capillary action allows plants to draw up water through roots

Properties of Water 1. Water is a polar molecule

2. Water is the “universal solvent”

3. Pure water has a neutral pH of 7

4. Water is both adhesive and cohesive

5. Solid water is less dense than liquid water

Solid water is less dense Liquid water becomes condenses as it cools to freezing

And yet…ice is less dense than liquid water

Fish can survive in the winter because ice floats!

The amount of hydrogen ions or hydroxide ions in a solution

Acids and Bases Acids

Have an abundance of H+ ions and pH values lower than 7

Acids and Bases Bases

Have more OH- ions than H+ ions and have pH values higher than 7

Acids and Bases Most biological processes occur in neutral pH or weak

acids/bases

pH range of 6.5 to 7.5

Buffers: react with acids or bases to keep pH within a certain range

Buffers in blood keep pH about 7.4

Antacids help neutralize stomach acid

Large molecules that are formed by joining smaller organic molecules together.

Biological Macromolecules Macro = “Large”

Also known as polymers. Poly = “Many”

Many what? Many monomers!

Monomers are smaller repeating subunits that make up polymers

Monomers are the building blocks of polymers!

All biological macromolecules are organic molecules, meaning they contain the element CARBON.

Biological Macromolecules 1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic Acids

Biological Macromolecules 1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic Acids

Carbohydrate Building Blocks Building blocks of carbohydrates:

Monosaccharides, or simple sugars

Glucose, fructose

Carbohydrate Function Your body’s main source

of energy!

Simple sugars provide you with fast acting energy

Complex sugars (starches) provide you with long lasting energy

Additional Functions:

Structure and support

Carbohydrate Examples

Grains, Pastas, Fruits, Vegetables, Sugar, Honey,

Potatoes

Cellulose

Carbohydrate Additional Info Compounds composed of carbon, hydrogen, and

oxygen in a ratio of one oxygen and two hydrogen atoms for each carbon

(CH2O)n

If two monosaccharides join together, they form disaccharides

Sucrose (table sugar), lactose

If many monosaccharides join together, they form polysaccharides, or complex sugars

Starches, glycogen, cellulose

Biological Macromolecules 1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic Acids

Lipid Building Blocks FATS, oils and waxes!

No true monomer (building block)

Composed of fatty acids, glycerol and other components

Lipid Function Primary function is to store energy!

Additional functions:

Insulation

Walrus

Prevent water loss – lipids don’t mix with water!

Cell membrane

Waxy cuticle on plant leaves

Honeycomb in a beehive

Lipid Examples Butter

Oils

Olive, Vegetable, Peanut

Avocados

Wax

Plant cuticles (wax)

Steroids

Cholesterol

Lipid Additional Information Hydrophobic: “water

fearing”

Lipid solid at room temperature

“Triglyceride”

Lipid liquid at room temperature

“Oils”

Lipid Additional Information Lipids with only single bonds = saturated fats

Lipids with at least one double bond = unsaturated fats

Lipids with many double bonds = polyunsaturated fats

Biological Macromolecules 1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic Acids

Protein Building Block The building blocks of proteins are

amino acids

20 different amino acids

Our bodies can make 10 of the 20 amino acids

The other 10 amino acids (“essential amino acids”) come from…our food!

Foods with proteins!

Protein Function Involved in nearly every function of your body

Structural support

Build muscle

Communicate signals between cells

Speed up chemical reactions (ENZYMES)

Control cell growth

Protein Examples Meats

Eggs

Nuts

Beans

Fish

Cheese

Milk

Hemoglobin

Insulin

Protein Additional Info **The structure of a protein determines its function**

Made of carbon, nitrogen, oxygen, hydrogen and sometimes sulfur

Make up ~15% of your total body mass!

Hair, skin, nails…all made of protein!

Amino acids are held together by peptide bonds in order to form proteins

Made by the ribosome!

Biological Macromolecules 1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic Acids

Nucleic Acid Building Blocks Smaller repeating subunits called

nucleotides 1. Sugar (Deoxyribose or Ribose)

2. Phosphate

3. Nitrogen Base (Adenine, Guanine, Cytosine or

Thymine/Uracil)

DNA and RNA!

Deoxyribonucleic acid / Ribonucleic acid

Nucleic Acid Function Store and transmit genetic information

Nucleic Acid Examples

RNA DNA

Nucleic Acid Additional Info Composed of carbon,

nitrogen, oxygen, phosphorous and hydrogen atoms

DNA

Double stranded

Only in nucleus

RNA

Single stranded

Anywhere in cell