properties of water - my blog...water in the world water makes up 70% of the earth’s surface as it...
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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