Biology Unit 6: Water & Basics of Biochemistry

Condensation Reaction (Dehydration Synthesis)

Using simple shapes to represent monomers, diagram a condensation reaction

Hydrolysis Reaction

Using simple shapes to represent monomers, diagram a hydrolysis reaction

Anabolism: The synthesis of complex molecules in living organisms from simpler ones together with the storage of energy; constructive metabolism. Monomer: A molecule that can be bonded to other identical molecules to form a polymer. Polymer: A substance that has a molecular structure consisting chiefly or entirely of a large number of similar units bonded together, e.g., many synthetic organic materials used as plastics and resins.

Define anabolism, monomer, and polymer

Catabolism: The breakdown of complex molecules in living organisms to form simpler ones, together with the release of energy; destructive metabolism.

Define catabolism

A condensation reaction is a chemical reaction where 2 molecules are joined together by a covalent bond to make a larger, more complex, molecule, with the loss of a small molecule. Water is often the small molecule that is given off at the creation of every covalent bond that links the two molecules together. When two amino acids combine in a condensation reaction, a covalent bond forms between the amine nitrogen of one amino acid and the carboxyl carbon of the second amino acid. A molecule of water is then removed as a second product.

Describe condensation (dehydration synthesis) reactions

Adhesion: Water attaching to a non-water structure through hydrogen bonding or attraction to an ionic charge Cohesion: Water attaching to other water through hydrogen bonding

Contrast adhesion with cohesion

Anabolism refers to the process which builds molecules the body needs; it usually requires energy for completion. Catabolism refers to the process that breaks down complex molecules into smaller molecules; it usually releases energy for the organism to use.

Contrast anabolism and catabolism

All bonding involves electrons or the charges that result from the giving/taking of electrons. Covalent bond: Electrons are shared between two atoms Ionic bond: Attraction between cation and anion (no sharing of electrons) Hydrogen bond: An attraction (not a true "bond") between polar molecules

Contrast covalent, ionic, and hydrogen bonds

Hydrolysis, the opposite of condensation, is a chemical reaction in which water breaks down another compound and changes its makeup. Most instances of organic hydrolysis combine water with neutral molecules, while inorganic hydrolysis pairs water with ionic molecules. Hydrolysis means "splitting by water," and begins when a water molecule encounters a reactant and divides into a hydrogen cation, or proton, and a hydroxyl anion. These attach to the components of the reactant, which have also separated into individual molecules. The water's oxygen atom slowly forms a covalent bond with the reactant component, while the two hydrogen ions attach rapidly.

Describe hydrolysis reactions

Polar means a molecule (like water) has regions of slight charge due to the unequal sharing of electrons in a polar covalent bond. Cause: In water, the oxygen has a greater "pull" on the electrons than the hydrogen atoms. As a result, there is unequal sharing of the electrons, with the electrons drawn closer to the oxygen. Effect: Because electrons have a negative charge, the unequal sharing within the bond leads to a separation of positive and negative charge, "partial charges" denoted as s+ and s-.

Describe the cause and effect of the polar nature of water

Water forms hydrogen bonds between the partial positive hydrogen of one water molecule and the partial negative oxygen of another water molecule. The partial positive and partial negative attract. The polar covalent bond within one water molecule while hydrogen bond between two water molecules

Describe where and how water is able to form hydrogen bonds

- Melting and boiling points: water melts (0 degree) and boils (100 degree) at relatively high temperatures for a compound made of such light elements; this is due to the hydrogen bonding between water molecules causing them to stick together and to resist being pulled apart (which is what happens when ice melts and water boils to become a gas). Without this, water would not be liquid over much of surface of the Earth and we would not have an ocean. - High specific heat ("heat capacity"): it takes a relatively large amount of heat energy to raise temperature of water. This is a benefit because the temperature of large bodies of water remains relatively constant, protecting life from possibly lethal temperature fluctuations. - Density: because of the H-bonding structure, solid water (ice) is less dense than liquid water. So, ice floats on top of lakes like a blanket, insulating the living organisms living in the lake.

Explain three thermal properties of water that are useful to living organisms

Water is a good solvent because it can form hydrogen bonds with a variety of different substances. Water is called "the universal solvent" because it dissolves more substances than any other liquid.

Explain why water is such a good solvent

First, look for indication of a charge, noted by a positive or negative symbol. If there is a charge, the molecule will be hydrophilic. Then, look for the presence of polar covalent bonds. For our purposes, these will primarily be between an O and a H (sometimes between a N or a H). Water is attracted to the resulting partial charges, making molecules many -OH groups hydrophilic. If there are no charges (full or partial) then the molecule is hydrophobic. In our class, these will usually be hydrocarbons.

Given a diagram of a molecular structure, determine if the molecule is hydrophilic or hydrophobic

Proteins: Polymers of animo acids Carbohydrates: Have ring structures with an oxygen in the ring and multiple hydroxyl (-OH) groups Lipids: Take a variety forms, but are primarily hydrocarbon molecules with few if any polar hydroxyl (-OH) groups [i.e triglyceride] Nucleic Acids: Will have molecular rings that contain nitrogen (nitrogenous base) connected to a monosaccharide carbohydrate [i.e guanine nucleotide]

Identify the four major classes of carbon compounds used by living organisms from given diagrams

Carbohydrates - Monosaccharides - Disaccharides - Polysaccharides Proteins - Amino acids - Dipeptides - Polypeptides Lipids - Fatty acids - Sterols - Triglycerides - Phospholipids Nucleic Acids - Nucleotides - DNA - RNA

List the four major classes of carbon compounds used by living organisms

Substances that water dissolves must be either polar or charged ionic compound

List the types of molecules that water will dissolve

Melting and boiling points: water melts (0 degree) and boils (100 degree) at relatively high temperatures for a compound made of such light elements; this is due to the hydrogen bonding between water molecules causing them to stick together and to resist being pulled apart (which is what happens when ice melts and water boils to become a gas). Without this, water would not be liquid over much of surface of the Earth and we would not have an ocean.

Outline a benefit to life of water's high boiling point

"Heat of Vaporization" is a measure of how much energy needs to be added to vaporize water. It takes an unusually high amount of heat energy to vaporize water because hydrogen bonds must be broken in order for water molecules to fly off as a gas. As the water evaporates, the surface left behind becomes cooler. This is called evaporative cooling. It allows organisms to cool with sweating so a consistent body temperature is maintained.

Outline a benefit to life of water's high latent heat of vaporization

High specific heat ("heat capacity"): it takes a relatively large amount of heat energy to raise temperature of water. This is a benefit because the temperature of large bodies of water remains relatively constant, protecting life from possibly lethal temperature fluctuations.

Outline a benefit to life of water's high specific heat capacity

- Water cohesion allows for surface tension. Insects such as the water strider are able to stay on the surface of water - Water cohesion creates a chain of water molecules that allows for the transport of water from the roots to the leaves of plants - Water cohesion is responsible for the high heat capacity of water, maintaining a relatively temperature stable internal and external environment for living organisms

Outline an example of cohesive property of water being of benefit to life

Along with cohesion, adhesion is needed for water to move from the roots to the leaves of plants. Water sticks to the sides of the xylem wall through adhesion.

Outline an example of the adhesive property of water being of benefit to life

Non-polar, non-ionic molecules are hydrophobic because no full or partial charges for the partial negative oxygen of water and/or the partial positive hydrogen of water to be attracted.

State that non-polar, non-ionic molecules are hydrophobic

Polar and ionic molecules are hydrophilic because water's partial charges are attracted. Glucose is hydrophilic because it has many polar covalent bonds between O and H. Water can H-bond to the resulting partial positive and partial negative. Ions are hydrophilic because water is attracted to the negative and positive charges.

State that polar and ionic molecules are hydrophilic

Water is H2O. There are polar covalent bonds between each hydrogen atom and the oxygen atom

Write the molecular formula for water and draw the atomic structure of the molecule