1.1 - Structure of Water and Hydrogen Bonding

The subcomponents of biological molecules determine the properties of that molecule

• Water is composed of 2 main elements, oxygen and hydrogen, in a 1:2 ratio, respectively

• Covalent bonds are the bond type in which atoms share electrons

• Oxygen is more electronegative compared to hydrogen, resulting in an unequal sharing of electrons between oxygen and hydrogen

• Covalent bonding can result in polarity when there are differences in atomic electronegativities

  • a water molecule has polarity

• A hydrogen bond is a weak bond interaction between the negative and positive regions of two separate molecules

• Water can form hydrogen bonds with other water molecules or with other charged molecules

• When two of the same molecules form hydrogen bonds with each other, it is called cohesion

• When two different molecules form hydrogen bonds with each other, it is called adhesion

Living systems depend upon properties of water

• The hydrogen bonds between water molecules can result in surface tension

  • surface tension is a result of increased hydrogen bonding forces between water molecules at the surface

• Cohesions, adhesion, and surface tension allow for water to demonstrate additional chemical behaviors known as emergent properties

• Life depends on water’s properties

  • water’s adhesive property gives water a high solvency ability in its liquid state

  • water’s cohesive property allows for unique hydrogen bond interactions to occur when water is in a solid state, making ice less dense than liquid water

  • water’s cohesive property allows it to absorb a lot of thermal energy before changing chemical states, resisting sudden changes in temperature

• Capillary action is a result of both the adhesive and cohesive properties of water

Key Takeaways:

1. Water contains 1 oxygen atom covalently bonded to 2 hydrogen atoms

2. Oxygen has a higher electronegativity compared to hydrogen resulting in a water molecule having polarity

3. Polarity allows molecules to form hydrogen bonds when oppositely charged regions of two molecules interact

4. The term cohesion refers to molecules of the same type forming hydrogen bonds with one another and adhesion refers to different types of molecules forming hydrogen bonds with one another

5. Living systems depend upon water’s properties, like surface tension

1.2 - Elements of Life

Living systems require a constant input of energy

• The law of the conservation of energy states that energy cannot be created or destroyed, only transformed

• Living systems follow the laws of energy

• Living systems need a constant input of energy to grow, reproduce, and maintain organization

• Living systems mainly use the energy stored in chemical bonds

Living systems require an exchange of matterI

• Atoms and molecules from the environment are necessary to build new molecules

• Carbon is used to build biological molecules such as carbohydrates, proteins, nucleic acids and lipids

  • carbon can bond to other carbon atoms creating carbon skeletons to which other atoms attach

  • carbon skeletons allow for the creation of very large and complex molecules

  • carbon containing molecules can be used to store energy

  • carbon containing molecules can be used to form basic cell structures

• Nitrogen is used to build proteins and nucleic acids

• Phosphorus is used to build nucleic acids and certain lipids

Key Takeaways:

1. Living systems need a constant input of energy to grow, reproduce, and maintain organization

2. Atoms and molecules from the environment are necessary to build new molecules

3. Carbon is used to build all macromolecules, store energy and form cells

4. Nitrogen is used to build proteins and nucleic acids

5. Phosphorus is used to build nucleic acids and certain lipids

1.3 - Introduction to Biological Macromolecules

Monomers have important properties

• Monomers are chemical subunits used to create polymers

• A polymer is a macromolecules made of many monomers

• A covalent bond is formed between two interacting monomers

• Monomers have specific chemical properties that allow them to interact with one another

• Polymers are specific to the monomers they consist of

Dehydration synthesis reactions form covalent bonds

• Dehydration synthesis reactions are used to create macromolecules

• The subcomponents of a water molecule (H and OH) are removed from interacting monomers and a covalent bond forms between them

• The H and OH join together to form a molecule of water as a byproduct of the reaction

Hydrolysis reactions cleave covalent bonds

• Polymers are hydrolyzed (broken down) into monomers during a hydrolysis reaction

• Covalent bonds between the monomers are cleaved (broken) during a hydrolysis reaction

• A water molecule is hydrolyzed into subcomponents (H and OH) and each subcomponents is added to a different monomer

Key Takeaways:

1. All monomers contain carbon and are used to build biological macromolecules

2. Covalent bonds are used to connect monomers together

3. Dehydration synthesis reactions are used to connect monomers together

4. Hydrolysis reactions use water to break down biological macromolecules

1.4 - Properties of Biological Macromolecules

Function is related to structure

• Living systems are organized in a hierarchy of structural levels

• At every level of organization, function is related to structure

• A change in structure generally results in a change in function

• In living systems, the properties of biological molecules are determined by the structure and function of the molecules

The structure of nucleic acids determine function

• Nucleic acids are polymers comprised of monomers called nucleotides

• Nucleotides have a basic structure that contains 3 main subcomponents: a five-carbon sugar, a phosphate group and a nitrogen base

• All nucleic acids store biological information in the sequence of nucleotide monomers

There are differences in nucleic acid structure

• DNA and RNA are examples of nucleic acids

• DNA and RNA nucleotides differ in the type of sugar contained

• DNA and RNA nucleotides can differ int he nitrogen base contained

• Although both DNA and RNA store biological information, the structural differences between them result in specific functional differences

Proteins have different structures and functions

• Amino acids are the monomers that make up proteins

• Amino acids have directionality with an amino (NH₂) terminus and a carboxyl (COOH) terminus

• A polypeptide, the primary structure of a protein, consists of a specific order of amino acids and determines the overall shape the protein can achieve

The chemical properties of R groups vary

• Amino acids differ in the R group, the atom(s) attached to the central carbon

• The R group can be hydrophobic, hydrophilic, or ionic

• A protein can have different amino acids in the polypeptide allowing the protein to have regional differences in structure and function

Carbohydrates and lipids vary in structure and function

• Complex carbohydrates can have monomers whose structures determine the properties and functions of the carbohydrate

• Lipids are nonpolar macromolecules that do not have true monomers but are comprised of subunits such as fatty acids and glycerol

• Lipids have fatty acid components that determine structure and function based on saturation

• Specialized lipids, called phospholipids, contain hydrophilic and hydrophobic regions that determine their interactions with other molecules

Membranes contain lipids and proteins

• Phospholipids and proteins are two main molecules that make up biological membranes

• Phospholipids and some membrane proteins have hydrophobic and hydrophilic regions

• The hydrophilic regions of phospholipids and proteins can interact with each other and the water environments

• The hydrophobic regions of phospholipids and membrane proteins can interact with each other but cannot interact with water environments

Key Takeaways:

1. Nucleotides can vary in the sugar and base components resulting in nucleic acids with different structure and function

2. The amino terminus and carboxyl terminus give amino acids directionality and determine how amino acids assemble into protein polymers

3. R group properties determine how amino acids interact within the polypeptide and determine the structure and function of the protein

4. Differences in the components of carbohydrate monomers determine how the monomers assemble into complex carbohydrates and determine function

5. Lipids are nonpolar macromolecules and difference in saturation determine the structure and function of lipids

6. Phospholipids contain polar regions that interact with other polar molecules and nonpolar regions

1.5 - Structure and Function of Biological Macromolecules

1.6 - Nucleic Acids