AP bio organic compounds

🧬 Molecules of Life

Life is built on carbon. We eat food, break it down into building blocks, and then weave those building blocks together to make living things.

For example, proteins in a burger are broken down into amino acids, which are then used to create the proteins in our bodies. Similarly, the sugars in the bun's carbohydrates are broken down to produce sugars that are used in cellular respiration to create ATP. The fat in the burger is used to create lipids that form our cell membranes.

🧮 Carbon and its Bonding Properties

Life is built on carbon because it can form fairly stable, large molecules. Carbon has four valence electrons, allowing it to bond easily.

C6  ⟹  2 electrons in first level, 1 electron in each of four outer valence shellsC6​⟹2 electrons in first level, 1 electron in each of four outer valence shells

If not carbon, silicon might be the basis for life, as seen in the silicon-based life form, the Horta, in Star Trek.

🧱 Functional Groups

Life is made up of carbon chains, like those found in DNA, with functional groups attached to the outside. These groups give the molecules specific behaviors and functionalities. Here are some important functional groups:

• Carboxyl Group:

  • Abbreviated as CO.

  • Donates a hydrogen ion, forming carboxylic acids.

  • Important in amino acids.

• Carbonyl Group:

  • Carbon with a double-bonded oxygen.

  • If in the middle of a chain, it is a ketone; if at the end, it is an aldehyde.

• Methyl Group:

  • Carbon with three hydrogens (CH3).

  • Important in methylation, where they can make carbon compounds nonfunctional.

• Amino Group:

  • NH2

  • Nitrogen is needed to make amino acids.

  • Amino acids are the building blocks of proteins, made of a carboxyl group and an amino group.

• Phosphate Group:

  • Found on the end of ATP and used for energy transfer.

  • Used to build DNA.

• Hydroxyl Group:

  • OH

  • Makes molecules polar and readily dissolvable.

🧱 Polymers and Monomers

Molecules of life are mostly polymers, which are large macromolecules made up of smaller building blocks called monomers.

Polymers are built through a process called dehydration and broken down through hydrolysis.

Dehydration

Dehydration involves removing a water molecule (H2O) to form a covalent bond between monomers. For example, when two amino acids join, a water molecule is removed, forming a peptide bond.

Hydrolysis

Hydrolysis involves adding a water molecule to break a bond and separate monomers. For example, when breaking down proteins from a burger, water is added to break the bonds between amino acids.

🧬 Four Major Macromolecules

There are four major macromolecules in biology:

1. Nucleic Acids

2. Proteins

3. Carbohydrates

4. Lipids

Nucleic Acids

Nucleic acids, such as RNA and DNA, are polymers made of nucleotide monomers.

• DNA stores information in the cell.

• RNA assists DNA.

Each nucleotide consists of a base, a sugar, and a phosphate group. Nucleotides attach to each other through dehydration reactions to form DNA or RNA.

Proteins

Proteins are polymers made of amino acid monomers.

Each amino acid consists of:

• An amino group

• A carboxyl group

• A central carbon atom with a hydrogen atom

• An R or side chain

The R side chain is different for each of the 20 amino acids that humans need to survive.

🧬 Proteins

• Proteins are large three-dimensional structures composed of thousands of amino acids linked together.

• The sequence of amino acids, determined by DNA, dictates the protein's structure.

• Once assembled, the protein folds into a characteristic shape, influenced by:

  • Alpha helices: Formed by hydrogen bonds.

  • Polar side chains: Orient towards the outside of the protein.

  • Non-polar side chains: Hide in the middle.

  • Positive and negative charges: Attract each other.

• Tertiary structure: Refers to the overall three-dimensional shape of a single polypeptide chain.

• Quaternary structure: Involves multiple polypeptide chains interacting.

• Proteins are built from monomers called amino acids.

• Amino acids are charged due to the presence of hydroxy and amino groups

🍔 Lipids

• Lipids are primarily composed of hydrocarbons (chains of carbon atoms surrounded by hydrogen atoms).

  Hydrocarbons: Organic compounds consisting entirely of carbon and hydrogen.

• Examples of lipids include:

  • Fatty acids: A carboxylic acid with a long aliphatic tail (chain), which is either saturated or unsaturated.

  • Triglycerides: A type of fat found in blood.

  • Phospholipids: A class of lipids that are a major component of all cell membranes.

  • Cholesterol: A type of fat found in your blood.

• Lipids are used for energy and to build membranes.

• Types of Lipids:

  Type	Description	Example
  Saturated	Straight chains with hydrogen atoms surrounding the entire structure.	Animal fat
  Unsaturated	Bent chains due to double bonds, preventing close packing. They are liquid at room temperature.	Olive oil
  Trans Fats	Unsaturated fats that have been artificially saturated by bubbling hydrogen through them to transform the fat.	Margarine

🍬 Carbohydrates

• Carbohydrates come in three types:

  Type	Description	Example
  Monosaccharides	Simple sugars	Glucose
  Disaccharides	Two monosaccharides joined together	Sucrose
  Polysaccharides	Hundreds of monosaccharides linked together	Starch

• Polysaccharides, such as starch in potatoes and bread, are long chains of glucose molecules linked by covalent bonds.

• To break down carbohydrates, hydrolysis is used to separate the sugar molecules.

  Hydrolysis: The chemical breakdown of a compound due to reaction with water.

• The resulting sugars can then be used in cellular respiration.