Topic 3:

Notes/Study Guide

Sooo....Ms. Hudson what are organic molecules anyways?!

I'm so glad you asked! ORGANIC MOLECULES are molecules that always contain two key elements: Carbon (C) and Hydrogen (H).

All biological molecules (molecules organisms use to gain or store energy) are organic molecules.

THE CARBON ATOM

The chemistry of the carbon atom in all organic molecules accounts for the structure and formation of all large biomolecules. Why?

For one carbon contains four valence electrons (electrons in its outermost shell). And in order to get the "happy" number of 8 electrons in this outermost shell carbon is able to form covalent bonds with up to FOUR different atoms.

Each electron on carbon can join with an electron from another atom to form a strong COVALENT BOND. Each line between atoms in a molecular drawing represents one covalent bond.

A carbon atom can bond to other carbon atoms, which gives carbon the ability to form chains that are almost unlimited in length. These long chains of carbon and the hydrogens attached to them are called HYDROCARBON CHAINS. These carbon-carbon bonds can be SINGLE, DOUBLE, OR TRIPLE covalent bonds.

Chains of carbon can fold and close upon themselves forming rings!!

The carbon chains of an organic molecule is often referred to its skeleton. Just as a skeleton defines our bodies shape and function, the carbon skeleton of organic molecules defines its shape and function.

The other elements found in organic molecules (besides Carbon) are:

Hydrogen(H), Oxygen (O), Nitrogen (N), and Phosphorus (P).

Nitrogen is found in Proteins and Nucleic Acids and Phosphorus is found in Nucleic Acids.

Therefore, the elements found in all four organic molecules are Carbon (C), Hydrogen (H), & Oxygen (O).

MACROMOLECULES

Macromolecules = Giant Molecules

Macromolecules are made from thousands or even hundreds of thousands of smaller molecules.

Most of these macromolecules (carbohydrates, proteins, and nucleic acids) are called POLYMERS and are created by the joining of smaller molecules called MONOMERS.

MONOMERS: a small molecule that is a subunit of a polymer (larger molecule). Example: glucose is a monomer of starch.

POLYMER: macromolecule made up of covalently bonded monomers.

Example: A polypeptide is a polymer made up of amino acid monomers.

Dehydration Synthesis

&

Hydrolysis

Dehydration Synthesis

A chemical reaction in which a hydroxyl group (-OH) and a hydrogen atom (H), which is the equivalent to a water molecule, are REMOVED in order to form a polymer.

Dehydrate = loss of water

Synthesis = to create

Dehydration Synthesis = Creating a polymer from monomers by losing a water molecule.

Hydrolysis

A chemical reaction in which Water is ADDED in order degrade or break a polymer into monomers.

Hydro = water

Lysis = to break

Hydrolysis = breaking the bonds of a polymer by adding a water molecule.

Types of Macromolecules

Macromolecules aka Organic Molecules are the molecules of life and are built around hydrocarbon chains that are often quite long.

There are FOUR types of organic macromolecules. They are carbohydrates, lipids, nucleic acids, and proteins.

CARBOHYDRATES

DINB Help: Carbohydrates Key Information

Carbohydrates are macromolecules, which are also known as ORGANIC compounds or BIOLOGICAL molecules.
We can find them in our bodies and some foods such as BREADS.
Carbohydrates contain only carbon, HYDROGEN, and oxygen.
The length of a carbohydrate chain can vary considerably. They can be divided into three categories: monosaccharides, DISACCHARIDES, and polysaccharides.
Carbohydrates act as store of ENERGY in the body. This is why many athletes "carb-load" before a big event.
Their energy is released from indidual glucose molecules in a process called RESPIRATION.
Depending on the type of carbohydrate, the energy may be released quickly, e.g. simple sugars, or it may be a slow release e.g. COMPLEX carbohydrates.

ELEMENTS: The chemical elements that make up the molecule are Carbon, Hydrogen, and Oxygen. Carbohydrates are compounds made up of carbon, hydrogen, and oxygen atoms usually in a ratio 1 : 2 : 1
FUNCTION: Living things use carbohydrates as their main source of immediate (quick) energy. Plants and some animals use carbohydrates for structural purposes (ex: plant cell walls & exoskeltons of inects).
Monomers of Carbohydrates: are simple sugars known as MONOSACCHARIDES. These simple sugars consist of 5 or 6 carbons.
- EXAMPLES: Three of the most abundant 6 carbon monosaccharides are glucose, fructose, and galactose. All three of these simple sugars have the same chemical formula, but arrange themselves in slightly different ways.
Polymer of Carbohydrates: POLYSACCHARIDES are polymers of carbohydrates made of more than 6 monosaccharides. Generally, polysaccharides contain hundred or even thousands of simple sugars and are one of the largest known molecules.
- EXAMPLES: Some of the best-known polysaccharides are starches, glycogen, cellulose, and chitin.
  - Starches are polysaccharides made in plants and are chains of glucose molecules.
  - Glycogen is a polysaccharide found in animals and some algae and fungi and is also made of glucose chains that are arranged differently than those in starch.
  - Starch and glycogen are storage polysaccharides, they function to hold glucose until it is needed to provide energy for the organism.
  - Cellulose is a very large polysaccharide and is the major component of plant cell walls. It is a structural polysaccharide. Cellulose is the major component of both wood and paper

Three Types of Monosaccharides

Three Types of Polysaccharides

LIPIDS

ELEMENTS: Chemical Elements that make up the molecule are Carbon, Hydrogen, and Oxygen.
- Lipids are made mostly from carbon and hydrogen atoms.
FUNCTION: Lipids have many biological functions, including long-term energy storage, insulation (maintaining warmth/heat), waterproofing surfaces, acting as chemical messengers, and making up cell membranes.
- Lipids contain more energy per gram than any other organic molecule.

Pictured Above: Triglyceride Molecule

Relationship with Water: Lipids are defined by one of their properties and not their structure. They are NOT soluble in water. They are HYDROPHOBIC (water-fearing). This is because most of the bonds in lipids are nonpolar.
EXAMPLES: The common categories of lipids are fats, phospolipids, waxes, oils, and steroids.
- Fats tend to be of animal origin (lard, butter). Fats have many functions in the body including long term energy storage, and insulation.
- Oils are usually of plant origin (corn oil, peanut oil)
- Waxes are lipids that contain long fatty acid chains. Their major biological function is waterproofing.
Parts of a Triglyceride: Triglycerides are a common type of lipid that contain one unit of GLYCEROL and three FATTY ACID CHAINS (long hydrocarbon chains that ends in COOH). They are known as TRIGLYCERIDES because there is one glycerol and 3 fatty acid chains.

PHOSPHOLIPIDS: are lipids that contain a phosphate group. They are very similar to most fats but instead of the 3rd fatty acid chain there is polar phosphate group.
- The addition of this phosphate groups means that the phospolipid has a polar/hydrophilic (water loving) region!
- Because of the structure of phospholipids they serve as the primary component of cellular membranes, with the water loving (hydrophilic) phosphate head facing the watery solution and the water fearing (hydrophobic) fatty acid tail away from it.

STEROIDS are a form of lipids that act as chemical messengers.
- Steroids have a four carbon ring backbone.
- CHOLESTEROL is a steroid that enters the body that also enters the body as part of our diet. It is found in the phospholipid cell membrane of cells and is the precursor to several hormone (ex. testosterone, estrogen).

PROTEINS

ELEMENTS: Chemical Elements that make up the molecule are Carbon, Hydrogen, Oxygen, Nitrogen, and sometimes Sulfur
FUNCTIONS: Proteins have many biological functions, including:
- Structure or support (Example: Keratin protein makes up hair and nails.
- Speeding up the rate of chemical reactions. These proteins are called enzymes and we'll learn all about those next Target!
- Immunity (Antibodies)
- Chemical messengers (Hormones, neurotransmitters)
- Control Movement or muscle contraction (Example: Myosin and Actin)
- Transport molecules (Example: Hemoglobin carrying oxygen in our blood, transport channel proteins in the cell membrane that allow things to pass through.)
MONOMERS: Proteins made up of AMINO ACID monomers.
- An amino acid contains a central carbon, bonded to a hydrogen atom, two functional groups and one variable group/R-group.
  - The two functional groups are an amino/amine group (NH2) and a carboxyl/carboxylic acid group (COOH). This is why they are called amino acids!
  - The third group attached to the central carbon is an R-group. This group can vary depending on the amino acid, and determines the unique qualities each amino acid has. (This is the group that makes the amino acid different and unique!)
  - There are more than 20 different amino acids found in nature.
POLYMERS: The linking of amino acid protein monomers forms a polymer called a POLYPEPTIDE.
BOND that CONNECTS MONOMERS: Amino acid can be linked together through the carboxyl end of one amino acid to the amino end of another. This bond is called a PEPTIDE BOND.

Amino Acid Structure

How Peptide Bonds are Formed

NUCLEIC ACIDS

ELEMENTS: Chemical Elements that make up the molecule are Carbon, Hydrogen, Oxygen, Nitrogen, and Phosphorus
MONOMERS: Nucleic Acids are made from monomers called NUCLEOTIDES.
- A nucleotide contains three parts:
  - Phosphate Group (PO4-)
  - Nitrogenous Base
  - Pentose Sugar/Five Carbon Sugar. This sugar can be either ribose (RNA) or deoxyribose (DNA)
FUNCTIONS: The biological function of nucleic acids is to store and transmit hereditary/genetic information.
EXAMPLES: The two types of nucleic acids are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)
- DNA is typically double stranded and RNA is typically single stranded

Macromolecules Review Slides

Amoeba Sisters Video on Organic Molecules

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