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Synthesizing organic molecules


Synthesize: to form by combining parts.

Synthesis: bonding smaller molecules together to form larger molecules.

Digestion: breaking larger molecules apart into smaller molecules

monomer: a single unit

polymer: many units put together



Sugars                                     Carbohydrates, or fiber


Carbohydrate sources

from http://dtc.ucsf.edu/living-with-diabetes/diet-and-nutrition/understanding-carbohydrates/

Rice, grains, cereals, and pasta, breads, tortillas, crackers, bagels and rolls

Dried beans, split peas and lentils

Vegetables, like potatoes, corn, peas and winter squash

Fruit, Milk, Yogurt, Sugars (like table sugar and honey)

Foods and drinks made with sugar, like regular soft drinks and desserts


Our small intestine has enzymes that can digest many carbohydrates into their component sugars, but not all. Plant carbs that our body can not break down are termed fiber.

Some fiber is in fruit, vegetables and whole grains. Most have near-zero calories.

Soluble fiber dissolves in water

Insoluble fiber doesn’t dissolve in water

Fiber is a polymer of sugars, just joined together in a way that we can’t digest.



A major category of biological molecule, with many uses:

energy storage, building cell membranes, creating electrical insulation around our nerves so that they can transmit signals

Fats are built from “fatty acids” monomers that are assembled together into larger molecules.

Fatty acid: long chain of C and H atoms, with a cap of COOH atoms.

Glycerol: A simply chemical that the body uses as sort of a cap, to tie together fatty acids

Glycerol + Fatty Acids = triglycerides


Phospholipids ar ethe building blocks of cell membranes.

They make a double-layer (bilayer) around every cell.

A simple drawing of this lipid bilayer is here

lipid bilayer

A more realistic drawing is here

antigens on cell membrane

antigens on cell membrane

Let’s look at a single phospholipid molecule. There are many forms.

This is just one type.

black = carbon

white = hydrogen

red = oxygen

blue = nitrogen











The main building blocks of deoxy ribo nucleic acid

These are monomers (single pieces)

Yet these small molecules are just monomers – the cell bonds them together into longer units, polymers, called genes.


Then DNA nucleotides are synthesized into genes


Amino acids (monomers) are synthesized into peptides, or proteins (polymers)

A peptide is just a small protein, less than 50 amino acids (aa) long.

Proteins are much larger, 100 aa, 500 aa, even 1,000 aa.

Many amino acids join together to form a peptide (small protein)



Proteins then fold into coils and sheets. They become biological machines. Their shape determines their function (“job”.)


Learning Standards

Massachusetts Curriculum Frameworks: Biology

8.MS-PS1-1. Develop a model to describe that (a) atoms combine in a multitude of ways to produce pure substances which make up all of the living and nonliving things that we encounter, (b) atoms form molecules and compounds that range in size from two to thousands of atoms, and (c) mixtures are composed of different proportions of pure substances.

Clarification Statement: Examples of molecular-level models could include drawings, three-dimensional ball and stick structures, and computer representations showing different molecules with different types of atoms.

 HS-LS1-6. Construct an explanation based on evidence that organic molecules are primarily composed of six elements, where carbon, hydrogen, and oxygen atoms may combine with nitrogen, sulfur, and phosphorus to form monomers that can further combine to form large carbon-based macromolecules.
Clarification Statements:
• Monomers include amino acids, mono- and disaccharides, nucleotides, and fatty acids.
• Organic macromolecules include proteins, carbohydrates (polysaccharides), nucleic acids, and lipids.


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