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Synthesizing organic molecules

Content objective:

What are we learning and why are we learning this? Content, procedures, or skills.

Vocabulary objective

Tier II: High frequency words used across content areas. Key to understanding directions & relationships, and for making inferences.

Tier III: Low frequency, domain specific terms.

Building on what we already know

Make connections to prior knowledge. This is where we build from.

monomers polymers Amoeba sisters GIFs


Synthesize: to form by combining parts.

Synthesis: bonding 2 molecules together to form a larger molecule.

Digestion: breaking larger molecules apart into pieces

monomer: a single unit

polymer: many units put together

polymerization: bonding many of the same molecule together, again and again, to make a large structure.


Cells bond small molecules – monomers – together to make a larger molecule – a polymer.

Here’s a simple way to think about it:

Monomer Polymer Lego analogy

 Polymerization can be more complex, like this:

plastic monomers connecting to make polymers

Here we see (many of) 2 monomers, repeatedly being connected to form a polymer. From http://www.dynamicscience.com.au/tester/solutions1/chemistry/monomers%20DM.htm

Sugars & carbohydrates

The monomer here is a sugar

The polymer here is a carbohydrate

(There are many kind of carbs, including starch, fiber, etc.)

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. Fiber has 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.

Details of how two glucose bond to form maltose.

Formation of the disaccharide maltose

from BioTopics by Richard Steane

During digestion, your body has enzymes that digest carbs.

Hydrolysis of maltose into glucose

from BioTopics by Richard Steane

Water needs to be added in this process; since water is used to break the molecule, we call this process hydrolysis. (Latin: water-breaking)



How fats are used:

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

The monomers discussed here will be glycerol, and fatty acids.

The polymer here could be triglycerides or phospholipids

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

Glycerol: Used as a cap to tie together fatty acids.
It can also  provide energy for cellular metabolism.

 Glycerol + Fatty Acids = triglycerides


The monomer here is a phospholipid

The polymer here is the lipid bilayer (cell membrane)

A cell membrane is double-layer of fat molecules, which we find around every cell.

Here’s a simple drawing

lipid bilayer

Here’s a more detailed drawing

antigens on cell membrane

antigens on cell membrane

Let’s look at a single phospholipid molecule.

There are many forms. This is just one example

black = carbon

white = hydrogen

red    = oxygen

blue   = nitrogen



The main building blocks of deoxy ribo nucleic acid

The monomer here is a nucleotide

The polymer here is a gene

These are 4 different monomers.

The cell bonds nucleotides together into genes.

Here you can study DNA structure in more detail.


Then DNA nucleotides are synthesized into genes


The monomer here is an amino acid.

The polymer here is a peptide or protein.

These are 20 different types of common amino acids.

Amino acids are bonded together to make peptides, or proteins.

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.

A chain of amino acids folds up into a shape.
Every protein has its own shape.

Click here to see how we make peptide bonds – the atom-by-atom details.

Proteins then fold into coils and sheets.

They become biological machines.

Their shape determines their function (“job”.)

Related articles

When we digest nutrients, we are breaking large molecules down into smaller ones

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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