Bio Module 3.1

Polymer: a molecule consisting of many similar or identical monomers


Monomers: subunit that serves as the building block of the polymer 


Dehydration Synthesis: a reaction that removes water from the molecules, and is used to form a larger molecule 


Hydrolysis: a reaction that adds water to the molecule, and is used to break apart molecules into two smaller molecules  (hydro: water; lysis: breaks down) 


4 major classes of biological molecules:

  1. Carbohydrates

  2. Proteins 

  3. Nucleic acids 

  4. Lipids 

Proteins: a substance that consists of one or more polypeptides

3 functional groups in proteins: 

  1. Amino acids (NH2)

  2. Carboxyl group (COOH)

  3. Side chain (r group) 


R group determines the identity and properties of amino acids 


Polypeptide: linear chain of amino acids

Peptide bonds are formed by dehydration synthesis 


Protein structure and function:

Primary structure: linear sequence of amino acids in polypeptide chain 

Secondary structure: structures that form within a polypeptide 

Tertiary structure: the overall 3-dimensional shape of a fully folded polypeptide primarily due to the interaction between the R group 

Quaternary structure: the overall 3-dimensional shape of a protein composed of more than one polypeptide 


Protein duration: a protein loses its higher-order structure, but not its primary sequence 


Denaturation: proteins do not function normally; a change in temp causes denaturation 


Nucleic acids: Polyneculotides composed of nucleotides (many nucleotides)


2 types of nucleic acids in living organisms:

DNA (deoxyribose acid): stores hereditary information 

RNA (ribonucleic acid): helps express hereditary information 


The major difference between the two:

DNA is missing oxygen in 2 prime 

DNA is a double helix 

RNA is  single-stranded 

RNA has a more diverse function


They are both made form 4 different nucleotides 


Nitrgenous bases:

Cystine (C)

Thymine (T) (DNA)
Uracil (U) (RNA)

These three are pyrimidines 


Adenine (A)

Guanine (G)

These two are purines


Deoxyribose (DNA)

Ribose (RNA)

These two are sugars


Carbohydrates: sugars or polymers of sugars 


3 major groups of carbohydrates:

  1. Monosaccharides

  2. Disaccharides

  3. polysaccharides


Monosaccharides: the simplest form of carbohydrates, with one sugar molecule 

  • The building blocks for more complex sugars like glucose, fructose, and galactose 

  • Hydrophilic

  • Serves as a major nutrient for cells 

Common six-carbon monosaccharides

  1. Glucose- most common monosaccharide; the primary energy source

  2. Fructose- fruits and veggies

  3. Galactose- component of lactose in milk 

Common five-carbon monosaccharides

  1. Ribose- found in RNA

  2. Deoxyribose- found in DNA


Disaccharides: 2 monosaccharide molecules linked together (double sugars)

  • Short-term storage of monosaccharides in plants 

  • Energy sources for infants of mammals 

  • When digested they are broken down into their monosaccharide components


Common disaccharides

  1. Sugar (table sugar)

  2. Lactose (milk sugar)

  3. Maltose (malt sugar)


Polysaccharides: polymers consisting of hundreds to thousands of linked monosaccharides 

  • Complex carbohydrates made up of long chains of monosaccharide units 

  • Hydrophobic 


Starch: some glucose in roots and seeds of plants 

Glycogen: stores glucose in the liver and muscle of animals 

Cellulose: a polymer of glucose that forms the main structure of plant cell walls and plant fibers 

Chitin: A polymer of modified glucose as a major part of the cell walls of many fungi and the exoskeleton of arthropods 

Cellulose and Chitin are structural polysaccharides 

Lipids: a diverse group of large hydrophobics organic molecules that are made up of mostly hydrocarbon chains or ring 


  • They are NOT polymer. 

  • No lipids dissolve in water. 


3 major groups of lipids:

  1. Triglycerides (fats)

  2. Phospholipids (found in all cells)

  3. Steroids 

(these are all primarily made of hydrogen)


Fats (triglycerides)

  • Hydroponic (don't mix well with water)

  • They are long-term energy storage molecules in animals and plants 


Fatty acids:  an organic molecule consisting of a long unbranched hydrocarbon chain with a carboxylic acid functional group at one end 


Saturated fatty acids: all carbons in the hydrocarbon tail are connected by single bonds 

  • Typically stored at room temperature

  • Most animals are saturated 

  • Saturated fats are saturated with hydrogen 


Unsaturated fatty acids: two or more carbons in the hydrocarbon tail are connected by double bonds 


Phospholipids:  lipids consisting of glycerol backbone linked to 2 fatty acids tails and a phosphate-containing head by dehydration synthesis 

  • NOT polymer 

  • From the structural foundation of cell membranes in all organisms 

  • Have 2 fatty acid tails attached to the glycerol 

  • The head is hydrophilic (Has an affinity for water)

  • The tail is hydrophobic (repels water)


Steroids: lipids consisting of characteristics backbone of 4 fused hydrocarbon rings with various chemical groups attached 


2 major functions:

  1. Important components of cell membranes 

  2. Signaling molecules 


Cholesterol is found only in animals. 

  • One of the best known steroids 

  • It is a VITAL component of the membrane that insulates nerve cells in the brain.

  • Without Cholderton there would be no sex hormones, and without sex hormones, there would be no meiosis