Biological Macromolecules

Biology 11

biochemistry

is the chemistry of life

polymers

chain-like, built by joining smaller subunits called monomers

a polymer is many repeating monomers bonded to form long chains

monomer

a single unit that makes up polymers

4 biological macromolcules

carb, lipid, proteins, fats

carbohydrates

• Most abundant biological compounds (known as simple sugars)

• Contain carbon, hydrogen and oxygen.

• Monomer unit is a monosaccharide(ex. glucose)

monosaccharides

• “Mono” means one.  

• known as simple sugars. 

• They can be a single linear chain (when in dry state) of carbon atoms with a hydroxyl (-OH) group, but can also form a ring structure (when in water). 

• Monosaccharides can be distinguished by their carbonyl group ( C=O, composed of a carbon atom double-bonded to an oxygen atom) or by the number of carbons in their carbon backbone. 

• An example of a monosaccharide is glucose. Glucose is a simple sugar.

disaccharides

• (all disaccharides are formed by a process called dehydration synthesis).

dehydration synthesis

• is the creation of larger molecules from monomers where a water molecule is released as a byproduct in the process. 

oligosaccharides

• (oligo means “a few”) are 2-9 monosaccharide units bonded together by glycosidic bonds. (ex. Maltose & sucrose). 

polysaccharides

• are complex carbohydrates and most are made up of 10 or more monosaccharides (ex. Starch and glycogen)

glycosidic bond

• a type of chemical bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate.

polysaccharides

• “Poly” means many. 

• Polysaccharides are complex carbohydrates. 

• Most are made up of 10 or more monosaccharides joined by glycosidic linkages/bonds.

• Polysaccharides can be used for structure in living things or functions like an energy source when it’s needed immediately by cells!

• Examples of structural polysaccharides are cellulose (ex. in the cell wall) and chitin (ex. insect exoskeletons). 

• Examples of storage polysaccharides are starch and glycogen.

lipids

• All  nonpolar organic molecules are lipids.

• They contain carbon, hydrogen , and oxygen.  

• Lipids do not form polymers, however their basic unit is a fatty acid, their equivalent to a type of monomer. 

• Lipids do not form polymers because in order for the basic unit to be called a monomer, the unit must occur in repetitive chains, which lipids do not. 

• Lipids are nonpolar and are therefore hydrophobic (so they do not dissolve in water!) 

• Lipids are used for energy storage (ex. In liver cells), structure (ex. In the cell membrane, insulation/protection of some cells), and as chemical messengers (ex. steroid hormones).

4 types of lipids

fats, phospholipids, steroids, waxes

proteins

• Very diverse and important molecules.

• They contain carbon, hydrogen, oxygen, and nitrogen. 

• They act as structural building blocks for living things and they are functional molecules that are involved in almost everything that a cell does.

• Cells contain thousands of different proteins each performing a specific task. 

• The monomer units for a protein are amino acids. 

• There are 20 amino acids found in living things in total and they are classified as either essential or nonessential amino acids. 

essential/non essential amino acids

essential: we must get through our diet (8 essential amino acids)

non essential: made by your body

peptide

a chain of 12-20 amino acids

polypeptide

a chain of 20-50 amino acids

protein amino acids #

50 or more

what is an amino acid made up of

• An amino acid is made up of a carboxyl group ( -COOH), and amino group/ “amine” (-NH₂), a hydrogen atom, and an R-group/ “sidechain” , which represents the grouping that is unique to each amino acid. 

protein folded

• Proteins are amino acid chains that are folded into a specific 3D shape. 

• The function of the protein is directly related to the specific 3D shape.

• Proteins can be unfolded or “denatured” by heat, alcohol, pH, and heavy metal salts. 

• If a protein is unfolded, it is said to be inactive or “denatured” .

nucleic acids

• Nucleic acids are nitrogen containing compounds composed of units called nucleotides.  

• Nucleic acids are found in the nucleus of cells.  

• There are two types of these acids: DNA and RNA.  (Deoxyribose Nucleic Acid and Ribonucleic Acid)

• DNA is a double-stranded molecule that contains the genetic and hereditary material for an organism.  

• Used by all organisms to store the hereditary information that determines the structural and functional characteristics of an organism.

• RNA is a single-stranded molecule that works 

  with DNA to direct the activities of the cell.

nucleic acid monomer

• The monomer unit for nucleic acids is a nucleotide:

• Each nucleotide has a phosphate (PO₄^2-) group, a sugar, and a nitrogen base.

dna vs rna

dna: double stranded, deoxyribose sugar, bases CGAT, self replicate

rna: single stranded, ribose sugar, bases CGAU, can’t self replicate

both: contain a sugar, phosphate, and a base