Unit 1 (Macromolecules)

Carbohydrates 

Bond: Covalent Bonds

Elements: C, H, O

Monomer: Monosaccharides (ex., glucose)

Polymers: Disaccharide (two, ex,. sucrose) and polysaccharide (many)

Functional Groups: hydroxyl and carbonyl

Carbohydrates functions

• Fuel cells

• Structural support in plants (cellulose that forms cell walls)

• Building blocks for amino acids

Polysaccharides

Storage polysaccharides:

• Plants store starch (a glucose polymer)

• Animals store glycogen (a glucose polymer)

Structural polysaccharides:

• Cellulose: tough substance that forms plant cell walls

• Chitin: forms the exoskeleton of arthropods

Proteins

Bond: Peptide bonds (amino group bonded to a carboxyl group)

Elements: C, H, O, N, S

Monomer: Amino acids

Functional groups: amino group (n-terminus), carboxyl group (c-terminus)

Protein functions

• Build + repair tissue

• Antibodies: Protect the body from disease

• Messenger: Transmits signals (ex., hormones)

• Transport/storage: Carry small atoms and molecules through the body

• Enzymes: Carry out chemical reactions or assist in creating new molecules

Amino Acids

• Molecules that contain an amino group, a carboxyl group, and an R variable side chain.

• Each AA has a unique R group based on its physical and chemical properties.

Side chains can be grouped as…

Nonpolar: Hydrophobic

Polar: Hydrophilic

Charged/ionic: Hydrophobic

• Side chain interactions determine the shape and function of the protein.

• pH levels can affect the structure of the side chains/r groups.

Protein structure

Primary:

• Linear chain of AA

• Determined by genes

• Dictates secondary and tertiary forms

Secondary:

• Coils and folds due to hydrogen bonding within the polypeptide backbone.

Tertiary:

• 3d folding due to interactions between the R variables of the AAs.

Quaternary:

• Interaction of 2 or more polypeptides (only some proteins)

Nucleic Acids

Bond: Phosphodiester linkage and hydrogen bonds between nitrogenous bases

Elements: C, H, O, P, N

Monomer: Nucleotides

Functional Groups: hydroxyl, phosphate, carbonyl, amino

Directionality: 5’ → 3’

• DNA is antiparallel, so one strand is 5’ → 3’ and the other is 3’ → 5’

Nucleic Acid Functions

• Store, transmit, and express hereditary information (DNA)

• Transmit information for protein synthesis (RNA)

Nitrogenous Bases

Pyrimidines: One ring with 6 atoms

↳ Cytosine, thymine (DNA), uracil (RNA)

Purines: One ring with 6 atoms bonded to one ring with 5 atoms

↳ Adenine and guanine

Polynucleotide

Phosphate groups link adjacent nucleotide groups

• The sequence of bases along the DNA or mRNA is unique for each gene.

• Dictates AA sequence → primary structure of a protein → 3D structure of a protein

DNA

• Consists of 2 polynucleotides

• Forms a double helix

• Stands are anti-parallel (5’ = Phosphate group, 3’ = Hydroxyl group)

• Held together by hydrogen bonds between bases

• Cytosine → Guanine/Adenine → thymine

• DNA is synthesized in a leading and lagging strand.

RNA

• Single-stranded polynucleotide

• Variable in shape

• Cytosine → Guanine/Adenine → uracil

• Makes codons and anticodons (Ex, AGC = UGC)

• Dictates primary structure through protein synthesis (Transcription and Translation)

• Less stable than DNA because of it’s sugar

Protein Synthesis in RNA

1. Transcription: In the nucleus, DNA is copied into mRNA. The mRNA then carries genetic information from DNA to the ribosomes.

2. Translation: In the ribosomes (cytoplasm), the mRNA sequence assembles AAs into a protein, and tRNA brings the correct AAs to match the mRNA code.

Lipids

Bond: Ester linkage

Elements: C, H, O, P

Functional Groups: hydroxyl and the others vary

Lipids functions

• Insulation (traps heat)

• Protection of cells (bilayer of the cell membrane)

• Help with cell function (store energy)

Fats

• Hydrophobic

• Glycerol: classified as an alcohol (hydroxyl groups)

• Fatty acids: Long carbon chains (carbonyl group at one end)

• 3 fatty acids join to a glycerol via an ester linkage

• Bonds between a hydroxyl and a carboxyl group

• Classified as a saturated fatty acid or an unsaturated fatty acid

Saturated: No double bonds between carbons in the carbon chains = more hydrogen (Saturated w/ hydrogen)

• Solid at room temperature

Unsaturated: Contains one or more double bonds

• Liquid at room temperature

Phospholipid

A major component of the cell membranes

Two fatty acids are attached to a glycerol and a phosphate

• Assemble as a bilayer in H20

• Hydrophilic head, hydrophobic tail

Steroids

• Have four fused rings

• Unique groups attached to the ring determine the type of steroid

Dehydration Synthesis

Bonds two monomers with the loss of H20.

• The -OH of one monomer bonds to the -H of another monomer, forming H20, which is then released.

• A + B → AB + H20

Hydrolysis

Breaks the bonds in a polymer by adding H20

• One -H of the H20 bonds to one monomer, and the remaining -OH of the H20 attaches to the other monomer.

• AB + H20 → A + B