Biomolecules

Biomolecule

Carbon is the central elementAll biomolecules contain a Carbon chain or ringCarbon has 4 outer shell electrons (valence = 4)Therefore its bonding capacity is greatIt forms covalent bonds hence, has strong bondsOnce bound to other elements (or to other Carbons), it is very stable

Carbon linkagesSingle chainsRings

Carbon binds to more than just hydrogen

To OH groups in sugarsTo NH2 groups in amino acidsTo H2PO4 groups of nucleotides of DNA, RNA, and ATP

OH, NH2, PO4 are called functional groups!

Functional groups

Isomers have the same molecular formulas but different structuresStructural isomer = difference in the C skeleton structureStereoisomer = difference in location of functional groups

Enantiomers are special types of stereoisomersEnantiomers are mirror imagesof each other-One such enantiomer contains C bound to 4 different molecules and is called a chiral molecule-Chiral molecules rotate polarized light to the right (D form) or to the left (L form) molecules

Monomers and polymersMonomers are made into polymers via dehydration reactionsPolymers are broken down into monomers via hydrolysis reactions

Carbohydrates

Carbohydrates

Simple sugars (monosaccharides)Only one 3-C, 5-C, 6-C chain or ring involved

Examples of sugar monomers

Carbohydrates

Double sugars (disaccharides)Two 6-C chains or rings bonded together

Carbohydrates

Complex carbos (polysaccharides)StarchCelluloseGlycogenChitin

Glycogen to glucose in animals

Polysaccharides : Starch structure

Polysaccharides : Glycogen structure

Polysaccharides: Cellulose structure

Polysaccharides: Chitin Structure

Protein

Proteins

Composed of chains of amino acids

20 amino acids exist

Amino acids containCentral CarbonAmine groupCarboxyl groupR group

The 20 Amino AcidsAll differ with respect to their R group

Peptide bonds occur between amino acidsThe COOH group of 1 amino acid binds to the NH2 group of another amino acid

Forms a peptide bond

Functions of proteinsEnzyme catalysts specific for 1 reactionDefense antibody proteins, other proteinsTransport- Hgb, Mgb, transferrins, etcSupport keratin, fibrin, collagenMotion actin/myosin, cytoskeletal fibersRegulation- some hormones, regulatory proteins on DNA, cell receptorsStorage Ca and Fe attached to storage proteins

There are four levels of protein structurePrimary structure:the linear arrangment of amino acids in a protein and the location of covalent linkagessuch as disulfide bonds between amino acids.

Secondary structure:areas of folding or coiling within a protein; examples include alpha helices and pleated sheets, which are stabilized by hydrogen bonding.

Tertiary structurethe final three-dimensional structure of a protein, which results from a large number of non-covalent interactionsbetween amino acids.

Quaternary structurenon-covalent interactions that bind multiple polypeptides into a single, larger protein. Hemoglobin has quaternary structure due to association of two alpha globin and two beta globin polyproteins.

Lipids

LipidsCentral core of glycerolBound to up to 3 fatty acid chainsThey exhibit a high number of C-H bonds therefore much energy and non-polarWhen placed in water, lipids spontaneously cluster togetherThey help organize the interior content of cells phospholipids

Glycerol and fatty acid chains

Saturated and unsaturated fats

The difference resides in the number of Hs attached to Cs in the fatty acid chains; the amount of saturation on the Cs

Saturated vs unsaturated fats and dietSaturated fats raise LDL-cholesterol levels in the blood (animal fats, dairy, coconut oil, cocoa butter)Polyunsaturated fats leave LDL-cholesterol unchanged; but lower HDL-cholesterol (safflower and corn oil)Monounsaturated fats leave LDL and HDL levels unchanged (olive oil, canola, peanut oil, avocados)One variety of polyunsaturated fat (Omega-3 fatty acids) guards against blood clot formation and reduce fat levels in the blood (certain fish, walnuts, almonds, and tofu)

Phospholipids and cell membranes

P-lipids make up the majority of cell membranes including:The plasma membraneNuclear envelopeEndoplasmic reticulum (ER)Golgi apparatusMembrane-bound vesicles

Cell environment organizes P-lipid bilayer to proper orientation

Hydrophilic (polar) heads of P-lipid oriented to the exterior; hydrophobic (non-polar) tails oriented to the interior

Nucleic acids: DNA and RNA

DNA = deoxyribonucleic acidDNA is a double polymer (chain)Each chain is made of nucleotidesThe 2 chains bond together to form a helix

DNA nucleotidesEach nucleotide in DNA contains:5-C sugar(deoxyribose)PhosphateNitrogen base-adenine (A)-guanine (G)-cytosine (C)-thymine (T)

One polymer of nucleotides on one backbone of nucleic acid

Members

Rattiyakorn Inthasri M.6/1 No.39

Nattanan Sittapirom M.6/1 No.41