Biologically Important Molecules Chapter 1.2 McGraw-Hill Ryerson Biology 12 (2011)

Macromolecules 4 Important macromolecules: Carbohydrate Nucleic Acid Protein Lipid Polymers are composed of repeating monomers Monomer = single unit

CARBOHYDRATES Carbohydrates may be classified into 3 main groups: monosaccharides – simple sugars oligosaccharides – sugars containing 2 or 3 simple sugars attached by covalent bonds called glycosidic linkages polysaccharides – polymers composed of several hundred to several thousand monosaccharide subunits

Carbohydrate Monosaccharide = one sugar e.g. Glucose, Fructose, Galactose The 3 examples above are isomers of each other Isomers = same molecular formula but different structure Isomers causes different characteristics, despite same exact molecular formula

Carbohydrate Disaccharide = 2 sugars e.g. Lactose = Glucose + Galactose, Sucrose = Glucose + Fructose Covalent bond between monosaccharides is called a glycosidic linkage.

Carbohydrate Glucose can come in two forms: Alpha glucose Beta glucose Different forms give rise to different linkage patterns in the polysaccharides Alpha – allows branching seen in starch and glycogen (energy storage) Beta – allows linearity as seen in cellulose (structural)

Carbohydrate Polysaccharide = many sugars e.g. Starch, glycogen, cellulose Many monosaccharides joined together by glycosidic bonds to create long chains

Lipids Large amount of carbon-hydrogen bonds Makes it hydrophobic Many C-H bonds stores lots of energy but less accessible than carbohydrates

Lipids Triglyceride = Glycerol molecule with 3 fatty acids Saturated fatty acids Carbon chain is fully filled with max number of Hydrogen atoms (i.e. no double bonds) Straight chains Unsaturated fatty acids Double bonds present between some carbons Double bonds causes kinks in chain leading to bent shape

Lipids Phospholipid = glyceride with 2 fatty acid chains and a phosphate group Phosphate group is attached to a polar R group Thus creates hydrophobic tail and hydrophobic head Makes up phospholipid bilayer in cell membranes

Lipids Steroid = Compound composing 4 carbon-based rings Examples: Cholesterol, Testosterone, Estrogen Waxes = lipids with long carbon-based chains Examples: spermaceti, beeswax, paraffin wax

Protein Made up of amino acids Amino acid is a molecule where a central carbon is attached to an amino group, carboxyl group, a hydrogen atom, and an R group R group is different for each type of amino acids, giving rise to distinct characteristics

Protein

Protein Polypeptide = polymers of amino acids Amino acids are joined by covalent bonds called peptide bonds

Protein Polypeptides are long strands that can take shape due to the interactions of all the amino acids: Primary structure Refers to the linear sequence of the amino acids Secondary Structure Polypeptides can sometimes coil into an alpha-helix shape Polypeptides can sometimes fold into a beta-pleated sheet Tertiary Structure Combination of different secondary structures gives rise to a three-dimensional shape Done through folding and interactions of the R groups of different amino acids Molecular chaperones also facilitate the folding Quaternary Structure Amalgamation of many tertiary structures

Protein Proteins’ shape and confirguration of its structures gives rise to unique characteristics and functions: - Enzymes (biological catalysts) - Structural support - Transport - Enabling mobility - Regulate Cellular processes - Provide defence

Protein Proteins’ shape and confirguration of its structures gives rise to unique characteristics and functions Protein denaturation occurs when the protein is exposed to: - extreme temperatures - extreme pH conditions - extreme salt environments Can you explain why? If a protein becomes denatured, can it perform its function?

Nucleic Acids Nucleic acids = macromolecules composed of nucleotide monomers Nucleotide: a carbon-based sugar attached to both a phosphate group and a nitrogenous base

Nucleic Acids 2 types of nucleic acid: DNA: Deoxyribonucleic acid Nucleotides in DNA contain a deoxyribose sugar RNA: Ribonucleic acid Nucleotides in RNA contain a ribose sugar

Nucleic Acid Nucleotides differ from each other according to their nitrogenous base Do you remember which pair up?

Nucleic Acid Nucleotides polymerize into strands by forming phosphodiester bonds Phosphodiester bonds are formed between phosphate group of one nucleotide and a hydroxyl group on the sugar of the next nucleotide in the strand

Nucleic Acid DNA is made up of two strands of nucleic acid The two strands wind around and is often referred to as a “double helix” Double helix structure causes nitrogenous base to be facing each other and bond to each other through hydrogen bonds Adenine pairs with Thymine (2 H bonds) Cytosine pairs with Guanine (3 H bonds) The two strands run antiparralel i.e. they run in opposite directions

Nucleic Acid RNA is made up of just one strand of nucleic acid DNA contains Adenine, Guanine, Cytosine, and Thymine RNA contains Adenine, Guanine, Cytosine, and Uracil

Homework Pg 31 #1-6, 8, 11, 12