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.
Download ReportTranscript 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.
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 carbonbased 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 alphahelix shape • Polypeptides can sometimes fold into a betapleated 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