BIO3114 Biology 1 - The Biology of Molecules PDF

CENTRE FOR PRE-UNIVERSITY STUDIES BIO3114 (BIOLOGY 1) Topic 1: The biology of molecules Part I NORLAILA NAJWA BINTI RAHMAN [email protected]  Division of Marks Coursework Marks : Final...

CENTRE FOR PRE-UNIVERSITY STUDIES BIO3114 (BIOLOGY 1) Topic 1: The biology of molecules Part I NORLAILA NAJWA BINTI RAHMAN [email protected]  Division of Marks Coursework Marks : Final Examination : Online quiz ( 5 % ) - Written Exam (100 marks) Practical ( 20% ) 70 MCQ and 30 Structure - skills 5%, teamwork 5%, report 10% Mid-term test (15%) Total : 40% Total : 60 % must achieve at least 20% coursework marks and attendance > 80% in order to sit for final Learning outcomes Define and explain the terms of monomer, polymers and macromolecule Describe and explain the function and roles of carbohydrates, protein, lipids and nucleic acids Describe and draw molecular structure of monomers and polymers of carbohydrates, protein, lipids and nucleic acids. Describe and explain the synthesis and breakdown of polymers i.e condensation and hydrolysis with reference to the terminologies glycosidic bonds, ester bonds, peptide bonds, and phosphodiester bonds. Learning outcomes Describe and draw the arrangement and formations of the polymer (carborhydrates, protein, lipids) based on the structure of the molecules with reference to the hydrogen bonding, van der waals, ionic bonding and covalent bondings. Explain effects of the arrangement of the polymer on the organisms. Explain how hydrogen bonding occurs between water molecules Explain the properties of water to its roles in living organism. Introduction The study of biological molecules forms an important branch of biology, aka. Molecular biology. Molecular Biology - studies the composition, structure and interactions of cellular molecules – such as nucleic acids and proteins – that carry out the biological processes essential for the cell's functions and maintenance. The building blocks of life. The 4 most common elements in living organisms are hydrogen, carbon, oxygen and nitrogen. Monomers, polymers, and macromolecules Monomers is a relatively simple molecule which is used as a basic building block for the synthesis of a polymer Monomer is single unit Polymer is a giant molecule made from many similar repeating subunits joined together in a chain Polymer is many monomers bound together A macromolecule is a large biological molecule such as a protein, polysaccharide or nucleic acid. Carbohydrates A carbohydrate contains carbon (C), hydrogen (H) and oxygen (O). It can be found in wide varieties of food. One of the importance of carbohydates is as main source of energy. The ‘hydrate’ part of the name comes from the fact that hydrogen and oxygen atoms are present in the ratio of 2 : 1, as they are in water (‘hydrate’ refers to water). Carbohydrates are divided into three main groups Monosaccharides Disaccharides Polysaccharides Carbohydrates | Monosaccharides (CH2O)n The simplest carbohydrates (simple sugar) Linear or ring form Examples : glucose, fructose and galactose Characteristics : - colourless, water soluble - has sweet taste, crystalline solids - reducing sugar Main types of monosaccharides (if classified according to the number of carbon atoms. Trioses (3C) Pentoses (5C) >> Ribose and deoxyribose Hexoses (6C) >> Glucose, fructose and galactose Carbohydrates | Ring structure of glucose Carbohydrates | Disaccharides Two monosaccharides can be joined by a glycosidic linkage to form a disaccharide via condensation Glycosidic linkage can be broken by adding water to the bond via hydrolysis Characteristics : - water soluble, sweet taste, crystallized The three most common disaccharides are :: 1) maltose (glucose + glucose), 2) sucrose (glucose + fructose) 3) lactose (glucose + galactose). Example : Formation and breakdown of Maltose Carbohydrates | Polysaccharides Polysaccharides : polymers of hundreds to thousands of monosaccharides joined by the glycosidic linkages The chains formed may be : - variable in length - branched or unbranched - straight or coiled Characteristics : - tasteless, insoluble in water - cannot be crystallized Example : Starch, Glycogen & Cellulose Carbohydrates | Starch Polysaccharide formed from a-glucose Major storage form of carbohydrate in plants Insoluble in water. So it can be stored in large amount with little effect on the water potential Made up of 2 components : 1. Amylose (unbranched chain) 2. Amylopectin (branched chain) Carbohydrates | Starch Carbohydrates | Glycogen Major storage form of carbohydrates in animals Present mainly in liver and muscle cells where high metabolic activities take place Insoluble in water Glycogen, like amylopectin, is made of chains of 1,4 linked α-glucose with 1,6 linkages. structure similar to amylopectin Glycogen have more branched than amylopectin. Glycogen molecules clump together to form granules, which are visible in liver cells and muscle cells, where they form an energy reserve. Carbohydrates | Cellulose Important structural materials in plants Long chains of b-glucose which are held together by b-1,4- glycosidic linkage straight chain polymer parallel strands of cellulose are linked by hydrogen bonds, making the cell wall a very stable structure Lipids Water insoluble organic molecules but soluble in organic solvents such as alcohol, ether and chloroform Contain C, H and O Functions of lipid include component of cell membrane, energy storage, insulation etc The most familiar lipids are fats and oils. Fats, animal origin(butter) are solid at room temperature Oils, plant origin (corn oil) are liquid at room temperature Chemically they are very similar. Fatty acids is the building block of lipids. Lipids | Fatty acids Fatty acids are a series of acids, some of which are found in fats (lipids). They contain the acidic group –COOH, known as a carboxyl group. The larger molecules in the series have long hydrocarbon tails attached to the acid ‘head’ of the molecule. carboxyl group  Lipids | Triglycerides The most common lipids are triglycerides. consists of one glycerol and 3 fatty acids the molecules are joined together by ester linkage which is formed by a condensation or esterification reaction between a hydroxyl group of glycerol and a carboxyl group of fatty acids. in each reaction, a water molecule is removed (total 3 water molecules are removed) Lipids | Phospholipids 2 fatty acids are attached to glycerol and a phosphate group Example : in cell membrane structure When phospholipids are added to water, they self-assembled into aggregates with the hydrophobic tails pointing toward the center and the hydrophilic heads on the outside. Nucleic acids DNA and RNA molecules are nucleic acid DNA contains information that is essential for almost all cell activities, including cell division. RNA stores and transfers information, essential for the manufacturing proteins Nucleic acids are polymers made up of monomers called nucleotides. Nucleotides are made up of three smaller components. These are: a nitrogen-containing base a pentose sugar (5C) a phosphate group. Nucleic acids : Nucleotide 1) Pentose sugar Ribose in nucleotides of RNA Deoxyribose in nucleotides of DNA The only difference between ribose and deoxyribose is the lack of an oxygen atom on carbon number two in deoxyribose sugar 2) Nitrogenous base Rings of carbon and nitrogen 2 types : purines & pyrimidines  Nucleic acids To form the polynucleotides DNA and RNA, many nucleotides are linked together into a long chain. Condensation occur between sugar and phosphate group of different nucleotides, forming phosphodiester bond Phosphodiester bonds - The covalent sugar– phosphate bonds link the 5-carbon of one sugar molecule and the 3-carbon of the next. Polynucleotide sequences are referenced in the 5’ to 3’ direction Nucleic acids : DNA Two polynucleotides, running in opposite directions, held together by hydrogen bonds between the bases. Complementary base pairing: A links with T by two hydrogen bonds; C links with G by three hydrogen bonds. In RNA, Uracil (U) will replace Thymine (T) Part of a DNA molecule What is correct for cytosine? Has a single ring structure is a pyrimidine joins to its complementary base with 3 hydrogen bonds A yes yes yes B yes no yes C no yes no D no no yes Which statements about the nucleotide containing uracil are correct? I. Uracil is pyrimidines II. The carbohydrate is always ribose III. base pairing occurs with three hydrogen bonds A. I, II and III B. I and II only C. I and III only D. II and III only Nucleic acids : RNA Single stranded molecule Contain ribose sugar 4 different nucleotide bases (A, G, C and U) Three types of RNA 1. mRNA : transcribes the DNA and directs the translation of protein 2. rRNA : involved in the translation of protein 3. tRNA : delivers amino acids to the ribosomes during translation Differences between DNA and RNA RECAP! Thank you and all the best!