Biological Molecules Week 2d PDF

BIOLOGICAL MOLECULES Biological Molecules Biologicalmolecules are often referred to as the molecules of life (bio-molecules) that are basically found in a living cell and categorized as organic and inorganic molecules in general. Organic biomolecules The organic biomolecules are proteins, ca...

BIOLOGICAL MOLECULES Biological Molecules Biologicalmolecules are often referred to as the molecules of life (bio-molecules) that are basically found in a living cell and categorized as organic and inorganic molecules in general. Organic biomolecules The organic biomolecules are proteins, carbohydrates, lipids and nucleic acids. Without any of these four molecules, a cell and organism would not be able to live. Important either structurally or functionally for cells. Inorganic molecules Most known inorganic molecules are water and minerals, which are still important for the normal functioning of the cell. Carbohydrates A carbohydrate molecule is made of atoms of carbon, hydrogen and oxygen. They are an important source of energy. They also provide structural support for cells and help with communication between cells (cell-cell recognition). They are found in the form of either a sugar or many sugars linked together, called saccharides. Carbohydrates Based on the number sugar units they contain; they are categorized into three; A single sugar molecule containing carbohydrate is known as a monosaccharides, while two and many having are regarded as disaccharides and polysaccharides. Each of the sugar molecules are bonded together through the glycosidic linkage/s. Carbohydrates are polyhydroxy aldehydes or ketones, or substances that yield these compounds on hydrolysis. Example: Glucose is aldehyde and fructose is Ketone. Carbohydrates Monosaccharides - simple sugars with multiple OH groups. Based on number of carbons (3, 4, 5, 6), a monosaccharide is a triose, tetrose, pentose or hexose. Disaccharides - 2 monosaccharides covalently linked Oligosaccharides - a few monosaccharides covalently linked. Polysaccharides - polymers consisting of chains of monosaccharide or disaccharide Monosaccharides Monosaccharides containing the aldehyde group are classified as aldoses, and those with a ketone group are classified as ketoses. Aldoses are reducing sugars; ketoses are non-reducing sugars.. Glucose Glucoseis the most important carbohydrate fuel in human cells. Its concentration in the blood is about 1 gdm-3 (1 gram per cubic decimeter) Energy is released when the molecules are metabolized. Two glucose molecules react to form the disaccharide maltose. Starch and cellulose are polysaccharides made up of glucose units. Galactose Galactose reacts with glucose to make the disaccharide lactose. Galactose cannot play the same part in respiration as glucose. Fructose Fructose, glucose and galactose are all hexoses. Glucose and galactose are aldoses (reducing sugars), fructose is a ketose (a non-reducing sugar). Fructose reacts with glucose to make the disaccharide sucrose. Ribose and deoxyribose Ribose and deoxyribose are pentoses. The ribose unit forms part of a nucleotide of RNA. The deoxyribose unit forms part of the nucleotide of DNA Disaccharides Monosaccharides are rare in nature. Most sugars found in nature are disaccharides. These form when two monosaccharides react. Disaccharides are soluble in water, but they are too big to pass through the cell membrane by diffusion. They are broken down in the small intestine during digestion to give the smaller monosaccharides that pass into the blood and through cell membranes into cells. Hydrolysis reaction Hydrolysis reaction and is the reverse of a condensation reaction and it releases energy. Condensation reaction Condensation reaction takes place by releasing water. This process requires energy. A glycosidic bond forms and holds the two monosaccharide units together. The three most important disaccharides are sucrose, lactose and maltose. They are formed from the forms of the appropriate monosaccharides. Sucrose is a non-reducing sugar. Lactose and maltose are reducing sugars.  Monosaccharides are used very quickly by cells. Cellmay not need all the energy immediately and it may need to store it. Monosaccharides are converted into disaccharides in the cell by condensation reactions. Condensation reactions result in the formation of polysaccharides. These are giant molecules which, importantly, are too big to escape from the cell. These are broken down by hydrolysis into monosaccharides when energy is needed by the cell. Polysaccharides Monosaccharides can undergo a series of condensation reactions, adding one unit after another to the chain until very large molecules (polysaccharides) are formed. This is called condensation polymerization, and the building blocks are called monomers. Starch Starch is often produced in plants as a way of storing energy. It exists in two forms: amylose and amylopectin. Amylose is an unbranched polymer of α- glucose. The molecules coil into a helical structure. It forms a colloidal suspension in hot water. Amylopectin is a branched polymer of α- glucose. It is completely insoluble in water. Glycogen Glycogen is amylopectin with very short distances between the branching side-chains. Starch from plants is hydrolyzed in the body to produce glucose. Glucose passes into the cell and is used in metabolism. Inside the cell, glucose can be polymerized to make glycogen which acts as a carbohydrate energy store.  Cellulose Cellulose is a third polymer made from glucose. Cellulose serves a very different purpose in nature to starch and glycogen. It makes up the cell walls in plant cells. These are much tougher than cell membranes. This toughness is due to the arrangement of glucose units in the polymer chain and the hydrogen-bonding between neighboring chains. Cellulose is not hydrolyzed easily and, therefore, cannot be digested so it is not a source of energy for humans. The stomachs of Herbivores contain a specific enzyme called cellulase which enables them to digest cellulose. Summary of carbohydrates The most abundant organic molecules in nature Are polyhydroxy aldehydes or ketones, or substances that yield these compounds on hydrolysis Provide a significant fraction of the energy in the diet of most organisms Important source of energy for cells Can act as a storage form of energy Summary of carbohydrates Can be structural components of many organisms Can be cell-membrane components mediating intercellular communication Can be cell-surface antigens Can be part of the body’s extracellular ground substance Can be associated with proteins and lipid Part of RNA, DNA, and several coenzymes  Lipids Lipidsare a highly variable group of molecules that include fats, oils, waxes and some steroids. They are esters of fatty acids and alcohol (glycerol or chains of alcohols). Fatty acids are made mostly from chains of carbon and hydrogen, and they bond to a range of other types of atoms to form many different lipids. The primary function of lipids is to store energy. Lipids A lipid called a triglyceride is a fat if it is solid at room temperature and an oil if it is liquid at room temperature. In addition, triglycerides are stored in the fat cells , also called adipocytes or lipocytes, and are responsible in storing fats and lipids which will facilitate energy store in animal’s body. Lipids Fat cells are categorized in white fat cells and brown fat cells. The different is made from their ways of storing lipids. White fat cells store one large lipid drop while brown fat cells store smaller and multiple droplets of lipids spreading in the whole body of the cell. Lipids Various types of lipids occur in the human body, namely: 1) triacylglycerol 2) cholesterol 3) polar lipids, which include phospholipids, glycolipids and sphingolipids. Plantleaves are coated with lipids called waxes to prevent water loss, and the honeycomb in a beehive is made of beeswax. Lipids The basic structure of a lipid includes fatty acid tails. Each tail is a chain of carbon atoms bonded to hydrogen and other carbon atoms by single or double bonds. Lipids that have tail chains with only single bonds between the carbon atoms are called saturated fats because no more hydrogens can bond to the tail. Lipids that have at least one double bond between carbon atoms in the tail chain can accommodate at least one more hydrogen and are called unsaturated fats. Fats with more than one double bond in the tail are called polyunsaturated fats. What are Lipids? Properties of lipids Insoluble in water Longer chains  More hydrophobic, less soluble Double bonds increase solubility Melting points: Depend on chain length and saturation Double bonds lead acyl chain disorder and low melting temperatures Unsaturated fatty acids are solid at room temperature. Importance of lipids As the main component of cell membranes (phospholipids) Insulation of heat and water, Storing energy, protection and cellular communication. Proteins A protein is a compound made of small carbon compounds called amino acids. Amino acids are small compounds that are made of carbon, nitrogen, oxygen, hydrogen, and sometimes sulfur. There are 20 different variable groups, and proteins are made of different combinations of all 20 different amino acids. Several covalent bonds called peptide bonds join amino acids together to form proteins. Protein Structure Primary Structure: It is a specific sequence of amino acids. The order of amino acids bonded together is detected by information stored in genes. Secondary Structure: It is a three-dimensional form of a local segment of proteins. They are formed by hydrogen bonds between the atoms along the backbone of the polypeptide chain. Tertiary Structure: It is determined by R-groups. It is a three- dimensional shape of a protein. Many numbers of tertiary structure fold to form Quaternary Structure. Quaternary Structure: It is the arrangement of multiple folded protein subunits in a multi-subunit complex. Types of Proteins and Their Functions  Proteins Proteins make up about 15 percent of our total body mass and are involved in nearly every function of our body. For example, your muscles, skin, and hair all are made of proteins. The cells contain about 10,000 different proteins that provide structural support, transport substances inside the cell and between cells, communicate signals within the cell and between cells, speed up chemical reactions, and control cell growth. Nucleic acids Nucleic acids are complex macromolecules that store and transmit genetic information. Nucleic acids are made of smaller repeating subunits called nucleotides. Nucleotides are composed of carbon, nitrogen, oxygen, phosphorus, and hydrogen atoms. There are six major nucleotides, all of which have three units a phosphate, a nitrogenous base, and a ribose sugar. When a phosphate group is added to a nucleoside (one sugar molecule plus one nitrogenous base), it forms a nucleotide. Sugar molecule The sugar molecule in nucleotides could be either ribose (C 5H10O5) or deoxyribose (C5H10O4) and both the sugars are in their Pentagon or furanose state. Nucleic acids There are two types of nucleic acids in living organisms: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). In nucleic acids such as DNA and RNA, the sugar of one nucleotide bonds to the phosphate of another nucleotide. There are five different bases found in nucleotide subunits that make up DNA and RNA, Adenine, Cytosine, Guanine, Thymine and Uracil. Each of these nitrogenous base that sticks out from the chain is available for hydrogen bonding with other bases in other nucleic acids. Nucleic acid A nucleotide with three phosphate groups is adenosine triphosphate (ATP). ATP is a storehouse of chemical energy that can be used by cells in a variety of reactions. It releases energy when the bond between the second and third phosphate group is broken.  Vitamins Vitamins are organic compounds that are needed in small amounts for metabolic activities. Many vitamins help enzymes function well. Vitamin D is made by cells in your skin. Some B vitamins and vitamin K are produced by bacteria living in the large intestine.  Vitamins Sufficient quantities of most vitamins cannot be made by the body, but a well-balanced diet can provide the vitamins that are needed. Some vitamins that are fat-soluble can be stored in small quantities in the liver and fatty tissues of the body. Other vitamins are water- soluble and cannot be stored in the body. Foods providing an adequate level of these vitamins should be included in a person’s diet on a regular basis.  Water Water molecules are formed by covalent bonds that link two hydrogen (H) atoms to one oxygen (O) atom, and each water molecule has the same structure. It is one of the most plentiful and essential of compounds, which is a tasteless and odorless, existing in gaseous, liquid, and solid states.  Water Ithas the important ability to dissolve and as a media for transportation of many other substances. The versatility of water as a solvent is essential to living organisms, as well. Water molecules have an unequal distribution of charges and are called polar molecules, meaning that they have oppositely charged regions.  Minerals Minerals are inorganic compounds used by the body as building material, and they are involved with metabolic functions. For example, the mineral iron is needed to make hemoglobin and it binds to hemoglobin in red blood cells and is delivered to body cells as blood circulates in the body.  Minerals Calcium, and other minerals, is an important component of bones and is involved with muscle and nerve functions and they serve as cofactors for enzymes. Magnesium is an important component of the green pigment, chlorophyll, involved in photosynthesis.  Summary Carbon compounds are the basic building blocks of living organisms. Biological macromolecules are formed by joining of small carbon compounds into polymers. There are four types of biological macromolecules; carbohydrates, proteins, lipids, and nucleic acids Summary Monosaccharides undergo condensation to form disaccharides and poly saccharides through the glycosidic linkages Peptide bonds join amino acids in proteins. Lipids are esters of fatty acids and alcohols THANK YOU !