Biochemistry PDF

Biochemistry  Biomolecules Biochemistry can be defined as the study of the molecular levels of life. Biomolecules are in the Native state when they form life. Factors can affect this state through a process called denaturation. Molecular Logic of life: This...

Biochemistry  Biomolecules Biochemistry can be defined as the study of the molecular levels of life. Biomolecules are in the Native state when they form life. Factors can affect this state through a process called denaturation. Molecular Logic of life: This can be illustrated as when individual molecules (from a living organism) are seen as inanimate(lifeless)but when these molecules are arranged in specific proportions they prove to be living organisms. These molecules are what we refer to as “BIOMOLECULES”. Biomolecules include: i)Carbohydrates ii)Protein iii)Nucleic acids iv)Lipids CARBOHYDRATES It is composed of Carbon,Hydrogen and Oxygen. In carbohydrates, the type of covalent bond found is called “Glycosidic bond”. We have 1,4 glycosidic bond and 1,6 glycosidic bond.  PROTEINS It contains Carbon,Hydrogen, Oxygen ,Nitrogen and Sulphur. The bond in protein is called “Peptide bond”. Peptide bond is a linear bond in its native state but it can be rearranged to perform specific physiological functions(secondary functions). NUCLEIC ACIDS Nucleic acids are made up of Carbon, Hydrogen, Oxygen,Nitrogen and Sulphur and Phosphorus. The covalent bond in Nucleic acid is Phosphodiester bond. LIPIDS It is made up of Carbon, Hydrogen, Oxygen (Phosphorus and Nitrogen). The bond here is ester bond. Special forms of lipid i)Sphingolipid- Nitrogen ii) Phospholipid-Phosphorus  Other complex organisms contain calcium,magnesium,sodium,potassium etc in small amounts. They are gotten through nutrients. These are the additional bonds: Electrostatic bond Van Der Waal bond Ionic bond Hydrogen bond etc. Lets talk extensively on Proteins The name protein is derived from a Greek word PROTOS which translates to “The first or supreme”. Proteins are macromolecules composed of amino acids linked together with peptide bonds. The 20 amino acids which have been found to occur in all proteins are known as Standard amino acids There are two types of amino acids 1)Essential amino acids:These are amino acids which are not produced by the body but are gained through diet. 2)Non-essential amino acids: These are amino acids which are produced in our body. Non-e!e"ial amino acids E!e"ial amino acids Glycine Valine Alanine Leucine Senine Isoleucine Tyrosine Threoine Cysteine Methionine Asparagine Arginine Aspartic Lysine Glutamic acid Histidine Glutamine Phenylalanine Proline Tryptophan  PROPERTIES OF PROTEIN contains C H O N S it is compised of amino acids together by peptide bond It responds to stimuli it undergoes denaturation it acts as catalysts/enzymes. CLASSIFICATION OF PROTEINS Proteins are classified based on the following: 1. Source 2.Physical properties 3.Functions 4.Structure 5.Biological function 6.Composition 7.Nutritional basis BASED ON SOURCES Proteins are grouped into Animal protein eg eggs, fish, milk etc and Plant protein eg peas,beans etc. Plant proteins are also known as second class proteins. BASED ON PHYSICAL PROPERTIES Physical properties that include shape and solubility proteins are divided into: i) Fibrous proteins which include collagen,elastin and keratin. It is rod like in shape and insoluble in water. They also resist digestion. ii)Globular proteins which include albumins,globulins etc.It is spherical in shape and soluble in water.  BASED ON FUNCTIONS i) Catalytic proteins which include enzymes. ii) Non-catalytic proteins which include Receptor proteins Carrier proteins Membrane transport protein Structural proteins Contractile proteins Protein hormones Antibodies BASED ON STRUCTURE i)Primary structure-peptide and disulphide bonds ii)Secondary structure-hydrogen bonds iii) Tertiary structure-hydrogen bonds iv) Quatenary structure -hydrogen bonds,ionic interactions and hydrophobic interactions.  BASED ON BIOLOGICAL FUNCTIONS Transport protein eg Haemoglobin and albumin Storage protein Contractile protein eg actin and myosin Structural protein eg keratin and collagen Regulatory protein BASED ON COMPOSITION i) Simple proteins: According to definiton they contain only amino acids eg Albumins, Globulins, Protamines,prolamines,Lectins and Scleroproteins. ii) Conjugated proteins :They are the combinatiom of proteins with a non protein part called Prosthetic group. Eg glycoproteins,Lipoproteins,nucleoproteins Chromoproteins,phospoproteins and metalloproteins. iii)Derived proteins: They are degradation products of native proteins. Progressive hydrolysis of proteins result in smaller and smaller chains: protein>peptones>peptides>amino acids.  BASED ON NUTRITIONAL VALUE i)Complete or Nutritionally rich proteins:they contain all the essential aminoacids in their required proportion. Eg casein of milk. ii)Incomplete protein: they lack one essential amino acid. They cannot promote chuld growth but may be able to sustain body weight in adults. iii) Poor proteins: they lack in many essential amino acids. NB: When 10 or less number of amino acids are joined together, it is called Oligopeptide. Some importance of proteins it makes up 15% of the mass of an average person enzymes which are proteins act as biological catalysts storage and transportation eg casein and haemoglobin  defense eg antibodies hormones eg insulin components of hair,skin,nails eg keratin Movement of muscles eg actin and myosin.  VITAMINS Vitamins are natural and essential nutrients required in small quantities and play a major role in growth and development,repair and healing wounds,maintaining healthy bones and tissues for proper functioning of an immune system and other biological functions. These essential organic compounds have diverse biochemical functions. The most prominent of their functions is to serve as coenzymes (prosthetic group). CHARACTERISTICS OF VITAMINS 1.They are vital,organic,dietary substances that are necessary in only very small amounts to perform a specific metabolic function or prevent an associated deficiency disease. 2.It is not synthesized by the body therefore must be supplied through food. 3.They are non-caloric ie they do not provide energy unlike other organic nutrients.  CLASSIFICATION OF VITAMINS Depending on solubility vitamins are classified into water-soluble and fat-soluble vitamins. Fat-soluble vitamins which include vitamin C(ascorbic acid) and vitamin B complex. A number of water soluble vitamins are grouped into B complex because they occur together in the same food source. Examples Thiamine(B1), Riboflavin(B2), Niacin(B3),Panthotenic acid(B5), Pyridoxine(B6), Biotin(B7), Folic acid and Cyanocobalamin(B12). The B vitamins are widely distributed in foods and their influence is felt in many parts of the body. They help function as coenzymes that help the body obtain energy from food.  DIFFERENCES BETWEEN FAT SOLUBLE AND WATER SOLUBLE VITAMINS 1.STORAGE Fat soluble vitamins are stored in the liver and the fatty tissues of the body. Water soluble vitamins are not stored except Vitamin B12. 2.ABSORPTION Fat soluble vitamins are first incorporated into chylomicrons along with fatty acids and transported through the lymphatic system to the bloodstream and then to the liver. Water soluble vitamins are absorbed directly from the small intestine into the bloodstream. 3.TOXICITY Fat soluble vitamins are toxic and even lethal when taken into the body in excessive quantities and not usually excreted. Water soluble vitamins are usually non-toxic since excess amounts are easily excreted in the urine. 4. FUNCTION Fat soluble vitamins function as coenzymes, hormones and antioxidants. Water soluble vitamins function as precursors for coenzymes and antioxidants. WATER SOLUBLE VITAMINS THIAMINE The active form of thiamine is Thiamine pyrophosphate(TPP). Dietary thiamine is readily absorbed and phosphorylated to its active form in the liver. SOURCES Pork,legumes,fish,peas,liver,wheat,oil seeds,nuts,egg yolk , yeast, milk,bread,pasta etc. RDA 1-1.5mg/day ABSORPT ION AND T RANSPORT It is absorbed in the small intestine by active transport mechanism and simple diffusion. It reaches the liver through circulation. FUNCT IONS 1.It helps to release energy from foods,promotes normal appetite and plays a role in muscle contraction,conduction of nerve signals. DEFICIENCY PEOPLE WHO ARE AT A RISK OF GETTING THIS CONDITION; HIV/AIDS Those that have undergone bariatic surgery (surgery to manage obesity and obesity related conditions). Those with low dietary intake like older adults Alcoholics(this is because alcohol reduces the absorption of thiamine). SYMPTOMS OF THIAMINE DEFICIENCY; Mental confusion Muscle weakness and wasting Water retention(edema) Enlarged heart Beri-beri They are four types of beriberi:Dry beriberi(peripheral neuritis),Wet beriberi(cardiac manifestation),Cerebral beriberi(Wernicke- Korsakoff’s syndrome) and Infantile beriberi.  RIBOFLAVIN ST RUCTURE It is relatively heat stable but decomposes in the presence of visible light(photosensitive). It is yellow,fluorescent and has the capacity to absorb UV light. SOURCES eggs,kidney,liver,fish,milk and milk products,dark green veggies,cereals,legumes etc NB:Ultraviolet rays are known to destroy riboflavin which is why most milk is packaged in opaque containers instead of clear ones. DEFICIENCY Under consumption of B2 is rare. Groups at risk of B2 deficiency are; Vegan athletes Pregnant and breastfeeding mothers and their babies. SYMPTOMS Skin disorders Cracks at the corners of mouth Hair loss Itchy and red eyes Reproduction problems Cataracts(clouding of the lens of the eye) NIACIN OR NICOTINAMIDE OR NICOTINIC ACID FUNCT IONS It is involved in energy production and critical cellular functions SOURCES Fish, beef , chicken ,eggs , peas , nuts, seeds , etc DEFICIENCY Its deficiency is not common. It is mostly limited to people who eat very limited diets and diets low in protein. NB: Pellagra is the disease state that occurs as a result of severe nuacin deficiency. Symptoms are dermatitis,diarrhea and dementia. ST MPTOMS skin problems,digestive issues,mental confusion RDA Standard required consumption of vitamin B3 is 35mg/day. Consuming more than this may cause flushed skin, rashes, hypotension symptoms or liver damage However, overconsumption is not a problem if attained through food.  PATHOTENIC ACID FUNCT IONS It aids in energy production It aids in formation of hormones. It also helps in the metabolism of fats, proteins and carbohydrates from food. SOURCES Almost all plant-based abd animal-based foods contain pantothenic acid in varying amounts Richest dietary sources include fortified breakfast cereals, liver, kidney , meats and seeds. DEFICIENCY Gopalan’s BURNING FOOT SYNDROME is manifested as paresthesia (burning,lightning pain) in lower parts of the body. RDA It is assumed to be about 10mg/day.  VITAMIN B6:PYRIDOXINE, PYRIDOXAL, PYRIDOXAMINE FUNCT IONS Vitamin B6 aids in protein metabolism. It aids in red blood cell formation and behaves as an antioxidant molecule. It is also involved in the body’s production of chemicals such as neurotransmitters and haemoglobin. SOURCES They include legumes,organ meats , fish , meats , starchy vegetables, and whole grains and fortified cereals. DEFICIENCY Deficiency symptoms of vitamin B6 include; Dermatitis Swollen tongue Peripheral neuropathy  Anemia Depression and confusion Weakened immine function Also vitamin B6 deficiency in infants can cause irritability, acute hearing issues, and convulsive seizures. Note that the excessive intake of vitamin B6 can result in nerve damage. VITAMIN B7: BIOTIN OR VITAMIN H FUNCT IONS Biotin helps release energy from carbohydrates and aids in the metabolism of fats,proteins and carbohydrates from food. SOURCES liver,kidney, egg yolk, most fresh vegetables, yeast breads and cereals. DEFICIENCY Biotin deficiency is uncommon. A few of the symptoms of biotin deficiency include hair loss, Skin rashes and brittle nails. FOLATE:FOLIC ACID OR FOLACIN FUNCT IONS It aids in protein metabolism. It aids in promoting red blood cell formation. It aids in lowering the risk of neural tube birth defects. Folate may also play a role in controlling homocysteine levels, thus reducing the risk of coronary heart disease. SOURCES They include liver, kidney, dark green vegetables, meats, legumes, fish, whole grains, and fortified grains and cereals. DEFICIENCY Folate deficiency affects cell growth and protein production which can lead to overall impaired growth. Anemia is the primary clinical sign of folate deficiency and includes symptoms like fatigue headache and heart palpitations. Also, folate deficiency in women who are pregnant or of child bearing age may result in the delivery of baby with neural tube defects such as Spina bifida. VITAMINB12:COBALAMIN FUNCT IONS It aids in the building of genetic material It ainds in the production of normal red blood cells It aids in the maintenance of the nervous system SOURCES It can be found in foods such as meats, liver, kidney, fish, eggs, milk and milk products, oysters, shellfish. Some fortified food like breakfast cereals, and nutritional yeast may also contain vitamin B12. DEFICIENCY Cobalamin deficiency most commonly affects vegans, infants of vegan mothers and the elderly. Symptoms include Anemia and neurological changes such as numbness and tingling in the hands and feet. VITAMIN C :ASCORBIC ACID OR ASCORBATE Vitamin C is part of the water soluble vitamins and the body needs vitamin c to remain in proper working condition. Vitamin C benefits the body by holding cells together through collagen synthesis. Collagen is a connective tissues that holds muscles, bones, and other tissues together. So therfore vitamin C is essential for wound healing. Other functions include: bone and tooth formation Strengthening blood vessel walls Improving immune system function Increasing absorption and utilization of iron Acting as an antioxidant. HOW VITAMIN C ACT S AS AN ANT IOXIDANT Vitamin C works with vitamin E as an antioxidant which plays a crucial role in neutralizing free radicals throughout the body. The two vitamins work together as antioxidants to protect the body from damage caused by free radicals which are unstable molecules that can harm cells. This vitamin C helps regenerate vitamin E after it neutralizes free radicals ensuring continued protectiok against oxidative stress which can contribute to aging and diseases. SOURCES Many fruits and vegetables. The best sources are citrus fruits, peppers, kiwi, strawberries, and broccoli. DEFICIENCY Although rare,severe vitamin C deficiency may result in the disease known as SCURVY causing fatigue and a loss of collagen strength throughout the body. Loss of collagen results in loose teeth, bleeding and swollen gums and improper wound healing. Despite being a water soluble vitamin that the body excretes when in excess, vitamin C overdoses increase the risk of adverse health effects like kidney stones,diarrhea,rebound scurvy, and increased oxidative damage.  FAT SOLUBLE VITAMINS:ADEK The four fat soluble vitamins A D E K. They are related structurally because all have a basic structural unit of the molecule a five-carbon isoprene segment. CHARACT RIST ICS OF FAT SOLUBLE VITAMINS Protect cell membranes from free radical damage;act within the cell’s nucleus to influence gene expression Absorbed into lymph with fats from food Large storage capacity in fatty tissues Do not need to be consumed daily to prevent deficiency (may take months to develop). Toxicity is more likely VITAMIN B They exist in three forms which are; 1)Retinol(OH) 2)Retinal(CHO) 3)Retinoic acid(COOH) SOURCES Animal source:They occur in food of animal origin such as liver,butter,egg yolk etc. Plant source:In plant origin vitamin A presents as a Provitamin called B-carotone and it is found in some cereals. Note: Vitamin A is taken in diet as Retinyl ester in animals and in plants as B-carotone