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Semester 1: Nutritional Biochemistry
Water electrolytes: Fluid components, distribution, water intake output, water balance, Composition of electrolytes in fluid compartments, buffer system, acid base balance-blood, Kidney imbalance disorders- dehydration edema
Water electrolytes
Fluid components
Body fluids are composed of water and various electrolytes, which are charged particles essential for numerous physiological functions such as nerve signaling, muscle contraction, and maintaining acid-base balance.
Distribution of fluids
Body fluids are distributed among different compartments: intracellular fluid (within cells), extracellular fluid (outside cells), and interstitial fluid (between cells). The distribution is regulated by osmotic gradients and membrane permeability.
Water intake and output
Water intake occurs through beverages, food, and metabolic processes. Output includes urine, feces, perspiration, and respiration. A balance must be maintained to ensure homeostasis.
Water balance
Water balance refers to the equilibrium between water intake and output. Disruption can lead to dehydration or overhydration, both of which can impair bodily functions.
Composition of electrolytes in fluid compartments
Key electrolytes include sodium, potassium, calcium, magnesium, chloride, bicarbonate, and phosphate. Their concentration varies across intracellular and extracellular compartments, influencing cell function and fluid balance.
Buffer system and acid-base balance
Buffer systems, including bicarbonate, phosphate, and proteins, help regulate pH levels in the blood. Maintaining acid-base balance is crucial for metabolic processes and overall homeostasis.
Kidney imbalance disorders
The kidneys play a pivotal role in regulating water and electrolyte balance. Disorders such as dehydration (excessive water loss) and edema (excess fluid retention) can arise from various factors, affecting kidney function and overall health.
Enzymes: Classification and Role of Enzymes
Enzymes: Classification and Role of Enzymes
Definition of Enzymes
Enzymes are biological catalysts that speed up chemical reactions in the body without being consumed in the process. They are mostly proteins and play a crucial role in metabolic processes.
Classification of Enzymes
Enzymes can be classified based on their function and source. The primary categories include: 1. Oxidoreductases: Catalyze oxidation-reduction reactions. 2. Transferases: Transfer functional groups from one molecule to another. 3. Hydrolases: Catalyze hydrolysis reactions. 4. Lyases: Catalyze the addition or removal of groups to or from double bonds. 5. Isomerases: Catalyze the rearrangement of isomers. 6. Ligases: Catalyze the joining of two molecules with the use of ATP.
Factors Affecting Enzyme Activity
Enzyme activity can be influenced by several factors including temperature, pH level, substrate concentration, and enzyme concentration. Each enzyme has an optimal temperature and pH at which it functions most efficiently.
Role of Enzymes in Metabolism
Enzymes play a vital role in various metabolic pathways, including catabolism and anabolism. They help in the breakdown of nutrients for energy and the synthesis of necessary biomolecules.
Enzyme Inhibition
Enzyme activity can be inhibited by inhibitors, which can be competitive, non-competitive, or uncompetitive. Understanding enzyme inhibition is important for developing drugs and understanding metabolic regulation.
Enzymes in Nutritional Biochemistry
In nutritional biochemistry, enzymes are essential for digestion and absorption of nutrients. They facilitate the breakdown of macromolecules into smaller units for utilization by the body.
Carbohydrate metabolism: Classification, Review of digestion and absorption, Oxidation of glucose glycolysis, oxidative decarboxylation, citric acid cycle, Pentose phosphate pathway, Glycogen Glycogenesis, Glycogenolysis, Gluconeogenesis, Inborn errors of metabolism, Glycogen storage diseases
Carbohydrate metabolism
Classification of Carbohydrates
Carbohydrates can be classified as monosaccharides, disaccharides, oligosaccharides, and polysaccharides based on their structure and complexity.
Digestion and Absorption
Carbohydrate digestion begins in the mouth with salivary amylase. It continues in the small intestine with pancreatic amylase. Absorption occurs primarily in the jejunum, where monosaccharides are transported into the bloodstream.
Oxidation of Glucose
Glucose oxidation is a critical process for energy production. It occurs through several pathways including glycolysis and the citric acid cycle.
Glycolysis
Glycolysis is a cytoplasmic pathway that converts glucose into pyruvate, producing ATP and NADH. It consists of ten enzyme-catalyzed steps.
Oxidative Decarboxylation
This process converts pyruvate into acetyl-CoA, linking glycolysis to the citric acid cycle and releasing carbon dioxide.
Citric Acid Cycle
The citric acid cycle, or Krebs cycle, takes place in the mitochondria. It further oxidizes acetyl-CoA, producing NADH, FADH2, and GTP.
Pentose Phosphate Pathway
This pathway generates NADPH and ribose-5-phosphate. It is crucial for nucleotide synthesis and lipid metabolism.
Glycogen
Glycogen is the storage form of glucose in animals, primarily stored in the liver and muscle tissues.
Glycogenesis
Glycogenesis is the synthesis of glycogen from glucose, primarily occurring in the liver and muscle cells, initiated by insulin.
Glycogenolysis
This process involves the breakdown of glycogen to release glucose. It is regulated by glucagon and epinephrine.
Gluconeogenesis
Gluconeogenesis is the synthesis of glucose from non-carbohydrate precursors. It occurs mainly in the liver and is essential during fasting.
Inborn Errors of Metabolism
These are genetic disorders that affect carbohydrate metabolism, such as galactosemia and fructose intolerance, leading to accumulation of toxic metabolites.
Glycogen Storage Diseases
These are a group of inherited disorders characterized by abnormal glycogen metabolism, such as Pompe disease and McArdle disease.
Protein metabolism: Classification of protein, Review of digestion and absorption, Deamination, transamination, trans-deamination, decarboxylation, deamidation, Urea cycle, inborn errors of amino acid metabolism
Protein metabolism
Classification of proteins
Proteins can be classified based on their structure, function, solubility, and origin. Major classifications include: 1. Structural proteins: provide support and shape (e.g., collagen). 2. Enzymatic proteins: act as catalysts (e.g., digestive enzymes). 3. Transport proteins: carry substances (e.g., hemoglobin). 4. Regulatory proteins: control biological processes (e.g., hormones). 5. Storage proteins: store amino acids (e.g., casein). 6. Contractile proteins: involved in movement (e.g., actin and myosin).
Review of digestion and absorption
Protein digestion begins in the stomach, where pepsinogen is activated to pepsin. In the small intestine, pancreatic enzymes like trypsin and chymotrypsin further break down proteins into peptides. Brush border enzymes complete digestion into amino acids. Absorption occurs via active transport and facilitated diffusion through intestinal epithelial cells into the bloodstream.
Deamination
Deamination is the process of removing an amino group from an amino acid, resulting in the formation of a keto acid and ammonia. It primarily occurs in the liver and is crucial for the metabolism of amino acids for energy production or conversion into glucose.
Transamination
Transamination is the transfer of an amino group from one amino acid to a keto acid, forming a new amino acid and a new keto acid. It is a reversible reaction and is vital for amino acid synthesis as well as the interconversion of amino acids.
Trans-deamination
Trans-deamination refers to the simultaneous process of transamination followed by deamination. This is important in amino acid metabolism as it allows for the removal of nitrogen while producing energy-rich carbon skeletons.
Decarboxylation
Decarboxylation is the removal of a carboxyl group from an amino acid, producing carbon dioxide and an amine. This process is critical for the synthesis of neurotransmitters and other biologically active amines.
Deamidation
Deamidation is the removal of an amide group from an amino acid, resulting in the conversion into a different amino acid. This can lead to changes in protein structure and function and is a key aspect of protein turnover.
Urea cycle
The urea cycle is a biochemical pathway in the liver that converts ammonia, a toxic byproduct of amino acid catabolism, into urea, which can be excreted by the kidneys. Key enzymes in this cycle include carbamoyl phosphate synthetase, ornithine transcarbamylase, and arginase.
Inborn errors of amino acid metabolism
Inborn errors of amino acid metabolism are genetic disorders that affect the body's ability to metabolize specific amino acids. Examples include phenylketonuria (PKU), tyrosinemia, and maple syrup urine disease. These conditions can lead to toxic accumulation of amino acids or their byproducts, requiring dietary management.
Nucleic acid metabolism: Classification, Biological oxidation, Electron transport chain, nucleic acid metabolism, structure of DNA RNA, genetic code, DNA replication, biosynthesis of protein
Nucleic Acid Metabolism
Classification
Nucleic acids are classified into two main types: DNA and RNA. DNA (deoxyribonucleic acid) serves as the genetic material, while RNA (ribonucleic acid) is primarily involved in protein synthesis. Further classifications include mRNA, tRNA, and rRNA based on the functions of RNA.
Biological Oxidation
Biological oxidation involves the transfer of electrons from substrates to molecular oxygen, resulting in energy production in cells. This process occurs during the metabolism of nucleic acids and produces ATP, which is vital for cellular functions.
Electron Transport Chain
The electron transport chain is a series of protein complexes located in the inner mitochondrial membrane. It facilitates the transfer of electrons derived from NADH and FADH2 to oxygen, generating a proton gradient that drives ATP synthesis through oxidative phosphorylation.
Structure of DNA and RNA
DNA is a double helix composed of nucleotides that include deoxyribose, phosphate, and nitrogenous bases (adenine, thymine, cytosine, guanine). RNA, single-stranded, contains ribose and uracil instead of thymine. The structure of these nucleic acids is crucial for their function in genetic information storage and transmission.
Genetic Code
The genetic code consists of sequences of nucleotides in DNA that encode for amino acids. Each set of three nucleotides (a codon) corresponds to a specific amino acid, dictating the sequence of protein synthesis during translation.
DNA Replication
DNA replication is a semiconservative process that occurs before cell division. It involves the unwinding of the double helix and the synthesis of new strands using DNA polymerase, resulting in two identical copies of the DNA molecule.
Biosynthesis of Protein
Biosynthesis of proteins involves transcription and translation. During transcription, DNA is transcribed into mRNA, which then travels to the ribosome. In translation, ribosomes read the mRNA sequence with the help of tRNA to assemble amino acids into a polypeptide chain, forming proteins.
Lipid metabolism: Classification, Oxidation of fatty acid, Biosynthesis of fatty acid, TGL, Cholesterol synthesis, synthesis of bile acids bile pigments, ketosis, ketone bodies, acidosis fatty liver
Lipid metabolism
Classification of Lipids
Lipids can be classified into several categories: 1. Fatty acids - Saturated and unsaturated fatty acids. 2. Triglycerides - Storage form of fatty acids. 3. Phospholipids - Major components of cell membranes. 4. Sterols - Includes cholesterol and steroid hormones.
Oxidation of Fatty Acids
Fatty acid oxidation occurs mainly in the mitochondria. The process includes: 1. Activation - Fatty acids are activated to acyl-CoA. 2. Beta-oxidation - Sequential removal of two-carbon units from the fatty acid chain, producing acetyl-CoA, NADH, and FADH2.
Biosynthesis of Fatty Acids
Fatty acid synthesis primarily occurs in the cytoplasm. It involves: 1. Acetyl-CoA as a building block. 2. Fatty acid synthase complex catalyzing reactions to extend the carbon chain. 3. Reduction, dehydration, and re-reduction reactions to form palmitate.
Triglyceride (TGL) Metabolism
Triglycerides are stored in adipose tissue and released as free fatty acids during fasting. The metabolism includes: 1. Lipolysis - Breakdown of triglycerides into glycerol and fatty acids. 2. Re-esterification - Process of converting free fatty acids back to triglycerides.
Cholesterol Synthesis
Cholesterol is synthesized in the liver and involves: 1. Acetyl-CoA as a precursor. 2. Multiple enzymatic steps including HMG-CoA reductase, which is a key regulatory enzyme.
Synthesis of Bile Acids and Bile Pigments
Bile acids are derived from cholesterol and help emulsify fats. Key points: 1. Bile acids are synthesized in the liver. 2. Bile pigments, such as bilirubin, are produced from the breakdown of hemoglobin.
Ketosis and Ketone Bodies
Ketosis occurs when carbohydrate intake is low, leading to the production of ketone bodies from acetyl-CoA. Key aspects: 1. Ketone bodies include acetoacetate, beta-hydroxybutyrate, and acetone. 2. They serve as an alternative energy source for tissues during fasting.
Acidosis and Fatty Liver
Acidosis may arise from excessive ketone body production, contributing to diabetic ketoacidosis. Fatty liver disease is associated with: 1. Excessive accumulation of fat in liver cells. 2. Potential consequences include inflammation and liver damage.
