Introduction to Biochemistry

• Biochemistry is the study of the chemical processes within and relating to living organisms.
• It combines biology and chemistry to investigate the composition, structure, and function of biological molecules.
• It also covers chemical processes such as metabolism and heredity.

Core Concepts

• Biochemistry seeks to explain the chemical reactions involved in biological processes at the molecular level.
• It provides insights into the complex mechanisms that govern life.
• Key areas include the structure and function of biomolecules, metabolic pathways, and the flow of genetic information.

Biomolecules

• Biomolecules are organic molecules essential for life.
• Four major classes include carbohydrates, lipids, proteins, and nucleic acids.

Carbohydrates

• Carbohydrates are composed of carbon, hydrogen, and oxygen, typically in a ratio of 1:2:1.
• They serve as a primary source of energy for living organisms.
• Simple carbohydrates (monosaccharides) include glucose, fructose, and galactose.
• Disaccharides, such as sucrose and lactose, consist of two monosaccharides linked together.
• Polysaccharides are complex carbohydrates made up of many monosaccharide units.
• Starch, glycogen, and cellulose are examples of polysaccharides with different functions in energy storage and structural support.

Lipids

• Lipids are hydrophobic molecules composed mainly of carbon and hydrogen.
• They include fats, oils, phospholipids, and steroids.
• Fats and oils (triglycerides) are composed of a glycerol molecule and three fatty acids.
• Saturated fatty acids have no double bonds, while unsaturated fatty acids have one or more double bonds.
• Phospholipids are major components of cell membranes, composed of a glycerol, two fatty acids, and a phosphate group.
• Steroids, such as cholesterol, have a ring structure and serve various functions as hormones and membrane components.

Proteins

• Proteins are complex biomolecules made up of amino acid subunits.
• Amino acids contain an amino group, a carboxyl group, and a unique side chain (R group).
• There are 20 common amino acids, each with a different R group, determining its chemical properties.
• Amino acids are linked together by peptide bonds to form polypeptide chains.
• The sequence of amino acids determines the protein's primary structure.
• Secondary structure refers to local folding patterns, such as alpha helices and beta sheets.
• Tertiary structure is the overall three-dimensional shape of a protein, stabilized by various interactions between R groups.
• Quaternary structure describes the arrangement of multiple polypeptide subunits in a multi-subunit protein.
• Proteins serve diverse functions, including catalysis (enzymes), structural support, transport, and immune defense.

Nucleic Acids

• Nucleic acids store and transmit genetic information.
• There are two main types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
• Nucleic acids are polymers of nucleotides.
• Each nucleotide consists of a sugar (deoxyribose in DNA, ribose in RNA), a phosphate group, and a nitrogenous base.
• DNA contains the bases adenine (A), guanine (G), cytosine (C), and thymine (T).
• RNA contains uracil (U) instead of thymine.
• DNA is a double-stranded helix, with A pairing with T and G pairing with C.
• RNA is typically single-stranded and plays various roles in gene expression.

Enzymes

• Enzymes are biological catalysts that accelerate chemical reactions in living organisms.
• They are typically proteins and highly specific for their substrates.
• Enzymes lower the activation energy of a reaction, making it proceed faster.
• The active site of an enzyme is the region where the substrate binds and the reaction occurs.
• Enzyme activity can be regulated by factors such as temperature, pH, and the presence of inhibitors or activators.

Metabolism

• Metabolism encompasses all the chemical reactions that occur within a cell or organism.
• It includes catabolism (breaking down complex molecules) and anabolism (building complex molecules).

Catabolism

• Catabolic pathways release energy by breaking down complex molecules into simpler ones.
• Cellular respiration is a major catabolic pathway, breaking down glucose to produce ATP (adenosine triphosphate).
• ATP is the primary energy currency of the cell.
• Other catabolic processes include glycolysis, the citric acid cycle, and oxidative phosphorylation.

Anabolism

• Anabolic pathways consume energy to build complex molecules from simpler ones.
• Examples include protein synthesis, DNA replication, and photosynthesis.
• Photosynthesis is the process by which plants and other organisms convert light energy into chemical energy in the form of glucose.

Central Dogma of Molecular Biology

• The central dogma describes the flow of genetic information in cells.
• It states that DNA is transcribed into RNA, and RNA is translated into protein.
• Transcription is the process of synthesizing RNA from a DNA template.
• Translation is the process of synthesizing protein from an RNA template.
• This process is mediated by ribosomes and transfer RNA (tRNA).

Biochemical Techniques

• Various techniques are used to study biomolecules and biochemical processes.
• Spectrophotometry measures the absorption and transmission of light through a sample.
• Chromatography separates molecules based on their physical and chemical properties.
• Electrophoresis separates molecules based on their size and charge.
• Mass spectrometry identifies and quantifies molecules based on their mass-to-charge ratio.
• X-ray crystallography determines the three-dimensional structure of biomolecules.
• Nuclear magnetic resonance (NMR) spectroscopy provides information about the structure and dynamics of molecules.

Applications of Biochemistry

• Biochemistry has wide-ranging applications in medicine, agriculture, and industry.
• In medicine, it aids in understanding the molecular basis of diseases and developing new therapies.
• In agriculture, it helps improve crop yields and develop pest-resistant plants.
• In industry, it is used in the production of pharmaceuticals, enzymes, and biofuels.
• Understanding enzyme function, structure, and mechanisms allows for the design of drugs that can inhibit or enhance their activity.
• Metabolic engineering uses biochemical knowledge to modify metabolic pathways in organisms for the production of valuable compounds.
• The study of gene expression and regulation is critical in understanding development, disease, and adaptation to environmental changes.
• Biochemical approaches are used to develop diagnostic tools for detecting diseases, such as enzyme assays and immunoassays.
• The principles of protein folding and protein-protein interactions are crucial in understanding protein function and disease.
• Biochemical research underlies the development of personalized medicine, tailoring treatments to an individual's genetic makeup.