Introduction to Biochemistry

• Biochemistry studies the chemistry of life, crucial for understanding biological and medical sciences at a molecular level, including remedies for ailments.
• Modern medical practices rely heavily on laboratory analysis of body fluids like blood and urine to detect disease manifestations.
• Abnormal biochemical constituents indicate disease, which biochemical studies aim to distinguish from normal levels.
• Examples of biochemical tests include blood tests, urine analysis, and tissue samples.
• Biochemistry is an interdisciplinary field encompassing molecular biology, molecular genetics, microbiology, and organic and inorganic chemistry.
• Pure research expands knowledge, while applied research solves practical problems.
• Biochemistry emerged in the early 20th century by combining chemistry, physiology, and biology.
• It examines the structure and behavior of complex biological molecules and their interactions in cells, tissues, and organisms.

Chemistry Basics

• Chemistry studies the composition, changes, and combinations of substances.
• An element is a distinct kind of atom.
• Compounds form from two or more combined elements.
• Inorganic compounds originate from nonliving substances.
• Water (H2O) is a universal solvent due to its bent molecular shape and polarity, dissolving other polar compounds.
• The human body is 70-80% water.
• Organic compounds originate from living substances.
• Carl Alexander Neuberg introduced the term "biochemistry" in 1903.

Organization of Life

• Atoms/Elements form molecules, which form organelles, then cells, tissues, organs, organ systems, and finally organisms.
• All organic compounds contain carbon, except for carbon dioxide (CO2).
• Organic compounds are complex, containing many atoms.
• Glucose (C6H12O6) serves as an example.
• Four main types of organic compounds exist: carbohydrates, proteins, lipids, and nucleic acids (DNA and RNA).

Cells

• The basic unit of life.
• Cells perform various activities using many cell organelles.
• Cells function together as a unit to form a tissue.

Skin Cells

• Keratinocytes produce keratin, making skin waterproof and resistant to damage.
• Melanocytes produce melanin, determining skin, hair, and eye color.
• Merkel cells are sensory receptors for light touch.
• Langerhans cells are immune cells that respond to foreign substances.
• Adipocytes are fat cells providing insulation and cushioning.
• Squamous cells are shed from the outer layers of the epidermis as new ones form.
• Cells grow, reproduce, use energy, adapt, and respond to their environment.

Tissues & Organs

• Cells may be unicellular or part of a multicellular organism.
• Similar tissues form an organ.
• Functioning organs group into an organ system.
• Cells perform activities in coordination to help an organism survive.

Cell Functions

• Cells are structural building blocks forming tissues and organs.
• Cells function independently under the right conditions.
• They define boundaries, use sugars for energy, and contain replication information.
• Plants can be reproduced from a single cell.

Prokaryotic Cell Structure

• Prokaryotic cells lack a nuclear membrane, with genetic material in the nucleoid.
• They can be spherical, rod-shaped, or spiral.
• Capsule: a protective outer covering for moisture retention and attachment.
• Cell Wall: the outermost layer providing cell shape.
• Cytoplasm: a gel-like substance with enzymes, salts, and organelles.
• Cell/Plasma Membrane: regulates substance entry and exit.
• Pili: hair-like structures for motility, adhesion, and genetic exchange.
• Flagella: whip-like structures aiding in locomotion.
• Ribosomes: involved in protein synthesis.
• Plasmids: non-chromosomal DNA structures.
• Nucleoid Region: the area where genetic material resides.

Eukaryotic Cells - Organelles and Their Functions

• Cell membrane: a selectively permeable phospholipid bilayer controls substance passage.
• Cytosol: the fluid within the cell containing water, ions, proteins, and small molecules.
• Cytoskeleton: provides shape, support, and aids in cell signaling.
• Nucleus: contains DNA and regulates cell growth and division.
• Nuclear membrane/envelope: protects DNA.
• Nucleolus: produces and assembles ribosomes.
• Ribosomes: synthesize proteins.
• Endoplasmic reticulum: transports proteins.
  • Rough ER (RER): contains ribosomes for protein synthesis.
  • Smooth ER (SER): synthesizes and metabolizes lipids and detoxifies chemicals.
• Vesicles: transport molecules between organelles.
• Golgi apparatus: packages proteins into vesicles for transport.
• Mitochondria: the "powerhouse" of the cell, releases energy in the form of ATP.
  • Cellular respiration: the process by which cells breakdown glucose to produce energy in the form of ATP, using oxygen and releasing CO2 and H2O as byproducts.
• Lysosomes: break down cellular waste and damaged organelles.
  • Known as "suicidal bags" due to their ability to cause cell lysis (autolysis).
• Vacuole: removes waste in animal cells and maintains water balance in plant cells.
• Cytoplasm: composed of water, salts, and organic molecules and it holds and protects cell components.
• Peroxisomes: contain enzymes for lipid metabolism and detoxification.
• Cell Wall: provides strength, stability, support, and shape to plant cells.
  • Composed of polysaccharides: cellulose, pectin, and hemicellulose.
• Chloroplasts: conduct photosynthesis, converting light energy into chemical energy (ATP and NADPH).
  • Stroma: the site of the Calvin Cycle, converting CO2 into sugars using energy from light-dependent reactions.
  • Chlorophyll: absorbs light energy.