Biochemistry: Chemical Compounds

• Biochemistry studies the chemistry of life and is key to understanding biological and medical sciences at a molecular level
• It helps find treatments for human and animal diseases and relies on lab analysis of body fluids like blood and urine
• Abnormal constituents in body fluids, revealed through biochemical tests, indicate disease

Chemical Elements and Compounds

• Chemistry studies the composition, changes, and combinations of substances
• Atoms of the same kind are known as elements
• Elements include Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N)
• Compounds form when two or more elements combine, e.g., H2O, CO2, HCl, NaCl

Inorganic Compounds

• Inorganic compounds originate from nonliving substances
• Water (H2O) acts as a universal solvent due to its bent shape and polarity, dissolving polar compounds
• 70-80% of the body consists of water

Organic Compounds and Biochemistry

• Organic compounds come from living substances
• Carl Alexander Neuberg introduced the term "biochemistry" in 1903, and is considered the "father of modern biochemistry"
• Biochemistry uses chemistry to study biological processes at cellular and molecular levels
• It is interdisciplinary, including molecular biology, genetics, microbiology, and organic/inorganic chemistry
• Pure research expands knowledge, while applied research solves practical problems
• Biochemistry emerged in the 20th century, combining chemistry, physiology, and biology to study living systems
• Studies the structure/behavior of complex molecules in living material
• Examines how molecules interact to form cells, tissues, and organisms

Organization of Life

• Life is organized from atoms/elements to molecules, organelles, cells, tissues, organs, organ systems, and organisms

Cell Chemistry

• Carbon is a key element in organic compounds, with CO2 being an exception
• Organic compounds are complex, containing many atoms, e.g., Glucose (C6H12O6)
• Four main types of organic compounds: carbohydrates, proteins, lipids, and nucleic acids (DNA and RNA)

Cells as Building Blocks

• Cells are the basic, smallest living units, which perform various activities with the aid of organelles
• Similar cells form a tissue, like muscle tissue
• Diverse cells include muscle, bone, nerve, skin, and visual cells
• Skin cells consist of:
• Keratinocytes (waterproof with keratin)
• Melanocytes (produce pigment)
• Merkel cells (sensory receptors)
• Langerhans cells (immune response)
• Adipocytes (fat cells)
• Squamous cells (shed)
• Cells grow, reproduce, use energy, adapt, and respond to the environment
• They can be entire organisms (unicellular) or part of multicellular organisms

Tissue, Organ, and System Formation

• Similar tissues combine to form an organ (e.g., stomach, liver), and organs form organ systems (e.g., digestive, respiratory)
• Cells function independently, defining boundaries, using sugars for energy, and containing replication information

Cell Function

• Structural building blocks for tissues and organs, and group to form tissues
• Tissues with similar functions form organs, and organs form an organ system

Cell Characteristics

• Can define boundaries and protect itself from external changes
• Can use sugars to derive energy for different processes
• Contains all the information required for replicating itself and interacting with other cells in order to produce a multicellular organism

Prokaryotic Cells

• Lack a nuclear membrane; genetic material in a nucleoid
• Capsule, an outer protective covering, helps with moisture retention and cell attachment
• The cell wall is the outermost layer
• Cytoplasm contains enzymes, salts and cell organelles
• Cell/plasma membrane surrounds the cytoplasm, regulating substance entry and exit
• Pili are hair-like for bacterial motility, adhesion, and genetic exchange
• Flagella are whip-like; aid locomotion
• Ribosomes synthesize proteins
• Plasmids are non-chromosomal DNA structures
• The Nucleoid region is where genetic material is present inside the cytoplasm

Eukaryotic Cells

• The cell membrane is a double-layered phospholipid membrane and is selectively permeable
• Controls what enters and exits the cell due to phospholipid bilayer and embedded proteins, and maintains the internal environment
• Cytosol is the intracellular fluid, mainly water, ions, proteins and small molecules
• Cytoskeleton tubules and filaments support and shape the cell and helps with cell signaling
• The cell’s "skeleton"

Nucleus and Genetic Control

• Nucleus: contains DNA (genetic material) in the nucleolus and regulates growth/division
• Nuclear membrane: It is the outer covering of the nucleus and protects the DNA
• Nucleolus: produces and assembles ribosomes, and rRNA is transcribed

Ribosomes and Endoplasmic Reticulum

• Ribosomes: synthesize proteins by translating mRNA into amino acid sequences, found freely or on endoplasmic reticulum
• Endoplasmic reticulum: a network of membranous sacs (cisternae) from the nuclear membrane

Types of Endoplasmic Reticulum

• Rough ER (RER): covered in ribosomes
• Smooth ER (SER): synthesizes and metabolizes lipids; also detoxifies chemicals

Vesicles and Golgi Apparatus

• Vesicles: transport molecules between organelles
• Golgi apparatus: receives proteins from the ER and packages them for transport

Mitochondria and Lysosomes

• Mitochondria: "powerhouse of the cell" that releases energy as ATP during cellular respiration
• Cellular respiration: cells breakdown glucose to produce energy in the form of ATP, using oxygen and releasing CO2 and H2O as byproducts.
• Lysosomes: contain digestive enzymes to break down waste and damaged organelles, and acts as a "garbage disposal"

Lysosomes Functions

• Known as ‘suicidal bags’ destroy the cell membrane with its digestive enzymes, causing lysis of the cell (also called autolysis)

Vacuoles and Cytoplasm

• Vacuole: a membrane-bound cell organelle , small in animal cells (remove waste) and maintain water balance in plant cells (large)
• Cytoplasm: a gelatinous liquid that fills the space inside a cell and holds the internal components of cells in place and protects them from damage

Peroxisomes and Cell Walls

• Peroxisomes: contain enzymes for metabolic processes and detoxification which are necessary for human health and development
• Cell wall: an outer layer in plant cells made of polysaccharides (cellulose, pectin, hemicellulose) which gives strength, maintains stability, and provides shape and structure

Chloroplasts and Photosynthesis

• Chloroplasts: plastids that convert light energy into chemical energy (ATP and NADPH) through photosynthesis
• The stroma is the fluid within chloroplasts, where light-independent reactions occur (Calvin Cycle)
• Chlorophyll is a structure that absorbs light energy