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Biological macromolecules include proteins, nucleic acids, and polysaccharides.
These macromolecules are polymers made of repeating monomeric units.
Polymers are synthesized via condensation reactions, linking activated monomers and removing water.
After synthesis, polymers fold into stable, three-dimensional shapes without further energy input.
Key focus on the chemical nature of monomers and properties of resulting polymers.
The study of proteins is prioritized due to their crucial roles in cellular structure and functions.

Proteins: Key structural and functional molecules in the cell.
Nucleic acids: Genetic material necessary for information storage and transfer.
Polysaccharides: Important for energy storage and structural integrity.
Lipids: Not true polymers but essential components resembling polymers in synthesis.

Proteins are vital macromolecules, essential in nearly all cellular processes.
Derived from the Greek term "proteios" meaning 'first place', indicating their preeminence in biological functions.

Enzymes: Catalysts that speed up chemical reactions.
Structural Proteins: Provide support and shape to cells, contributing to cellular architecture.
Motility Proteins: Involved in cell movement and muscle contraction.
Regulatory Proteins: Control and coordinate cellular activities.
Transport Proteins: Facilitate movement of substances within and outside the cell.
Signaling Proteins: Mediators of communication between cells.
Receptor Proteins: Allow cells to respond to external signals.
Defensive Proteins: Protect against disease (e.g. antibodies).
Storage Proteins: Reservoirs for amino acids.

Structure: All proteins are linear polymers of amino acids. 20 standard amino acids are utilized in synthesis, featuring:
- Amino group:
- Carboxyl group:
- Hydrogen atom:
- R group (side chain): Different for each amino acid, conferring unique properties.
Amino Acid Diversity: Although 60 different amino acids exist, only 20 are commonly used in proteins. Variability in amino acid sequences results in diverse protein functions.

Formed through condensation reactions between the carboxyl group of one amino acid and the amino group of another.
Peptide bonds give rise to polypeptide chains with intrinsic directional properties (N-terminus to C-terminus).

Primary Structure: Linear sequence of amino acids.
Secondary Structure: Local folding into helices (α-helix) or sheets (β-sheet) stabilized by hydrogen bonds.
Tertiary Structure: Overall 3D shape caused by various bonds and interactions (e.g., disulfide bonds, hydrogen bonds, ionic interactions).
Quaternary Structure: Assembly of multiple polypeptide chains into a functional protein.

Proper folding is critical for function; misfolded proteins can lead to diseases like Alzheimer's.
Disulfide Bonds: Covalent bonds between cysteine residues, stabilizing protein conformation.
Noncovalent Interactions: Hydrogen bonds, ionic bonds, and hydrophobic effects significantly influence protein stability and folding.

Alzheimer's Disease: Caused by protein misfolding leading to amyloid plaques and neurofibrillary tangles:
- Amyloid Plaques: Formed by aggregation of amyloid-beta peptide outside neurons.
- Neurofibrillary Tangles: Composed of hyper-phosphorylated Tau protein, leading to cell death.

X-ray Crystallography: A method to determine protein structure by crystallizing proteins and analyzing the diffraction patterns of X-rays. Steps include:
1. Protein Crystal Production: Producing high-quality crystals of the target protein.
2. Irradiation: Directing X-rays onto the crystal.
3. Data Analysis: Analyzing diffraction patterns to build 3D models of the protein structures.