Unit 1 Bio

Importance of microscopic understanding for macroscopic phenomena
Understanding atomic behavior leads to connections between molecular structure and function
Energy and matter exchange are vital for life processes
Overview of topics covered:
- Introduction to water
- Common elements and reactions for life
- Four groups of biological molecules: carbohydrates, proteins, lipids, nucleic acids

Water (H2O): two hydrogen atoms bonded to one oxygen atom via polar covalent bonds
- Oxygen's high electronegativity leads to an uneven charge distribution:
- Oxygen: partial negative charge
- Hydrogen: partial positive charge
Water as a polar molecule:
- Opposite charges attract, leading to hydrogen bonding between water molecules
- Water is known as the universal solvent due to its polarity
Hydrogen bond dynamics:
- Hydrogen bonds constantly break and reform in liquid water
- High specific heat due to the energy needed to break hydrogen bonds
- Lower density of ice as hydrogen bonds stabilize further apart, allowing ice to float

Cohesion: Attraction of water molecules to themselves
- Important in processes like transpiration in plants
- Example: Water moves up plant tissues via cohesion and adhesion
Adhesion: Attraction of water molecules to other polar surfaces
- Example: Meniscus formed in a graduated cylinder due to stronger adhesion to glass than cohesion between water molecules
Surface Tension: Caused by cohesive forces; allows some insects to walk on water due to stronger hydrogen bonds

Organisms need to exchange matter for growth, reproduction, and organization
Matter and Atoms:
- Matter: anything that has mass and takes up space
- Atoms consist of:
- Protons (positive charge, in the nucleus)
- Neutrons (no charge, in the nucleus)
- Electrons (negative charge, in orbit around the nucleus)
Metabolism:
- Sum of all chemical reactions in organisms
- Involves catabolic (bond-breaking) and anabolic (bond-forming) reactions
Organic Molecules: contain carbon; examples include carbohydrates, proteins, and lipids
CHNOPS: six most common elements in living organisms:
- C: carbon in all biological molecules
- H: hydrogen
- N: nitrogen in nucleic acids and proteins
- O: oxygen
- P: phosphorus in nucleic acids and phospholipids
- S: sulfur in some amino acids influencing protein structure

Water plays a key role in metabolism:
- Dehydration Reactions: join monomers to form polymers (removal of water)
- Hydrolysis Reactions: break down polymers into monomers (addition of water)

Four types of biological macromolecules: proteins, carbohydrates, lipids, nucleic acids

Polymers of amino acids
Amino acids consist of a central carbon, hydrogen, carboxyl group, amino group, and variable R group
Peptide Bonds: covalent bonds formed between the amino group of one amino acid and the carboxyl group of another
Protein Structure Levels:
- Primary: amino acid sequence
- Secondary: localized folding (alpha helices, beta sheets)
- Tertiary: overall 3D shape due to R-group interactions
- Quaternary: multiple polypeptide chains bonded together
Protein denaturation affects function but does not change primary structure
Functions of Proteins:
- Structural support, transport, enzyme catalysis, signaling, cellular communications

Composed of carbon, hydrogen, oxygen in a 1:2:1 ratio
Polysaccharides: formed from monosaccharide monomers using glycosidic linkages
Functions:
- Energy storage (starch, glycogen)
- Structural roles (cellulose in plants, chitin in exoskeletons)
- Identical chemical formulas but differing structures lead to different functions (e.g., glucose vs. fructose)

Diverse, primarily hydrophobic molecules
Made of carbon, hydrogen, oxygen (no true monomer)
Types:
- Fats: triglycerides formed from glycerol and fatty acids
- Phospholipids: cell membrane components, amphipathic (hydrophobic tails, hydrophilic head)
- Steroids: formed by fused carbon rings
Functionality: energy storage, membrane structure, hormone signaling

Carry genetic information (DNA & RNA)
Composed of nucleotides:
- Components: 5-carbon sugar, phosphate group, nitrogenous base
DNA vs RNA:
- DNA: contains deoxyribose, double-stranded, thymine as a base
- RNA: contains ribose, single-stranded, uracil in place of thymine
Phosphodiester Bonds: link nucleotides together, form the backbone of nucleic acids
Base pairing:
- Adenine (A) pairs with Thymine (T) or Uracil (U)
- Guanine (G) pairs with Cytosine (C)

Water: crucial for life, properties governed by its polarity (cohesion, adhesion, surface tension)
Organic molecules built from carbon contain various structures and fulfill essential metabolic roles
Focus on four main biological macromolecules to understand their importance in biological systems.