Biology Chapter: Isomers and Biological Molecules

Isomers

• Isomers are compounds with the same molecular formula but different structural arrangements.
• Types of isomers include structural isomers, geometric isomers (cis/trans), and optical isomers (enantiomers).

Trans-Fats

• Trans-fats are unsaturated fats with hydrogen atoms on opposite sides of the double bond, leading to a straighter structure.

Functional Groups

• Hydroxyl (-OH), Carboxyl (-COOH), Amino (-NH2), Phosphate (-PO4), and Sulfhydryl (-SH) are common functional groups, each featuring distinct structures and properties.

Biological Molecules

• Four main biological molecules: Carbohydrates (energy), Lipids (energy storage, membranes), Proteins (catalysis, support), Nucleic Acids (genetic information).

Dehydration vs. Hydrolysis

• Dehydration reactions link monomers by removing water, forming polymers.
• Hydrolysis reactions break polymers into monomers by adding water.

Monomers of Biological Molecules

• Carbohydrates: Monosaccharides (e.g., glucose); structure includes carbon rings.
• Lipids: Fatty acids and glycerol; fatty acids have long hydrocarbon chains.
• Proteins: Amino acids; structure features an amino group, carboxyl group, and side chain (R group).
• Nucleic Acids: Nucleotides; consist of a sugar, phosphate group, and nitrogenous base.

Bonds in Biological Molecules

• Carbohydrates: Glycosidic bonds.
• Lipids: Ester bonds.
• Proteins: Peptide bonds.
• Nucleic Acids: Phosphodiester bonds.

Structures of Biological Molecules

• Carbohydrates: Ring or linear structures.
• Lipids: Glycerol and fatty acid tails.
• Proteins: Folded chains with various shapes.
• Nucleic Acids: Double helix (DNA) or single-stranded (RNA).

Complex Carbohydrates

• Starch: Energy storage in plants.
• Glycogen: Energy storage in animals.
• Cellulose: Structural component in plant cell walls.
• Chitin: Structural component in fungi and exoskeletons of insects.

Emergent Properties

• Emergent properties arise from the interactions and organization of components in systems, leading to new characteristics not seen in individual parts.

Saturated vs. Unsaturated Fats

• Saturated fats have no double bonds, are solid at room temperature, and typically come from animal sources.
• Unsaturated fats have one or more double bonds, are liquid at room temperature, and come from plant sources.

Nucleotide Bonding Rules

• Adenine pairs with Thymine (in DNA) or Uracil (in RNA), and Cytosine pairs with Guanine.

Antiparallel

• Refers to the opposite orientation of the two strands of DNA in a double helix.

DNA vs. RNA

• DNA: Double-stranded, stores genetic information, contains Thymine.
• RNA: Single-stranded, involved in protein synthesis, contains Uracil.

Protein Structures

• Primary: Linear sequence of amino acids.
• Secondary: Local folding into alpha-helices or beta-sheets.
• Tertiary: Overall 3D structure formed by interactions among R groups.
• Quaternary: Assembly of multiple polypeptide chains.

Denaturation

• Denaturation is the unfolding of proteins, caused by factors like heat, pH changes, or chemical exposure.

Wax Properties

• Waxes are long-chain fatty acids esterified to long-chain alcohols, providing water-repelling and protective properties.

Surface Area to Volume Ratio

• As a cell increases in size, its surface area to volume ratio decreases, which is detrimental as it limits efficiency in nutrient uptake and waste removal.

Cell Size Comparison

• Adult cells can be larger than baby cells, but generally, cells do not grow indefinitely; they divide out of necessity.

Types of Cells

• Two main types: Prokaryotic (lack a nucleus, simpler structure) and Eukaryotic (contain a nucleus, complex structure).

Animal vs. Plant Cells

• Animal cells lack cell walls and chloroplasts, while plant cells have a rigid cell wall and chloroplasts for photosynthesis.

Protein Creation Pathway

• Begins in the nucleus (DNA), processed in the rough endoplasmic reticulum, modified in the Golgi apparatus, and transported to destination (e.g., membranes or secreted).

Eukaryotic Organelles

• Organelles include nucleus (genetic material storage), endoplasmic reticulum (protein/lipid synthesis), Golgi apparatus (modification/packaging), lysosomes (digestion), mitochondria (energy production).

Ribosome Function

• Ribosomes synthesize proteins by translating messenger RNA (mRNA) into amino acid sequences.

Endomembrane System Parts

• Comprising the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, and vesicles, it functions in synthesis, modification, and transport of biomolecules.

Cytoskeleton Roles

• Provides structural support, facilitates intracellular transport, enables motility through structures like cilia and flagella.

Cytoskeletal Structures

• Microfilaments: Thin fibers, assist in cell movement and shape.
• Intermediate filaments: Provide mechanical strength.
• Microtubules: Hollow tubes, guide vesicle movement and form spindle fibers during cell division.

Endosymbiotic Theory

• Proposes that eukaryotic cells originated from symbiotic relationships between different species of prokaryotes, leading to organelles like mitochondria and chloroplasts.

Cell Junctions

• Tight junctions: Prevent leakage between cells.
• Desmosomes: Anchor adjacent cells together.
• Gap junctions: Allow communication between cells.
• Plasmodesmata: Channels for transport and communication in plant cells.

Cholesterol in Cells

• Only animal cells contain cholesterol, which stabilizes membrane fluidity.

Diffusion

• Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached.

Concentration Gradient

• A concentration gradient is the difference in concentration of a substance across a space.

Passive vs. Active Transport

• Passive transport requires no energy, moving molecules down their concentration gradient, while active transport requires energy to move substances against the gradient.

Tonicity Differences

• Hypotonic: Cell swells as water enters.
• Hypertonic: Cell shrinks as water leaves.
• Isotonic: No net water movement, cell maintains size.

Molecular Passage through Phospholipid Bilayer

• Small nonpolar molecules (e.g., oxygen, carbon dioxide) pass freely; polar molecules and ions require transport proteins.

Endocytosis Types

• Phagocytosis: Cell engulfs large particles or cells.
• Pinocytosis: Cell takes in small amounts of liquid.
• Receptor-mediated endocytosis: Specific molecules are ingested after binding to receptors.

Test your knowledge on isomers and their types, the structure of trans-fats, and the four main biological molecules. You will differentiate between dehydration and hydrolysis reactions and identify the monomers and bonds associated with each biological molecule. This quiz covers essential concepts in biology related to molecular structures and functions.