Chemical Bonds

covalent bonds

shared electron pairs

ex: H2O
Oxygen shares its electrons w/
two Hydrogen atoms, making a
stable electron configuration

polar covalent bond

electrons are shared unequally due to difference in electronegativity (EN)

ex: H2O
Oxygen has a higher EN, so Hydrogen's electrons are pulled toward Oxygen

ionic bonds

attraction between
charged ions

ex: NaCl
Na has a charge of +1
and Cl has a charge of -1

Hydrogen bonds

polar

Hydrogen bonded to a highly
electronegative atom

Hydrogen bonding occurs w/
FON (Florine, Oxygen, Nitrogen)

electronegativity:
Measure of the ability of an atom to attract electrons in the context of a chemical bond

present in DNA and proteins

Van der Waals interaction

weak interactions between atoms;
interaction of electrons of nonpolar substances

Hydrophilic interactions

interaction of polar substances in
the presence of nonpolar substances

Water

cohesion:
interaction with molecules
of the same substance.

adhesion:
interaction with molecules of different substance

ex: allows water to travel up the trees

has high specific heat

w' Hydrogen bonds, helps regulate temperature

Hydrophobic interactions

interaction of nonpolar substances in the presence of polar substances

Dipole-Dipole

interaction between polar molecules

Ion-Dipole

attractive force between an ion and
a neutral molecule

Biological Molecules

Carbohydrates

Monomer: Monosaccharides (Glucose, Fructose)

Polymer: Polysaccharides (Starch, Glycogen, Cellulose)

Found in: Cell walls (cellulose, peptidoglycan), cell membranes (glycoproteins, glycolipids)

Lipids

Phospholipids, Triglycerides, Steroids

Found in: Cell membranes (phospholipid bilayer), Hormones (steroids), Energy stores (fat droplets)

Proteins

Monomer: Amino Acids

Structure: Primary, Secondary (α-helix, β-sheet), Tertiary, Quaternary

Functions: Enzymes (catalysts), Transport proteins, Receptors, Structural components (cytoskeleton, extracellular matrix)

Polymer: Polypeptides

Nucleic Acids

Monomer: Nucleotides (A, T, G, C, U)

Functions: Store genetic information, Direct protein synthesis

Polymer: DNA & RNA

Cell Components

Prokaryotic Cells (Bacteria & Archaea)

No membrane-bound organelles

Cell Wall (Peptidoglycan in bacteria)

Ribosomes (Protein + rRNA)

Plasma Membrane (Phospholipid bilayer)

Nucleoid (Circular DNA, No nucleus)

Flagella (Protein-based movement structure)

Eukaryotic Cells (Plants, Animals, Fungi, Protists)

Membrane-bound organelles

Larger & more complex

Cell Membrane, Cytoplasm, and cytoskeleton

Cell Membrane

Phospholipid Bilayer (Hydrophobic tails, Hydrophilic heads)

Proteins – Transport, signaling

Carbohydrates (Glycoproteins, Glycolipids) – Cell recognition

Cholesterol (in animals)

Cytoplasm & Cytoskeleton

Cytosol (Water, enzymes, dissolved molecules)

Cytoskeleton (Protein Filaments)

Microtubules (Tubulin) – Transport, spindle fibers

Microfilaments (Actin) – Shape, movement

Intermediate Filaments – Structural support

Nucleus, ER, Golgi, mitochondria, lysosomes, and vaculoes

Nucleus

Nuclear Envelope – Regulates transport

Chromatin – Genetic storage

Nucleolus (rRNA Synthesis) – Ribosome assembly

Endoplasmic Reticulum (ER)

Rough ER (Ribosomes attached, Protein synthesis & transport)

Smooth ER (Lipid synthesis, Detoxification, Calcium storage)

Golgi Apparatus

Modifies, sorts, packages proteins & lipids

Produces lysosomes

Mitochondria

Double membrane (Inner membrane forms cristae)

Own DNA & Ribosomes (Endosymbiotic Theory)

ATP production via Cellular Respiration

Lysosomes (Animal Cells)

Contain Hydrolytic Enzymes

Break down waste, foreign particles, old organelles

Vacuoles

Plants: Large central vacuole (Stores water, ions, nutrients, maintains pressure)

Animals: Small vesicles for storage & transport