Molecular BIo

Reductionism

Taking a big subject overall and reducing it into smaller parts to then further dive deeper into each part.

Mechanisms of metabolism

Glycolysis, Photosynthesis, Oxidative metabolism.

Viruses

Infectious diseases understood to be due to bacteria.

Viroids

When viruses are outside of living cell (inside if capsid) with no protein, known to infect higher plants.

Prions

Prion protein cellular misfolds which lets other proteins misfold.

Covalent bond

The sharing of a pair of valence electrons by two atoms.

Ionic bond

Occurs when atoms have such an unequal attraction for electrons that one strips an electron completely from the other.

Hydrogen bonds

Occurs when a hydrogen atom covalently bound to one electronegative atom is also attracted to another electronegative atom.

Electronegativity

Affinity for electrons.

Structural complementarity

Complementary shapes.

Chemical complementarity

Complementary bonding capacities.

Hydrophilic

Form bonds to water.

Hydrophobic

Does not form bonds or dissolve in water.

Synthesis

A reaction resulting in an increase in structural complexity.

Polymerization

A type of synthesis; every polymerization is a synthesis, not every synthesis is a polymerization.

Condensation

Two large molecules come together but a small molecule is lost in the process.

Dehydration

Two large molecules come together but a water molecule is lost in the process.

Hydrolysis

Two large molecules come together but a water molecule is doing the breaking.

Simple sugars/monosaccharides

Single sugars, glucose and fructose.

Disaccharides

Two monosaccharides joined together (ex. Sucrose and lactose).

Oligosaccharides

Plant based monosaccharides combined often attached to lipids and proteins.

Polysaccharides

Lots of monosaccharides combined into a long chain.

Glycosidic bond

Type of bond connecting saccharides.

Glycogen

A type of polysaccharide that is important for long term energy storage.

Starch

Energy storage in plants.

Cellulose

Important for structure.

Fatty acid

Long hydrocarbon chains, energetically unfavorable.

Triglyceride

Glyceride and three fatty acids.

Phospholipid

Cell membrane - amphipathic.

Nucleotide

Nitrogenous base - 5 carbon sugar - phosphate.

Peptide bond

Covalent bonds formed between the carboxyl group of one amino acid and the amino group of another.

Primary structure

Sequence of amino acids.

Secondary structure

Regular arrangement of amino acids in localized regions.

Tertiary structure

Folding based on properties of R-groups.

Quaternary structure

Associations between separate polypeptides.

Catabolism

Energy derived from breakdown of organic molecules.

Anabolism

Used to drive synthesis of needed cell components.

Activated carriers

Little molecules that store energy in rich bonds for the cell when needed.

Gluconeogenesis

Building from other organic molecules.

Oxidation

Loss of electron density.

Reduction

Gain of electron density.

Free energy

That form or portion of a system's energy that can be used to do work.

Exergonic

When Delta G is negative so the system releases energy.

Endergonic reactions

When Delta G is positive so the system absorbs energy from surroundings.

Activation energy

The minimum energy required to initiate a chemical reaction.

Transition state

A high-energy, unstable intermediate stage in a chemical reaction.

Competitive inhibitor

Inhibitor competes for active site.

Allosteric modification

Binds somewhere else and changes shape of the enzyme.

Feedback inhibition

Regulation of enzyme activity.

Covalent modification

Regulation of enzyme activity by covalently attaching or removing chemical groups (commonly phosphorylation), which can activate or inhibit the enzyme.

Feedback inhibition

A regulatory mechanism where the final product of a metabolic pathway inhibits an earlier enzyme, preventing overproduction.

Kinases

Enzymes that add phosphate groups (usually using ATP).

Phosphatases

Enzymes that remove phosphate groups.

Vmax

The maximum reaction rate of an enzyme when it is fully saturated with substrate.

Km

Michaelis constant; the substrate concentration at which the reaction rate is ½ of Vmax; indicates enzyme affinity for the substrate (lower Km = higher affinity).

Nucleus

Contains DNA and is the site of DNA replication and transcription.

Lysosomes

Membrane-bound organelles that contain hydrolytic enzymes for digestion and recycling of macromolecules.

ER

A membrane network involved in protein and lipid synthesis.

Golgi

Modifies, sorts, and packages proteins and lipids for transport or secretion.

Mitochondria

Site of cellular respiration and ATP production.

Chloroplasts

Site of photosynthesis in plant cells.

Peroxisomes

Contain enzymes that break down fatty acids and detoxify harmful substances using oxidation.

Cytoskeleton

A network of protein fibers that provides cell shape, organization, transport, and movement.

Nuclear pores

Protein complexes that regulate transport of molecules between the nucleus and cytoplasm.

Endomembrane system

A group of membranes (nuclear envelope, ER, Golgi, vesicles, lysosomes) that work together to synthesize and transport materials.

Rough ER

Studded with ribosomes; protein synthesis for secretion or membranes.

Smooth ER

No ribosomes; lipid synthesis, detoxification, Ca²⁺ storage.

Free ribosomes

Synthesize proteins that function in the cytosol.

Bound ribosomes

Attached to rough ER; synthesize secreted, membrane, or lysosomal proteins.

Fluid mosaic model

Describes membranes as a fluid phospholipid bilayer with proteins embedded and able to move laterally.

Lipid rafts

Cholesterol- and sphingolipid-rich membrane microdomains involved in cell signaling and protein sorting.

Peripheral (extrinsic) membrane proteins

Proteins loosely attached to the membrane surface or to integral proteins; do not penetrate the bilayer.

Integral (intrinsic) membrane proteins

Proteins that span or are embedded in the lipid bilayer, often with transmembrane domains.

Hydropathy plot

A graph showing hydrophobic and hydrophilic regions of a protein to predict transmembrane segments.

Β-barrel

A membrane protein structure composed of β-sheets forming a cylindrical pore, commonly found in outer membranes of bacteria and mitochondria.