BIO1330 Unit 1 Flashcards - Structure, Membranes, and Atoms (Vocabulary)

A comprehensive set of vocabulary-style flashcards covering Unit 1 topics: cell structure, the endomembrane system, organelles, endosymbiosis, basic atomic theory, bonding, and membrane transport concepts.

Plasma membrane

The lipid bilayer that encloses all living cells; it is the boundary that regulates entry and exit of substances.

Nucleus

Membrane-bound organelle in eukaryotes that houses the cell’s genetic material and controls activities via transcription; absent in prokaryotes.

Nucleoid

Region in prokaryotic cells where the circular chromosome resides; not enclosed by a membrane.

Prokaryotic chromosome

Circular, usually single, double-stranded DNA molecule; not contained within a membrane-bound nucleus.

Ribosomes

Ribonucleoprotein particles composed of rRNA and proteins; sites of protein synthesis; consist of small and large subunits.

Nucleolus

Substructure within the nucleus where rRNA is synthesized and ribosomal subunits begin to assemble.

Endomembrane system

Interconnected membranes including the nuclear envelope, ER, Golgi, lysosomes, vesicles, vacuoles, and plasma membrane that coordinate protein and lipid production and transport.

Nuclear envelope

Two lipid membranes surrounding the nucleus; contains nuclear pores for transport.

Nuclear pore complex

Protein channels that regulate traffic between the nucleus and cytoplasm.

Ribosomal subunits assembly

Assembly of ribosomal RNA and proteins begins in the nucleolus and finished subunits are exported to the cytoplasm.

Membrane-bound organelle

An organelle enclosed by a phospholipid membrane, creating a distinct internal environment.

Rough endoplasmic reticulum

ER region studded with ribosomes; site of synthesis for proteins destined for secretion or membranes.

Smooth endoplasmic reticulum

ER lacking ribosomes; synthesizes lipids, detoxifies compounds, and stores calcium.

Golgi apparatus

Organelle that modifies, sorts, and packages proteins and lipids for delivery to final destinations.

Lysosome

Organelle containing digestive enzymes that break down waste; involved in intracellular digestion.

Food vacuole

Vesicle that stores ingested material; digestion is coordinated with lysosomes in some organisms.

Peroxisome

Organelle that carries out fatty acid oxidation and detoxification; produces and breaks down hydrogen peroxide.

Cytoskeleton

Network of protein filaments (microfilaments, intermediate filaments, microtubules) that provide structure and enable movement and transport.

Chloroplast

Plant (and some algal) organelle where photosynthesis occurs; contains chlorophyll and its own DNA.

Cell wall

Rigid layer outside the plant cell membrane; made of cellulose; provides shape and protection.

Large central vacuole

Large plant cell organelle that stores water and maintains turgor pressure.

Endosymbiosis

Theory that mitochondria and chloroplasts evolved from free-living bacteria that were taken inside early eukaryotic cells.

Mitochondria

Organelle evolved from bacteria; site of cellular respiration; contains circular DNA and ribosomes, enabling semi-autonomous function.

Circular DNA

A closed-loop chromosome found in mitochondria and chloroplasts (and bacteria), typical of endosymbiotic origin.

Atom

The basic unit of matter composed of a nucleus (protons and neutrons) and electrons in orbit or shells.

Proton

Positively charged subatomic particle located in the nucleus.

Electron

Negatively charged subatomic particle orbiting the nucleus in electron shells.

Valence shell

Outermost electron shell of an atom; its electrons determine bonding behavior.

Chlorine (atomic number 17)

Element with electron configuration 2-8-7; seven valence electrons; tends to gain or share electrons to complete an octet.

Electronegativity

Tendency of an atom to attract electrons in a chemical bond; differences influence bond polarity.

Oxygen (most electronegative atom in biology)

Highly electronegative element that strongly attracts electrons in bonds among biological molecules.

Nonpolar covalent bond (C–H example)

Covalent bond with little to no electronegativity difference between atoms, resulting in equal sharing of electrons.

Hydrogen bond

Weak electrostatic attraction between a hydrogen atom covalently bonded to a highly electronegative atom (O, N, F) and another electronegative atom.

Polar covalent bond

Covalent bond with unequal sharing of electrons due to differences in electronegativity, creating partial charges.

Amphipathic

Molecule containing both hydrophobic (nonpolar) and hydrophilic (polar) regions; a key property of phospholipids.

Phospholipid bilayer

Double layer of phospholipids forming the core structure of cell membranes, with hydrophobic tails inward and hydrophilic heads outward.

Hydrophobic region (bilayer)

The fatty acid tails of phospholipids; nonpolar and water-repelling.

Hydrophilic region (bilayer)

The phosphate-containing heads; polar and water-attracting.

Peripheral membrane proteins

Proteins loosely attached to the membrane surface; can be removed with mild treatments without disrupting the bilayer.

Integral membrane proteins

Proteins embedded in the lipid bilayer; removal disrupts bilayer integrity and requires detergents.

Membrane protein functions

Include transport, receptors, enzymes, signaling, and cell adhesion roles.

Direct diffusion across membranes

Movement of small, nonpolar molecules directly through the lipid bilayer without proteins.

Small, nonpolar molecules diffusion example

Oxygen and carbon dioxide readily diffuse through the lipid bilayer.

Ion (charged) transport across membranes

Charged ions cannot pass through the hydrophobic core directly; require channels or carriers.

Channel protein

Membrane protein that forms a pore for specific ions or molecules to pass through by facilitated diffusion.

Carrier protein

Membrane protein that binds a molecule and changes shape to shuttle it across the membrane (facilitated diffusion).

Facilitated diffusion

Movement of substances down their concentration gradient via membrane proteins, requiring no direct energy input.

Permeability factors

Temperature, lipid composition (cholesterol), presence of proteins, and membrane fluidity influence what passes through.

Covalent bonds in membranes

Membrane structure relies on noncovalent interactions; phospholipids are not covalently bonded to form the bilayer.

Plasma membrane presence in cells

All cells have a plasma membrane; it defines cell boundaries and controls exchange with the environment.

Selective permeability

Property of membranes that allows some substances to cross more easily than others, maintaining internal conditions.

Diffusion

Net movement of molecules from high to low concentration due to random motion.

Direct diffusion (across bilayer)

Simple diffusion of substances directly through the lipid bilayer without transport proteins.

Osmosis

Diffusion of water across a semipermeable membrane, driven by solute concentration differences.

Hypotonic solution

Solution with lower solute concentration than inside the cell; causes water influx and swelling.

Isotonic solution

Solution with equal solute concentration to the cell; no net water movement.

Hypertonic solution

Solution with higher solute concentration than inside the cell; causes water efflux and cell shrinkage.

Plasma membrane transport in hypotonic/isotonic/hypertonic contexts

Water movement and cell volume change depend on external tonicity relative to the cell.

Blood loss treatment (isotonic vs water)

Isotonic saline is used to restore volume; pure water can disrupt electrolyte balance and cause harm.

Sea water ingestion effects

Drinking seawater increases osmolar load, promoting dehydration by drawing water from cells to the extracellular space.

Osmosis as energy concept

Osmosis is a passive process requiring no energy input; it follows the water potential gradient.

Facilitated diffusion example

Transport of substances down their gradient via a protein, without direct energy use.

Active transport energy source

Energy from ATP (or another energy source) drives pumps against the concentration gradient.

ATP

Adenosine triphosphate; main energy currency used by pumps to actively transport substances.

Exocytosis

Process by which cells export large materials by vesicle fusion with the plasma membrane.

Endocytosis

Process by which cells take in large materials via vesicle formation from the plasma membrane.