Bio: Evolution, Membrane Dynamics, and Cell Structure

Vocabulary flashcards covering core concepts of evolutionary biology, unifying themes of life, membrane structure and transport dynamics, lipid biochemistry, carbohydrates, and eukaryotic/prokaryotic cell anatomy based on BIOL 1020 lectures.

Reductionism

The approach of reducing complex systems to simpler components that are more manageable to study.

Emergent Properties

Novel properties that emerge at each level of biological organization due to the arrangement and interaction of parts as complexity increases.

Systems Biology

An approach to studying biology that aims to explore a biological system by analyzing the dynamic interactions among its integrated parts.

Eukaryotic Cell

A type of cell characterized by having membrane-enclosed organelles, including a membrane-enclosed nucleus containing DNA.

Prokaryotic Cell

A simpler, generally smaller cell structure lacking a membrane-enclosed nucleus and membrane-bound organelles, with DNA located in an unbound nucleoid region.

Gene Expression

The process by which information encoded in DNA directs the manufacturing of cellular products such as proteins.

Genome

The entire set of genetic instructions that an organism inherits.

Genomics

The large-scale study of whole sets of genes and their interactions within and between species.

Proteomics

The systematic study of full sets of proteins encoded by the genome (proteomes).

Bioinformatics

The use of computational tools and software to process, manage, and analyze large volumes of biological data.

Negative Feedback

A primary mechanism of feedback regulation in which the response or product reduces the initial stimulus.

Taxonomy

The branch of biology that names and classifies species into groups of increasing breadth based on shared characteristics.

Natural Selection

A process in which individuals with favorable inherited traits are more likely to survive and reproduce in a given environment than other individuals.

Adaptation

An inherited characteristic of an organism that enhances its survival and reproduction in a specific environment.

Artificial Selection

The selective modification of other species by humans through breeding individuals that possess desired inherited traits.

Homologous Structures

Anatomical resemblances present in different species that represent variations on a structural theme present in a common ancestor.

Vestigial Structures

Remnants of anatomical features that served important functions in an organism's historical ancestors but have reduced or no function in modern organisms.

Convergent Evolution

The independent evolution of similar features in distantly related lineages as they adapt to similar environments in similar ways.

Analogous Traits

Characteristics that share similar function and appearance but do not share common ancestry due to convergent evolution.

Biogeography

The scientific study of the geographic distribution of species.

Relative Fitness

The contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals in the population.

Directional Selection

Natural selection that shifts the overall makeup of a population by favoring variants at one extreme of the phenotypic distribution.

Disruptive Selection

Natural selection that favors phenotypic variants at both extremes of the distribution over intermediate variants.

Stabilizing Selection

Natural selection that removes extreme variants from a population and preserves intermediate phenotypic types.

Sexual Selection

A process in which individuals with certain inherited characteristics are more likely than other individuals of the same sex to obtain mates.

Sexual Dimorphism

Marked differences between the sexes in secondary sexual characteristics not directly linked to survival or reproduction.

Intrasexual Selection

Direct competition among individuals of one sex (often males) for mates of the opposite sex.

Intersexual Selection

Selection in which individuals of one sex (usually females) are choosy in selecting their mates from the other sex; also known as mate choice.

Balancing Selection

Natural selection that maintains two or more phenotypic forms in a population.

Frequency-Dependent Selection

A mode of balancing selection in which the fitness of a phenotype declines if it becomes too common in the population.

Heterozygote Advantage

Occurs when heterozygous individuals have higher fitness than both types of homozygous individuals at a particular gene locus.

Lipids

A diverse class of hydrophobic biological molecules that consist mostly of nonpolar hydrocarbon chains and do not form polymers.

Triacylglycerol

A fat molecule constructed from three fatty acids joined to a single glycerol molecule by ester linkages.

Saturated Fatty Acid

A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, resulting in a solid state at room temperature.

Unsaturated Fatty Acid

A fatty acid with one or more double bonds in its hydrocarbon chain, introducing kinks that prevent tight packing and keep it liquid at room temperature.

Trans Fats

Unsaturated fats containing trans double bonds created synthetically during hydrogenation, associated with cardiovascular disease.

Phospholipid

An amphipathic lipid consisting of a glycerol backbone bound to two hydrophobic fatty acid tails and a hydrophilic phosphate head group.

Steroids

Lipids characterized by a carbon skeleton consisting of four fused rings, such as cholesterol.

Amphipathic Molecule

A molecule possessing both hydrophilic (water-loving) and hydrophobic (water-fearing) regions.

Fluid Mosaic Model

A model describing cell membrane structure as a mosaic of protein molecules drifting laterally in a fluid phospholipid bilayer.

Peripheral Proteins

Membrane proteins that are loosely bound to the surface of the membrane or to integral proteins, not embedded in the lipid core.

Integral Proteins

Membrane proteins that penetrate the hydrophobic interior of the lipid bilayer; those that span the entire membrane are called transmembrane proteins.

Glycoproteins

Proteins with covalently attached carbohydrate side chains that serve as key identification tags in cell-cell recognition.

Glycolipids

Lipids with covalently attached carbohydrates found on the extracellular surface of plasma membranes.

Selective Permeability

A fundamental property of biological membranes allowing them to regulate the passage of substances across the cell boundary.

Aquaporins

Channel proteins in the plasma membrane that specifically facilitate the rapid transport of water molecules into and out of cells.

Diffusion

The spontaneous movement of molecules down their concentration gradient until dynamic equilibrium is established.

Passive Transport

The diffusion of a substance across a biological membrane down its concentration gradient without any expenditure of cellular energy.

Osmosis

The diffusion of free water molecules across a selectively permeable membrane from a region of lower solute concentration to a region of higher solute concentration.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water depending on solute concentration differences.

Isotonic

A surrounding solution whose solute concentration is equal to that inside the cell, causing no net movement of water.

Hypertonic

A surrounding solution with a higher solute concentration than inside the cell, causing the cell to lose water.

Hypotonic

A surrounding solution with a lower solute concentration than inside the cell, causing the cell to gain water.

Osmoregulation

The control of solute concentrations and water balance in organisms living in hypertonic or hypotonic environments.

Plasmolysis

A phenomenon in plant or walled cells where the cytoplasm shrivels and the plasma membrane pulls away from the cell wall in a hypertonic environment.

Facilitated Diffusion

Passive movement of molecules or ions across a membrane down their concentration gradient aided by transport proteins (channels or carriers).

Active Transport

The movement of a solute across a cell membrane against its concentration gradient, requiring energy expenditure (usually ATP hydrolysis) and transport proteins.

Sodium-Potassium Pump

An active transport system in animal cells that pumps sodium ions ($\text{Na}^+$) out of the cell and potassium ions ($\text{K}^+$) into the cell against their respective concentration gradients.

Membrane Potential

The electrical voltage difference across a plasma membrane resulting from the unequal distribution of positive and negative ions.

Electrochemical Gradient

The combined dual drive acting on an ion across a membrane, consisting of a chemical force (concentration gradient) and an electrical force (membrane potential).

Electrogenic Pump

A transport protein that generates voltage across a membrane while actively pumping ions across it.

Proton Pump

The main electrogenic pump of plants, fungi, and bacteria that actively transports hydrogen ions ($\text{H}^+$) out of the cell using ATP.

Cotransport

A mechanism where the active transport of one solute indirectly drives the transport of another solute across a membrane against its gradient.

Monosaccharides

The simplest sugar monomers, usually having chemical formulas that are multiples of $\text{CH}_2\text{O}$, serving as fuel and building blocks.

Glycosidic Linkage

A covalent bond formed between two monosaccharides through a dehydration reaction.

Polysaccharides

Carbohydrate macromolecules composed of many sugar monomers joined by glycosidic linkages, functioning in storage or structure.

Starch

A plant storage polysaccharide consisting entirely of glucose monomers linked together.

Glycogen

An extensively branched storage polysaccharide of glucose found in animal liver and muscle cells.

Cellulose

A major structural polysaccharide of plant cell walls, composed of glucose monomers joined by $\beta$ glycosidic linkages.

Chitin

A structural polysaccharide with modified glucose monomers that provides support for fungal cell walls and arthropod exoskeletons.

Nucleoid

An unbound, non-membrane-enclosed region in a prokaryotic cell where its genetic material (DNA) is localized.

Chromatin

The complex of DNA molecules and associated proteins that makes up eukaryotic chromosomes.

Nucleolus

A specialized region within the eukaryotic nucleus where ribosomal RNA ($\text{rRNA}$) is synthesized.

Ribosomes

Cellular complexes constructed from ribosomal RNA and proteins that carry out protein synthesis in the cytosol or bound to the ER.

Endomembrane System

A network of internal membranes in eukaryotic cells that includes the nuclear envelope, ER, Golgi apparatus, lysosomes, vacuoles, and plasma membrane.

Smooth Endoplasmic Reticulum

The portion of the endoplasmic reticulum that lacks ribosomes and functions in lipid synthesis, carbohydrate metabolism, calcium ion storage, and drug detoxification.

Rough Endoplasmic Reticulum

The portion of the ER studded with ribosomes on its outer surface, which synthesizes glycoproteins, secretes proteins, and acts as a membrane factory.

Golgi Apparatus

An organelle consisting of flattened membranous sacs (cisternae) that modifies, sorts, packages, and routes cellular products received from the ER.

Lysosome

A membrane-bound organelle containing hydrolytic enzymes used by animal cells to digest macromolecules and cellular debris.

Phagocytosis

A process by which a cell engulfs another cell or large particle, forming a food vacuole that fuses with a lysosome for digestion.

Autophagy

A lysosomal recycling process in which a cell degrades and recycles its own damaged organelles and organic macromolecules.

Contractile Vacuole

A membranous organelle present in many freshwater protists that pumps excess water out of the cell to maintain osmotic balance.

Central Vacuole

A large membranous sac in mature plant cells that stores water, organic compounds, and ions while supporting cell growth and structure.

Endosymbiotic Theory

The theory stating that mitochondria and chloroplasts originated as prokaryotic cells engulfed by an ancestral eukaryotic host cell.

Cristae

Infoldings of the inner mitochondrial membrane that expand its surface area for ATP-synthesizing enzymes.

Mitochondrial Matrix

The inner fluid-filled compartment of a mitochondrion containing enzymes, circular DNA, and ribosomes.

Thylakoids

Flattened, interconnected membranous sacs inside a chloroplast containing chlorophyll where light energy is captured during photosynthesis.

Stroma

The dense fluid within the chloroplast surrounding the thylakoid membranes, containing chloroplast DNA, ribosomes, and metabolic enzymes.

Peroxisome

A specialized oxidative organelle bounded by a single membrane that produces hydrogen peroxide ($\text{H}_2\text{O}_2$) and converts it to water.

Cytoskeleton

A network of fibers extending throughout the cytoplasm that organizes structures and activities, anchors organelles, and supports cell shape.

Microtubules

Hollow rods constructed from tubulin proteins that shape the cell, guide organelle transport, and separate chromosomes during cell division.

Centrosome

A region near the nucleus of animal cells that functions as the microtubule-organizing center and contains a pair of centrioles.

Dynein

A large motor protein attached to microtubule doublets in cilia and flagella that drives bending movements via ATP hydrolysis.

Microfilaments

Solid rods composed of twisted double chains of actin subunits that bear tension and facilitate cellular motility like amoeboid movement.

Intermediate Filaments

Cytoskeletal fibers intermediate in diameter between microfilaments and microtubules, composed of proteins such as keratin, that fix organelle positions and reinforce cell shape.

Cytoplasmic Streaming

A circular flow of cytoplasm within large plant cells driven by actin-myosin interactions that accelerates the distribution of materials.

Extracellular Matrix

A meshwork surrounding animal cells consisting of secreted glycoproteins (such as collagen, proteoglycans, and fibronectin).

Integrins

Cell-surface receptor proteins spanning the plasma membrane that connect the extracellular matrix to the cytoskeleton.

Plasmodesmata

Membrane-lined channels perforating plant cell walls that connect the cytoplasm of adjacent plant cells, allowing water and small solutes to pass freely.

Tight Junctions

Intercellular junctions in animal cells where neighboring plasma membranes are pressed tightly together by proteins to prevent extracellular fluid leakage.