Cells

what are cells?

The fundamental building block of all living organisms

what is cell theory?

all living things are made of cells, the cell is the basic unit of life, and all cells arise from pre-existing cells

what is a cell membrane?

the flexible barrier surrounding all cells that separates their internal contents from the outside environment

what is the nucleus?

the membrane-bound "control center" of a eukaryotic cell, housing the cell's genetic material (DNA)

what are Eukaryotic cells?

complex cells characterized by a true, membrane-bound nucleus that houses their DNA, and various other membrane-enclosed organelles (like mitochondria, ER, Golgi) that perform specialized functions

what are prokaryotic cells?

simple, single-celled organisms (like bacteria and archaea) that lack a membrane-bound nucleus and other internal organelles

what is cytoplasm in a cell?

the jelly-like substance filling a cell, enclosing organelles and other components, consisting mainly of water, salts, and organic molecules

what is organelles in a cell?

specialized, membrane-bound structures within a cell (like the nucleus, mitochondria, ER, Golgi) that perform specific jobs, much like organs in a body, to keep the cell functioning, producing energy, synthesizing proteins, and managing waste

what is ribosomes in a cell?

a tiny cellular machine, found in all living cells, that builds proteins by translating messenger RNA (mRNA) into chains of amino acids, acting as the cell's protein factories essential for structure, function, and survival

what is endoplasmic reticulum in a cell?

a vast network of membranes in eukaryotic cells, acting as a cellular factory for making proteins and lipids, and serving as a transport system

what is golgi apparatus in a cell?

a vital organelle in eukaryotic cells, acting like a cellular post office(modifies and sorts)

what is vacuole in a cell?

a membrane-bound sac inside a cell that acts as a storage, waste disposal, and internal transport system, holding water, nutrients, and waste

what is lysosome in a cell?

a membrane-bound organelle in animal cells, acting as the cell's "recycling center" by using powerful digestive enzymes to break down waste, cellular debris, foreign invaders (like bacteria), and old cell parts, essentially cleaning house and providing nutrients for the cell

what is cytoskeleton in a cell?

a dynamic network of protein filaments (microfilaments, microtubules, intermediate filaments) within a cell that provides structural support, maintains cell shape, enables movement (of the cell and organelles), and helps with intracellular transport, acting like a cellular skeleton and highway system

what is chloroplast in a cell?

a vital organelle in plant and algal cells, acting as the site for photosynthesis, where it converts sunlight, water, and carbon dioxide into glucose (food) and oxygen, using chlorophyll pigments

what is mitochondria in a cell?

essential organelles in eukaryotic cells, often called the "powerhouses" because they generate most of the cell's energy (ATP) through cellular respiration, converting food into usable energy

what is cell wall in a cell?

a rigid outer layer in plants, fungi, bacteria, and algae that provides structural support, protection, and maintains cell shape

what is lipid bilayer in a cell?

the fundamental double layer of fats (phospholipids) forming the cell membrane

what is selective permeability?

the cell membrane's crucial ability to control what enters and exits the cell

what is homeostasis in biology?

the essential ability of living organisms to maintain a stable, relatively constant internal environment

what is diffusion in biology

the passive movement of molecules from an area of higher concentration to an area of lower concentration, driven by the random motion of particles (kinetic energy), until equilibrium is reached, essential for gas exchange (like oxygen/CO2) and nutrient/waste transport in and out of cells

what is facilitated diffusion in biology?

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a type of passive transport where molecules move down their concentration gradient (high to low) across a cell membrane with the help of specific membrane proteins, like channel or carrier proteins, without requiring cellular energy (ATP)

what is aquaporin in biology?

integral membrane proteins forming water channels that allow rapid, selective transport of water (and sometimes small solutes like glycerol, urea) across cell membranes

what is osmosis in biology?

the passive movement of water molecules across a semipermeable membrane from an area of higher water concentration (lower solute) to an area of lower water concentration (higher solute) to equalize solute concentrations

what is isotonic in biology?

has the same solute concentration (like salt or sugar) as another solution, typically the inside of a cell, meaning there's no net movement of water across the cell membrane, keeping the cell's shape and function stable

what is hypertonic in biology?

a solution with a higher solute concentration (and thus lower water concentration) compared to another solution, typically a cell

what is hypotonic in biology?

has a lower solute concentration (and thus higher water concentration) than another solution, usually the inside of a cell, causing water to move into the cell via osmosis, making the cell swell

what is osmotic pressure in biology?

the minimum pressure required to stop the net movement of water across a semipermeable membrane from a region of low solute concentration to a region of high solute concentration