Biology Lecture Notes: Cell Structure and Function

A collection of vocabulary flashcards covering key terms and concepts related to cell structure, function, and processes.

Cell

The simplest collection of matter that can live.

Prokaryotic Cells

Cells that do not contain a nucleus or membrane-bound organelles, and have DNA concentrated in a nucleoid.

Eukaryotic Cells

Cells that contain a nucleus and membrane-bound organelles.

Nucleus

The membrane-bound organelle that contains most of the cell's genetic material.

Plasma Membrane

The boundary that separates the living cell from its surroundings, exhibiting selective permeability.

Endoplasmic Reticulum (ER)

An organelle involved in the synthesis of lipids and proteins; can be rough (with ribosomes) or smooth (without ribosomes).

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

Lysosome

A membranous sac of hydrolytic enzymes that can digest macromolecules.

Mitochondria

Organelles in eukaryotic cells that are the sites of cellular respiration, generating ATP.

Chloroplasts

Organelles found in plant cells and algae that are the sites of photosynthesis.

Cytoskeleton

A network of protein fibers extending throughout the cytoplasm, involved in maintaining cell shape and facilitating movement.

Microtubules

Hollow rods that are the thickest components of the cytoskeleton, involved in cell shape and organelle movement.

Microfilaments (Actin Filaments)

Solid rods that thicken the cytoskeleton and are involved in cellular movement and maintaining shape.

Intermediate Filaments

Fibrous proteins that support cell shape and anchor organelles.

ECM (Extracellular Matrix)

A complex of proteins and carbohydrates that provide structural support to cells in animal tissues.

Osmosis

The diffusion of water across a selectively permeable membrane.

Passive Transport

The movement of molecules across a cell membrane without the use of energy.

Active Transport

The movement of molecules against a concentration gradient, requiring energy.

Endocytosis

The process by which cells take in large molecules by forming vesicles.

Exocytosis

The process by which cells expel material in vesicles that fuse with the plasma membrane.

Phagocytosis

A form of endocytosis where the cell engulfs solid particles.

Pinocytosis

A form of endocytosis where the cell engulfs liquids and small molecules.

Receptor-mediated endocytosis

Endocytosis triggered by the binding of ligands to receptors on the cell surface.

Tight Junctions

Specialized connections between animal cells that prevent leakage of substances.

Gap Junctions

Channels that allow for communication between adjacent animal cells.

Desmosomes

Anchoring junctions that fasten cells together into strong sheets.

Prokaryotic cells

Cells without a nucleus, with DNA in a nucleoid region, and no membrane-bound organelles. They are characteristic of Bacteria and Archaea.

Eukaryotic cells

Cells with DNA enclosed within a nucleus (with a nuclear envelope) and containing membrane-bound organelles. Examples include protists, fungi, animals, and plants.

Resolution (Microscopy)

A key factor in image quality for microscopy, referring to the clarity of an image or the minimum distance two points can be separated and still be distinguished as separate points.

Surface area to volume (S:V) ratio

A critical ratio for cell exchange with the environment; smaller cells have a greater S:V ratio, which supports faster exchange of substances.

Phospholipid bilayer

The basic structure of a plasma membrane, consisting of two layers of phospholipid molecules where hydrophilic heads face outward and hydrophobic tails face inward.

Fluid mosaic model

The model describing the plasma membrane as a dynamic lipid bilayer with embedded and associated proteins, giving it a fluid-like quality.

Amphipathic

A characteristic of phospholipids, meaning they have both hydrophobic (water-fearing) and hydrophilic (water-loving) regions.

Nucleus

An organelle in eukaryotic cells that houses most of the cell's genes and is enclosed by a double-membrane nuclear envelope with pore complexes.

Endoplasmic Reticulum (ER)

A network of membranes in eukaryotic cells that can be rough (with ribosomes for protein synthesis) or smooth (for lipid synthesis, detoxification, and calcium storage).

Mitochondria

Organelles found in most eukaryotic cells, responsible for cellular respiration and ATP production; they have a double membrane with cristae and their own DNA.

Chloroplasts

Organelles found in plants and algae that are the sites of photosynthesis; they contain thylakoids, granum, and stroma, and have their own DNA.

Ribosomes

Cellular structures responsible for protein synthesis; they can be free in the cytosol or bound to the ER/nuclear envelope.

Cytoskeleton

A network of protein fibers within the cytoplasm that provides structural support, aids in cell movement, and transports vesicles and organelles.

Diffusion

The passive movement of substances down their concentration gradient, from an area of higher concentration to an area of lower concentration.

Osmosis

The diffusion of water across a selectively permeable membrane, moving from a region of higher water concentration to a region of lower water concentration.

Active transport

The movement of substances across a membrane against their concentration gradient, which requires energy (typically ATP) and specific transport proteins.

Denaturation

The loss of a protein's native three-dimensional structure due to changes in pH, salt concentration, or temperature, leading to a loss of biological activity.

Signal transduction

One of the six major functions of membrane proteins, involving the transmission of signals from outside the cell to the inside, often causing a cellular response.

Hydrolytic enzymes

Enzymes contained within lysosomes that are responsible for the digestion of macromolecules and cellular waste.

Plasmodesmata

Channels that perforate plant cell walls, allowing for direct cytoplasmic connections and transport between adjacent plant cells.