General Biology 1 - Week 2: Introduction to Cells and Organelles

Vocabulary flashcards covering key terms and definitions from the Week 2 biology notes on cells and organelles.

Cell Theory

Unifying foundation of cell biology: all organisms are made of cells, cells are the basic units of life, and cells arise from pre-existing cells.

Omni cellula e cellula

Latin motto meaning 'all cells come from cells'—new cells arise by division of existing cells.

Nucleus

Largest organelle in eukaryotic cells; acts as the information center housing DNA and often containing the nucleolus.

Nucleolus

Dark-staining region inside the nucleus where ribosomal RNA (rRNA) synthesis occurs.

Chromatin

DNA packaged with proteins in the nucleus; condenses into chromosomes during cell division.

Chromosome

X-shaped structure formed when chromatin condenses; visible during cell division.

Ribosome

Molecular machine for protein synthesis; composed of RNA and proteins; found in all cell types, free in cytoplasm or attached to ER.

Endomembrane system

Interconnected membranes within a cell (ER, Golgi, lysosomes, vesicles) that synthesize, modify, and transport proteins and lipids.

Rough Endoplasmic Reticulum (RER)

ER with ribosomes on the surface; site of synthesis of proteins destined for export, lysosomes, or plasma membrane.

Smooth Endoplasmic Reticulum (SER)

ER lacking ribosomes; synthesizes lipids and carbohydrates, detoxification, and Ca2+ storage.

Golgi apparatus

Flattened membrane-bound stacks that modify, sort, and package proteins and lipids for delivery inside or outside the cell.

Vesicle

Small membrane-bound sac used to transport proteins and other molecules between organelles or to the plasma membrane.

Lysosome

Membrane-bound digestive vesicle containing hydrolytic enzymes that break down macromolecules and old organelles.

Peroxisome

Organelle with enzymes for fatty acid oxidation and detoxification, including breakdown of hydrogen peroxide.

Mitochondrion

ATP-generating organelle with two membranes; contains cristae, a matrix, and an intermembrane space.

Cristae

Folded inner membrane of mitochondria that increases surface area for cellular respiration.

Matrix

Interior space of the mitochondrion inside the inner membrane where the Krebs cycle occurs.

Intermembrane Space

Region between the inner and outer mitochondrial membranes.

Chloroplast

Photosynthetic organelle in plants and algae; contains chlorophyll and its own DNA, two membranes, grana, thylakoids, and stroma.

Grana

Stacks of thylakoids inside chloroplasts where light-dependent reactions occur.

Thylakoid

Disk-shaped membrane-bound sacs within chloroplasts that house pigments and electron transport chains.

Stroma

Fluid surrounding the grana in chloroplasts; site of the Calvin cycle.

Plastids

Family of related organelles including chloroplasts, leucoplasts, and amyloplasts, involved in storage and photosynthesis.

Leucoplast

Colorless plastid; includes amyloplasts for starch storage.

Amyloplast

Leucoplast that stores starch (amylose) in plant cells.

Plasmodesmata

cytoplasmic channels through plant cell walls linking neighboring cells for transport and communication.

Cell wall (plants, fungi, many protists)

Rigid layer outside the plasma membrane; provides protection and support; mainly cellulose in plants.

Primary cell wall

Initial flexible cell wall formed during growth.

Secondary cell wall

Rigid layer deposited inside the primary wall in some cells for extra support; often lignified.

Middle lamella

Sticky layer between adjacent plant cell walls that glues cells together.

Plasma membrane

Phospholipid bilayer that encloses the cell; controls transport and cell signaling; fluid mosaic model.

Microvilli

Finger-like projections increasing surface area for absorption.

Cytoskeleton

Network of protein filaments (actin filaments, microtubules, intermediate filaments) that gives shape, support, and movement.

Actin filament (microfilament)

Thin, 7 nm fibers built from actin; involved in cell movement and shape change.

Microtubule

Hollow tubes (~25 nm) made of tubulin; provide structural support and tracks for vesicle movement during transport and cell division.

Intermediate filament

Durable cytoskeletal fibers providing mechanical strength.

Centrosome

Microtubule-organizing center in many eukaryotic cells; often associated with the pair of centrioles in animal cells.

Centrioles

Barrel-shaped structures near the nucleus; usually in pairs; organize spindle fibers during cell division.

Microtubule-organizing center (MTOC)

Region that organizes microtubule assembly; includes the centrosome in many animal cells.

Flagellum

Long, whip-like structure used for cell movement; powered by dynein; occurs in some cells and bacteria.

Cilium

Short, hair-like projection used for movement or sensing; often numerous on cell surfaces.

Tonoplast

Membrane surrounding the central vacuole in plant cells, involved in osmoregulation and transport.

Central vacuole

Large storage organelle in plant cells that maintains turgor and stores water and other substances.

Mitochondria generate ATP

Primary energy-producing organelles; convert chemical energy from nutrients into ATP.

Nuclear envelope

Double membrane surrounding the nucleus; contains nuclear pores for transport.

Nuclear pore

Protein-lined channels in the nuclear envelope that regulate transport between nucleus and cytoplasm.

Nucleolus function

Site of intensive ribosomal RNA (rRNA) synthesis within the nucleus.