Cell: The Unit of Life - Vocabulary Flashcards

Vocabulary flashcards covering key concepts and terms related to cell structure and function from the notes.

Cell

The basic structural and functional unit of all living organisms; can be unicellular or multicellular.

Unicellular organism

An organism composed of a single cell that performs all life processes independently.

Multicellular organism

An organism made up of many cells with division of labour and specialization.

Cell theory

The idea that all living organisms are made of cells and that all cells arise from pre-existing cells.

Prokaryotic cell

A cell lacking a membrane-bound nucleus and other membrane-bound organelles; typically smaller and having naked DNA.

Eukaryotic cell

A cell with a true nucleus and membrane-bound organelles; more complex than prokaryotic cells.

Plasma membrane

The phospholipid bilayer enclosing the cell, with embedded proteins and cholesterol; selectively permeable.

Cell wall

Rigid outer layer in plants, fungi, and some bacteria; provides shape and protection.

Cytoplasm

Semi-fluid interior of the cell where metabolism occurs; contains cytosol and organelles.

Nucleus

Membrane-bound organelle containing genetic material (DNA) and nucleolus; controls cellular activities.

Chromatin

DNA-protein complex in the nucleus that condenses into chromosomes during cell division.

Nucleolus

Dense region within the nucleus where ribosomal RNA synthesis occurs.

Nuclear envelope

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

Nuclear pore

Openings in the nuclear envelope that regulate exchange of RNA and proteins between nucleus and cytoplasm.

Ribosome

Non-membrane-bound particle that synthesizes proteins; 70S in prokaryotes, 80S in eukaryotes.

Endoplasmic reticulum

Network of membranous tubules and sacs; site of protein and lipid synthesis; connected to the nuclear envelope.

Rough endoplasmic reticulum

ER with ribosomes on its surface; synthesizes and processes proteins.

Smooth endoplasmic reticulum

ER lacking ribosomes; site of lipid synthesis and detoxification processes.

Golgi apparatus

Stacked sacs that modify, package, and ship proteins and lipids; cis face receives from ER, trans face ships.

Lysosome

Membrane-bound vesicles with hydrolytic enzymes for digestion of macromolecules.

Vacuole

Membrane-bound storage organelle; large in plant cells; tonoplast surrounds; involved in osmoregulation and storage.

Mitochondrion

Double-membrane-bound organelle producing ATP; contains cristae and matrix; has own DNA and ribosomes.

Crista

Infoldings of the inner mitochondrial membrane that increase surface area for respiration.

Matrix

Inner mitochondrial compartment containing enzymes for respiration and mitochondrial DNA.

Plastid

Pigment-containing organelles in plant cells; include chloroplasts, chromoplasts, and leucoplasts.

Chloroplast

Plastid containing chlorophyll; site of photosynthesis; contains thylakoids, grana, and stroma.

Grana

Stacks of thylakoids within chloroplasts.

Thylakoid

Flattened membrane-bound sacs where light-dependent reactions of photosynthesis occur.

Stroma

Fluid surrounding thylakoids in chloroplasts; contains enzymes for carbon fixation.

Chlorophyll

Green pigment in chloroplasts that captures light energy for photosynthesis.

Ribosome subunits

The two subunits of ribosomes: 70S (50S+30S) in prokaryotes and 80S (60S+40S) in eukaryotes.

Cytoskeleton

Elaborate network of protein filaments (microtubules, microfilaments, intermediate filaments) that give shape and aid movement.

Microtubule

Cylindrical protein structures that support the cell and form the mitotic spindle and cilia/flagella.

Microfilament

Thin actin filaments involved in cell movement and shape changes.

Intermediate filament

Cytoskeletal filaments providing mechanical support and resilience.

Cilia

Short hair-like projections on the cell surface that move fluids or the cell; many have a 9+2 axoneme structure.

Flagellum

Long projection enabling cell movement; structurally different in prokaryotes and eukaryotes.

Basal body

Structure at the base of cilia/flagella formed from centrioles that nucleates their growth.

Centrosome

Organelles usually containing two centrioles; organizes spindle apparatus for cell division and helps form basal bodies.

Centriole

Nine triplets of microtubules forming part of the centrosome; critical for spindle formation and cilia/flagella basal bodies.

Nucleoplasm

Material inside the nucleus excluding the nucleolus; contains chromatin and nuclear matrix.

Kinetochore

Protein structure at the centromere where spindle fibers attach during chromosome separation.

Centromere

Constriction point on a chromosome; position determines chromosome type (metacentric, sub-metacentric, acrocentric, telocentric).

Satellite

Small, non-staining chromosome segment or secondary constriction at a constant location.

Endomembrane system

Interconnected membranes (ER, Golgi, lysosomes, vacuoles) coordinating synthesis, trafficking, and processing of cellular materials.

Mesosome

Infoldings of the prokaryotic plasma membrane; associated with respiration, secretion, and DNA distribution.

Plasmid

Small circular DNA molecule in bacteria; carries accessory genes and can confer antibiotic resistance.

Pili

Hair-like surface appendages on bacteria that aid in attachment and conjugation.

Fimbriae

Fine hair-like structures on bacteria that help attachment to surfaces.

Glycocalyx

Outer layer of polysaccharides around some bacteria; can be a slime layer or capsule; aids in protection and adhesion.

Inclusion bodies

Membrane-free storage granules in prokaryotes for nutrients like phosphate and glycogen.