Chapter 6: A Tour of the Cell - Vocabulary

A complete set of vocabulary flashcards based on Chapter 6: A Tour of the Cell lecture notes.

Magnification

The ratio of an object's image size to its real size.

Resolution

A measure of the clarity of an image, defined as the minimum distance two points can be separated and still be distinguished as two points.

Cell Fractionation

A procedure where whole cells are broken up in a blender and centrifuged repeatedly to isolate specific organelles by size for biochemical study.

Nucleoid

A region in a prokaryotic cell that is not enclosed by a membrane, where the cell's DNA is concentrated.

Microvilli

Long, thin projections from the cell surface that increase surface area without an appreciable increase in cell volume.

Nuclear Envelope

A double membrane consisting of two lipid bilayers that encloses the nucleus, separating its contents from the cytoplasm.

Nuclear Lamina

A netlike array of protein filaments that mechanically supports the nuclear envelope to maintain the shape of the nucleus.

Nuclear Matrix

A framework of protein fibers extending throughout the interior of the nucleus that helps organize genetic material.

Chromatin

The complex of DNA and proteins within the nucleus that condenses to form distinct chromosomes when a cell prepares to divide.

Nucleoli

Structures visible within a nondividing nucleus where imported proteins are assembled with rRNA into large and small ribosomal subunits.

Ribosomes

Cellular complexes composed of a large subunit and a small subunit that carry out protein synthesis.

Free Ribosomes

Ribosomes suspended in the cytosol that primarily produce proteins functioning within the cytosol.

Bound Ribosomes

Ribosomes attached to the outside of the endoplasmic reticulum or nuclear envelope that synthesize proteins destined for insertion into membranes, packaging within organelles, or secretion.

Endomembrane System

A network of cellular membranes that includes the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, vacuoles, and plasma membrane.

ER Lumen

The cavity or cisternal space inside the endoplasmic reticulum membrane, continuous with the space between the two nuclear envelope membranes.

Smooth ER

The region of the endoplasmic reticulum lacking surface ribosomes, involved in lipid synthesis, drug and poison detoxification, and calcium ion storage.

Rough ER

The region of the endoplasmic reticulum studded with ribosomes on its outer surface that functions as a membrane factory and processes secretory proteins.

Glycoproteins

Proteins that have carbohydrates covalently attached to them in the endoplasmic reticulum.

Golgi Apparatus

An organelle consisting of flattened membranous sacs (cisternae) where transport vesicles fuse at the cis face, contents are modified, and vesicles filled with products bud from the trans face.

Lysosome

A membranous sac of hydrolytic enzymes with an acidic internal pH that animal cells use to digest macromolecules.

Phagocytosis

A process of intracellular digestion where a cell engulfs smaller organisms or food particles to form a food vacuole that fuses with a lysosome.

Autophagy

A process where lysosomes fuse with a double membrane enclosing a damaged organelle or cytosol to dismantle the material and recycle organic monomers.

Tay-Sachs Disease

A genetic disorder in which a lipid-digesting hydrolytic enzyme in lysosomes is missing or inactive, causing lipid accumulation and brain impairment.

Contractile Vacuoles

Organelles that pump excess water out of certain freshwater cells to maintain a suitable concentration of ions and molecules.

Central Vacuole

A large plant cell organelle holding cell sap (inorganic ions) that plays a major role in plant growth through water absorption.

Endosymbiont Theory

The evolutionary model stating that an early ancestor of eukaryotic cells engulfed an oxygen-using nonphotosynthetic prokaryote, which eventually merged into a single eukaryotic organism containing a mitochondrion.

Mitochondria

Double-membrane cellular respiration sites that convert oxygen and fuels like sugars and fats into ATP.

Chloroplasts

Three-compartment photosynthetic organelles that absorb sunlight to drive the synthesis of organic compounds from carbon dioxide and water.

Cristae

Infoldings of the inner mitochondrial membrane that increase surface area and enhance the productivity of cellular respiration.

Peroxisomes

Specialized metabolic compartments with enzymes that remove hydrogen atoms from substrates and transfer them to oxygen, producing toxic hydrogen peroxide ($H_2O_2$) as a sequestered by-product.

Magnification

The ratio of an object's image size to its real size.

Resolution

A measure of the clarity of an image, defined as the minimum distance two points can be separated and still be distinguished as two points.

Scanning Electron Microscopy (SEM)

A type of microscopy that results in images displaying the 3-D components of a specimen.

Transmission Electron Microscopy (TEM)

A type of microscopy that profiles a thin section of a specimen, resulting in various views of internal cell structures.

Cell Fractionation

A procedure where whole cells are broken up in a blender and centrifuged several times to isolate organelles; ribosomes are the smallest components isolated by this procedure.

Nucleoid

The non-membrane-enclosed region in a prokaryotic cell where its DNA is concentrated.

Microvilli

Long, thin projections from the cell surface that increase surface area without an appreciable increase in volume.

Surface Area-to-Volume Ratio

A critical physical relationship where as a cell increases in size, its surface area grows proportionately less than its volume, requiring cells to remain small to facilitate material exchange.

Nuclear Envelope

A double membrane consisting of two lipid bilayers that encloses the nucleus, separating its contents from the cytoplasm.

Nuclear Lamina

A netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope.

Nuclear Matrix

A framework of protein fibers extending throughout the nuclear interior that helps organize genetic material.

Chromatin

The material composed of proteins and DNA that makes up eukaryotic chromosomes and condenses to form distinct chromosomes as a cell prepares to divide.

Nucleoli

Structures visible in a nondividing nucleus where proteins imported from the cytoplasm are assembled with rRNA into large and small ribosome subunits.

Ribosomes

Cellular complexes composed of a large subunit and a small subunit that carry out protein synthesis.

Free Ribosomes

Ribosomes suspended in the cytosol that synthesize proteins that function within the cytosol.

Bound Ribosomes

Ribosomes attached to the outside of the endoplasmic reticulum or nuclear envelope that produce proteins for membrane insertion, organelle packaging, or secretion.

Endomembrane System

The collection of cellular membranes including the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, vacuoles, and plasma membrane.

ER Lumen

The internal cavity or cisternal space of the endoplasmic reticulum, continuous with the space between the two membranes of the nuclear envelope.

Smooth ER

The portion of the endoplasmic reticulum lacking ribosomes on its outer surface, responsible for lipid synthesis, drug detoxification, and calcium ion storage.

Rough ER

The portion of the endoplasmic reticulum studded with ribosomes that acts as a membrane factory and processes secretory proteins.

Transitional ER

A specialized region of the rough ER from which transport vesicles wrapped in membranes bud off.

Glycoproteins

Secretory proteins formed in the rough ER that have carbohydrates attached to them.

Cis Face of the Golgi

The receiving side of the Golgi apparatus where transport vesicles from the endoplasmic reticulum fuse and add their contents.

Trans Face of the Golgi

The shipping side of the Golgi apparatus from which vesicles filled with modified products bud off.

Lysosome

A membranous sac of hydrolytic enzymes with an acidic internal pH used by animal cells to digest macromolecules.

Phagocytosis

A process of cellular eating where a cell engulfs smaller organisms or food particles to form a food vacuole that fuses with a lysosome for digestion.

Macrophages

A type of human white blood cell that uses phagocytosis to engulf and destroy bacteria and other invaders.

Autophagy

A lysosomal recycling process where damaged organelles or cytosol are enclosed in a double membrane and dismantled by hydrolytic enzymes.

Tay-Sachs Disease

A genetic disorder caused by a missing or inactive lipid-digesting hydrolytic enzyme in lysosomes, resulting in an accumulation of lipids in brain cells.

Contractile Vacuoles

Specialized vacuoles that pump excess water out of the cell to maintain suitable concentrations of ions and molecules inside.

Central Vacuole

A large vacuole in mature plant cells formed by the coalescence of smaller vacuoles that aids cell growth by absorbing water.

Cell Sap

The solution stored inside the central vacuole of a plant cell that serves as the main repository of inorganic ions, including potassium and chloride.

Endosymbiont Theory

The theory stating that an early ancestor of eukaryotic cells engulfed an oxygen-using nonphotosynthetic prokaryote, eventually merging into a single organism containing mitochondria.

Mitochondria

The cellular sites of respiration that use oxygen to generate ATP by extracting energy from sugars, fats, and other fuels.

Chloroplasts

Photosynthetic organelles that convert solar energy to chemical energy by absorbing sunlight to drive the synthesis of organic compounds.

Cristae

Infoldings of the inner mitochondrial membrane that give it a large surface area to enhance the productivity of cellular respiration.

Peroxisomes

Metabolic compartments containing enzymes that remove hydrogen atoms from substrates and transfer them to oxygen, producing hydrogen peroxide ($H_2O_2$) as a by-product.