Chapter 4: A Tour of the Cell Flashcards

Vocabulary flashcards covering the key structures, organelles, and functions presented in Chapter 6: A Tour of the Cell.

Magnification

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

Resolution

A measure of the clarity of an image; it is the minimum distance two points can be separated and still be distinguished as two points.

Major Disadvantage of Electron Microscopy

The methods used to prepare the specimen kill the cells.

Scanning Electron Microscopy (SEM)

A microscopy technique that produces 3-D images of a specimen's surface.

Transmission Electron Microscopy (TEM)

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

Cell Fractionation

A process where whole cells are broken up in a blender and centrifuged several times to isolate smaller and smaller cell components for biochemical study.

Prokaryotic Domains

The two domains consisting of prokaryotic cells: Bacteria and Archaea.

Prokaryotic Cell Structure

A single-celled organism featuring a cell wall, plasma membrane, nucleoid containing DNA, ribosomes for protein synthesis, and flagella for locomotion.

Nucleoid

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

Cell Wall (Prokaryotic)

Rigid structure located outside the plasma membrane of prokaryotic cells.

Plasma Membrane

Membrane enclosing the cytoplasm that acts as a selective barrier regulating material exchange between a cell and its environment.

Flagella

Locomotion organelles present in some bacteria.

Surface Area-to-Volume Ratio Principle

As a cell increases in size, its volume grows proportionally more than its surface area; thus, smaller cells have a higher surface area-to-volume ratio facilitating material exchange.

Microvilli

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

Nuclear Envelope

A double membrane consisting of two lipid bilayers connected by nuclear pores 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 complex of DNA and protein that condenses to form distinct chromosomes when a cell prepares to divide.

Nucleoli

Structures visible in non-dividing nuclei where proteins imported from the cytoplasm are assembled with rRNA into ribosomal subunits.

Ribosomes

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

Free Ribosomes

Ribosomes suspended in the cytoplasm that synthesize proteins functioning within the cytosol.

Bound Ribosomes

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

Endomembrane System

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

Endoplasmic Reticulum Structure

A vast membranous network continuous with the nuclear envelope, composed of smooth ER, rough ER studded with ribosomes, an ER lumen, and budding vesicles.

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

Region of the ER lacking ribosomes that functions in lipid synthesis (oils, phospholipids, steroids), drug and poison detoxification, and calcium ion storage.

Rough ER

Region of the ER studded with ribosomes that acts as a membrane factory and processes secretory proteins (glycoproteins) packaged into transport vesicles.

Transport Vesicles

Membranous sacs that bud off from the transitional ER to transport proteins and membranes to the Golgi apparatus and other destinations.

Golgi Apparatus Structure

An organelle consisting of flattened membranous sacs (cisternae) with a receiving Cis face and a shipping Trans face for processing cell products.

Cis Face of Golgi

The receiving side of the Golgi apparatus located near the ER where transport vesicles fuse to deliver their contents.

Trans Face of Golgi

The shipping side of the Golgi apparatus where transport vesicles filled with modified products pinch off to head to specific cellular destinations.

Lysosome

A membranous sac of hydrolytic enzymes with an acidic interior used by animal cells to digest (hydrolyze) macromolecules.

Phagocytosis

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

Macrophages

A type of human white blood cell that defends the body by engulfing and destroying bacteria and invaders through phagocytosis.

Autophagy

A recycling process where a lysosome fuses with a double membrane enclosing damaged organelles or cytosol, dismantling the contents to return organic monomers to the cytosol.

Tay-Sachs Disease

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

Contractile Vacuoles

Vacuoles that pump excess water out of unicellular organisms to maintain a suitable concentration of ions and molecules.

Central Vacuole

A large organelle in plant cells storing cell sap (inorganic ions) that plays a major role in plant growth by absorbing water.

Endosymbiont Theory

Theory stating that eukaryotic cells originated when an early ancestor engulfed an oxygen-using nonphotosynthetic prokaryote (becoming mitochondria) and later a photosynthetic prokaryote (becoming chloroplasts).

Mitochondrion Structure

A double-membrane organelle containing an outer membrane, inner membrane folded into cristae, intermembrane space, matrix, ribosomes, and circular DNA.

Mitochondria Function

Sites of cellular respiration, using oxygen to generate ATP by extracting energy from sugars, fats, and other fuels.

Cristae

Infoldings of the inner mitochondrial membrane that expand its surface area to enhance the productivity of cellular respiration.

Chloroplast Structure

A plant organelle bounded by double membranes featuring three inner compartments: thylakoids, stacked grana, and fluid stroma.

Chloroplasts Function

Sites of photosynthesis that convert solar energy into chemical energy by absorbing sunlight to drive sugar synthesis from carbon dioxide and water.

Thylakoid

Flattened, interconnected membranous sacs inside a chloroplast that increase surface area for photosynthetic processes.

Stroma

The fluid contained within the inner membrane of a chloroplast, surrounding the thylakoids.

Granum

A stack of thylakoids located inside a chloroplast.

Peroxisomes

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

Cytoskeleton

A meshwork of protein fibers extending throughout the cytoplasm that maintains cell shape, provides mechanical support, and facilitates cell motility.

Three Types of Cytoskeletal Fibers

Microtubules, microfilaments, and intermediate filaments.