Chapter 6: A Tour of the Cell Flashcards

A complete set of vocabulary flashcards covering cellular structure, organelle functions, microscopy types, energy transformation, cytoskeleton components, and intercellular junctions from Chapter 6.

Light microscope (LM)

An optical instrument where visible light passes through a specimen and glass lenses to magnify the image, with a minimum resolution of about $200\,nm$ and effective magnification up to about $1,000$ times.

Scanning electron microscope (SEM)

A microscope that focuses a beam of electrons onto the surface of a specimen, providing images that look 3D.

Transmission electron microscope (TEM)

A microscope that focuses a beam of electrons through a specimen, used mainly to study the internal ultrastructure of cells.

Cell fractionation

A technique using ultracentrifuges to take cells apart and separate major organelles from one another to determine their functions.

Cytosol

The semifluid substance within cells in which subcellular components are suspended.

Nucleoid

The unbound region in a prokaryotic cell where its DNA is located.

Plasma membrane

A selective barrier composed of a double layer of phospholipids that allows sufficient passage of oxygen, nutrients, and waste to service the cell volume.

Nuclear envelope

A membranous structure enclosing the nucleus that separates its contents from the cytoplasm.

Ribosomes

Cellular particles made of ribosomal RNA (rRNA) and protein that carry out protein synthesis in the cytosol or on the outside of the endoplasmic reticulum or nuclear envelope.

Smooth ER

A region of the endoplasmic reticulum that lacks ribosomes and functions in lipid synthesis, carbohydrate metabolism, calcium storage, and poison detoxification.

Rough ER

A region of the endoplasmic reticulum studded with ribosomes that produces proteins and membranes distributed by transport vesicles.

Golgi apparatus

An organelle consisting of flattened membranous sacs called cisternae that modifies ER products, manufactures certain macromolecules, and sorts and packages materials into transport vesicles.

Cis face

The receiving side of the Golgi apparatus located near the ER where transport vesicles coalesce.

Trans face

The shipping side of the Golgi apparatus where transport vesicles form and pinches off to deliver contents to other locations.

Lysosome

A membranous sac of hydrolytic enzymes used by animal cells to digest macromolecules and recycle cellular components through autophagy.

Phagocytosis

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

Autophagy

A lysosomal recycling process in which enzymes break down damaged organelles and macromolecules to reuse their components.

Contractile vacuole

A membrane-bound sac found in many freshwater protists that pumps excess water out of the cell.

Central vacuole

A large membrane-bound organelle found in mature plant cells that holds organic compounds and water.

Cristae

Infoldings of the inner membrane of a mitochondrion that present a large surface area for enzymes that synthesize ATP.

Mitochondrial matrix

The compartment enclosed by the inner membrane of a mitochondrion containing metabolic enzymes, mitochondrial DNA, and free ribosomes.

Chloroplast

A member of the plastid family of plant and algal organelles that contains chlorophyll, thylakoids, and stroma to carry out photosynthesis.

Peroxisome

A single membrane-bounded metabolic organelle containing catalase to convert toxic hydrogen peroxide ($H_2O_2$) into water ($H_2O$).

Cytoskeleton

A network of molecular fibers extending throughout the cytoplasm that maintains cell shape, anchors organelles, and drives cellular motility.

Microtubules

Hollow rods about $25\,nm$ in diameter and $200\,nm$ to $25\,\mu m$ long made of protein that shape the cell, guide organelle movement, and separate chromosomes during cell division.

Dynein

A motor protein attached to outer microtubule doublets that drives the bending movements of cilia and flagella.

Microfilaments

Solid rods about $7\,nm$ in diameter built as a twisted double chain of actin subunits that function to bear tension and assist in cellular motility.

Pseudopodia

Cellular extensions ("false feet") driven by the assembly and contraction of actin filaments that enable amoeboid movement.

Cytoplasmic streaming

A circular flow of cytoplasm within cells, driven by actin-myosin interactions in plant cells, that speeds the distribution of materials.

Intermediate filaments

Cytoskeletal fibers ranging from $8\text{ to }12\,nm$ in diameter that reinforce cell shape and fix organelles in place as permanent cell fixtures.

Plasmodesmata

Channels perforating plant cell walls that allow water, small solutes, proteins, and RNA to pass between adjacent cells.

Extracellular matrix (ECM)

An elaborate meshwork of glycoproteins and macromolecules surrounding animal cells that provides support, adhesion, movement, and regulation.

Tight junctions

Intercellular junctions in animal tissues where neighboring cell membranes are pressed tightly together to prevent leakage of extracellular fluid.

Desmosomes

Anchoring junctions in animal cells that fasten cells together into strong sheets.

Gap junctions

Communicating junctions in animal cells that provide cytoplasmic channels between adjacent cells.