Chapter 4 Keyterms

Vocabulary flashcards covering key concepts from the Biology of the Cell lecture notes.

Cytology

The study of cells.

Microscopy

Using a microscope to view small-scale structures; staining techniques provide contrast.

Light microscope (LM)

Produces a two-dimensional image by passing light through a specimen.

Electron microscope (EM)

Uses a beam of electrons to illuminate a specimen; greater magnification and resolution than LM.

Transmission Electron Microscope (TEM)

Directs electrons through thin-cut sections to produce 2-D images.

Scanning Electron Microscope (SEM)

Directs electrons across the surface to produce 3-D images.

Erythrocyte

Red blood cell; typically 7–8 μm in diameter.

Oocyte

Human egg cell; approximately 120 μm in diameter.

Plasma membrane

Forms the outer barrier of the cell and regulates movement; contains extensions like cilia, flagellum, and microvilli.

Nucleus

Largest cell structure; contains DNA and nucleolus; enclosed by the nuclear envelope.

Nucleolus

Dark-staining body inside the nucleus that produces ribosome subunits.

Nucleoplasm

Inner fluid of the nucleus.

Cytoplasm

Cellular contents between the plasma membrane and nucleus, including cytosol, organelles, and inclusions.

Cytosol

Intracellular fluid; high water content with dissolved macromolecules and ions.

Organelles

Membrane-bound or non-membrane-bound structures within cells; “little organs.”

Membrane-bound organelles

Organelles enclosed by a membrane (e.g., ER, Golgi, lysosomes, peroxisomes, mitochondria).

Non-membrane-bound organelles

Organelles not enclosed by a membrane (e.g., ribosomes, cytoskeleton, centrosome, proteasomes).

Inclusions

Molecules stored in the cytosol (not organelles), such as pigments, glycogen, triglycerides.

Phospholipid bilayer

Basic structure of the plasma membrane formed by two parallel sheets of phospholipids.

Phospholipids

Amphipathic molecules with a hydrophilic head and hydrophobic tails; form the bilayer.

Cholesterol (membrane)

Four-ring lipid that strengthens and stabilizes the membrane.

Glycolipids

Lipids with attached carbohydrate groups; located on the outer phospholipid region and help form glycocalyx.

Glycocalyx

Carbohydrate-rich coating on the cell surface formed by glycolipids and glycoproteins.

Integral proteins

Membrane proteins embedded in the bilayer and often spanning it; hydrophobic regions interact with the interior.

Peripheral proteins

Membrane proteins loosely attached to external or interior surfaces of the membrane.

Endoplasmic reticulum (ER)

Extensive interconnected membrane network; rough ER has ribosomes; smooth ER lacks ribosomes; site of protein and lipid synthesis.

Golgi apparatus

Stack of cisternae that modifies, packages, and sorts proteins; forms secretory vesicles.

Lysosomes

Small sacs with digestive enzymes; digest endocytosed material and participate in autophagy.

Peroxisomes

Vesicles containing enzymes; involved in lipid metabolism and detoxification.

Endomembrane system

Extensive network of membrane-bound structures (ER, Golgi, vesicles, lysosomes, peroxisomes, plasma membrane, nuclear envelope) that transports substances within cells.

Mitochondria

Double-membrane organelles; powerhouse of the cell; sites of ATP production via oxidative phosphorylation; cristae increase surface area.

Ribosomes

Ribonucleoprotein particles that synthesize proteins; bound ribosomes on the RER and free ribosomes in cytosol.

Centrosome

Pair of centrioles that organize microtubules and assist in cell division.

Centriole

Cylindrical structure within the centrosome; organizes microtubules.

Cytoskeleton

Network of protein filaments (microfilaments, intermediate filaments, microtubules) that provides support and enables movement.

Microfilaments

Actin filaments; maintain cell shape and support microvilli.

Microtubules

Largest cytoskeletal filaments; tubulin polymers; provide shape, intracellular transport, and chromosome movement during division.

Intermediate filaments

Ropelike filaments providing structural support and cell junction integrity.

Cilia

Hairlike projections that move substances along the cell surface; contain microtubules.

Flagella

Longer projections that propel the entire cell.

Microvilli

Extensions of the plasma membrane that increase surface area; supported by actin filaments.

Tight junctions

Protein strands linking cells to prevent passage of substances and maintain epithelial polarity.

Desmosomes

Protein plaques that bind neighboring cells for strong adhesion.

Hemidesmosomes

Anchoring junctions attaching the basal layer of epithelial cells to the underlying basement membrane.

Gap junctions

Connexon channels that form direct cytoplasmic connections between neighboring cells.

Mitosis

Cell division of somatic (non-sex) cells; includes prophase, metaphase, anaphase, and telophase.

Meiosis

Cell division that produces gametes (sperm or oocytes) with half the chromosome number.

Somatic cell division

One cell divides to produce two genetically identical daughter cells.

M phase

Mitotic phase; includes mitosis and cytokinesis, resulting in two new cells.