Cell Structure and Organelles (Membranous and Nonmembranous)

Vocabulary flashcards covering membranous and nonmembranous organelles, cytoskeletal components, and related cellular concepts from the lecture notes.

Nucleus

Double-membrane bound organelle that houses the cell’s genetic material; DNA is in the form of chromatin most of the time and the nucleolus is within this structure.

Chromatin

Uncoiled DNA and protein complex inside the nucleus when the cell is not dividing.

Chromosome

Condensed DNA structure visible during cell division.

Nucleolus

Smallest distinct structure visible under light microscopy; ribosome production occurs here.

Ribosome

Molecular machines that synthesize proteins; can be free-floating or attached to rough ER; produced in the nucleolus.

Mitochondrion

Powerhouse of the cell; site of ATP production; contains cristae, a matrix, and its own DNA.

Cristae

Folded inner mitochondrial membranes that increase surface area for respiration.

Matrix

Fluid-filled interior of the mitochondrion where enzymes and substrates participate in ATP production.

Mitochondrial DNA

Genetic material inside mitochondria used in evolutionary studies.

ATP

Adenosine triphosphate; cellular energy currency produced during respiration.

Endoplasmic Reticulum

Network of membranes forming fluid-filled chambers involved in synthesis and transport of cellular products.

Rough Endoplasmic Reticulum

ER studded with ribosomes; site of protein synthesis.

Smooth Endoplasmic Reticulum

ER lacking ribosomes; synthesizes lipids such as phospholipids and cholesterol; involved in steroid hormone production.

Golgi Apparatus

Modification, sorting, and packaging center; sends products to vesicles for delivery.

Vesicles

Small membrane-bound sacs that transport materials; can become lysosomes, fuse with the plasma membrane, or become secretory vesicles.

Lysosome

Membranous sac containing digestive enzymes that break down old/damaged organelles and pathogens; involved in autolysis.

Autolysis

Programmed cell death where a cell digests itself during development or remodeling.

Peroxisome

Membranous sacs with oxidase enzymes that detoxify harmful substances and break down hydrogen peroxide into water and oxygen.

Hydrogen peroxide

Reactive oxygen species detoxified by peroxisomes; byproduct that is converted to water and oxygen.

Cytoskeleton

Dynamic framework of the cell composed of microfilaments, intermediate filaments, and microtubules that supports shape and movement.

Microfilaments

Smallest cytoskeletal filaments (actin) located under the plasma membrane; support shape and enable movement.

Intermediate Filaments

Cytoskeletal filaments with high tensile strength that resist pulling forces.

Microtubules

Hollow tubules that anchor and move organelles and form the mitotic spindle during cell division.

Centrosome

Center of the cell that organizes microtubules; contains centrioles in many cells.

Centriole

Cylindrical microtubule structures within the centrosome that organize spindle formation.

Mitotic spindle

Microtubule-based apparatus that separates chromosomes during cell division.

Microvilli

Finger-like extensions of the plasma membrane that increase surface area for absorption; non-motile.

Cilia

Hair-like projections that move substances across the cell surface via beating; examples include mucus clearance and egg transport in Fallopian tubes.

Flagellum

Long whip-like projection that enables sperm motility.

Endocytosis

Process of taking substances into the cell by invagination of the plasma membrane to form vesicles.

Exocytosis

Vesicles fuse with the plasma membrane to release contents outside the cell.

Phagocytosis

Cellular eating process where large particles are engulfed and digested by lysosomes; example: amoeba digesting prey.

Steroid hormones

Lipid-derived hormones formed from cholesterol; produced mainly in gonads via smooth ER; examples include testosterone and estrogen.

Cholesterol

Lipid that helps maintain membrane fluidity and serves as a precursor for steroid hormones.

Phospholipids

Amphipathic lipids that form the plasma membrane bilayer and contribute to fluidity.

Plasma membrane

Phospholipid bilayer surrounding the cell; regulates movement of substances in and out; supports features like microvilli.

Surface area to volume ratio

Ratio affecting nutrient/waste exchange and heat transfer; limits cell size and influences absorption efficiency.

Absorption

Process by which substances cross membranes into cells, enhanced by microvilli.

Nucleus

Stores genetic information, primarily as chromatin; chromosomes visible during cell division.

Nucleolus

The smallest observable structure under light microscopy; site of ribosome production.

Mitochondria

The 'powerhouses of the cell'; site of ATP production from sugars via respiration, consuming O extrm{2} and producing CO extsubscript{2}.

Rough ER

A network of membranes forming fluid-filled chambers for intracellular transport; studded with ribosomes, synthesizes proteins.

Smooth ER

A network of membranes that lacks ribosomes; synthesizes lipids (phospholipids, cholesterol) and other lipids; site for lipid-based membrane maintenance and steroid hormone synthesis.

Golgi apparatus

The 'cell’s post office'; receives vesicles from ER, sorts and packages them into vesicles for various fates (lysosomes, cell membrane fusion, secretory vesicles).

Lysosomes

Membranous sacs with digestive enzymes; digest old/damaged organelles and pathogens; can cause autolysis (programmed cell death).

Peroxisomes

Organelles containing oxidase enzymes that detoxify harmful substances (e.g., alcohol, formaldehyde, free radicals) and break down hydrogen peroxide to water and oxygen.

Cytoskeleton

A network of protein filaments that provides support and enables movement; composed of microfilaments, intermediate filaments, and microtubules.

Microfilaments

The smallest cytoskeleton filaments, located just under the plasma membrane; maintain cell shape and surface integrity.

Intermediate filaments

Cytoskeleton filaments with high tensile strength that resist pulling forces.

Microtubules

Hollow tubes of the cytoskeleton that anchor and position organelles, act as tracks for movement, and form the mitotic spindle during cell division.

Centrosome

A central body near the cell’s center containing two centrioles; functions as the microtubule organizing center and is essential for mitotic spindle formation.

Microvilli

Finger-like extensions of the plasma membrane that dramatically increase surface area to enhance absorption, found in cells like intestinal cells.

Cilia

Motile extensions built from microtubules that move substances along the cell surface (e.g., mucus in airways, movement of eggs in fallopian tubes).

Flagella

Long extensions used for cellular locomotion, such as a sperm tail.

ATP

The cellular energy currency produced in the mitochondria.