Cell Structure and Function Practice Flashcards

Vocabulary-style flashcards covering cell theory, prokaryotic and eukaryotic structures, membrane dynamics, transport mechanisms, and organelle functions based on lecture notes.

Cell Theory

A biological theory stating that the cell is the smallest structural and functional unit of life, every living organism is made of one or more cells, and cells only come from pre-existing cells.

Characteristics of Life

A set of standards including being composed of cells, reproduction, growth and development, genetic code, energy requirement, organization, environmental response/adaptation, and homeostasis.

Prokaryotes

Independent, single-celled organisms such as bacteria and archaea that lack a membrane-bound nucleus.

Haloarcula

A genus of bacteria known for its rectangular cell shape.

Atrichous

A term describing a cell without any flagellar projections.

Peritrichous

A flagellar arrangement where flagella are attached over the entire cell surface.

Amphitrichous

A flagellar arrangement with one flagellum at each pole of the cell.

Fimbrae

Numerous short appendages that allow cells to adhere to surfaces.

Pili

Longer appendages (one or two per cell) used for motility and the transfer of DNA during conjugation.

Peptidoglycan

The substance from which bacterial cell walls are made, providing shape and preventing rupture.

Glycocalyx

A viscous coating for the cell wall composed of polysaccharides, polypeptides, or both, forming a capsule when firmly attached.

Archaeal Cell

Independent single-celled organisms that may lack peptidoglycan in their cell walls and are often found in extreme environments like thermal vents (thermophiles).

Eukaryotes

Organisms with cells containing a membrane-bound nucleus and specialized structures called organelles.

Pseudostratified

A cell arrangement consisting of a single layer of cells that appears like it is composed of several layers.

Fluid-mosaic model

A model of cell membrane structure proposed in 1972 by S. Jonathan Singer and Garth Nicolson, describing a dynamic bilayer of proteins and phospholipids.

Phospholipids

Molecules constituting $75\%$ of membrane lipids, featuring a hydrophilic glycerol/phosphate head and two hydrophobic fatty acid tails.

Integral proteins

Membrane proteins that pass all the way through the cell membrane; many are glycoproteins contributing to the glycocalyx.

Simple Diffusion

Passive transport involving the movement of solute molecules from a higher concentration gradient to a lower concentration gradient (e.g., $O_2$ or $CO_2$).

Facilitated Diffusion

A type of passive transport where a transport protein temporarily binds with lipid-insoluble molecules, such as glucose, to move them across the membrane.

Osmosis

The movement of water molecules through a semi-permeable membrane from a higher concentration of water to a lower concentration.

Filtration

Movement across the membrane caused by hydrostatic pressure, such as the filtering of blood by the kidney.

Primary Active Transport

Movement of substances against a concentration gradient using carrier proteins and requiring $ATP$ energy, such as the sodium-potassium pump.

Pinocytosis

A form of endocytosis involving the inward invagination of the membrane to bring in water with dissolved substances.

Phagocytosis

A form of endocytosis where the membrane projects outward to catch a solid substance, such as macrophages ingesting bacteria.

Cytosol

The semifluid portion of the cytoplasm that surrounds organelles and constitutes about $55\%$ of total cell volume.

Lysosomes

Spherical membrane-bound organelles containing acid hydrolase enzymes used for digesting organic molecules.

Proteasomes

Barrel-shaped structures containing proteases that destroy unneeded, damaged, or faulty proteins.

Mitochondria

The site of cellular respiration and $ATP$ generation, featuring an inner membrane folded into cristae and its own circular DNA.

Grana

Tight stacks of thylakoids found within the chloroplast.

Peroxisome

Organelles that transfer Hydrogen to $O_2$ to produce $H_2O_2$, which is then converted to $H_2O$; involved in detoxifying alcohol in liver cells.

Nuclear Lamina

A net-like array of protein intermediate filaments that maintains the shape of the nucleus.

Nucleolus

The region within the nucleus where ribosomal RNA is synthesized and assembled with proteins into subunits.

Smooth ER

ER surface lacking ribosomes; site for lipid synthesis, carbohydrate metabolism, and detoxification of drugs and poisons.

Golgi Apparatus

An organelle that sorts, packages, and secretes proteins and lipids, characterized by cisternae and having a cis face and a trans face.

Microtubules

The thickest cytoskeleton fibers made of the protein tubulin; involved in organelle movement and chromosome division.

Microfilaments

Also known as actin fibers, these are the thinnest cytoskeleton fibers and help muscle cells contract.

Intermediate Filaments

Permanent protein fibers made of keratin that help maintain cell shape and the spatial organization of organelles.

Centrosome

The region near the nucleus containing the pericentriolar area and centrioles, serving as an organizing center for the mitotic spindle.

Glyoxysome

Specialized organelles found in plant fat-storing tissues that convert fatty acids to sugar, which are absent in animal and bacterial cells.