Chapter 2 Notes Flashcards
Plasma Membrane
The plasma membrane, sometimes called the cell membrane, forms the outer, limiting barrier separating the internal contents of the cell from the external environment.
Cytoplasm
Cytoplasm is a general term for all cellular contents located between the plasma membrane and the nucleus. The three components of the cytoplasm are cytosol (a viscous fluid), inclusions (nonfunctional, temporary structures that store cellular products), and organelles (tiny structures that perform specific cellular functions).
Nucleus
The nucleus is the cell’s control center. It controls protein synthesis (production of new proteins), and in so doing, it directs the functional and structural characteristics of the cell
Plasma Membrane Structure
Phospholipid bilayer containing cholesterol and proteins (integral and peripheral) and some carbohydrates (externally
Plasma Membrane Function
Contains receptors for communication; forms intercellular connections; acts as physical barrier to enclose cell contents; regulates material movement into and out of the cell
Cytoplasm Structure
Contains cytosol, a viscous fluid, and inclusions and organelles
Cytoplasm Function
Place of many metabolic processes of the cell; stores nutrients and dissolved solutes
Cytosol Structure
Viscous fluid medium with dissolved solutes (ions, nutrients, proteins, carbohydrates, lipids, and other small molecules)
Cytosol Function
Provides support for organelles; serves as viscous medium through which diffusion occurs
Organelles Structure
Membrane-bound and non-membrane-bound structures that have unique functions and activities
Organelle Function
Carry out specific metabolic activities of the cell
Inclusions Structure
Droplets of melanin, protein, glycogen granules, or lipid; usually non-membrane-bound
Inclusions Function
Store materials
Nucleus Structure
Surrounded by double membrane nuclear envelope (each membrane is a phospholipid bilayer); contains nucleolus and chromatin
Nucleus Function
Acts as cell control center; controls all genetic information (DNA); site of ribosome subunit assembly
Nucleur Envelope Structure
Double membrane boundary between cytoplasm and nuclear contents
Nucleur Envelope Function
Physical barrier that controls movement of materials between the nucleus and the cytoplasm
Nucleur Pore Structure
Openings through the nuclear envelope
Nucleur Pore Function
Allow for passage of materials between nucleus and cytoplasm
Nucleuolus Structure
Spherical, dark-staining, dense granular region in the nucleus
Nucleuolus Function
Synthesizes rRNA and assembles ribosomes in the nucleus
Chromatin and chromosomes Structure
Filamentous association of DNA and histone proteins
Chromatin and Chromosome Function
Site of genes in the DNA
Smooth endoplasmic reticulum (smooth ER) Structure
Interconnected network of membrane tubules and vesicles; no ribosomes
Smooth ER Function
Synthesizes lipids; metabolizes carbohydrates; detoxifies drugs, alcohol
Rough endoplasmic reticulum (rough ER) Structure
Flattened intracellular network of membrane sacs called cisternae; ribosomes attached on cytoplasmic surface
Rough ER Function
Synthesizes proteins for secretion, new proteins for the plasma membrane, and lysosomal enzymes; transports and stores molecules
Golgi Apparatus Structure
Stacked series of flattened, smooth membrane sacs with associated transport vesicles (also called shuttle vesicles)
Golgi Apparatus Function
Modifies, packages, and sorts newly synthesized proteins for secretion, inclusion in new plasma membrane, or lysosomal enzyme synthesis
Lysosomes Structure
Membrane sacs with digestive enzymes
Lysosome Function
Digest materials or microbes ingested by the cell; remove old/damaged organelles; self-destruct (autolyze)
Peroxisomes Structure
Membrane-enclosed sacs; usually contain large amounts of specific enzymes to break down harmful substances
Peroxisome Functions
Convert hydrogen peroxide formed during metabolism to water
Mitochondria Structure
Double membrane structures with cristae; fluid matrix contents at center
Mitochondria Function
Synthesize most ATP during cellular respiration; “powerhouses of cell”
Ribosomes Structure
Dense cytoplasmic granules with two subunits (large and small); may be free in cytoplasm (free ribosomes) or bound to rough ER (bound ribosomes)
Ribosomes Function
- Synthesize proteins for:
- use in the cell (free ribosomes)
- secretion, incorporation into plasma membrane, or lysosomes (bound ribosomes)
Cytoskeleton Structure
Organized network of protein filaments or hollow tubules throughout the cell
Cytoskeleton Function
Provides structural support; facilitates cytoplasmic streaming, organelle and cellular motility, transport of materials, and chromosomal movement and cell division
Microfilaments Structure
Actin protein monomers formed into filaments
Microfilaments Function
Maintain cell shape; aid in muscle contraction and intracellular movement; separate dividing cells
Intermediate Filaments Structure
Various protein components
Intermediate Filaments Function
Provide structural support; stabilize cell junctions
Microtubules Structure
Hollow cylinders of tubulin protein; able to lengthen and shorten
Microtubules Function
Support cell; hold organelles in place; maintain cell shape and rigidity; direct organelle movement within cell and cell motility as cilia and flagella; move chromosomes at cell division
Centrosome Structure
Amorphous region adjacent to nucleus; contains a pair of centrioles
Centrosome Function
Organizes microtubules; participates in spindle formation during cell division
Centrioles Structure
Paired perpendicular cylindrical bodies; composed of microtubule triplets
Centrioles Function
Organize microtubules during cell division for movement of chromosomes
Cilia Structure
Short, membrane-attached projections containing microtubules; occur in large numbers on exposed membrane surfaces
Cilia Function
Move fluid, mucus, and materials over the cell surface
Flagellum Structure
Long, singular membrane extension containing microtubules
Flagellum Function
Propels sperm in human male
Microvilli Structure
Numerous thin membrane folds projecting from the free cell surface
Microvilli Function
Increase membrane surface area for absorption and/or secretion
