The Cell Flashcards
Plasma Membrane structure
Phospholipid bilayer containing cholesterol and
proteins (integral and peripheral) and some
carbohydrates (externally); forms a selectively
permeable boundary of the cell
Cilia structure
Short, numerous membrane extensions
supported by microtubules, which occur on
exposed membrane surfaces of some cells
Flagellum structure
Long, singular membrane extension supported
by microtubules; present on sperm cells
Microvilli structure
Numerous thin membrane folds projecting from
the free cell surface; supported by
microfilaments
Nucleus structure
Large structure enclosed within a double
membrane; contains chromatin, nucleolus, and
nucleoplasm
Nuclear envelope structure
Double membrane boundary between cytoplasm
and nuclear contents; continuous with rough
endoplasmic reticulum
Nuclear Pores structure
Openings through the nuclear envelope
Nucleolus structure
Large, prominent structure within the nucleus
Cytoplasm structure
Contents of cells between the plasma
membrane and nuclear envelope
Cytosol structure
Viscous fluid medium with dissolved solutes
(eg, ions, proteins, carbohydrates, lipids)
Organelles structures
Membrane-bound and nonmembrane bound structures
Rough endoplasmic reticulum (rough ER) structure
Extensive interconnected membrane
network that varies in shape (eg, cisternae,
tubules); ribosomes attached on
cytoplasmic surface
Smooth endoplasmic reticulum (smooth ER) structure
Extensive interconnected membrane
network lacking ribosomes
Golgi apparatus structure
Series of several elongated, flattened
saclike membranous structures
Vesicles structure
Spherical-shaped membrane-bound sacs;
contain various types of materials to be
transported through the cell.
Lysosomes structure
Spherical-shaped membrane-bound
organelles formed from the Golgi
apparatus; contain digestive enzymes
Peroxisomes structure
Smaller, spherical-shaped membrane bound organelles formed from the ER or through fission; contain oxidative enzymes produced by ribosomes
Mitochondria structure
Double membrane-bound organelles
containing a circular strand of DNA (genes
for producing mitochondrial proteins)
Ribosomes structure
Organelles composed of both protein and
ribosomal RNA (rRNA) that are organized
into both a large and small subunit; may be
bound to a membrane or free in cytosol
Cytoskeleton components
Actin microfilaments, Intermediate filaments, Microtubules
Cytoskeleton structure
Organized network of protein filaments and
hollow tubules, including microfilaments,
intermediate filaments, and microtubules
Microfilaments structure
Actin protein monomers organized into two
thin, intertwined protein filaments (actin
filaments)
Intermediate filaments structure
Various protein components
Microtubules structure
Hollow cylinders composed of tubulin
protein
Centrosomes structure
Amorphous region adjacent to nucleus;
contains a pair of centrioles
Proteasomes structure
Large, barrel-shaped protein complexes not associated with any membrane located in both the cytosol and nucleus
Inclusions structure
Aggregates of specific types of molecules
(eg, melanin protein, glycogen, or lipid)
Plasma Membrane function
Acts as a physical barrier to
enclose cell contents; regulates
material movement into and out of
the cell; establishes and maintains
an electrical charge difference
across the plasma membrane;
functions in cell communication
Cilia function
Move substances (eg, mucus and
dissolved materials) over the cell
surface
Flagellum function
Propels sperm
Microvilli function
Increase membrane surface area
for greater absorption
Nucleus function
Houses the DNA that serves as the
genetic material for directing
protein synthesis
Cellular regulation and Production of ribosomal subunits
Nuclear envelope function
Separates nucleus from cytoplasm
Nuclear Pores function
Allow passage of materials between the
cytoplasm and nucleoplasm, including
ribonucleic acid (RNA), protein, ions,
and small water-soluble molecules
Nucleolus function
Functions in synthesis of ribosomes
Cytoplasm function
Responsible for many cellular processes
Cytosol function
Provides support for organelles; serves as the
viscous fluid medium through which diffusion
occurs
Organelles function
Carry out specific metabolic activities of the
cell
Rough endoplasmic reticulum (rough ER) function
Modifies, transports, and stores proteins
produced by attached ribosomes; these
proteins are secreted, become components of
the plasma membrane, or serve as enzymes of
lysosomes
Smooth endoplasmic reticulum (smooth ER) function
Synthesizes phospholipids, detoxification of alcohol and drugs, and controlled release of Ca++ which is important in muscle cells.
transports and stores lipids (eg. steroids); metabolizes carbohydrates;
detoxifies drugs, alcohol, and poisons; forms vesicles and peroxisomes
Golgi apparatus function
Modifies, packages, and sorts materials that
arrive from the ER in transport vesicles; forms
secretory vesicles and lysosomes
Vesicles function
Transport cellular material
Lysosomes function
Digest microbes or materials (eg, ingested by
the cell, worn-out cellular components, or the
entire cell)
Peroxisomes function
Spherical organelles that carry enzymes, produced by ribosomes, that produce and break down H2O2. The H2O2 is used to destroy toxic molecules.
Detoxify specific harmful substances either
produced by the cell or taken into the cell;
engage in beta oxidation of fatty acids to
acetyl CoA
Mitochondria function
Synthesize most ATP during aerobic cellular
respiration by digestion of fuel molecules (eg,
glucose) in the presence of oxygen
Ribosomes function
Engage in protein synthesis: Bound ribosomes
produce proteins that are secreted,
incorporated into plasma membrane, and
within lysosomes; free ribosomes produce
proteins used within the cell
Cytoskeleton function
Maintains intracellular structural support
and organization of cells; participates in cell
division; facilitates movement
Microfilaments function
Maintain cell shape; support microvilli;
separate two cells during cytokinesis (a
process of cell division); facilitate change in
cell shape; participate in muscle contraction
Intermediate filaments function
Provide structural support; stabilize
junctions between cells
Microtubules function
Maintain cell shape and rigidity; organize
and move organelles; support cilia and
flagella; participate in vesicular transport;
separate chromosomes during the process
of cell division
Centrosomes function
Organizes microtubules; participates in
mitotic spindle formation during cell division
Proteasomes function
Small protein complexes that are not associated with any membrane. Unlike lysosomes, they digest individual molecules.
Degrade and digest damaged or unneeded
proteins; ensure quality of exported proteins
Inclusions function
Serve as temporary storage for specific types of molecules (eg. melanin protein, glycogen, or lipid)
Two major lipids
Phospholipid (various types) and Cholesterol
What are lipids?
Lipids are biomolecules of C, H, and O that are soluble in nonpolar solvents. They are hydrophobic.
Simple lipids
Fatty acids
Waxes
Glycerides (glycerol + fatty acids)
Compound lipids
Phospholipids (glycerol + fatty acids + PO4)
Glycolipids
Derived lipids
Sterols
Steroids
Carotenoids
What are fats?
A fat is an ester of fatty acids
What is a fatty acid?
A carboxylic acid with a linear (unbranched) chain
How do small molecules cross the plasma membrane?
Diffusion
Osmosis
Channels
Protein carriers
Pumps
How do large molecules cross the plasma membrane?
Exocytosis: moving from inside to outside of the cell
Ex: Release of neurotransmitter by nerve cells
Endocytosis: moving from outside the cell to inside the cell
(Three types: Phagocytosis, Pinocytosis, and Receptor-mediated endocytosis)
Phagocytosis
Type of endocytosis in which vesicles are formed as particulate materials external to the cell are engulfed by pseudopodia
Ex: White blood cell engulfing bacterium
Pinocytosis
Type of endocytosis in which vesicles are formed as interstitial fluid is taken up by the cell
Ex: Formation of small vesicles in capillary wall to move substances
Receptor-mediated endocytosis
Type of endocytosis in which plasma membrane receptors first bind specific substances; receptor and bound substance then taken up by the cell
Ex: Uptake of cholesterol (LDL) into cells, mediated by atorvastatin (statin drug)