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Flashcards in Cell Structure Quiz Deck (21):

Plasma Membrane

forms the cell's flexible outer surface, separating the cell's internal environment form the external environment
FUNCTION: regulates the flow of materials into and out of a cell to help establish and maintain the appropriate environment for normal cellular activity.
also plays a key role in communication among cells between cells and their external environment.
protects cellular contents.
contains channels , carriers, receptors, enzymes, cell-identity markers, linker proteins



consists of all the cellular contents between the plasma membrane and the nucleus.
consists of cytosol (the fluid portion of the cytoplasm, containing water, dissolved solutes, and suspended particles) and organelles that have a specific shape and function
EXAMPLES: ER, Golgi complex, lysosomes, peroxisomes and mitchondria
FUNCTION: site of all intracellular activities except those occurring in the nucleus



large organelle that houses most of a cell's DNA.
consists of a nuclear envelope with pore, nucleoli, and chromosomes, which exist as a tangles mass of chromatin in interphase cells
FUNCTION: Within the nucleus, each chromosome contains thousands of hereditary units (genes) that control most aspects of cellular structure and function
nuclear pores control the movement of substances between the nucleus and cytoplasm, nucleoli produces ribosomes, and chromosomes consist of genes that control cellular structure and direct cellular functions



a single molecule of DNA associated with several proteins


Lipid Bilayer

two back to back layers made up of three types of lipid molecules - primary phospholipids with smaller amounts of cholesterol and glycolipids



a lipid that contains phosphorous.
has polar (hydrophilic) parts, but the two fatty acid tails are hydrophobic and nonpolar.
Found in the plasma membrane interior


Cholesterol molecules

found in both layers of plasma membrane.
They are steroids with an attached hydroxyl group (OH) which is the only polar region of choloesterol.
The hydroxyl group group forms hydrogen bonds with the polar heads of phospolipids and glycolipids, but most is nonpolar.



lipids with attached carbohydrate groups that form polar heads and fatty acid tails that are nonpolar.
They only appear in the layer of the plasma membrane that faces the extracellular fluid



a network of proteins filaments that extends throughout the cytosol - microfilaments, intermediate filaments, microtubules
FUNCTION: maintain shape and general organization of cellular contents; responsible for cellular movements



composed of water, solutes, suspended particles, lipid droplets, and glycogen granules
FUNCTION: medium in which many cell's metabolic reactions occur



specialized structures with characteristic shapes
FUNCTION: each organelle carries out specific function



a pair of centrioles plus pericentriolar material
FUNCTION: the pericentriolar material contains tubulins, which are used for growth of the mitotic spindle and microtubule formation


cilia and flagella

motile cell surface projections that contain 20 microtubules and a basal body
FUNCTION: cilia move fluids over a cell's surface
flagella move an entire cell



composed of two subunits containing ribosomal RNA and proteins; may be free in cytosol or attached to rough ER
FUNCTION: protein synthesis


Rough Endoplasmic Reticulum (ER)

membranous network of flattened sacs or tubules; covered by ribosomes and is attached to the nuclear envelope
FUNCTION: synthesizes glycoproteins and phospolipids that are transferred to cellular organelles, inserted into the plasma membrane, or secreted during exocytosis


Smooth Endoplasmic Reticulum (ER)

membranous network of flattened sacs or tubules; lacks ribosomes
FUNCTION: synthesizes fatty acids and steroids; inactivates or detoxifies drugs; removes the phosphate group from glucose 6-phosphate; and stores and releases calcium ions in muscle cells


Golgi complex

consists of 3-20 flattened membranous sacs called cisternae; structurally and functionally divided into entry face, medial cisternae, and exit face
entry face=accepts proteins from rough ER
medial cisternae= forms glycoproteins, glycoplipids, and lipoproteins
exit face= modifies the molecules further, then sorts and packages them for transport to their destinations



vesicles formed from golgi complex; contains digestive enzymes
FUNCTION: fuses with and digests contents of endosomes, pinocytic vesicles, and phagosomes and transports the final products of digestioninto cytosol; digests worn-out organelles (autophagy), entire cells (autolysis), and extracellular material



vesicles containing oxidases (oxidative enzymes) catalase (decomposes hydrogen peroxide); new peroxisomes bud from preexisting ones
oxidizes amino acids and fatty acids; detoxifies harmful substances, such as alcohol



tiny barrel-shaped structure that contains proteases (proteolytic enzymes)
FUNCTION: degrades unneeded, damaged, or faulty proteins by cutting them into smaller peptides



consists of an outer and inner mitochondrial membrane, cristae, and matrix; new mitochondria form from preexisting ones
FUNCTION: site of aerobic cellular respiration reactions that produce most of a cell's ATP