Flashcards in Histology Chapters 2 & 3 Deck (83)
What is the plasma membrane composed of?
phospholipids, cholesterol, proteins, and chains of oligosaccharides
What is the function of the plasma membrane? (3)
Site where materials are exchanged between the cell and its environment; regulates the ion concentration of the cytoplasm; also recognition, regulatory, and interaction functions.
what is the thickness of the plasma membrane?
7.5 to 10 nm thick (EM)
what is the structure of the plasma membrane?
Trilaminar (EM); fluid mosaic model
Where does osmium tetroxide deposit on the plasma membrane?
On the outer hydrophilic heads away from the hydrophobic tails.
What are the three kind of proteins in the plasma membrane?
Integral, transmembrane, and peripheral
What are structures that are always on the outside of the cell attached to the plasma membrane?
What are the three kinds of Endocytosis?
Phagocytosis, pinocytosis, and receptor-mediated endocytosis
"Cell-eating"; phagosome; then fuses with lysosome
Also called fluid-phase endocytosis is "cell-drinking"; pinocytotic vesicle; then fuses with lysosomes.
Define receptor-mediated endocytosis.
Binding of the ligand to a receptor causes coated pits made of clathrin to form; pinches off to form a coated vesicle; fuses with endosomal compartment to form endosomes.
Release of material across plasma membrane into the extra cellular space; involves vesicle fusing with plasma membrane and releasing its contents.
What is the function of a lysosome?
Sites of intracellular digestion and turnover of cellular components.
What is the size of a lysosome?
0.05 - 0.5 micrometers
What is the structure of a lysosome?
Membrane bound vesicles that contain about 40 different hydrolytic enzymes.
what is the relative size of an lysosome versus a RBC?
about 1/16th of the size
What is the function of a ribosome?
What is the size of a ribosome?
20nm x 30nm
What is the structure of a ribosome?
Composed of two different sized subunits; the subunits are composed of rRNA and proteins; can be found free within the cytoplasm or attached to membrane of the endoplasmic reticulum.
What is the structure of the endoplasmic reticulum?
Network of intercommunicating channels and sacs of membranes which enclose a space called a cisterna.
What defines rough endoplasmic reticulum (RER), and what does the RER do?
There are ribosomes on the cytosolic side of the membrane; produces proteins for secretion.
What defines the smooth endoplasmic reticulum (SER); and what does the SER to?
Regions of ER without ribosomes; cisternae are much more tubular; important in the production of phospholipids; abundant in cells that synthesize steroid hormones.
What are two types of human organ cells that have an abundance of smooth ER?
neurons and liver cells
What is the function of the golgi apparatus?
Completes post-translational modifications, packages, and sorts proteins synthesized in the RER.
What is the Structure of the golgi apparatus?
Composed of smooth membranous saccules; has a cis (entry) face and a trans (exit) face.
What is the function of the mitochondria?
Membrane-enclosed organelles with enzyme arrays specialized for aerobic respiration and production of adenosine triphosphate (ATP).
What is the size of a mitochondria?
0.5-1.0 micrometer in diameter and 5-10 micrometers in length
What is the structure of mitochondria?
Two membranes (inner and outer) and two compartments (matrix and intermembrane space); inner membrane folded to form cristae which project into matrix.
Give an example of cells that would have a lot of mitochondria due to their high energy needs.
Muscle, kidney, liver