Histology Week 1 Flashcards
Describe a cell:
The smallest unit of living structure capable of independent existence, composed of a membrane enclosed mass of protoplasm and containing a nucleus. Highly variable and specialized in structure and function, though all must at some stage replicate proteins and nucleic acids, utilize energy and reproduce themselves.
Describe an organelle:
One of the specialized parts of a cell; these subcellular units include mitochondria, the Golgi apparatus, nucleus and centrioles, smooth and rough endoplasmic reticulum, vacuoles, lysosomes, plasma membrane, and certain fibrils
Which organelles have single membrane: intracellular compartments:
- lysosome - perosisome - rER (rough surface - golgi appartus
What structures are bound by two membranes within the cell?
- nucleus - mitochondria
Which organelles are not bounded by membranes:
- nucleolus - actin filaments - centrosome - microtuble - free ribosomes
H&E stain: Hematoxylin and eosin; describe pink vs blue color stain:
Proteins: pink Basophilic dye: negatively charged (blue/purple) - DNA/RNA/ribosomes
What does a pale staining nucleus indicate? What does a dark staining nucleus indicate?
loose packed (euchromatin) more active tightly packed (heterochromatin) less activity
Difference between EM and LM?
EM all in black and white and more detailed; LM in color
Sketch a typical eukaryotic cell.
see pic
Describe Plasma membrane:
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 • made of phospholipids, cholesterol and proteins • is a lipid bilayer • contains proteins (receptors, pumps, channels) • is not homogeneous in composition
Cilia:
short numerous membrane extensions supported by microtubules, which occur on exposed membrane surfaces of some cells. Move substances
Microvilli:
Numerous thin membrane folds projecting from the free cell surfaces support by microfilaments. Increases membrane surface area for greater absorption
Nucleus:
large enclosed structure with double membrane, contains chromatins, nucleolus and nucleoplasm. Houses DNA that serves as the genetic material for directing protein synth.
Nucleolus:
functions in synthesis of ribosomes (initial ribosomal assembly) rRNA
Nuclear pores:
opening through the nuclear envelope. portal for substances to enter and leave
Ribosomes
structures essential for protein synthesis, composed of RNA and ribosomal proteins. Exit nucleus through nuclear pore. Macromolecular structure and can only be resolved by EM. 50% RNA by mass
Cytoskeleton
a system of hollow tubules/filaments and their associated proteins (microfilaments, intermediate filaments, microtubles). Filaments self assemble. Responsible for the cell shape and forms mechanical linkages, movement
Microfilament:
actin (protein) filament, found throughout the cytoplasm but concentrated just beneath the plasma membrane in the apical projections named microvilli. Also found in the contractile apparatus of muscle