Cytology I & II Flashcards
Two basic parts of the cell
- Nuclear Envelop: includes the Nucleus & DNA
- Cytoplasm: includes matrix, cytoskeleton, organelles
Unit Membrane
Selective barrier around cells and some organelles
- appears trial I are under TEM
- E face (outer leaflet): faces extra cellular space
- P face (inner leaflet): faces cytoplasm
- Peripheral (layer) and integral (integrated) proteins
- Glycocalyx: cell coat
Cellular Transport
- Passive transport: no energy required
- Active transport: energy is required
Vesicular Transport
Transportation of material into or out of a cell by membrane-bound vesicles
Exocytosis
Release of cellular products via vesicular transport
1. Material is packaged into secretory vesicles
2. Transported to membrane
3. Fused membrane and released into extra cellular space
Types of Secretion
- Regulated: vesicles congregate near plasma membrane; secretory granules, secretions condense; signal release into ECS
- Constitutive: continuous secretion; no accumulation of secretory vesicles, no signaling required
Goblet cells
Mucus cells; can be different colors due to the level of condensation because they hang out for different periods
Endocytosis
Uptake of material via vesicular transport (aka absorption)
1. Plasma membrane infolds to form vesicle containing inbound material
2. Vesicles fuse with lysosomes for processing
PInocytosis
Cellular “drinking”; the generalized type of absorption
Aids in “membrane trafficking” recycling plasma membrane
Phagocytosis
Cellular “eating”
1. Pseudopodia: engulf large particles, cell debris, bacteria
2. Characteristics: irregular outline; “bubbly” appearance (lysosomes); host defense and cleanup after injury
Nuclear envelope
The membrane of the nucleus
Nuclear pores
Small holes all around the envelope
Chromatin
Strands of DNA
Euchromatin
Uncoiled DNA; undergoing active transcription; more e- lucent
Heterochromatin
Condensed DNA; inactive; more e- dense
Nucleolus
Tight ball of rRNA inside the nucleus
Ribosomes
“Protein factories”
1. Free Ribosomes (polyribosomes): create cytoplasmic proteins
2. ER-bound ribosomes: create membrane & secretory proteins, attached to RER
Rough Endoplasmic Reticulum (rER)
Proteins are synthesized into the cisterna (the inner lumen) and then transported to the GA for packaging
Outer surface has ER-bound ribosomes
Interconnected, flattened membranous sacs
Golgi Apparatus
Shipping and receiving of the cell; interconnected, flattened sacs
Cis face = toward rER; trans face = plasma
“Packaged” with cisterna;
3 Destinations for GA
- Unit membranes
- Secretions via secretory vesicles
- Lysosomes
Lysosomes
Spherical, membrane-enclosed digestive compartment
Have varying e- densities due to different concentrations
3 things Lysosomes fuse with:
- Autophagosomes
- Endocytosis vesicles
- Phagosomes (in specialized cells)
Mitochondria
of mitochondria indicates the cells energy requirements
Site of ATP synthesis (chemical energy conversion)
Rod shaped; 2 unit membranes: the inner folded is the cristae and the outer is the smooth
Vesicular Mitochondria
Mainly seen in steroid hormone-producing cells
Has little dots b/c the cristae extend into the matrix as tubular folds
Smooth Endoplasmic Reticulum (sER)
Interconnected membrane-enclosed tubules that are abundant in cells that detoxify and secrete steroid hormones
Present in ALL cells (for autophagy, lipid, cholesterol metabolism)
Cytoskeletal Elements
Help with cell morphology (shape), mobility, and interacts with extracellular matrix
Actin, intermediate filaments, microtubules
Actin (thin filaments)
Smallest diameter
- Helps anchor cells to each other and ECM
- Form structural core of microvilli, stereocilia
- Movement (contraction, extending processes)
Intermediate filaments
Larger than actin; high tensile strength; constructed of different substances in different cells
- Cell-to-cell adhesion
- Cell-to-ECM adhesion
Microtubules
Largest cytoskeleton components; structural component of centrioles, cilia, flagella
- Provide rigidity to cell shape
- Aid intercellular transport
- Movement of cilia, cell, flagella
