CYTOLOGY THE STUDY OF CELLS - STRUCTURE
Jan 19, 2016
CYTOLOGY
THE STUDY OF CELLS - STRUCTURE
GENERAL
Cell = Smallest Living UnitProduced by Cell Division or FertilizationSurrounded by Interstitial / Extracellular
FluidComponents:
- Plasma (Cell) Membrane- Cytoplasm- Nucleus
THE PLASMA MEMBRANE
Structure
- Phospholipid bilayer
*self-orienting, reseals
*hydrophilic heads (face outward)
*hydrophobic tails (face inward)
- Proteins (floating or anchored)- Cholesterol (keeps it “fluid”)
THE PLASMA MEMBRANE
Functions:- Physical Barrier (Selective!)
* Fat-soluble do pass through* Water-soluble don’t
- Proteins:* Channels or Carriers (transport)* Enzymes (chemical reactions)* Receptor sites (“docking” of molecules)* Anchors
THE PLASMA MEMBRANE
CYTOPLASM
Material Between Plasma Membrane & Nucleus
Components* Cytosol (fluid with solutes)* Cytoplasmic Organelles* Inclusions (stored materials)
Site of chemical reactions
NUCLEUS
OrganelleDouble Nuclear Membrane with PoresDNA – Instructions for making proteins
* Chromatin - loose; protein synthesis * Chromosomes - dense, rod-like; cell
division
Nucleolus* Assembly of ribosomes
STRUCTURE OF THE NUCLEUS
CYTOPLASMIC ORGANELLES
Mitochondria- ATP synthesis
(cellular energy)- Self-replicating- Contains DNA
CYTOPLASMIC ORGANELLES
Ribosomes- Site of Protein
Synthesis
- Free or Attached
Rough Endoplasmic Reticulum- Membrane synthesis
- Proteins made for export
CYTOPLASMIC ORGANELLES
Smooth ER- Lipid synthesis
& breakdown- Detoxification
CYTOPLASMIC ORGANELLES
Golgi Apparatus
Prepares proteins for export
Makes lysosomes
Packages material to add to plasma membrane
CYTOPLASMIC ORGANELLES
Lysosomes
- Digestion within the cell
- Defense
- Recycle worn-out cells
Peroxisomes
- Detoxify
* Alcohol
* Formaldehyde
* Free Radicals
CYTOPLASMIC ORGANELLES
Cytoskeleton- Proteins
- Support & Shape
- Movement inside cell
Centrioles- Form Spindle
- Form base of cilia & flagella
CYTOPLASMIC ORGANELLES
Cilia – short, numerous, move substances over free surfaces
Flagella – long, singular, move cellMicrovilli – thin folds of cell membrane,
increase surface area to maximize absorption
Cytoplasmic Organelles
Proteosomes- Ring of stacked proteins around
central core- Break-up undesirable proteins
Vaults- Ribonucleoprotein (proteins + RNA)- May be involved in transport between nucleus
& cytoplasm?