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?