Cytology 1 Flashcards
Cells
Cell
Smallest living structural and functional unit is human body
Cells produced by
Cell division; mostly mitosis
Organelles
Specialized structural and functional units inside cells.
Parts of a cell
- Cell membrane
- Nucleus
- Nucleolus
- Mitochondrion
- Ribosome
- Rough Endoplasmic Reticulum (ER)
- Smooth Endoplasmic Reticulum (ER)
- Golgi apparatus
- Lysosome
- Phagocytic vesicle
- Secretory vesicle
- Centrosome
- Centrioles
- Peroxisome
- Microtubule network
- Cilia
- Microvilli
- Cytoplasm
Cellular Functions
- Covers and lines surfaces (epitheleal)
- Storage (hepatocytes, adipocytes)
- Movement (muscle)
- Attachment and support (fibroblasts)
- Defense (leukocytes)
- Communication (neurons)
- Reproduction (egg, sperm, fertilized egg)
Basic animal cell type “Eukaryotic” contains
- Nucleus
- Plasma Membrane
- Cytoplasm
- Organelles
- Cytosol
- Inclusions
** Organelles have membrane/double membrane; membrane bound
Nucleus structure and function
- Shape similar to cell
- Double nuclear membrane w/pores allowing large molecules to move inside
- Houses DNA
- Some cells multinucleate (many) or anucleate (none)
- Nucleoplasm
- Nucleolus
- Organelle in nucleus (non-membranous)
- assembles ribosomes
- DNA
- Chromatin (don’t divide) - loose; protein synthesis
- Chromosomes - dense, rodlike; cell division
- Nucleolus
Plasma Membrane structure
- Selectively permeable - regulates exchange w/extracellular fluid
- Limiting factor is mainly cell size
- Composed of mostly lipids and proteins
- Phospholipid Bilayer is basic structure
- Proteins determine function
Functions of a membrane
- Communication: contains receptors that respond to molecular signals
- Intercellular connection: establishes flexible boundary, protects cellular contents, and supports structure
- Physical barrier: phospholipid bilayer separates substances inside & out
- Selective permeability: Regulates exit and entry of ions, nutrients, and waste molecules through membrane
Phospholipid Bilayer characteristics
Molecules that combine to form polar (Amphipathic molecules***) and nonpolar (Hydrophobic) structure
Glycolipd
Glycogen (carbohydrate) attached to a lipid
Glycocalyx
Carbohydrate chain
Integral Protein
Embedded in phospholipid bilayer cell membrane
Peripheral Protein
Hangs on outside of cell membrane
Glycoprotein
Glycogen (carb) attached to protein
Plasma Membrane
- Lipids - insoluble in water
- cholesterol
- affects membrane fluidity
- thermal stability
- cholesterol
- Glycolipids (carb attached to phospholipid)
- outer surface
- Glycocalyx (carb chain) contributes to cellular recognition
20% is lipid, 5-10% glycolipid
- Proteins - highly diverse
- Integral - embedded
- channels and carriers
- receptors
- enzymes
- many are glycoproteins
- peripheral - attached to surface; may float
- enzymes
- Integral - embedded
Cytoplasm components
Three components:
- Cytosol - intracellular fluid
- Inclusions - temporarily stored substances (nutrients/pigments)
- Organelles
- diverse structures w/specialized functions
- vary among cells
- membrane-bound & non-membranous
Organelles
“Little organs”
- Membrane-bound organelles
- membrane isolates secretions, enzymes or toxins
- Non-membrane-bound organelles
Smooth Endoplasmic Reticulum function
- synthesis of lipids; metabolizes carbohydrates; detoxifies
- storage (synthesized materials or Ca+)
- membranous
- more in liver
Rough Endoplasmic Reticulum function
- attached ribosomes
- protein synthesis
- membranous*
Golgi Apparatus structure and function
- membranous
1. Structure: flattened membranous sacs w/vesicles
2. Function:- modifies new proteins for lysosomes & protein for secretion
- packages enzymes for lysosomes & protein for secretion
- sorts all materials for lysosome secretion and incorporation into plasma membrane
Exocytosis
Exiting the cell
Lysosome structure and function
- membranous
1. Structure: vesicles filled with digestive enzymes
2. Function:- intracellular digestion (wastes and ingested macromolecules)
- recycle worn-out organelles via Autophagy*
- self-digestion of cell via Autolysis*
Peroxisomes structure and function
- Membranous sacs of enzymes (oxidases=use O2 to break down free radicals to a safer form of H2O2)
- Break down amino acids and fatty acids
- Detoxify harmful/dangerous substances
- hydrogen peroxide (by-product of oxidization)
- alcohol
- formaldehyde
- free radicals
Mitochondria structure and function
- Structure: double membrane w/cristae & central fluid matrix
- Function: most ATP synthesis (cellular energy in the presence of O2)
- Contains DNA
- Self-replicating
- More numerous in certain cells and certain individuals (high numbers in cells that require energy, such as muscle cells)
Ribosomes structure and function
- NON-membranous
1. Structure: two subunits
2. Function: protein synthesis*
3. Two types:- Free - synthesis of proteins for intracellular use
- Fixed - synthesis of proteins for secretion, or incorporation into lysosomes, plasma membrane, or cell membranes; attached to Rough ER
Cytoskeleton structure and function
- NON-membranous
1. Network of protein structures
2. Acts as cell’s “muscles and bones”
3. Determines cell shape
4. Supports organelles
5. Involved in internal transport & cellular movements
Centrosomes structure
- “Cell center”
- closely adjacent to nucleus
- builds microtubules in non-dividing cells
- forms mitotic spindle during cell division
- 2 centrioles put together
Centrioles structure
- Paired perpendicular bodies in centrosome
- Assist in spindle formation
- 2 centrioles will make a centrosome
Cilia structure and function
- Non-membranous
1. Mobile projections of cell surface
2. Contain microtubules
3. Short, numerous, move substances over free surfaces - digestive system
Flagella structure and function
- Non-membranous
1. Mobile projections of cell surface
2. Contain microtubules
3. Long, singular, propel human sperm cells
Microvilli
Microscopic projections of plasma membrane that increase surface area of cell
