Cytology Flashcards
Cell
a mass of protoplasm limited in space by a membrane
Protoplasm
“living matter” composed of cytoplasm and nucleoplasm
Organelles
Little Organs
- have membranes
- perform specific energy requiring functions
Inclusions
Storage components
DO NOT PERFORM energy requiring functions
-ex: glycogen
-no membrane
-sometimes scaffolds for other functions
-primarily found in the cytoplasm, some found in nucleus
Cell membrane
Called plasmalemma or Plasma membrane
- selective barrier between the environment and cytoplasm
- Trilaminar structure due to phospholipids
- Hydrophobic=Fatty acids
- Hydrophilic polar head groups
Fluid Mosaic Model
Not rigid
-proteins and lipids can move around
Glycocalyx
Cell coat
-carbohydrates that extend from cell membrane
made from either:
- Glycoproteins-protein in the external face of plasma membrane
- glycolipids-phosphlipid molecules
Plasma Membrane: Globular Proteins
move around and spin within the plasma membrane
-ion channels, pumps, receptors, transducers, enzymes
Nucleus
Contains genetic material
Chromatin
-2 types
Heterochromatin -Dense coiled DNA -Dark staining on EM -Basophilic (Stains blue) on LM -Found in 3 locations 1 Margina Chromatin 2. Karyosomes 3. Nucleolar associated chromatin
Euchromatin
- uncoiled DNA more active
- lighter staining on EM
- unstained on LM
Nucleolus
site of rRNA synthesis
Nuclear Cytoskeleton
Nuclear Lamina: intermediate filament proteins
- serve as scaffolding for nuclear components
- is made of lamins (protein)
- about 10 nm thick
Lamins
lie between nuclear membrane and marginal heterochromatin
-disassemble due to mitosis and reassemble after
Nuclear Pores
allow passage of mRNA into cytoplasm
Ribosomes
made of rRNA and protein
- involved in translation
- large and small subunits come together to form ribosomes
Riboproteins
involved in binding of subunits to form ribosomes
Classification of ribosomes
Free
- located in cytoplasm
- proteins may stay in the cell
Endoplasmic Reticulum bound
- extracellular protein synthesis
- proteins produces are integral plasma membrane proteins or secreted
Intracellular Protein Synthesis
occurs on free polyribosomes
Extracellular Protein Synthesis
- occurs on ribosomes bound to ER
- includs proteins bound for membrane
Nascent protein
New/baby
-not yet a protein-needs modifications
Rough Endoplasmic Reticulum
-function
Studded with ribosomes
Function
protein synthesis for insertion into membrane or export/secretion -
-once synthesized protein travels to Golgi via vesicles
Smooth Endoplasmic Reticulum
Contains no ribosomes/no protein synthesis
Function:
synthesis of steroid hormones, glycogen, lipid synthesis
-HCL formation (gut)
-Ca2+ stored in the sarcoplasmic reticulum (muscle
-drug detoxification
Smooth Endoplasmic reticulum Specialization
SER in liver cells
- Hepatocytes in Liver well developed for detoxification
- Increased SER mean increased detox due to alcohol poisoning or drug abuse
Detox Enzymes:
-related to cytochrome 450 (p450)
Protein movement from ER to Golgi
Protein movement is bidirectional
- COPs tell them where to go
- COPs attached to each vesicle
Transfer vesicles move from RER to forming face of GOLGI
- carbohydrates are added to form glycoproteins
- then packaged into secretory granules for cellular export
COP
involved in transport of proteins after synthesis from ER to golgi
Coatomer protein
-COP1-retrograde G-> ER
-COP2- anterograde ER->G
Golgi Apparatus
Site of protein modification
-Produces glycocalyx for integral membrane proteins
Coatomer protein
COP
protein coated vesicle that moves proteins between RER and gouge
Lysosomes
formed at the golgi
- membrane bound
- contain hydrolytic enzymes used for digestion of extracellular or intracellular components
- custom made for different cell types by containing different enzymes
Function of Lysosomes
- Breakdown of cell constituents
- Cell remodeling
- Normal turnover of organelles/macromolecules
- Breakdown of bacteria and viruses
Primary Lysosomes
Newly formed
- not yet digesting material
- light on EM
Secondary Lysosomes
Actively digesting
-dark/opaque on EM
Lysosomes various enzymes
- Proteases-proteins
- Nucleases-nucleic acids
- Glycosidases- polysaccharides
- Lipases-lipids
- Phosphatases- organic linked phosphates
Tay Sachs
Lipid metabolism defect
- autosomal recessive trait
- missing enzyme=hexosaminidase
Gangliosides accumulate in neural tissue causing retardation and childhood death
Hexosaminidase
Found in lysosome
-used for splitting off hexose from a ganglioside
Ganglioside
complex form of a glycolipid found in gray matter cells in CNS
Peroxisomes
contain oxidative enzymes (catalase) that breaks down H2O2 (hydrogen peroxide)
Hydrogen Peroxide (H2O2)
Toxic to cells
-causes free radical formation, which cross link proteins making them nonfunctional
Mitochondria
Provide energy for the cell in the form of ATP
- contain their own Circular DNA and ribosomes for self replication
- No ER=free ribosomes
- contain Cristae
Function:
- ATP production
- calcium sink
- heat production (brown fat)
Where does the Citric acid cycle occur?
Matrix of the mitochondria
Cytoskeleton
Nonmembrane found organelles:
- Microtubules (MT)
- Intermediate Filaments (IF)
- Microfilaments (MF)
Microtubules
Type of cytoskeleton
- protein polymer made of tubulin subunits-alpha and beta subunit
- Tubulin polymerize to form a microtubule
- reversible polymerization-dependent on ATP, pH, Ca2+ conc.
- can change length depending on physiological conditions in the cell=DYNAMIC
- present in all cells
- line up to form spindle fibers in mitosis
MAPs
Microtubule Associated Proteins
- Link Microtubules (MT) to other cytoskeletal components and organelles
- associated with vesicle and organelle movement
- help stabilize Mirotubules (MT) in cilia and Flagella
Function of Microtubules
- Provide physical support for cells via cytoskeleton
- Chromosome movement during cell division-involved with ciliary movement
- Intracellular transport of secretory products
- Involved with cell division
Intermediate filaments
Not hollow protein polymer
- relativley stable compared to MT or MF
- all cells contain some type of intermediate filament
Function of Intermediate Filaments
Structural
What are the four major families of intermediate filaments
- Keratins-found in epithelial cells, tough=finger nails hair etc
- Vimentin and Vimentin like intermediate filaments: Not found in all cells
- Most widely distributed IF in the body - neurofilaments: found only in neurons
- Lamins: found in all nucleated cells
Microfilaments
protein polymer present in call cells
2 Basic types:
Actin and Mysoin
Microfilaments Function
- Contraction-cellular movement
- Cytokinesis-pinching of cell division
- Endocytosis
- Ameboid movement
- Structural support
Centrioles
Made of microtubules
-located near the nuclear=2 per cell
Structure: short cylinder
- microtubules arranged in 9 triplets (9x3)
- CCO patter connected by protein ilnks
Function of Centrioles
Serve as organizing centers for mitotic spindles during cell divison
- migrate to opposite polls of cell
- MTOC-microtubule organizing center
Cilia
3 portions:
- Shaft(axoneme): 9x2 + 2MT arrangement
- surround by plasmamembrane - Basal body: 9x3 MTarrangement like centriole
- Rootlet: anchors cilia to cytoskeleton
Cilia Fumciton
Movement
- Dynein arms cause movement
- uses energy of ATP to move
- found in respiratory tract and oviduct
Inclusions: Lipid or fat
May or may not be membrane bound
Inclusions: Glycogen
B glycogen: single subunit, 2x size of ribosome
alpha glycogen: cluster of beta glycoen
Inclusions: Residual Body
Tertiary Lysosome
Ex: Lipofuscin-accumulates with age
Microvilli
AKA striated border, brush border
- regular or irregular finger like projections that are extensions of the plasma membrane
- contain Villin-anchor found at tip
- contain actin filaments, fascinating, fibrin, and myosin I
- Have a TERMINAL WEB with SPECTRIN (ANCHORD), myosin II, tropomyosin
- Actin keeps MV rigid and discrete
NO MICROTUBULES in microvilli
Function of microvilli
increase surface area for exchange of material in the cell
-aid in absorption
Stereocilia
VERY LONG MICROVILLI
- found in sensory organs of the ear and male reproduction systems
- ARE NOT CILIA
Epithelia cells
cells that cover a free surface or line a tube or cavity
3 types of cell junctions
- Tight Junction=zonula occludens
- Belt Desmosome= zonula adherens
- Desmosome=macula adherens/spot desmosome
Tight Junction
AKA zonula occludens
- connect epithelial cell to epithelial cell
- membranes are in direct contact
Function:
- makes tight seal between cells
- prevent material from leaking between cells
- not a strong attachment
Belt Desmosome
AKA zonula occludens
-connects epithelial cell to epithelial cell
Contain:
- microfilament=actin
- dense cytoplasmic material
Function:
Very strong
-keeps cells from being pulled apart
Fascia adherens
attachments found between non-epithelial cells
- most found in cardiac muscle cells
- similar to structure to belt desmosomes
Desmosome
AKA macula adherens/spot desmosome
-connects cell to cell of all tissue types
Contain:
- tonofilaments=IF
- cytoplasmic plaque
- transmembrane linker protein
- Central Stratum=Dense intermediate line
Functions: For all cells
-holds cells together tightly
Hemidesmosome
One half of a desmosome
-connects epithelia to connective tissue
Contains:
- tonofilaments
- cytoplasmic plaque
- linker proteins
Gap Junction
Aka nexus junction
- the two membranes don’t touch
- allows for cell to cell communication
Made of 6 connexion protein subunits, aligned between adjacent cells
Function:
- allows for cell to cell communication
- involves electrochemical coupling
- small peptides can move from cell to cell
- move ions (moves charge)
Functional Complex
Connects epithelia to epithelia
consists of 3 types of junctions
- Tight Junction
- Belt desmosome
- Desmosome
Types of endocytosis
- Phagocytosis
- Pinocytosis
- Receptor mediated endocytosis
Phagocytosis
AKA clathrin independent and actin dependent endocytosis
- used for ingestion of larger particles
- involves actin depolymerization and repolymerization
- involves cell surface receptor that specifically bind a certain substance
Ligand
the specifice substance that binds to receptor
ex: hormone
Pinocytosis
Cell Drinking
- AKA clathrin independent endocytosis
- nonspecific ingestion of material in solution
- involves caveolae-uncoated vesicles
- DOESN”T INVOLVE RECEPTOR
Receptor mediated endocytosis
AKA clathrin dependent endocytosis
- specific ingestion of molecules into the cell
- coat pit forms
- Clathrin Coated vesicles made of triskelions is involved in the invagination and pinching off of the vesicle
The fats of the receptor ligand: 4 possibilites
- The receptor is recycled and ligand degraded
- The receptor and ligand are recycled
- The receptor and ligand are degraded
- The receptor and ligand are transported through the cell
Cholesterol
needed for steroid synthesis fo rate plasma membrane compounds
HDL
high density lipoprotein
- carry cholesterol to the liver for disposal
- cholesterol ends up in the bile
LDL
-what does name mean
low density lipoprotein
