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Histology Cell Cytoplasm


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What is a cell?
A structural and functional unit of every living organism - organization and compartmentalization
What is the structure of the Biological Membrane.
5-7.5nm thick
Phospholipid bilayer
asymmetric distribution of charge (resting potential)
Modified fluid mosaic
Integral membrane proteins and sugars (Glycocalyx)
What is the structure of phospholipids.
Hydrophilic end
Hydrophobic end (fatty acid chain)
-unsaturated (bent)
-saturated (straight)
How do cholesterol and unsaturatted fatty acids affect membrane fluidity?
cholesterol decreases fluidity
unsaturated fatty acids increase fluidity
What are some key intergral proteins of the cell membrane?
Receptor Proteins
Linker Proteins
Structural Proteins
What do membrane protein pumps do?
Active transport of ions, amino acids, and sugars
What are membrane protein channels? What are some types of membrane protein channels?
Passive transport (diffusion) of small molecules
Voltage gated
Ligand gated ion channels
Mechanically gated ion channels
What are membrane receptor proteins?
Recognition and localized binding
What are membrane linker proteins?
Anchor intracellular cytoskeleton to extracellular matrix
Membrane Enzymes
Variety of roles
ATPase (H+ transport)
Membrane Carrier Proteins and Characteristics of Transport
Passive transport (facilitated)
High specificity
High efficieny
Modified Fluid Mosaic
Semifluid phospholipid bilayer
Integral membrane proteins
peripheral membrane proteins
carbohydrates on proteins
carbohydrates on lipids
Hydrophobic and Hydrophilic molecules in transport
Hydrophobic freely diffuse
Hydrophilic must be transported
Cell Nucleus Function
Stores and produces genetic information
Cell Nucleus Structure
Chromatin, Nucleolus, Nuclear Envelope
Chromatin and types of chromatin
DNA, Histones, and non-Histone proteins
Euchromatin - active in transciption (pale + loose)
Heterochromatin - transcriptionally inactive (dark + condensed)
Dense, nonmembranous structure containing fibrillar and granular material
Site of ribosomal RNA synthesis (granular)
Regulation of cell cycle
Stains intensely with Hematoxylin and basic dyes
Nuclear Envelope
Mediates transport via pores
->Nucleus structural + enzymatic proteins
<-Nucleus mRNA, tRNA, ribosomal subunits
Ribosomes Function
Use mRNA to produce proteins in cytoplasm
rER-bound Ribosomes
Membrane proteins
Secretory proteins
Lysosomal proteins
sER-bound Ribosomes
Nuclear proteins
Mitochondrial proteins
Peroxisomal proteins
Cytosolyic proteins
Cytoskeletal proteins
Rough Endoplasmic Reticulum Structure and Function
Mainly cisternae
Ribosome attaching proteins
Protein Synthesis
Protein Modification
Smooth Endoplasmic Reticulum Structure and Function
Mainly tubules
Flattened sheets, sacs, and tubes of membranes
Lipid synthesis
Detoxification of xenobiotics
Storage of Ca2+
Metabolism of glycogen, lipids, + steroids
Golgi Apparatus Function
Posttranslational modification, storing, + packing of proteins
Membrane remodeling
Glycosylation, phosphorylation, +sulfination of proteins
5nm thick
Proteins similar to rER
Contains enzymes that cut sugar residues
7.5nm thick
Proteins similar to membrane
Contains enzymes that add sugar residues
Dictyosome and 3 types of vesicles
Subunit of the Gogli
-Empty, new membrane fragments
-secretory granules
-hydolase vesicles become lysosomes
Vesicle discharges its contents from cell fusion with cell membrane
Regulated secretion
Fusion between membranes requires similarity among membranes
Constitutive Exocytosis
Constant Process
Regulated Secretion Exocytosis
Dependent on external signals, hormones
Uptake of fluid + Macromolecules
Receptor mediated
Ingestion of large particles (debris + bactria)
cell membrane protudes outward
Receptor medicated
Specialized cells (inducible)
Costitutive - continuous dynamic formation of vesicles
In all cells
Receptor Mediated Endocytosis
Clathrin dependent (creates coat)
ligands dissociate from receptors at low pH in endosome
recycling and recirculation of clathrin and receptors
Major protein that interacts in endocytosis
Binds with receptors, coats outside of vesicle
Eventually uncoat, recylce, and recirculate
Early Endosomes
Derived from endocytosis
Vesiculo (tubular shape)
low acidic pH
recirculates membrane receptors
Lysosomes Structure and Function
Late endosomes
Contains - membrane, material to be digested, + hydrolytic enzymes
Digestion by hyrdolytic enzymes (split but adding water)
ATP->ADP transporting H+, creating an acidic environment
Lysosomal Enzymes
Acid phosphytase
Acid hydrolases, nucleases, proteases, glycoxidases, lipidases
Lysosomal Enzyme Incorporation
Synthesized in rER
Labelled w/ Manose-6-Phosphate
Picked up by TGN
Transported to late endosome
Digest external material (bone-osteoclasts, tumor cells, inflammation)
Digest material from within cell (ER surrounds organelle)
Mitochondria Function
Energy creator by proton gradient (proton motive force)
Controlled release of energy by ETC (stepwise)
Citric Acid Cycle
ATP production - oxidative phosphorylation
Synthesis of Steroids
Mitochondria Structure and Composition
Contains DNA, RNA, ATP, Ca2+
Inner and outer membranes
Aerobic bacteria ? Symbiotic relationship
Innermembrane space, matrix, matrix granules, crista, ATP synthase
Inner Mitochondrial Membrane, Folds, + Marker Enzyme
Cristae (folds)
80% proteins
controlled passage is very specific, transport via proteins
ETC system
globular particles
Cytochrome Oxidase (marker)
Outer Mitochondrial Membrane and Marker
Smooth contours
50% proteins
Molecular seave
Monoamioxidase (marker)
What is the structure of a peroxisome?
How do peroxisomes appear in cells?
Oxidative enzymes enclosed in a single membrane
Interconnected in groups
0.2-1um diameter
40+ enzymes (catylase, peroxisomal oxidase, lipid synthesising enzymes)
Peroxisomes Function
Decomposition of H2O2
B-Oxidation of long fatty acids
Synthesis of lipids, bile acids, + steroids
Microtubule Structure
Elongates polymeric structures
Equal parts alpha-Tubulin and B-Tubulin (create dimer gamma)
Create hollow cylindars 13 monomer circumference
9 Triplets
25nm Diameter
Mictotubule Function
Intracellular transport
Cell motility
Maintinance of shape
Separation in mitosis
Dynamic instability - always changing
Microtubule Types
Stable (cilia, flagella)
Moderately stable (cytoplasm)
Unstable (mitotic spindle)
Move along microtubules towards the minus end
Move from periphery to cell center
Move along microtubules towards the plus end
Move from center to periphery
Actin Filament (Microfilament) Structure
Two stranded polymers of actin protein
5-7nm Diameter
Actin Filament (Microfilament) Function
Maintain cell shape
Contract when interact w/ myosin
Transport of membrane
Extracellular attachment
Intermediate Filament Structure and Location
Ropelike fibers (levels of interwoven fibers)
10nm Diameter
In nucleus (lamins) and cytoplasm (tissue specific proteins)
Intermediate Filament Function
Support, contact, + stabalization

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