Exam 1 material Flashcards
Cell
a mass of protoplasm limited in space by a membrane
(protoplasm-living matter composed of cytoplasm and nucleoplasm
Protoplasm
living matter composed of cytoplasm and nucleoplasm
Organelles
“Little organs”
- have distinct structure-membranes
- perform specific energy requiring functions
Inclusions
Storage components (ie. glycogen, lipids, lipofuscin)
- no membrane
- sometimes scaffolds for other functions
Cytoplasm- glycogen lipids, lpiosion
Nucleus-many types
Difference between organelles and inclusions
Organelles have membranes
Inclusions do not
Cell Membrane
About 75 Angstroms thick
- a bilayer of phospholipids w/proteins
1. Plasma membrane (Plasmalemma)- selective barrier between the enviroment and cytoplasm
2. Trilaminar structure-due to phospholipids
Glycocalyx
Cell Coat
- carbohydrates that extend from cell membrane
- made from either proteins in the external face of Plasma membrane (glycoproteins) or from phospholipid molecules (glycolipids)
- Function: Cell to cell recognition, cell to cell adhesion
Globular Proteins
Move around and spin within the plasma membrane
-ion channels, pumps, receptors, transducers, enzymes
Nucleus
Contains genetic material-CALLED Nucleoplasm
-surrounded by nuclear envelope
Nuclear Structures
Chromatin (2 types)
Nucleolus
Nuclear Envelope
Nuclear Cytoskeleton
Chromatin
-2 types
(Protein/DNA)
1) Heterochromatin
- Dense coiled DNA
- Darker staining on EM
- Basophilic (stains blue) on LM
- Fund in 3 locations:
a) marginal chromatin(near edge)
b) Karyosomes (not near the edge)
c) nucleolar associated chromatin
2) Euchromatin
- uncoiled DNA more active
- lighter staining on EM
- Unstained on LM
Nucleolus
site of rRNA synthesis
Nuclear Cytoskeleton
Nuclear Lamina
-made of lamins (proteins)-intermediate filaments-serves as scaffolding for nuclear components
-
Lamins
Proteins that 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 large and small subunits to form ribosome
Classification of ribosomes
Free Ribosomes
- located in cytoplasm
- proteins they produce stay in the cell
ER (endoplasmic reticulum) bound:
- extracellular protein synthesis
- protein products usually integral plasma membrane proteins or secreted
Intracellular Protein Synthesis
Occurs on free polyribosomes
Polyribosomes
cluster of any type of ribosome linked by mRNA
Extracellular Protein synthesis
occurs on ribosomes bound to ER
-inclues proteins bound for membrane
Endoplasmic Reticulum (ER) -types?
Rough Endoplasmic reticulum (RER or rER)
Smooth endoplasmic Reticulum (SER or sER)
Rough Endoplasmic Reticulum (RER or rER)
- contain ribosomes
- protein synthesis for insertion into membrane or export
- contain cisternae
- membrane bound translation
Where does a protein that has been synthesized on the ER go afterwards?
Golgi Apparatus
Smooth Endoplasmic reticulum (SER or sER)
-contains no ribosomes/no protein synthesis
function-
- synthesis of steroid hormones, glycogen and lipids
- HCl formation (gut)
- Ca2+ stored in the sacroplasmic reticulum
- drug detoxification`
Golgi Apparatus
- site of protein modification
- transfer vesicles containing protein move from RER to forming/cis face of the golgi
- carbohydrates are added to form glycoproteins, then packaged in secretory grande;s for cellular export
- produces glycocalyx for integral membrane
Lysosomes
Formed at the Golgi-membrane bound
-contain hydrolytic enzymes used for digestion of extracellular or intracellular components
Function:
- breakdown of cell
- cell remodeling
- normal turnover of organelles/macromolecules
- breakdown of bacteria and viruses
2 Types
- Primary Lysosomes
- Secondary Lysosomes
Primary Lysosomes vs secondary Lysosomes
Primary:
- newly formed
- not yet digesting material
- Light on EM
Secondary:
- actively digesting
- Dark/opaque on EM
Lysosomes:
-enzyme specific for
Proteins: proteases Nucleic acids: Nucleases Polysaccharides: glycosidases Lipids: Lipases Organic Linked Phosphates: Phosphatases
Tay Sachs Disease
Lipid metabolism defect
-autosomal recessive trait
-missing enzyme (hexosaminidase-found in lysosome) for splitting off hexose form a ganglioside
-gangliosides accumulate in neural tissue causing retardation and childhood death
Ganglioside
complex form of a glycolipid found in gray matter cells in CNS
Peroxisomes
Contain many oxidative enzymes (catalase ex) that breakdown Hydrogen Peroxide (H2O2)
- H2O2 is toxic to cells-causes free radical formation (unpaired electrons)
- free radical cross linked proteins=non functional
Mitochondria
Provide energy for the cell in the form of ATP
- contain their own circular DNA and ribosomes for self replication
- found in all cells except RBC and terminal Keratinocytes (in skin)
- NO ER
- where TCA cycle occurs
Function:
-ATP production, calcium sink, and heat production (brown fat)
Cytoskeleton
Non membrane found organelles
3 types:
- Microtubules
- Intermediate Filaments
- Microfilaments
MAPS
Microtubule Associated proteins
- Link Microtubules (MT) to other cytoskeletal components and organelles
- associated with vesicle and organelle movement
- help stabilize microtubules (MT) in cilia and flagella
Microtubules
Largest of Cytoskeleton
- protein polymer made of tubulin subunits; has an alpha and beta tubulin subunit (protein dimer)
- tubulin dimer polyermize to form microtubule; reversible depending on ADP, pH Ca2+ concentration
- present in all cells
- can change length depending on physiological conditions within the cell
- line up to form spindle fibers in mitosis
Function
- 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
Type of cytoskeleton
- Protein polymer that isn’t hollow
- relatively stable compared to MT (microtubules0 or MF (microfilaments(
- Function=structural
4 major families of intermediate filaments
1) Keratins-found in epithelial cells, tough-fingernails, hair etc
2) Vimentin and vimentin like intermediate filaments:
- not found in all cells
- most widely distirubuted IF in the body
3) Neurofilaments
- found only in neurons
4) Lamins
- found in all nucleated cells
Microfilaments
MF
-2 basic types: Actin and myosin
Function:
- contraction (cellular movement)
- cytokinesis (pinching of cell division)
- Endocytosis-cell membrane invaginates
- Ameboid movement
- Structural support
Centrioles
- location
- structure
- made of?
- Function?
made of microtubules
Location: near the nucleus-2 per cell
Structure:
-short cylinder made of microtubules in 9 triplets (9x3)
-each triplet contains 3 microtubules in CCO pattern connected by protein links
Function:
- during cell division, migrate to opposite poles of cell
- serve as organizing centers for mitotic spindles (MTOC-microtuble organizing center)
- some drugs interfere with MT asesembly-during cell cycle
Inclusions
-types?
Do not perform energy-requiring functions
3 Types
1) Lipid or Fat: may or may not be membrane bound
2) Glycogen
-B glycogen: single subunit 2x size of ribosome
-Alpha glycogen: cluster of Beta glycogen
3) Residula body
-tertiary lyososome (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 at tip)
- contain actin filaments, fascin, fibrin, and myosin 1
- have a terminal web with spectrum (anchor), myosin II, tropomyosin
- Actin keeps MV rigid and discrete
Function:
- increases surface area for exchange of material in the cell
- aid in absorption
** no microtubules in microvilli
Stereocilia
very long microvilli
- found in sensory organs of the ear and male reproduction system
- NOT CILIA
Epithelia
cells that cover a free surface or line a tube or cavity
have attachment through each other through type of cell junctions:
- tight junction
- belt desmosome
- Desmosome
Tight Junction
AKA zonula occludens -connect epithelial cell to epithelial cell -membranes are in direct contact - function: -make tight seal between cells -prevent material from leaking between cells -not a strong attachment
Belt Desmosome
AKA zonula Adherens
-connects epithelial cells to epithelial cells
function: keeps cells from being pulled apart VERY STRONG
Composed of:
- microfilaments: actin
- dense cytoplasmic material
Fascia Adherens
attachments found between non-epithelial cells
- most found in cardiac cells
- similar structure to belt desmosomes
Desmosome
Macula Adherens or Spot Desmosome
- connects cell to cells; all types of cells
- contain monofilaments
- cytoplasmic plaque
Function:
holds cells together tightly
Hemidesmosome
one half of a desmosome
- connects epithelia to connective tissue
- tonofilaments
- cytoplasmic plaque
Gap Junction
Nexus Junction -two membranes don't touch! -allows for cell to cell communication - Function: -allows for cell to cell communication -involves electrochemical coupling -small peptides can move from cell to cell -move ions/charges-important in cardiac and smooth muscle
Functional Complex
connects epithelial cells to epithelial cells
Consists of 3 types of junctions:
- tight junction
- belt desmosome
- desmosome
