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MCB - Cell Structure

Oranganelles in Eukaryotic Cells

prokaryotic cell cells contain no membranous organelles and thus no extensive comparmentalization
eukaryotic cell cells contain membrane compartments to segregate energy production, metabolic rxns, biosynthetic pathways, and degradative processes
Describe the organization of the membrane according to the fluid mosaic model biological membranes are made of a phospholipid bilayer with embedded proteins and lipid rafts that can laterally diffuse
What are the 2 main classes of membrane molecules and briefly describe them (1)Integral (Transmembrane)membrane - partially/fully inserted in membrane that fxn as receptors, transporters, & enzymes. include glycoproteins (carbs on proteins) (3)Peripheral - attached by interactions with integral proteins
Lipid rafts domains that membrane compartmentalizes in to function as an organizing center for signaling complexes
What does membrane fluidity regulate and what 2 factors can alter fluidity? regulates transport and signaling alterations: increased cholestral = decreased fluidity (and thus decreased signaling and transport); increased unsaturated fatty acids = increased fluidity
simple diffusion concentration dependent (not specific) for small nonpolar (gases) or small uncharged polar (water)
facilitated diffusion transport is specific but no energy needed. for ions (via ion channels), water (aquaporins), or solutes such as glucose (solute carriers)
Active membrane transport transport recquires energy and moves against concentration gradient. Seen in pumps or vesicular/bulk transport
Describe the distinct structural elements of the nucleus Inner and outer membrane forms the nuclear envelope which contains nuclear pores that allows for exchange between the nucleus and cytoplasm. lining of inner nuclear membrane is made of intermediate filaments called lamins; outer is continuous with R.ER
What types of chromatin (DNA + protein) are found in the nucleus and how do they stain? heterchromatin - tightly coiled DNA that's inactive. stains in clumps of basophilic material euchromatin - uncoiled transcriptionally active DNA. Stains as light-colored bands due to it being less compact
Nucleolus area in nucleus involved in ribosomal RNA synthesis. Stains darkly due to basophilic RNA
Describe transport of nucleic acids and proteins through the nucleoporin complexes (NPC) receptor mediated - Karyopherins (importin and exportin) bind nuclear localization (to transport in Nuc.) and nuclear export signals (to transport out). GTP-dependent
How do chromosomes arrange themselves within the nucleus? organized in territories/globules with exons (active DNA) towards the inside of nucleus and introns towards the periphery. Chromosomes in different globules don't interact
What important role do the lamins in the nuclear envelope play? regulate nuclear structure through chromosomal structure and expression to help determine cellular fate (which is why laminopathies tend to be tissue-specific
Describe the general structures of nucleolus make of a granular component where initial ribosomes are assembled and fibrillar network (nucleolonema) which is further subdivided into fibrillar center for TFs, Pol 1, and rRNA genes; and a Dense Fibrillar Component where rRNA genes are transcribed
Give the structure, diameter, subunits, and fxn for microtubules hollow cylider made of 13 polymers with protein cap at - end; 25 nm; alpha & beta tubulin dimers; intracellular transport of organelles and vesicles, axoneme (core of cilia), centrioles (organize mitotic spindle & cytokinesis), cell shape and migration
Give the structure, diameter, subunits, and fxn for intermediate filaments solid fiberous cables; 10-12 nm; several classes of proteins including keratins,vimentin, desmin; structural support to maintain shape, anchor nucleus and organelles, nuclear lamina
Give the structure, diameter, subunits, and fxn for microfilaments linear polymers of actin; 5-7 nm; g-actin; resist tension and maintain cell shape, thin filaments in mm, cytokinesis inside cell, any contractile event, core of microvili
Give the 2 motor proteins for microtubules Dynein - retrograde (- end directed) mvmt towards nucleus Kinesin - anterograde (+ end directed) away from the nucleus
What is the motor protein for microfilaments? Myosin (found in both mm contraction and intracellular mvmt)
What are the 3 microtubule oranizing centers (which are interconnected with the nucleus) (1)centrosome - made of 2 centrioles of radil MTs (2)basal bodies - MT triplets that anchor cilia (3)golgi - found in all cells
What are the 3 main anti-mitotic alkaloids used as chemotherapy agents that target MT's to disrupt mitosis? (1)Colchicine - binds tubulin to prevent spindle from forming (2)taxol - depletes tubulin pool (3)vinblastine - depolymerizs MTs
Give the general structure of a mitochondria composed of outer and inner membrane folded into cristae; Space inside cristae is the matrix & where much of respiration occurs; outside cristae is innermembrane space & is H+ rich; inner memb. contain OXPHOS enzymes including SDH
What protein marker is used to labeled mitochondria and thus metabollically active cells? Succinate Dehydrogenase
Type 2 diabetes, Parkinson's, atherosclerosis, and stroke are all caused by what type of malfunction mitochondrial defects (often causes an increase in mitochondria numbers)
Where in the mitochondria is the Mt DNA, ribosomes, and RNA's found matrix
What are the 2 types of cytoplasmic inclusions found in cells (1)Glycogen - stored glucose, common in liver and mm cells near mitochondria (2) lipid droplets - stored triglycerides, common in fat and liver cells
What are the 2 main type of ribosomes? (1)Free - translate cytoplasmic proteins (2)Membrane-bound - found on RER, translate membrane proteins or secretory proteins
In which organelle does disulfide bonds formation, protein glycosolation, protein sorting and checking, and protein sythesis occur? Rough ER
What feature of the RER and golgi make them visible by light microscopes? rRNA that makes them basophilic (and thus can be stained with basic dyes
Which orangelle is responsible for steroid synthesis, degradation/neutralization of hormones alcohol and drugs, and membrane phospholipid synthesis Smooth ER
What cell would have abundant ribosomes, but lack RER, golgi, SER, and secretory vesicles? erythrocyte
What cell would have few ribosomes and SER, but abundant RER and Secretory vesicles? pancreatic acinar cells
What cell would have few ribosomes and RER, but abundant SER and Secretory vesicles? Leydig cell
What is contained inside lysosomes? many varieties of enzymes that are all low pH dependent. Proton pumps on lysosome membrane ensure a high [H+] inside lysosome
How are lysosomonal enzymes directed to lysosome? soluble proteins produced in the RER to form a mannose-6-phosphate that causes a coated vesicle to bud from the golgi and form a late endosome that matures into a lysosome
what are the 3 autophagic pathways that lysosomes degrade proteins and organelles (1)macroautophagy & (2)microautophagy - both nonspecific (3)chaperone - selective process for protein degradation; very abundant in liver + kidneys (organs for degrading proteins)
What often accumulates in the aged cells and is associated with age-related diseases? lysosomal residual bodies - nondigestable components (such as lipofuscins seen in macular degeneration)
Hurler syndrome, tay-sachs disease, gaucher disease, I-cell disease are what types of disorders? lysosomal storage disorders - cause accumulation of substance in lysosome until they reach toxic levels; treated with enzyme replacement therapy or substrate reduction therapy
proteasomes protease complexes that digest proteins tagged with poly-ub polymers
peroxisomes single membrane bound organelle that metabolizes lipids; found in all cells, especially in liver cells; oxidizes substrates to H2O2 and use catalase to convert H2O2 to water
Zellweger syndrome and x-linke adrenoleukodystrophy are what types of disorder peroximal disorders - Zellweger causes defective enzyme transport to peroxisome; adrenoleukodystrophy causes defective FA uptake
what are the 3 main vesicular trafficking methods in cells (1)Endocytosis (pinocytosis, phagocytosis, receptor-mediated) (2)exocytosis (3) transcytosis
pinocytosis uptake of fluids and small molecule; non-selective
phagocytosis uptake of particles through actin-powered invagination; non-selective; use Fc receptors to bind to antibodies attached to antigens
Receptor-mediated endocytosis uptake of specfic cargo for transport in clatherin-coated vesicles as well as many other proteins
What is the fate of a ligand-receptor complex in receptor-mediated endocytosis? degrade ligand, recycle both, degrade both, transcytosis.... regardless of fate, all contain a vesicle coat that sends it to an early endosome to sort cargo
Describe the pathway for endocytosed cargo destined for degradation? cargo endocytosed by a clatherin-coated vesicle; coat is shed as it fuses with an early endosome containing H+ pumps that decrease pH so the ligand dissociates from the receptor. a vesicle carrys ligand to late endosome which later fuses with the lysosome
what are the 2 means of exocytosis? (1)constitutive - most common method where cargo is continuously secreted and not allowed to accumulate (2)Regulated - some external stimulus triggers secretion
Created by: c.phill