Eukaryotic Cell Components PDF

Summary of Eukaryotic Cell Components Plasma membrane 6 membrane enclosed organelles (KNOW FXNs/CC’s for ALL of these!!!) ○ Nucleus ○ Mitochondria ○ Lysosomes ○ Peroxisomes ○ Endoplasmic reticulum ○ Golgi apparatus Cytoskeleton Plasma membrane S...

Summary of Eukaryotic Cell Components Plasma membrane 6 membrane enclosed organelles (KNOW FXNs/CC’s for ALL of these!!!) ○ Nucleus ○ Mitochondria ○ Lysosomes ○ Peroxisomes ○ Endoplasmic reticulum ○ Golgi apparatus Cytoskeleton Plasma membrane Selectively permeable to ions and organic molecules Phospholipid bilayer: 2 hydrophobic fatty acid tails joined to a hydrophilic head Major component: Lipids + Proteins ○ Lipids 75% phospholipids 20% cholesterol Membrane fluidity 5% glycolipids Cell recognition Antigenic determination ABO blood group ○ Proteins Integral membrane proteins permanent association Peripheral membrane proteins transient association Phospholipids Outer leaflet- facing extracellular environment Inner leaflet- facing intracellular environment Individual phospholipids can exchange positions between the same monolayer (lateral diffusion) but rarely exchange exchange between layers (flip-flopping) ○ Flippases- enzymes that can mediate exchange between the outer leaflet and inner leaflet The Bilayer ○ Small nonpolar molecules diffuse across the membrane (oxygen, nitrogen, CO2) ○ Small uncharged polar molecules also cross the bilayer (water, ethanol) ○ LARGE, UNCHARGED, POLAR molecules and IONS CANNOT pass, and thus require a transporter. Glucose, AA Na+, K+, H+, Cl- (ions) Ion Concentrations In & Out of the Cell: ○ Inside the cell: Potassium (K+) is King ○ Outside the cell: Sodium (Na+) and Cl- What helps establish this difference in ions in and out of the cell? (related more to content in Lecture 5 but this is a relevant preview) Sodium Potassium pump i.e. Na+/K+ ATPase --> pumps 3 Na+ out of the cell & 2 K+ into the cell (HY) How I remember it that is FOOLPROOF = 3 Na+ out, 2 K+ in ○ Na+ & out = 3 characters ○ K+ & in = 2 characters Nucleus Info storage, encoded by DNA Composed of DNA surrounded by a nuclear envelope with 2 lipid bilayers ○ INM: proteins formed by nuclear lamina → shape/rigidity ○ ONM: continuous w/ ER membrane Clinical Correlate: Progeria Mutation in Lamin A = normally helps form structural component of nuclear envelope called the nuclear lamina (below INM) Mutation leads to a cryptic splice site, resulting in the truncated protein “progerin” Progerin is not integrated into the nuclear lamina= disfigured nucleus and altered genomic integrity Premature aging of the MSK and CV systems Mitochondria Membrane bound (inner + outer) w/ matrix inside Functions: Energy (ATP), machinery for oxidative phosphorylation (ETC inner membrane), components of TCA (Krebs) cycle in matrix, enzymes for beta oxidation of FA, heme synthesis, steroid synthesis, multiple molecules associated with apoptosis Why is it special? FISSION and mtDNA ○ All mitochondria DNA (mtDNA) originate from mom, and it encodes for most of the proteins it requires, it is circular in shape (plasmid), no contribution of genetic diversity from dad Clinical Correlate- Mitochondrial Myopathies mtDNA has a high mutation rate due to lack of DNA repair mechanisms Symptoms vary but are typically rooted in weakness (ie drooping of eyelid, swallowing difficulty, etc) ○ Skeletal muscle fibers are sensitive due to high energy metabolism Severity depends on which organs are affected Difficult to diagnose Lysosomes Membrane bound, full of digestive enzymes (hydrolases), capable of breaking down most macromolecules Important in immunity --> pathogens are engulfed by phagocytic cells of the immune system and broken down within the lysosome Clinical Correlate- Autosomal recessive, defect in lysosomal enzyme Tay-Sachs Disease: deficiency in Hexosaminidase A (Hex A) ○ Results in build up of ganglioside (lipid) in neurons leading to neurological deterioration, cherry red spot on the retina ○ Begins ~3-6 mos old, death btwn ages 2-4 Hurler Syndrome: defect in alpha-L-iduronidase ○ Enzyme NORMALLY breaks down glycosaminoglycans (GAGs), so pts have build-up of GAGs ○ Skeletal muscle abnormalities in addition to mental defects ○ GAGs in urine Peroxisomes Provides an environment where oxidative reactions can take place which are typically very toxic like the breakdown of very long chain fatty acids (Beta oxidation) Contains catalase enzyme = converts H2O2 to H2O and O2 Think detoxification; liver + kidney Clinical Correlate- Zellweger Zellweger syndrome: mutation in peroxins (proteins that normally help form peroxisomes) ○ Accumulation of very long chain fatty acid levels in blood because B oxidation is no longer fxnal w/o fxnal peroxisomes ○ Impaired brain development ○ Fatal w/in 1st yr of life Endoplasmic Reticulum Membrane bound sacs/tubules continuous with ONM SER: major site of synthesis of new membrane ○ NO RIBOSOMES ASSOCIATED!!!!! RER: studded WITH RIBOSOMES, where secretory proteins are made ○ Proteins that need to be transferred to PM or incorporated into vesicles are synthesized here Storage for intracellular calcium = sarcoplasmic reticulum --> muscle contraction Unfolded Protein Response (UPR): quality control for newly synthesized proteins. ○ If proteins don’t fold into proper 3͒ structure, ER shuts down protein synthesis & cell may undergo apoptosis. Golgi Apparatus Source of secretory vesicles, has polarity ○ Cis face recieves transport vesicles ○ Trans face releases secretory vesicles 3 functions: (1) Modification (2) Packaging (3) Sorting Clinical Correlate- I cell Disease Deficiency in an enzyme that NORMALLY phosphorylates lysosomal enzymes coming from RER (GlcNac-1-phosphotransferase) --> so lysosomal enzymes coming from RER are NOT phosphorylated in the Golgi --> unphosphorylated enzymes are no longer properly directed to lysosomes, and are instead released from the cell...ie THE LYSOSOMES LACK THE NECESSARY ENZYMES TO FXN This leads to a build up of lysosomal enzymes are present in the BLOOD of patients with I-cell Defective growth and mental defects Death between 5-7 years Screenshot from Sophia’s disease chart BE ABLE TO DIFFERENTIATE THESE DISEASES!! They could give you a mutation and make you diagnose. Or give you symptoms and make you know the disease and mutation. Know this chart in and out!!!!! Use a whiteboard to practice, cover parts up and quiz yourself, or use flashcards. Do whatever works best for you, but make sure you do something!!!! Make sure you know which disease affects which organelle and HOW/WHAT IT LOOKS LIKE!!!!!! ANNDDD...this is another version of the same chart for y’all to see just how important this is! Organelle Disease/ Syndrome Mutation/Defect Features Nucleus Progeria Lamin A Premature aging of the MSK and CV systems Mitochondria Mitochondrial Myopathies mtDNA or nuclear DNA Neuromuscular disease symptoms Lysosomes Tay-Sachs Hex A Accumulation of ganglioside in neurons, neurological degeneration, cherry red spot Hurler Syndrome α-L-iduronidase Accumulation of GAGs in urine, skeletal muscle abnormalities, mental defects Peroxisomes Zellweger Peroxins Impaired brain development, liver and kidney lesions, diagnosed by very long chain fatty acids in blood Golgi Apparatus I cell disease GlcNac-1-phosphotransferase Defective physical growth and mental defects, secreted lysosomal enzymes are present in blood A five year old girl presents to her physician with delays in physical growth, and inability to form full sentences. Lab results show the presence of polysaccharides in her urine. What is most likely defected? a. Lamin A b. Alpha-L-iduronidase c. Hex A d. Peroxins