Basic Cell Biology, major cellular functions: cell division, cellular differentiation and cell death. History of Physiological Vs pathological cell death.

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Basic Cell Biology, major cellular functions
cell division, cellular differentiation and cell
death. History of Physiological Vs pathological
cell death. Chemistry of life Eukaryotic cells
Vs Prokaryotic cells Compartmentalization for
better regulations of gene expression and other
complex biological reactions Cell structure Cell
types Major cellular components Plasma
membrane An asymmetrical Lipid bi-layer Phasphatid
ylethenolamine, phasphatidylserine,
phasphatidylcholine, sphingomylein, membrane
proteins, glycolipids, glycoproteins Cholesterol
(important for provide structural rigidity to
membrane) Membrane proteins Receptor proteins,
ion channels and transport proteins Functions
as barrier between cytoplasm and extra-cellular
environment, Controlled transport of chemicals,
ions and macromolecules Exocytosis and
endocytosis Signal transduction, Generation of
action potential
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Welcome to the 0359-684 Cell death Apoptosis,
Necrosis and therapeutic opportunities
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Endomembrane system in eukaryotic cells
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Endoplasmic reticulum Lipid bilayer forming a
continuous sheet enclosing a single space called
ER lumen or cisternal space Rough and smooth
ER Functions Protein synthesis Post-translationa
l modification (glycosylation Glycolipd
synthesis Vesicular Protein transport and
secretion Detoxification (Smooth ER contain
cytochrome P450), water insoluble toxic compounds
are converted into excretable non-toxic soluble
compounds Ca2 sequestering Examples- muscle
cells (ER is called sarcoplamic reticulum), nerve
cells. Golgi bodies Membrane bound flattened
sacs stacked over each other. Functionally
distinct parts (cis and trans parts) Contains
protein modification enzymes e.g. glycosyl
transferase, nucleoside diphosphatase and acid
phosphatase Functions Posttranslational
modifications (glycosylation, dephosphorylation,
phosphorylation) Involved in sorting and
packaging macromolecule for secretion or for
delivery to other organelles. Proteins destined
for delivery to lysosomes are labelled with
mannose-6-phospate in Golgi bodies. Defect in
this process results in lysosomes without
hydrolytic enzymes and secretion of these enzyme
in I-cell disease or inclusion cell disease).
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Nuclear envelope Scanning Electron micrograph
of nuclear envelope showing nuclear pores.
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Nucleus and Nuclear envelope Chromatin Function
Replication, transcription Protein import and
RNP export across nuclear envelope
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Mitochondrial structure
Structure of chromatin
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Lysosomes Membrane-bound vesicles containing
hydrolytic enzymes Function Involved in
intracellular digestion Peroxisomes Membrane-boun
d vesicles containing oxidative enzymes such as
catalase and urate oxidase, and long chain fatty
acid oxidation during which there is production
of hydrogen peroxide. Functions Vestige of an
ancient organelle that carried out oxidative
reactions May play role in anti-oxidative
defence Mitochondria Double membrane-bound
structures, power plants of eukaryotic cells Site
for citric acid cycle and oxidative
phosphorylation and fatty acid metabolism in
energy generating biochemical pathway Outer
mitochondrial membrane Inter-membrane space Inner
mitochondrial membrane (contains components of
electron transport chain, ATP synthase, and
transport proteins) Matrix space (contains
enzymes and cofactors for citric acid cycle,
fatty acid metabolism, mitochondrial genome, and
transcription and translation machinery) Inner
mitochondrial potential is generated and
maintained by proton export out side ATP is
synthesis is driven by proton flow towards
inside Protein import into mitochondria
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Secretory cell of pancreas
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Role of solvent i.e. water and solute in the
origin of life
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Role of solvent i.e. water and solute in the
origin of life Importance of lipids in origin of
life Membrane formation is thermodynamically
favorable process
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• Cellular signalling and cell division
• Cellular signalling
• Evolution of social behaviour in cells
• Cell to cell communication and responses are
  essential for the organism as whole.
• Different types of cell signalling
• synaptic
• Endocrine
• Paracrine
• Autocrine
• Cell to cell signalling by direct contacts a)
  via receptors b) via gap junctions and
  plasmadesmata
• Extra-cellular signals
• Hormones
• Cytokines
• Growth factors
• Signalling Mechanisms

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Ion channel-linked Receptors Neurotransmitter
receptors NMDA receptors, serotonin,
acetylcholine receptors etc Binding----opening of
ion channel------influx of Na, or K or Ca
ions----downstream events Drugs barbiturates,
antidepressants used as blockers
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Receptor enzyme mediated Receptor tyrosine
kinases Examples- receptors for most of growth
factors e.g. FGF, PDGF, Insulin, IGF-1,
CSF Binding of ligand to RTK----activation of TK
activity------autophosphorylation-----binding of
GTPase activating protein or PI3 kinase or
phospholipase----Activation of PKC and/or
Ras---activation of MAPKKK----activation of
MAPKK---Activation of MAPK----c-Jun---activation
of transcription Receptor serine/threonine
kinases Examples- TGF-b family of receptors
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