unit of life introduction to molecular cell biology unit of life dr. fridoon jawad ahmad hec foreign...
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Introduction to Molecular Cell Biology
Unit of LifeUnit of LifeDr. Fridoon Jawad AhmadDr. Fridoon Jawad Ahmad
HEC Foreign ProfessorHEC Foreign ProfessorKing Edward Medical UniversityKing Edward Medical University
Visiting Professor LUMS-SSEVisiting Professor LUMS-SSE
OverviewOverview
Life
Life is not a random collection of some macromoleulces.
Life is a collection of macromoleulces that can perform unique functions because the are enclosed
in structural acompartment that provides consistency (homeostasis).
All organisms are composed of cells the basic unit of life and all cells come from preexisting cells
Cells are Small
Cells are small to maintain large surface area to volume ratio.
Larger volume requires a grater
exchange of materials from out
side which is a function of surface
area.
Prokaryotic Cells
No membrane enclosed internal compartments.
The plasma membrane regulates traffic is a barrier.
Nucleoid region contains DNA, most have cell wall.
Support & Cell shape
Protection From Phagocytes
Special Prokaryotic Cells
Cyanobacteria Chlorophyll containing have folds of plasma membrane, other have mesosomes (energy).
Some have actin like filaments and other have Flagella made-up of Flagellin.
Eukaryotic Animal Cell
Eukaryotic Plant Cell
How the Function of Organelles was
determined
The Nucleus
Chromatin and Chromosome
Ribosomes
Free or attached to ER involved in protein synthesis.
Present in Mitochondria & Chloroplasts.
Contain protein and RNA.
RER
Segregates newly synthesized Proteins.
Chemically modifies proteins (Glycosylation adress)
SER
Glycogen hydrolysis.
Secreting and detoxifying cells have abundant SER
Cis, Medial & Tarns
Golgi Apparatus
The Golgi apparatus receives materials from the rough ER
and modifies them.
Concentrates sorts and packages proteins and sends
them to other destinations.
Manufactures poly-saccharides for the plant wall.
Lysosomes
Lysosomes contain many digestive enzymes.
Lysosomes fuse with the phagosomes produced by phagocytosis (autophagy) to form secondary
lysosomes, where engulfed materials are digested.
Undigested materials are secreted from the cell when the secondary lysosome fuses with the plasma
membrane..
Mitochondria
Breakdown fuel molecules to make ATP.
Some protists have one, liver more than a thousan
and egg a few hundred thousand MT.
Mitochondria and chloroplasts contain their own DNA and ribosomes for making some of their
own proteins.
Endosymbiosis
The endosymbiosis theory of the evolutionary origin of mitochondria and chloroplasts states that these
organelles originated when larger prokaryotes engulfed, but did not digest, smaller prokaryotes.
Mutual benefits permitted this symbiotic relationship to be maintained, allowing the smaller cells to evolve
into the eukaryotic organelles observed today.
Photosynthesis
Detoxification of O2
Peroxisomes and Glyoxysomes
Peroxisomes collect and degrade toxic
Peroxide H2 O2
byproducts of chemical reactions
Glyoxysomes convert stored lipids into carbohydrates.
Cytoskeleton
Cytoskeleton
Actin (cortical) Stabilizes cell shape.Generates movement local general.
Constriction ring in cell divission (Cytokinesis). Movement of cytoplasam (cytoplasmic strreaming).
IF stabilize cell structure (hold organelles).Stabilize and maintain tissue rigidity (desmosomes).
Lamins in nucleus.Resist tention.
IF in Desmosomes
Microfilaments for Support
Celia are Made of Microtubules
movements
The movements of cilia and flagella result from the binding of the motor protein dynein to
the microtubules.
Dynein and another motor protein, kinesin, also bind to
microtubules to move organelles through the cell.
ECM in Animals
Bone