Download Unit of life MBBS Prof. Fridoon - King Edward Medical University

Introduction to Molecular Cell
Biology
Unit of Life
Dr. Fridoon Jawad Ahmad
HEC Foreign Professor
King Edward Medical University
Visiting Professor LUMS-SSE
Overview
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 polysaccharides 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