i want 30 multiple choice questions with their model answer below each question that covers different aspects of all the following information of : Mitochondria
Mitos =thread ,chondros==granule)
Definition : membranous
organelle containing
enzyme for aerobic
respiration & adenosine
triphosphate (ATP)
The number and size:Location of mitochondria:
Mitochondria are concentrated in
cytoplasmic region where energy
utilization is more intense e.g:
muscle cells, they lie adjacent to
contractile elements.
by LM :
✓ Can be seen & appear rounded or elongated.
✓ Contribute to eosinophilia of cytoplasm
✓ They are highly plastic, changing its shapeLM of mitochondriaEM of Mitochondria
1- Two membranes: with a
narrow intermediate space.
2- Both membranes contain
more protein molecules
than other membranes in
other cell organelles &
have reduced fluidity .The outer membrane:
➢ Smooth and contains
transmembrane integral ptn
called (porins) that form channel
through which small molecules
such as pyruvate and other
metabolite pass from cytoplasm
into intermediate space.
The inner membrane:
(less permeable & selective)
➢ It projects into the matrix
forming folds called cristae.
➢ It increase surface area for
chemical reactions.
➢ Their number corresponds to
energy needed.The roughness of the inner membrane due to
the attachment of elementray particles
These particles contain enzymes involved in
the oxidative phosphorylation & electron
transport systems.Oxidative
phoshorylationThe lumen of mitochondria :
full of (granular matrix):
Matrix = gel with high
concentration of enzymes ),
granular? due to some
ribosomes and DNA
molecule .mRNA,tRNA and
rRNA and calcium ionsFunctions of mitochondria:
1) Production of energy, needed for all cellular and body
functions.
2) Due to their DNA contents, mitochondria can divide
and their number can be duplicated during cell division.What is the source of your
mitochondria ?Clinical Application
Defective mitochondria
(mutant) will lead to lack of
energy which is usually of
maternal origin.
Myopathy/ Neuropathy2- Endoplasmic reticulum
A) Rough endoplasmic Reticulum (RER)
B) Smooth-Endoplasmic Reticulum
(sER).A) The (rER):
1- Flattened Cisternae form .
Parallel to one another.
2- Its membranous continous
with outer nuclear m.
3-Has attached Polyribosomes
----- basophilic by light
microscope.
4- BY EM…. These channels
appear separated but actually they
connectedRER• Site :
➢rER well prominent in ptns secretory
cells like. Pancreatic
acinar cell
FibroblastFunction of rER:
THE MAJOR FUNCTION IS:
A- Synthesis of the protein
by it’s attached
polyribosomes. Then
segregation of this
proteins inside
intracisternal space.
B - Initial glycosylation of
proteins.B) The smooth-surfaced ER (sER):
A- System of anastomosing network
of intercomunicating tubules or
saclike (its cisternae are more
tubular rather than flattened
cisternae.
B- Continuous with RER.
C- Their surface not covered with
polyribosomes (Not basophilic)
but acidophilic.
D- Best seen with TEMFunctions of sER:
1) Drugs & alchohol-detoxification: (in liver cell)
Via a special cytochrome p450 enzyme which
also metabolize bilirubin to be excreted as a bile
pigment .
2) Synthesis of phospholipids and steroid
hormones (e.g ---cells of the adrenal cortex)
via special enzymes present in it
3) Glycogen metabolism
4) Calcium storage: in the striated (skeletal).Basophilia & acidophila of cytoplasmClinical Application
Defective sER in liver
cells will lead to
neonatal Jaundice.
Defective rER in
bone cells will
lead to weak bone
structure.Non membranous
organelles
Ribosomes and
Polyribosomes
(Polysomes)
By L.M:
➢- responsible for the
basophilia of the
cytoplasm due to their
content of ribo-nucleic
acid (RNA).By E.M:
• Composed of both (Proteins + ribosomal
(rRNA)) that are organized into both large
and small subunit.
• Electron dense particles
• During Ptn synthesis, ribosomes are found in
clusters in the cytosol called; polyribosomes (or
polysomes), connected by a fine thread
messenger RNA (mRNA).Ribosome &polyribosomesFree polyribosomes
• Not bound to rER.
• Produced:
1- Proteins for Cytosole &
cytoskeleton
2- Nuclear & mitochondria
proteins
Attached polyribosomes
Bound to rER
Produced :
1)- Cell Membranous ptn
2)- Ptns of hydrolytic
enzymes in lysosomes.
3) Secretory ptn
• Ribosomes ---produces
ptns-----segregation into
endoplamic reticulum
cisternea