Explanation of mitochondria structure with working of ATP production at basic level Ribosomal structure and functions with disorders related to the same

1. MITOCHONDRIA
Diya Ranjan

2. INTRODUCTION
Mitochondria are membrane-bound
cell organelles (mitochondrion,
singular) that generate most of the
chemical energy needed to power the
cell's biochemical reactions.
They are called the 'powerhouse of
the cell'.
Chemical energy produced by the
mitochondria is stored in a small
molecule called adenosine
triphosphate (ATP).

3. Structure of
mitochondria
 Mitochondria are small,and are not visible under the
microscope unless they are stained.
 They have two membranes,an outer one and an
inner one.Each membrane has differentfunctions.
I. Outer membrane: Small molecules can pass
freely through the outer membrane.This outer
portion includes proteins called porins,which form
channels that allow proteins to cross. The outer
membranealso hosts a number of enzymeswith a
wide variety of functions.
II. Inner membrane: It is impermeable to most
molecules. Molecules can only cross the inner
membrane in specialmembrane transporters.The
inner membraneis where mostATP is created.

4.  Intermembrane space: This is the area
between the inner and outer membranes.
 Cristae:These are the folds of the inner
membrane. They increase the surface area of
the membrane, therefore increasing the space
available for chemical reactions.
 Matrix: This is the space within the inner
membrane. Containing hundreds of enzymes,
it is important in the production of ATP.
Mitochondrial DNA is housed here.

5. ATP PRODUCTION MECHANISM
In the mitochondria, *NADPH2and FADH2 are produced during the
Kreb cycle.
NADPH2 and FADH2 release H+ and electrons enter in Electron
transport system (ETS).
Electrons from these both molecules are given to the ultimate electron
acceptor which is oxygen.
Now the H+ ions gradient is created across the inner
membrane. Protons flow down their concentration gradient into the
matrix through the membrane proteinATP synthase, causing it to spin
(like a water wheel) and catalyze conversion ofADP toATP.
ATP synthetase enzyme becomes active and ATP is synthesized. This
is called oxidative phosphorylation.
NADPH2 - Nicotinamide
adenine dinucleotide
hydrogen phosphate
FADH2 - Flavin adenine
dinucleotide

7. APPLIED ASPECT
MLEAS
Mitochondrial encephalomyopathy, lactic acidosis and
stroke-likeepisodes (MELAS) is a mitochondrial disease
primarily affecting the nervous system and muscles.
MELAS presents in children or young adults as recurrent
episodes of *encephalopathy, myopathy, headache, and
focal neurological deficits.
 LEIGHS SYNDROME
Leigh syndrome is a severe neurological disorder that
usually becomes apparent in the first year of life. This
condition is characterized by progressive loss of mental
and movement abilities (psychomotor regression) and
typically results in death within two to three years, usually
due to respiratory failure. Leigh syndrome can be caused
by mutations in mitochondrial DNA
*Encephalopathy-
alteredmental status

8. RIBOSOMES

9. INTRODUCTION
A ribosome is an intercellular
structuremade of both RNA
and protein, and it is the site
of protein synthesis in the cell.
The ribosome reads the
messengerRNA (mRNA)
sequence and translates that
genetic code into a specified
string of amino acids, which
grow into long chains that fold
to form proteins.

11. STRUCTURE
A ribosome is made out of RNA and
proteins, and each ribosome consists of two
separate RNA-protein complexes, known as the
small and large subunits. The large subunit sits
on top of the small subunit, with an RNA
template sandwiched between the two.
The small subunit (“*40S” in eukaryotes)
decodes the genetic message and the large
subunit (“60S” in eukaryotes) activates
peptide bond formation.
FUNCTION
A ribosome is an intercellular structure made of
both RNA and protein, and it is the site of
protein synthesis in the cell. The ribosome
reads the messenger RNA (mRNA) sequence
and translates that genetic code into a specified
string of amino acids, which grow into long
chains that fold to form proteins.
*40S- 'S' denotes svedberg's
unit

12. APPLIED ASPECT
• Ribosomopathies are diseases caused by
abnormalities in the structure or function
of ribosomal component proteins or rRNA
genes, or other genes whose products
are involved in ribosome biogenesis.
EXAMPLE
Shwachman Diamond syndrome
Shwachman-Diamondsyndrome (SDS) is a rare,
inherited bone marrow failure, characterized by
a low number of white blood cells, poor growth
due to difficulty absorbing food, and, in some
cases, skeletal abnormalities.