ORGANELL DESCRIPTION FUNCTIONS

ES

Mitochondri
▪ These are tiny, sausage ▪ It is the seat for the Kreb's
a
shaped structures of cycle (citric acid cycle)
diameter 0.5 to 1
▪ It contains enzymes for
micrometer.
Oxidative phosphorylation
▪ It is called as "Power which helps in producing
house of the cell" as it energy rich ATP molecule
generates energy in the
▪ It provides intermediates for
form of
AdenosineTriphosphate synthesis of cytochrome,
(ATP) which required by chlorophyll, and hemoglobin
all the cells. steroids

▪ It is packed with many ▪ Amino acids like glutamate

enzymes like pyruvate synthesized in it from alpha
dehydrogenase, ketoglutarate and oxalo
pyruvate carboxylase, acetate
enzymes for oxidation of ▪ Many fatty acids are
fatty acids, amino acids synthesized in the matrix
and enzymes of citric
acid cycle. ▪ Calcium can be stored in the
mitochondria and released
▪ It also contains the
whenever required.
mitochondrial genome,
mitochondrial
ribosomes, tRNAs,
dissolved oxygen,
carbon dioxide and
water.

Inner
▪ Folded and pleated ▪ It provides large surface area
Membrane
(double fold) and it is for different biochemical
called cristae processes as it contains many
oxidative enzymes.
▪ It is impermeable to
molecules and ions but
allows the free passage
of carbon dioxide,
oxygen and water.
▪ The metabolites are
transported across the
membrane with the help
of transport proteins.
 ▪ Within this membrane
are the proteins involved
in electron transport
chain, ATP synthase and
transport proteins.

Outer
▪ The outer membrane is ▪ It allows the free passage of
Membrane
a smooth phospholipid substances with molecular
bilayer enveloping the weight of less than 10,000.
mitochondria.
▪ It had enzymes like
monoamine oxidase and
NADH reductase. (NADH
Nicotinamide adenine
dinucleotide +
Hydrogen)
▪ An intrinsic protein
called porin form the
channels solutes and
metabolites.

Intermembran
▪ The space between the ▪ It is here that oxidative
e space
outer and inner phosphorylation oecus,
membrane. (Releasing energy by oxidizing
nutrients for ATP synthesis)

Endoplasmi
▪ It is a network of tubular ▪ RER helps in transporting
c reticulum
and vascular structures proteins from ribosomes to
extending from outer Golgi bodies.
membranes of nucleus
▪ Proteins that enter RER
to the cell membrane.
undergoes processing, folding
▪ It is seen to be spread and sorting.
throughout the
▪ SER is involved in the
cytoplasm and it
provides a large surface synthesis of lipids, including
area for various cholesterol and phospholipids.
physiological activities. ▪ In some cells, SER helps in the
The inside of the synthesis of steroid hormones
vesicles and tubules is from cholesterol
filled with an
endoplasmic matrix. ▪ In the cells of liver, SER helps
in detoxifying drugs and
▪ When the ribosomes are
harmful chemicals
attached on the outer
surface of membrane of
 the endoplasmic
reticulum, it is called as
Rough endoplasmic
reticulum (RER).
▪ It lies adjacent to the
cell nucleus and its
membrane is continuous
with the membrane of
the nucleus.
▪ When there are no
ribosomes attached to
the endoplasmic
reticulum, it is called as
Smooth endoplasmic
reticulum (SER).

Golgi
▪ It is a stack of ▪ The proteins that enter it
Apparatus
membranous sac, like a from RER is modified,
pile of disc. processed, sorted and
transported in the form of
▪ It is present between
vesicles to the cell
endoplasmic reticulum membrane and other
and cell membrane. destinations.
▪ Like endoplasmic ▪ Glycolipids, sphingomyelin
reticulum, it is a single are synthesized within it.
membrane bound
structure. ▪ In plant cells, it helps in the
synthesis of
▪ In animal cells, it is
polysaccharides needed by
present around the the cell wall.
nucleus while in plant
cell it is scattered ▪ It has a role in the
throughout the cell. synthesis of carbohydrates
These cell organelles like galactose.
pack and sort the
▪ Primary lysosomes develop
proteins before they are
sent to their from mature Golgi bodies.
destinations. It plays an important role in lipid
trafficking.

Ribosomes
▪ They are spherical ▪ It is the site for protein
shaped organelles seen synthesis.
either free in the
cytoplasm or attached
to RER.
▪ They are found in
 eukaryotes and
prokaryotes.
▪ They are synthesized by
the nucleolus
▪ The ribosomes link the
amino acids together in
the order that is
specified by the
messengers RNA.
▪ They are made up of two
subunits: a small sub
unit and a large sub
unit.
▪ The small sub unit
reads the mRNA while
the large subunit
assembles amino acids
to form large
polypeptide.
▪ The ribosomal sub units
are made up of one or
more eRNA and
proteins.

Lysosomes
▪ They are tiny sac like ▪ It helps in the digestion of
organelles f size 0.5 food releasing enzymes.
to 1.5 pm, which are
▪ They digest worn out
membrane bound
and found in organelles
hundreds in a single ▪ It helps in the defense, by
cell. digesting germ
▪ They are formed ▪ It helps sperm cells in
from the Golgi bodies entering the egg by
as small vesicles breaking through the egg
which bud off from membrane
them.
▪ It provides energy during
▪ Within the sac there
cell starvation by the
are several hydrolytic digestion of its own cell
enzymes that parts.
breakdown
macromolecules like
nucleic acid, proteins
and polysaccharides.
 ▪ They are also called
as "suicidal bags" as
enzymes contained
in them can digest
the cell's own
material when
damaged or dead.
▪ The important
enzymes in it are
DNA-ase, RNA-ase,
protease, lipase,
glycosidase,
phosphatase,
sulfates which are
synthesized in the
endoplasmic
reticulum and then
transported to the
Golgi bodies.

Peroxisome
▪ It is a type of ▪ The enzymes found in
s
microbody which is peroxisomes are usually
small, spherical used for different
shaped, with single metabolic reactions and for
membrane and of digesting different
size 0.5-1.5 um. cells. materials in the cell.
▪ Just like lysosomes ▪ They help in the oxidation
they contain many of many substances
enzymes which help resulting in the formation
in biological of hydrogen peroxide as a
reactions byproduct.
▪ They are formed ▪ But it contains enzyme
from the peroxidase or catalase
endoplasmic which decomposes this
reticulum unlike harmful hydrogen peroxide
lysosomes which are into water and oxygen or
formed from the uses it to oxidize other
Golgi bodies organic compounds like
phenol, alcohol,
formaldehyde, etc.
▪ They are also involved in
the catabolism of fatty
acids (beta oxidation), D-
amino acids and
polyamines.
 ▪ They are needed in the
synthesis of plasmalogens
(type of ether phospholipid
needed for functioning of
brain and lungs.)
▪ They participate in the
synthesis of cholesterol,
bile acids and myelin.
▪ In plants, it helps in the
photorespiration and
symbiotic nitrogen fixation.

Centriole
▪ It is cylindrical in ▪ It is involved in cell
shape and of length division.
0.5 micrometer.
▪ They are seen in the
▪ All centrioles are process of both meiosis
made up of protein and mitosis.
strands called
▪ It helps in the formation of
tubulin.
cilia and flagella
▪ Each centriole has 9
▪ It helps in the organization
sets of inter
connected peripheral and alignment of
tubules and each set microtubules within the
has 3 micro tubules cell
arranged at definite
angles making the
shape of cylinder.
▪ It has its own DNA
and RNA and
therefore, self-
duplicating.
▪ Two centrioles when
oriented at a right
angle, forms the
centrosome.

Vacuole
▪ It is a membrane ▪ It helps in removing waste
enclosed fluid filled products from the cell
sac present in animal
▪ It isolates substances that
and plant calls
including fungi. are harmful to the cell

▪ It contains organic ▪ It holds water and waste

and inorganic products within it

 molecules within it.
▪ It helps in maintaining the
▪ They do not have internal pH of cell
particular size or
▪ It helps to maintain
shape but adjust
themselves hydrostatic pressure within
according to the the cell
need of the cell. ▪ It plays a major role in
autophagy by maintaining
a balance between
biogenesis and
degradation

Nucleus
▪ It is a specialized ▪ It controls the hereditary
double membrane- characteristics of an
bound protoplasmic organism
body present at the
▪ Protein synthesis, cell
center of the cell
center as it houses division, growth and
the chromosomes. differentiation occur in it

▪ It is known as the ▪ Stores heredity materials

“cell's information” in the form of DNA

▪ The double ▪ It is the site for

membrane around transcription in protein

the nucleus is called synthesis
nuclear membrane or ▪ Nucleolus helps in the
nuclear envelope. synthesis of ribosomes
▪ It is made of proteins ▪ \It regulates the integrity of
and lipids. genes and gene expression
▪ It encloses the
nucleus to keep it
separate from
surrounding
materials off the cell.
▪ The outer membrane
is continuous with
endoplasmic
reticulum and it has
ribosomes attached
on the outer surface.
▪ It has several large
nuclear pores
through which
nuclear transport of
 large molecules,
small molecules and
ions occur.
▪ The space between
the nuclear
membranes is called
perinuclear space
and it is continuous
with the lumen of
rough endoplasmic
reticulum.
▪ Within the nuclear
membrane is a-like
substance called
karyolymph or
nucleoplasm.
▪ Within it, there is a
network of chromatin
fibrils which
condense to form
chromosomes during
cell division
▪ The nucleolus is
present within the
nucleus.
▪ It does not have a
membrane around it
▪ It synthesizes rRNA
and assembles it.

It regulates the synthetic

activity of nucleus