Transcript Cell organelles and functions

CELL ORGANELLES AND
FUNCTIONS
By:
Hemangi Atalia
INTRODUCTION
Cell is the structural and functional unit of life.
 Cells
Tissue
Organ
Organ system.
 Cells contain a variety of Internal Structures
called ORGANELLES.
 An organelle is a cell component that performs
specific functions for the cell.

NUCLEUS
Spherical in shape.
 Covered by nuclear membrane. The nuclear
membrane encloses nucleoplasm and nucleolus.
 Nuclear membrane is double layered and porous
in nature. This allows the nucleoplasm to
communicate (exchange of material) with the
cytoplasm.
 Nucleoplasm is a gel like substance that contains
large quantities of DNA, which forms the gene.
 One or more nucleoli are present in each nucleus.
 The nucleolus synthesizes ribosomes, which
inturn build proteins.

FUNCTIONS
1.
2.
3.
4.
Control of all the activites of the cell.
Control the cell division through genes.
Storage of hereditary information.
Sending genetic instruction to the cytoplasm for
protein synthesis through the mRNA.
RIBOSOMES
Granular and small dot like structures.
 Some are attached to RER while others are present as
free ribosomes in the cytoplasm.
 Ribosomes attached with RER are involved in the
synthesis of proteins like the hormonal proteins or the
proteins of the cell membrane.
 The free ribosomes are responsible for the synthesis of
proteins of hemoglobin, and mitochondria.


MAIN FUNCTION
SYNTHESIS OF PROTEINS.
ROUGH ENDOPLASMIC RETICULUM (RER)
Tubular in structure.
 Also known as “granular endoplasmic reticulum.”
due to the present of ribosomes attached to its outer
surface.

FUNCTION
1.
Synthesis of proteins in the cell.
INSULIN.
2.
Degradation of the worn out organelles and
later digested by lysosomal enzymes.
SMOOTH ENDOPLASMIC RETICULUM (SER)
“Agranular reticulum.”
 Smooth appearance

FUNCTION
1.
Synthesis of lipids and steroids.
2.
Storage and metabolism of calcium.
GOLGI APPARATUS
“Golgi body” or “Golgi Complex”
 Membraneous tubules
 Situated near the nucleus
 Also called “post office of the cell.”
 Site for lysosomes

FUNCTION
1.
Processing and delivery of proteins and other
molecules
lipids
2.
Labeling and sort out the processed and packed
materials for distribution to their proper
destinations.
“Shipping department of the cell.”
CYTOSKELETON


Complex network of structures of various sizes
present throughout the cytoplasm.
Consists of three protein components
Microtubule
Intermediate
filaments
Microfilaments
FUNCTION
1.
Determination of shape of the cell.
2.
Stability of cell shape.
3.
Cellular movements.
MITOCHONDRION
Globular in structure.
 Bilayered membranous organelle.
 “Power house of the cell”
 Outer membrane is smooth and contains enzymes
responsible for biological oxidation.

Inner membrane is folded like inward projection
called CRISTAE and it covers the inner matrix
space.
 The cristae contain many enzymes which are
involved in RESPIRATION and synthesis of ATP.

Matrix
Enzymes
HEAD
BASEPIECE
STALK
Capable of reproducing themselves
 Contain their own DNA.

FUNCTION
1.
Production of energy
2.
Synthesis of ATP
LYSOSOME
Membrane bound vesicular.
 Formed by Golgi Apparatus.
 Contain enzymes called Hydrolytic enzymes.
 “Garbage System”
their degradation activity.
 Autolysis

FUNCTION
1.
Degradation of macromolecules like bacteria.
2.
Degradation of worn out organelles
3.
Secretory function
PEROXISOME
Similar in structure as lysosomes.
 Pinched off from ER
 Contains oxidative enzymes such as

1.
2.
3.
catalase,
urate oxidase
D-amino acid oxidase.
FUNCTION
1.
2.
3.
4.
Degradation of toxic substances
Hydrogen
peroxide
Oxygen utilization
Breakdown of excess fatty acids
Role in formation of myelin and bile acids.
CENTRIOLE
2 cylindrical structure visible during cell division.
 Responsible for the movement of chromosomes
during cell division.
 Arranged perpendicular to each other and is
made up of proteins.

LYSOSOMAL STORAGE DISEASES
Hereditary disorders caused by a deficency in
specific lysosomal acid hydrolases.
 Therefore, lysosomes are unable to degrade
certain compounds, which accumulates and
interfere with cell function.

TAY-SACHS DISEASE
TAY-SACHS DISEASE
autosomal recessive disease caused by mutations in
both alleles of a gene (HEXA) on chromosome 15.
 HEXA codes for the alpha subunit of the enzyme βhexosaminidase A.
 This enzyme is found in lysosomes, Normally, βhexosaminidase A helps to degrade a lipid called GM2
ganglioside, but in this case, the enzyme is absent
allowing excessive accumulation of the GM2
ganglioside in the lysosomes of neurons.
 The large buildup of gangliosides in the neurons of
the brain results in marked degenerative changes in
the CNS, & death usually occurs before age 4 years.

Symptoms: seizures, vision and hearing loss, mental
retardation, and paralysis.
 No cure or treatment.

PEROXISOMAL DISEASES
ZELLWEGER SYNDROME



Is a genetic disease in which normal peroxisomes
are absent.
Infants with this syndrome have profound
neurological, liver, and kidney problems and usually
die within a few months.
There is no cure nor is there a standard course of
treatment.
ADRENOLEUKODYSTROPHY
Is caused by the inability of peroxisomes to
metabolize fatty acids. Therefore, lipids accumulate
in the nervous system and adrenal glands,
impairing their function.
 X-linked disease and affects males.
 Symptoms normally start between the ages of 4 and
10 and include loss of previously acquired neurologic
abilities, seizures, ataxia, as well as degeneration of
visual and auditory function.
 No cure for this therefore, infants die at young age.

REFERENCE LIST
http://my.clevelandclinic.org/disorders/Mitochondr
ial_Disease/hic_Mitochondrial_Disease.aspx
 http://www.ninds.nih.gov/disorders/taysachs/taysa
chs.htm
 http://rarediseases.about.com/cs/mitochondrialdis/
a/062103.htm
 http://en.wikipedia.org/wiki/Adrenoleukodystrophy
