4. Nucleus
• Spherical or oval shaped structure. Most prominent feature of a cell.
• Some cells have single nucleus while some has no nucleus eg mature RBCs
• Some cells have multiple nucleus eg skeletal muscle
• Nuclear envelope separates the nucleus from cytoplasm. Nuclear envelop is
double layered Both layers are lipid bilayers.
• The outer membrane of NE is continuous with RER and resembles in structure.
• Many openings extend from NE called Nuclear Pores.
• Nuclear pores control the movement substances b/w the nucleus and
cytoplasm.
• Small molecules move passively by diffusion while large molecules cannot pass
by diffusion.
5. Nucleus
Large molecules move by active transport in which
molecules selectively move through nuclear pore. eg
proteins move from cytosol into nucleus needed for
nuclear function.
Fluid content of nucleus is called nucleoplasm .The
nucleoplasm contain nuclear matrix, network of fine
filaments.
It also contain ions ,enzymes ,RNA ,DNA, nuclotides
Inside the nucleus one or more spherical bodies
called nucleoli. It produce ribosomes.
Nucleolus is cluster of protein, DNA, and RNA
Nucleoli is the site for synthesis of rRNA and proteins
into ribosomal subunits.
6. Nucleus
• There are many hereditary units called genes. Gene control cellular structure
and direct cellular activities . Genes are arrange along chromosomes.
• Human cells have 46 chromosomes 23 from each parent.
• Complex of DNA, proteins and RNA is called chromatin.The total genetic
information is carried in a cell or in its genome.
• In not dividing cells chromatin appears as granular mass. EM reveal that the
chromatin has a beads on a string structure. Each bead consists of double strand
DNA wrapped around a core of eight proteins called histones.
• Histones help to coiling and folding of DNA.The string b/w the bead called
linker DNA.
• In not dividing cells another histone promotes coiling of nucleosome into larger
diameter which then folds into large loops. Before cell division, the DNA
replicates and loops condensed to form chromatids. During cell division
chromatids converted into chromosomes.
7.
8.
9.
10. Endoplasmic Reticulm(ER)
• Network of intracellular membrane continuous with cytoplasm to
nuclear envelope.This network is called as cisternae (tubular and
spherical membrane that separate material present in these
channels from cytoplasm.
• Endo means “within” while Plasma refers to Cytoplasm
• Functions of ER:
• Synthesis
• Storage
• Transport
• Detoxification
11. Endoplasmic recticulm
• Types of ER
• Smooth ER
• Rough ER
• 1.Smooth ER
• There are no ribosomes
• Involved in the synthesis of lipids , Carbohydrates and detoxifications of drugs.
• Functions of SER
• Synthesis of phospholipids and cholesterol
• Synthesis of steroid hormones
• Synthesis of glycerides
• Synthesis and storage of glycogen
12. • Function as a combination workshop and shipping warehouse.
• Found where many proteins synthesized , packed and transport to the
Golgi apparatus.
• There are two forms of ribosomes free and fixed.
• Fixed ribosomes on the outer surface of RER gives it rough appearance.
• Inside RER each protein assumes its 2* and 3* structure.
• Some proteins are enzymes that work in ER while other are attach with
carbohydrates to form glycoprotein.
• Most of proteins are produced by RER and are packed into small sacs
that release from the tip of cisternae.
13.
14.
15.
16. Golgi Complex
Introduction (Discovered by Camillo Golgi in 1897)
Singal cisternal sac is called golgi body
Stack of cisternae sacs is called Golgi apparatus
Stack of cistarnae sacs with associated vesicles Golgi complex
Dictyosomes(Golgi apparatus present in plants)
Structure
Golgi apparatus is a stack of flattened membrane bound sac called cistarnae
Golgi complex is complex system of interconnected tubules.
Golgi apparatus has two faces 1.Forming face 2.maturing face
Forming face (convex) is outer face.Vesicles that bud off from smooth ER are
fused together to form cistarnae of Golgi complex
Maturing face (concave) is inner phase also called Trans face. Secretory
granules are pinched off from maturing face.
17.
18. Functions of Golgi complex
Help in cell
secretion
Modification of
molecules
Synthesis of
glycoconjugates
Phragmoplast
Formation primary
lysosomes
19. Peroxisomes
Similar to lysosomes but smaller in structure
Contain several oxidases enzymes that can oxidize organic substances;
eg. amino acids and fatty acids are oxidized in peroxisomes as part of normal metabolism.
Enzymes in peroxisomes oxidize toxic substances such as alcohol.
Very abundant in the liver where detoxification of alcohol occurs.
A byproduct is hydrogen peroxide H2O2 a potentially toxic compound.
Also contain enzyme catalase which decompose H2O2
Peroxisomes protect other parts of the cell from the toxic effects of H2O2.
Also contain enzymes that destroy superoxide
It can self replicate. New peroxisomes are formed by preexisting ones by enlarging and dividing.
20.
21. Lysosomes
Discovered by De Duve in 1949.
Lyso means “splitting” and Soma means “body”.
Sphere shaped sacs filled with hydrolytic enzymes that have
capability to breakdown many types of biomolecules is called
lysosomes.
These sacs produced by golgi apparatus contain digestive enzymes
such as hydrolytic enzymes.
Lysosomes fused vesicles that formed during endocytosis.
Lysosomes has Ph of 5 which more acidic than ph of cytosol that is
7. Because lysosomal enzymes work best at acidic ph.
22. Lysosomes
FUNCTIONS
Removal of organelles.
Autophagy :The process in which cell breakdown
and destroy in its cytoplasm.
Destruction of bactria that enter the cell from
extracellular fluid.
Cleanup and recycling inside the cell:
eg Muscle cells are inactive lysosomes breakdown
their contractile protein.
Autolysis : Programed cell death in which lysosome
burst and their enzymes are dispersed throughout
the cytoplasm.
23.
24. Mitochondria
Mitochondria was introduced
in 1898 by Benda and
originates from greek word
“mitos”(thread) and
“chondros” (granules).
It is commonly referred as
powerhouse of the cell
because it produces
approximately 90% of cell’s
energy content.
27. Mitochondria
Mitochondria are self-replicating organelles.
They have their own DNA and metabolic machinery to make new
mitochondrial proteins.
Mitochondrial genome has approximately 16,000 base pairs
while Nuclear genome has billions of base pairs.
28. Mitochondria
FUNCTIONS
Energy production (ATP
Synthesis)
Apoptosis (programmed cell
death)
Involvement of cytochrome c.
Storing calcium.
Heat production.
