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DONE BY :- S.Durgashree IX-A KENDRIYA VIDYALAYA KARAIKUDI

Endoplasmic reticulum class IX

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Class IX Science Chapter->The Fundamental Unit of Life

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Page 1: Endoplasmic reticulum class IX

DONE BY :-S.Durgashree

IX-A

KENDRIYA VIDYALAYA

KARAIKUDI

Page 2: Endoplasmic reticulum class IX

Discovered by Belgian biologist

Albert Claude (1899-1983).

Used the newly developed

electron microscope to explore

the interior of cells and along

with his associate Keith Porter in

1945 observed the presence of a

“lace-work structure.”

Page 3: Endoplasmic reticulum class IX

Rough ER appears as lumpy sheets of folded

membranes. The lumps are the ribosome. They

are not permanently attached, adhering only

when there is protein manufacturing work to

be done.

Smooth ER which isn't coated with ribosome's

looks like smooth tubes.

Page 4: Endoplasmic reticulum class IX

No specific base or point in a cell, as it extends

a network of membranes, tubules vesicles, and

sacs throughout the cell.

ER membranes are folded and stacked on top

of each other and connected to the nucleus.

Rough ER with ribosomes attached is closest

to the nucleus.

Page 5: Endoplasmic reticulum class IX

Endoplasmic - “within the cytoplasm”.

Reticulum - Latin for “a little net”.

-> Extensive network of folded membranes that

extends from the nuclear envelope to which it

is connected, throughout the cytoplasm.

-> Divided into two sub-compartments, rough

ER and smooth ER.

Page 6: Endoplasmic reticulum class IX

-> Defined by the presence of ribosomes bound

to its cytosolic surface.

-> Typically composed of a network of flattened

sacs (cisternae).

Page 7: Endoplasmic reticulum class IX

->Continuous with the outer

membrane of the nuclear

envelope, which also bears

ribosomes on its cytosolic

surface.

Page 8: Endoplasmic reticulum class IX

Secrete large quantities of proteins, such as

the :

(a) Acinar cells of the pancreas

Page 9: Endoplasmic reticulum class IX

(b) Mucus secreting cells of the lining of the

digestive tract.

Page 10: Endoplasmic reticulum class IX

Rough ER is the starting point of the

biosynthetic pathways of:

Proteins

Carbohydrate chains

Phospholipids

that journey through the membranous

compartments of the cell.

Page 11: Endoplasmic reticulum class IX

Lacks associated ribosomes.

Membranous elements are highly curved and

tubular, forming an interconnecting system of

pipelines curving through the cytoplasm.

Page 12: Endoplasmic reticulum class IX

Extensively developed in a number of cell

types, including those of skeletal muscle,

kidney tubules, and steroid-producing

endocrine glands FIGURE 1. The smooth ER (SER). Electron micrograph of a Leydig cell from

the testis showing the extensive smooth ER where steroid hormones are

synthesized.

Page 13: Endoplasmic reticulum class IX

Synthesis of fatty acids and steroid hormones,

such as estrogens and testosterone.

Detoxification in the liver of a wide variety of

organic compounds, including barbiturates and

ethanol.

Sequestering calcium ions within the

cytoplasm of cells.

Page 14: Endoplasmic reticulum class IX

Ribosomes on its

outer surface.

Not associated with

ribosomes.

Site of synthesis of

proteins destined for

secretion .

Involved in lipid

metabolism.

Page 15: Endoplasmic reticulum class IX

ON MEMBRANE - BOUND RIBOSOMES:

a. Secreted proteins

b. Integral membrane proteins

c. Soluble proteins in ER, Golgi complex, lysosomes,

endosomes, vesicles and plant vacuoles

ON FREE RIBOSOMES:

a. Cytosolic proteins

b. Peripheral proteins

c. Proteins transported to the nucleus

d. Proteins to be incorporated in peroxisomes,

chloroplasts and mitochondria

Page 16: Endoplasmic reticulum class IX

As each protein is synthesized

in the rough ER, it becomes

inserted into the lipid bilayer

in a predictable orientation

determined by its amino acid

sequence. This orientation is

maintained throughout its

travels in the endomembrane

system, as illustrated in this

figure.

Page 17: Endoplasmic reticulum class IX

I hope that you would

have gained knowledge

from this power point

presentation….

Page 18: Endoplasmic reticulum class IX