ENDOMEMBRANE SYSTEM

By-Lovnish Thakur

IBT-2ST SEM (ASU2014010100099)

COURSE-LIFE SCIENCE(BSBT201)

School of Bioscience

WHAT IS ENDOMEMBRANE SYSTEM

The endomembrane system is composed of the different membranes that are suspended in the cytoplasm within a eukaryotic cell. These membranes divide the cell into functional and structural compartments, or organelles.

It consist of-:

• Endoplasmic Reticulum,

• Golgi Apparatus,

• Lysosomes,

• Vacuoles, Vesicles.

ENDOPLASMIC RETICULUM

IT is a network of membrane connected to nuclear envelope & extends throughout cell.

It accounts for 50% membranes in eukaryotic cell.

Endoplasmic reticulum

Smooth endoplasmic reticulum

Does not contain ribosome.

Rough endoplasmic reticulum

Contain ribosome that make it look

rough.

Smooth endoplasmic reticulum

Function-:Factory processing operations like-• many metabolic processes• synthesis & hydrolysis

Enzymes of smooth ER help in-• synthesize lipids, oils,

phospholipids,• steroids & sex hormones• hydrolysis of glycogen• (in liver) into glucose• detoxify drugs & poisons

(in liver)ex. alcohol & barbiturates

Rough endoplasmic reticulum

Function-:• Produce proteins for

export out of cell

• protein secreting cells

• packaged into transport

vesicles for export

Endoplasmic reticulum -: Membrane Factory

Synthesize membrane phospholipids

build new membrane as ER membrane expands, bud off & transfer to other parts of cell that need

membranes

Synthesize membrane proteins

Golgi Apparatus

• The Golgi apparatus functions as a factory in which proteins

received from the ER are further processed and sorted for transport to their eventual destinations: lysosomes, plasma membrane, or secretion.

• Function

• finishes, sorts & ships cell products

• extensive in cells specialized for

Secretion

Structure

flattened membranous sacs = cisternae

2 sides = 2 functions

• Cis face receives

material by fusing

with vesicles = “receiving”

• Trans face buds off

vesicles that travel

to other sites = “shipping”

(transport)

Golgi processing

During path from cis to trans, products from ER are

modified into final form tags, sorts, & packages materials into transport vesicles

Golgi = “UPS headquarters”

Transport vesicles = “UPS trucks” delivering packages that have been tagged with their own barcodes

Lysosomes

Structure membrane-bounded sac

of hydrolytic enzymes

that digests macromolecules

enzymes & membrane

of lysosomes are

synthesized by rough

ER & transferred to the

Golgi

Function

A little “stomach” for the cell, lyso– = breaking things apart,

some = body. It is also called the “clean up crew” of the cell.

In addition to degrading

molecules taken up by

endocytosis, lysosomes

digest material derived

from two other routes:

1. phagocytosis

2. autophagy

What if a lysomome digestive enzyme doesn’t function?

Lysosomal storage diseases

don’t digest a biomolecule instead biomolecule collects in lysosomes

lysosomes fill up with undigested material, lysosomes grow larger & larger eventually disrupt cell & organ function

“Lysosomal storage diseases”are usually fatal.

For e.g-:

Tay-Sachs disease- lipids build up

in brain cells & child dies before age 5.

Sometimes its supposed to workthat way…

Apoptosis = cell death critical role in programmed destruction of cells in multicellular organisms.

auto-destruct mechanism-“cell suicide” some cells have to die in an organized fashion, especially during development.

e.g-: development of space between

your fingers during embryonic

development

Vacuoles & vesicles

A vacuole is a membrane-enclosed fluid filled sac found in the cells of plants including fungi.

Vacuoles can be large organelles occupying between 30% and 90% of a cell by volume.

Vacuoles appear to have three main functions

• contribute to the rigidity of the plant using water to develop hydrostatic pressure

• store nutrient and non-nutrient chemicals• break down complex molecules.

Type- Food vacuoles- phagocytosis, fuse with lysosomes Contractile vacuoles- in freshwater protists, pump

excess H2O out of cell Central vacuoles- in many mature plant cells

Putting it all together…

REFERENCES

www.ncbi.nlm.nih.gov › NCBI › Literature › Bookshelf

bscb.org/learning-resources/softcell-e-learning/vacuole-plants

www.ncbi.nlm.nih.gov › NCBI › Literature › Bookshelf

www.ncbi.nlm.nih.gov › NCBI › Literature › Bookshelf

www.rtsd.org/cms/lib/.../The%20Cell%20Endomembrane%20System.pdf

https://fc.deltasd.bc.ca/~jonzon/S030AAF27.11/endomembrane%20system.pdf

THANK YOU