Page 1 - Lesson Notes

SAI International School
Subject- Biology, Class- IX
Topic- The Fundamental Unit of Life
Subtopic- Endoplasmic Reticulum; Golgi Apparatus
Module- 5
LESSON NOTES
CYTOPLASM

 It is semi fluid matrix filled in between nucleus and plasma membrane
containing cell organelles such as mitochondria, ribosome, vacuoles,
endoplasmic reticulum, etc.
 It is the fluid part of the cytoplasm is called cytosol which contains many
water, ions, vitamins, enzymes, amino acids, lipid, etc.

FUNCTION
 Provides mechanical support to the cell by exerting pressure against the cell's
membrane which helps keep the shape of the cell. This pressure is known
as turgor pressure.
 It is the site of most cellular activities including metabolism, cell division and
protein synthesis.

CELL ORGANELLES

 The cellular components are called the Cell Organelles. They coordinate with
their functions efficiently for the normal functioning of the cell.
 Singlemembrane-bound organelles: Vacuole, Lysosome, Golgi apparatus,
Endoplasmic Reticulum are single membrane-bound organelles present only
in a eukaryotic cell.
 Double membrane-bound organelles: Mitochondria and chloroplast are double
membrane-bound organelles present only in a eukaryotic cell.

(1) ENDOPLASMIC RETICULUM (ER)

 Found in eukaryotic cells only.
 Large network of membrane bound tubes and sheets.
 Looks like long tubules or round or oblong bags (vesicles)
 It may be connected to both the outer nuclear membrane and plasma
membrane.
 The membrane of ER is same as of plasma membrane (phosphor lipids and
protein)
 There are two types of endoplasmic reticulum: smooth and rough ER:

Smooth Endoplasmic Reticulum:
 Does not have any ribosomes attached.
 Involved in the synthesis of lipids, including oils, phospholipids and steroids.
 Responsible for metabolism of carbohydrates, regulation of calcium
concentration and detoxification of poisons and drugs.