Cell Organelles
20.05.2018
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Natasha Batool, Aqsa Saqlain
Roll numbers: 15, 16 Respectively Cell
“It is the basic unit of all living organisms on the basis of structure and function.”
Cytology
The study of cell and their component is known as cytology. The cell contain a living substance called protoplasm.
Cell Organelles
Organelles are found only in eukaryotic cells and are absent from the cells of prokaryotes such as bacteria. The nucleus, the mitochondrion, the chloroplast, the Golgi apparatus, the lysosome, and the endoplasmic reticulum are all examples of organelles.
Cells are of two types
Prokaryotic Cell
Eukaryotic Cell
Prokaryotic Cell
A cell which does not have a well defined nucleus and DNA is not surrounded by nuclear membrane.…show more content… Chromosomes are composed of DNA and proteins. Membrane bound organelles are present. Ribosomes are large in size i.e 80s
Plasma Membrane (Cell Membrane)
It is thin, delicate, elastic and semi permeable, the outermost layer of animal cell but it plant it is located below the cell wall. It is capable of self repair.
Cytoplasm
It is dense, granular, consist of an aqueous ground substance present between plasma membrane and the nuclear membrane. It the part of protoplasm which consists of
Cytosol
The soluble part of cytoplasm is called cytosol. It forms the ground substance of the cytoplasm.
Organelles
Cytoplasm contains cytoplasmic bodies called organelles, such as mitochondria, ribosomes…show more content… Structure:
The ER are often continuous with plasma membrane and also appear to be in contact with the nuclear membrane. The network of channels is extending throughout the cytoplasm.
Cisternae:
The material present in these channels is separated from cytoplasmic material by the spherical or tubular membranes called cisternae. There are two types of cisternae.
SER (Smooth Endoplasmic Reticulum)
RER (Rough Endoplasmic Reticulum)
Ribosomes:
Ribosomes are small, dense, rounded, granules present in the cytoplasm in the free form or attached with the external surface of ER. Ribosome is about 20 nanometer in diameter and were first studied by Palade in 1955.
Chemical Composition:
They are composed of almost equal amount of RNA and proteins hence they are called ribonucleoprotein particles
Structure:
Ribosomes are synthesized in nucleolus of the nucleus which consist of two subunits.
Subunit:
Each ribosomes is consists of two subunits i.e one is larger and other is small.
Polysome:
Many ribosomes get attached to the same strand of mRNA for protein synthesis, this whole structure is called polysome.
There are two types of ribosomes
70s
80s
