StopLearnStopLearnCell organelles are defined as all the structures outside the nucleus but floating on the cytoplasm. Such materials include endoplasmic reticulum, mitochondrion, lysosome, golgi apparatus e.t.c. all the materials are bounded by cell membrane.
i.All living substances including nucleus are suspended in the semi-fluid cytoplasm
ii.The streaming of the content of the cytoplasm bring about inter change of material between the organelles with the cytoplasm
The cell wall is the non-living outer boundary of the cell made of cellulose. It has tiny pores or its pits through which nutrient pass from one cell to another. Cell wall is absent in animal cell
Functions
1.It gives rigidity to the cell and plant as a whole
ii.It allows free passage of material
The cell membrane is a thin and flexible living later that surrounds the entire cytoplasm and separates the cell from neighboring cells.
Functions
i.It regulates the movement of substances in and out of the cells
ii.It protects the cytoplasm
iii.It determines the content of the cytoplasm
iv.It forms a barrier between the cell and its surrounding
Endoplasmic reticulum is a system of canals found abundantly in the cytoplasm. It ribosome are attached to it in rough ER and if no ribosome are attached it is called smooth ER.
Functions
Rough endoplasmic reticulum
1.They transport metabolic products within cytoplasm between the cytoplasm and nucleus
2.They help in formation of enzymes and protein
3.They help in formation of nuclear membrane during nuclear division
4.They inter connect the organelles of the cell
5.They provide surface for the attachment of ribosome
1.It makes lipid (Fat molecules)
2.The enzymes of the S. ER in the liver detoxificate drugs
These are minute and spherical organelles found in large number attached to endoplasmic reticulum or suspended in the cytoplasm
Functions
1.They make proteins by joining amino acids together
2.They are also site for protein synthesis
These are tiny red-shaped bodies or granules in the cytoplasm. They are more concentrated in very active cells such as liver cells.
Function
1.They are center for cellular respiration in which food substances are oxidized to release energy for the activities of the cell
2.It contains enzymes and deoxyribo nucleic acid (DNA). The enzymes carry out oxidative phosphorylation of adenosine diphosphate (ADP) to adenosine triphosphate (ATP)
3.The DNA helps to code the synthesis of protein in mitochondria membrane
These are minute and rounded bodies containing enzymes found in animal cells
Function
1.They destroy worn out part of the cell by discharging enzymes into them thereby clearing the area for new cell to grow
2.Lysosomes discharge enzymes to degenerated tissues causing the breakdown of the cells
These bodies are found as flat tubes of threads. They are absent in mature sperm and red blood cells
Functions
1.They help to distribute proteins made by the cell
2.They help in the manufacture of lysosome
3.They help in the formation of membrane of endoplasmic reticulum and production of cellulose of cells of plant
These are usually two small, cylindrical bodies found near the nucleus. The two centrioles are mostly found in animal cells. They are absent in plant except some few algae and fungi
Functions
1.They provide spindle fibers to which chromosomes are attached during cell division
2.They help in the formation of cilia and flagella
Chloroplasts only occur in green plants. The organelles called chloroplast contain green pigment called chlorophyll. A chloroplast is surrounded by a membrane. In the leaves chloroplasts are oval or disk-shaped in algae
Function
1.It is the site of photosynthesis where organic foods are synthesized
Vacuoles
Vacuoles are found both plant and animal cell. It is bigger in plant. A vacuole is surrounded by a membrane called tonoplast and is filled with water, mineral salt, sugars and pigments called cell sap.
Function
1.The cell sap is osmotic in function
2.It stores nutrients and waste product
3.Sometimes vacuole contain colour pigments called anthocyanin which may blue, purple, yellow, red which give coloruration to flowers
The nuclear membrane permits substances to go in and out of the nucleus. Within the nucleus is a small spherical body called nucleolus and the chromatin materials which condense during cell division into chromosome (hereditary unit). The inside of the nucleus is filled with a semi fluid material called nuclear fluid or nucleoplasm.
The chromosomes are made up of DNA (deoxyribonucleic acid).
Functions
1.The nucleus controls the activities of the living cell
2.The nucleus carries chromosomes on which hereditary material (gene) are coded
3.The nucleolus produces several kinds of RNA which are passed of out the nucleus to cytoplasm to manufacture protein
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