Animal Cell

Cell Biology

Our DNA

A colourful picture of our DNA.

THE FUNDAMENTAL UNIT OF LIFE -Part 3

THE FUNDAMENTAL UNIT OF LIFE Lesson 1

Question and Answers Continued

3. What would happen if the plasma membrane ruptures or breaks down?
A massive rupture of the plasma membrane where the cytoplasm and cell organelles will be released will result in the death of the cell .


4. What would happen to the life of a cell if there was no Golgi apparatus?
Lysosomes which disposes the waste in animal cell and destroy foreign materials like bacteria and virus are formed in the Golgi apparatus. If there is no Golgi apparatus then the waste formation will accumulate in the cell.Foreign virus and bacteria will invade and destroy the cell.Golgi apparatus transfers proteins and cellular secretions from one part of the cell to another and is also involved in the synthesis of cell wall, plasma membrane and lysosomes.The cell will not be able to transport its products and function of the cell will be affected which will finally result in the destruction of the cell.


5. Which organelle is known as the power house of the cell? Why?
Mitochondria is known as the power house of the cell because they are considered as a seat of breakdown of food materials in the cells resulting in the release of energy during respiration.

6. Where do lipids and proteins constituting the cell membrane get synthesized?
Lipids and proteins get synthesized in the endoplasmic reticulum of the cells.

7. How does an Amoeba obtain its food?
An Amoeba obtains its food by the process of endocytosis. It is due to the flexibility of cell membrane as it enables the cell to engulf food and other materials from its external environment.

8. What is osmosis?
Osmosis is the diffusion of water through a semipermeable membrane. It takes place across the membrane till the equilibrium is reached. Water moves from a region of high chemical potential to a region of low chemical potential.

THE FUNDAMENTAL UNIT OF LIFE -Part 2

THE FUNDAMENTAL UNIT OF LIFE Lesson 1

Question and Answers Continued

1. Can you name two organelles we studied that contain their own genetic material?
Two cell organelles that contain genetic material are mitochondria and chroloplast.

2. If the organization of a cell is destroyed due to some physical or chemical influnce, what will happen?
If the organization of a cell is destroyed, then the cell would die.

3.Why are lysosomes known as suicidal bags?
Lysosomes are known as suicidal bags because they burst while releasing hydrolytic enzymes.

4. Where are proteins synthesized inside the cell?
The proteins are synthesized in the ribosomes.


1. Make a comparision to write down ways in which plant cells are different from animal cells.

Plant cell	Animal cell
1. Cell membrane is covered by a thick cell wall made of cellulose.	The cell is enclosed by only the cell membrane.. cell wall is abseny.
2. Plastids (only chloroplasts) are present.	Plastids are absent.
3. Vacuoles are large, central and prominent.	Vacuoles are either absent or of very small size.
4. Centrosomes are absent. Polar caps are instead present.	Centrosomes are present with 2 centrioles.
5. Cell division takes place by the formation of a cell plate.	Cell division takes place by the formation of a groove.
6. Golgi complex consisting of unconnected units is called the dictosomes.	Golgi complex presents near the nucleus of the cell.

THE FUNDAMENTAL UNIT OF LIFE -Part 1

THE FUNDAMENTAL UNIT OF LIFE Lesson 1

Question and Answers

1. Who discovered cells, and how?
Robert Hooke discovered cells when he observed a thin slice of cork under a microscope.

2. Why is the cell called the structural and functional unit of life?
The cell is the structural unit of life because they are the basic building blocks of the body and that all organisms are made up of cells. It is the functional unit of life because it performs different functions.

1. How do substances like CO2 and water move in and out of cell. Discuss.
Carbon dioxide moves across the cell membrane by the process of diffusion. Water obeys the law of diffusion and its movement through the cell membrane is called osmosis.

2. Why is the plasma membrane called a selectively permeable membrane?
The cell membrane is called a selectively permeable membrane because it only allows the entry and exit of some substances into and outside the cell.

Cell Membrane or Plasma Membrane



Differences between prokaryotic and eukaryotic cells

Prokaryotic cell	Eukaryotic cell
1. A cell wall formed of amino sugars is present.	A cell wall formed of cellulose is present in plant cells.
2. Membrane bound organelles such as endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, vacuoles etc are absent.	Membrane bound organelles such as endoplasmic reticulum, Golgi apparatus, mitochondria, lysosomes, vacuoles etc are present.
3. Chromosome is single and strand of DNA is present in the cytoplasm.	Chromosomes are multiple and formed of DNA which are present in the nuclear membrane.
4. Nucleoid is not enclosed in the nuclear membrane.	Nuclear material is enclosed in the nuclear membrane.
5. Nucleoli and microtic apparatus are absent.	Nucleoli and microtic apparatus are present.
6. They lack 9+2 axial filament structure.	They possess 9+2 aial filament structure.
7. Small sized (1-10 micrometer).	Big sized (5-100 micrometer).
8. Cell dividies only by budding or by fission. Mitosis does not occur.	Cell divides by mitosis and meiosis cell division.
9. Ribosomes are of 70S type.	Ribosomes are of 80S type.