Virtual Kollage: Cells and Tissues

Posted by / Saturday, 14 May 2016 / No comments

Cells and Tissues

THE CELL
The cell is the basic, structural and functional unit of living organisms. There are two types of cells:
ANIMAL CELL and PLANT CELL

PARTS OF THE CELL AND THEIR FUNCTIONS
NUCLEUS
It is usually found in the centre of the cell. It contains nucleolus which is rich in RIBONUCLEIC ACID (R.N.A) and chromosomes which is made up of DEOXYRIBONUCLEIC ACID(D.N.A).

FUNCTIONS
It is the powerhouse of the cell. That is it control all the metabolic activities in the cell.
It stores hereditary materials in the cell
It is responsible for cell division.

CELL MEMBRANE/ PLASMA MEMBRANE
It is a thin- flexible semi-permeable membrane which forms a boundary around the cell.

FUNCTIONS
It prevents the cell from injury
It is a channel through which substances enter or live the cell

VACUOLE
It is a sac containing watery fluid. It normally occupies a large volume of the cell.

FUNCTIONS
It is used to store foods in the cells
It stores waste products of individual cell
It imparts colour of food and flowers

MITOCHONDRION
It is a sausage-shaped organelle that is responsible for the breaking of food to release energy.

FUNCTIONS
It produces energy from respiration

It is responsible for the synthesis of amino acids

It is responsible for the synthesis of chlorophyll in plants.

CELL WALL
It is made up of cellulose and found outside the cell membrane of plant cells.

FUNCTIONS
It supports and protects the plants

It gives the cell its definite shape

CHLOROPLAST
These are small bodies containing the green-pigment call chlorophyll, which enables plants to manufacture their own food.

CYTOPLASM
It is a transparent fluid which contains smaller parts of the cell call organelles.

FUNCTIONS
All chemical reactions and life processes take place in the cytoplasm

It helps in the inter-cellular distribution of \molecules, enzymes and nutrients.

It helps in the breakdown of glucose.


DIFFERENCES BETWEEN PLANT CELL AND ANIMAL CELL
PLANT CELL
ANIMAL CELL
It has a cell wall
It has no cell wall
It has chlorophyll
It has no chlorophyll
It has a definite shape
It does not have a definite shape
It has a large vacuole
It has a small vacuole
It stores food as starch
It stores food as glycogen

SPECIALIZED CELLS
These are cells structurally adapted to perform specific functions. Some examples of specialized cells include the following:

Examples of specialized cells and functions:
Cell
Function
Muscle cell
Relaxes and contracts to produce movement
Red Blood Cell
Carry oxygen from lungs to tissue
White Blood Cell
Produces antibodies to fight against diseases
Nerve Cell
Transmit nerve impulses
Sperm Cell
Fertilizes egg
Palisade Cell
Contains chlorophyll to carry out photosynthesis
Leaf epidermal cell
Allow light to enter the leaf and reach photosynthetic tissues below them. 

TISSUE
A tissue is a group of similar cells, which are specialized and perform the same function. Example include Nerve tissue, blood tissue, vascular tissue, etc.

SOME TYPES OF TISSUES AND THEIR FUNCTIONS:
TISSUE
FUNCTION
Adipose tissue
It insulates the body against heat.
Muscle tissue
It contracts and relaxes to bring about movement
Skeletal tissue
It provides support for the body
Nerve tissue
It conducts and co-ordinates impulse messages
Photosynthetic tissue
It produces food
Phloem tissue
It transports food
Epidermal tissue
It covers the surface of plants
Strengthening tissue
It provides support for plants
Xylem tissue
It transport water and mineral salts




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