Animal Cells and Plant cells –Cell Structure and functions Class 8 NCERT Notes

Animal cell diagram.

Animal cells

Animal cell diagram.

Let’s begin with the components of the animal cells:-

Cell membrane

A cell is always surrounded by a thin membrane called plasma membrane.

The membrane has the following functions:-

  • It encloses the various cell structure and cytoplasm.
  • It gives definite shape to the cell.
  • It regulates the movement of substance into and from the cell. Only certain substances are allowed to enter or leave the cell so the membrane is selectively permeable membrane.

#Selectively permeable means something which is permeable allows material to pass in and out of it freely.

Nucleus 

  • The the most important organelle which controls all the vital activities of a cell is the nucleus.
  • It may be spherical or oval.
  • It is enclosed by a membrane called nuclear membrane filled with nucleoplasm.
  • It contains thread like structures arranged in a network called the chromatin
  • At the time of cell division chromatin threads get called become shorter and thicker forming chromosomes, each of which carries large number of genes.

# Genes controls and organisms hereditary character which are   passed down from the parent cell to the new cell.

 Mitochondria 

  • Mitochondria are the powerhouse of the cell they are essential for the completion of the respiratory process, which ends with the release of energy following the breakdown of food.
  • Mitochondria is a simple rod shaped or spherical body with double membrane.
  • The inner membrane has several folds which project inwards, forming   finger like structures called cristae.
    The cell may have a few hundred to a few lakh mitochondria.

Centrosome 

  • This small body lies in cytoplasm close to the nucleus.
  • It contains two minute granules called centrioles, which help in cell division.

Plant cell

Plant Cell Diagram

A plant cell is enclosed not only by the plasma membrane but also by a wall called the cell wall.

Also Check –Cell Structure and Its Function

Cell wall of Plant cell

It is made of nonliving substance called cellulose, a kind of carbohydrate.

Functions of cell wall in  the plant cell
  • It gives a definite shape to the plant cell.
  • It makes the cell rigid and strong.
  • Cell wall provides protection against variations in temperature, atmosphere moisture
  • Prevents water loss.
  • It protects the cell from injury.
  • It allows all substance to enter and leave the cell.
Plant cells have all the structure mentioned in the animal cell except centrosome. In addition they have following organelles.

Plastids-

  • Plastids are organelles containing pigment.
  • They are covered by double membrane.
  • Their shape varies from round to filamentous.

Plastids are of following types: –

Chloroplasts- 

These  Plastids have a green pigment called chlorophyll.  This gives plants their green colour.

Functions of chloroplast

  • Chloroplasts plays Vital role in photosynthesis.
  • Chloroplast helps the plant by trapping solar energy, which is then used to convert carbon dioxide and water to carbohydrates.
  • Chloroplast are essential for survival of not only plants, but also all other organisms which depend on plants to fulfill their carbohydrate requirement.

Chromoplasts 

  • All The Other color which we see in plants are produced by Chromoplasts.
  • For example, red, orange and yellow of ripe fruits and flowers are produced by this color Plastids.

Leucoplasts

  • These are colorless plastids found in roots and underground stems, such as potatoes and Ginger.
  • They store food like  starch proteins and fats.
  • Some leucoplasts turn into chloroplast when exposed to sunlight.

 Vacuoles

  • This bodies are like sacs or cavities.
  • The contain the fluid called  cell sap,  which consists of water ,sugar ,amino acids,  enzymes, salt, nitrogenous waste, and so on.

The functions of vacuoles are as follows

  • It maintains the shape of the cell.
  • It maintains the balance of water in the cell.
  • It stores Chemicals, food, water and salts.

Nonliving substance

  • A plant cell contains various non-living substances which are the products of its metabolic activities this substance as a whole are called cell inclusion.
  • They Include various types of carbohydrates, proteins, fats, oils and some waste products like resin, gums and mineral crystals.

 

12 Comments on “Animal Cells and Plant cells –Cell Structure and functions Class 8 NCERT Notes”

  1. I just want to say I am newbie to blogging and site-building and seriously loved you’re web site. Most likely I’m going to bookmark your blog. You amazingly come with fabulous articles and reviews. Thanks a lot for sharing your web site.

Leave a Reply

Your email address will not be published. Required fields are marked *