Plant cell

THE CELL

The cell is the smallest basic unit of life.

Unicellular organisms are only made up of a single cell e.g. amoeba, paramecium. Multicellular organisms are made up of many cells e.g. man, cows, bean plant, etc.

THE ORIGIN OF NEW CELLS

New cells are formed from already existing cells by a process called cell division. The already existing cell is called a parent/ mother cell; and the new cells formed are called daughter cells.

STRUCTURE OF A PLANT CELL

Plant cell

CELL ORGANELLES

Parts of cell and their functions

1.Cell Membrane

Is the outer living part of a cell and it is found in all cells. Its semi permeable i.e. has tiny holes through which only very small molecules like water can pass through.

Functions

  • It allows movement of materials of in and out of the cell.
  • It regulates the shape and strength of a cell.
  • Offers protection to the / inner parts of the cell.
  • Binds protoplasm/ cytoplasm

2.Cell Walls

It is found in plant cells and it is made up of cellulose (a nonliving substance) which gives it its rigid tough nature.

Functions

  • It gives the plant cell its shape.
  • Protects the inner parts of the cell cellular.
  • Allows movement of materials in and out of the cell.
  • It offers mechanical strength to the cell.

3.Nucleus

It is surrounded by double membrane called the nuclear membrane.

Functions of a nucleus

  • Controls cell activities.
  • Controls cell division
  • Stores the genetic material of a cell.
  • Plays an active role in protein synthesis.

Functions of the nuclear membrane

  • Binds the nucleus
  • Separates the nucleus plasma from the cytoplasm.
  • Allows for the exchange of materials between the nucleus and the cytoplasm.

4.Cell Vacuole

Contains a watery substance called cell sap and is surrounded by a single membrane called the tonoplast. Each Plant cell possesses one large permanent central vacuole while each animal cell has many temporary vacuoles.

Functions

  • Stores waste materials before they are expelled.
  • It is a temporary food store.
  • Gives shape to the cell.

5.CytoplasmIt

is a fluid material that contains many organelles e.g. mitochondria, nucleus etc.

Functions

  • Site for cell activities i.e. metabolic reactions.
  • Site for storage of energy producing materials e.g. starch and glycogen.

6.MitochondriaIt

is the cell power house and its function is to release energy through respiration.

7.Chloroplast

Found in only plant cells

  • Contains a green pigment called chlorophyll that traps sunlight for photosynthesis.

8.Golgi body

  • Involved in cell secretions i.e. secretes enzymes.
  • It transports materials in cells.

9.Lysosome

It secretes hydrolytic enzymes i.e. breaking down enzymes e.g. help in destruction of old or worn out cell

COMPARING A PLANT AND ANIMAL CELL

Differences:

Plant cellAnimal cell
i)Regular in shapeIrregular in shape
ii)Has a cellulose cell wallLacks a cellulose call wall.
iii)Has chloroplast.Lacks chloroplast.
iv)Large vacuole centrally located.Cell vacuole very small and positioned at the side.
v)Has a middle lamella.Lacks a middle lamella.
vi)Nucleus is positioned at one side.Nucleus centrally located.
vii)Store food as starch granulesStore food as glycogen granules.
viii)Has a tonoplast around the vacuoleHas no tonoplast
ix)Has a Thin layer of cytoplasmHas a thick layer of cytoplasm

SIMILARITIES:

Plant cell and animal cell

  • Both have a nucleus.
  • Both have mitochondria.
  • Both have a Golgi body.
  • Both have a vacuole.
  • Both have a cytoplasm.
  • Both have a cell membrane