cell structure and functions

1. CELL: STRUCTURE AND FUNCTIONS

2. CELL: STRUCTURE AND FUNCTIONS
• The cell is the basic structural and functional unit of all living organisms.
INTRODUCTION
 Discovery of cell
 Cell wall
 Cell membrane/plasma membrane
 Cytoplasm
 Nucleus
 Cell organelles-mitochondria,
vacuoles, plastid (chloroplast)
 Plant and animal cell
 Prokaryotic and eukaryotic ell

3. CELL: STRUCTURE AND FUNCTIONS
Plant cell Animal cell

4. CELL: STRUCTURE AND FUNCTIONS
INTRODUCTION
• Organisms Show Variety in number, cell shape, and cell size.
• Cell, Tissues, Organs, organ system and organism.

5. CELL: STRUCTURE AND FUNCTIONS
Discovery of cell:-
• All of us have seen the plants like rose, marigold, sunflower, cabbage, mushroom,
mango tree, oak tree, coconut tree, banana tree, ferns and many others.
• We also know the animals like dog, cat , man cow, horse , camel, lion, elephant,
mosquito , centipede, spider, grasshopper, and many others.
• In fact there is a large variety of organisms ( plants and animals) around us.
• They have different shapes and sizes.
• Their food habits and habitats (living space ) are also different.
• In spite of great variation in the size, shape, food habits and habitats, etc. all the
living organisms have basic similarity among them:
• They are made up of tiny units called ‘cells’
• Thus, in biology cells are the structural and functional units of life.

6. CELL: STRUCTURE AND FUNCTIONS
Discovery of cell:
• The cell was discovered by Robert Hooke, and English naturalist/scientist, in 1665. he used a
rudimentary compound microscope to study thin slices of cork (material obtained from the bark of a
tree). He observed that the cork slice was made up of million of little compartments shaped like
honeycombs.
• Then he coined the term CELL to describe these Compartments.
However, he did not understand their real structure or
function.

7. CELL: STRUCTURE AND FUNCTIONS
• The dead plant cells of cork observed by Robert Hooke were found to be empty.
• The microscope used by Robert Hooke was primitive.
• When better microscopes (having greater magnifying power) were made, scientist
investigated pieces of living plants and found that like cork, they also had a cell structure.
• The living plant cells were, however not empty like cork cells, they were found to contains a
number of tiny structures (called organelles)
• Anton von Leeuwenhoek designed improved microscope
and describe, for the first time, free living cells-bacteria.

8. CELL: STRUCTURE AND FUNCTIONS
• The idea that the cell is a fundamental unit of life was first put forth by two German
biologists, Matthias schleiden and Theodor schwann in 1839. Their findings formed the
basis of the cell theory.
• All known living things are made up of one or more cells.
• The cell is the fundamental unit of structure and function in all living organisms.
• All cells have the same basic chemical composition.
• The activity of the organism is determined by the way the cells function.
• The organization of the cells determines the structure of the organism.

9. CELL: STRUCTURE AND FUNCTIONS
• Cells are the basic units of life.
• All the living things( plants and animals) are made from cells.
• Just as a house is made up of bricks, in the same way, a living organisms is made up of cells.
• Thus, cells are the building blocking of plants and animals.
• A baby, banyan tree and a bacterium look very different from one another, but they are all
made up of tiny cells.

10. CELL: STRUCTURE AND FUNCTIONS
• Our nose, skin, muscles and bones are all made up of cells.
CELL NUMBER
• Organisms may be made up of a single cell or several cells. Single celled organisms such as Amoeba,
Paramecium, Yeast and Bacteria are called unicellular organisms.
• Unicellular organisms are thought to be the oldest form of life.
• The single cell carries out all the important functions necessary for an organism to live, such as
ingestion, digestion, respiration, movement, excretion and reproduction.
• Thus, the single cell can exist independently. Most unicellular organisms are microscopic.
• However , there are some types of bacteria and algae that are visible to the naked eye.
It is likely that eukaryotic cells, of which humans are made,
evolved from bacteria about tow billion year ago. One theory
is that eukaryotic cells evolved via symbiotic relations hip
between two independent prokaryotic bacteria,