FUNDAMENTAL UNIT OF LIFE

CELLS

CELL THEORY

All living organisms are composed of one or more cells.

The cell is the basic unit of structure, function, and organization in all organisms.

All cells come from preexisting, living cells.

Usually credited to Matthias Schleiden and Theodor Schwann. However, many other scientist like Rudolf Virchow contributed to the theory.

CELLS WERE FIRST DISCOVERED BY HIM IN 1665

ROBERT HOOKE

ROBERT OBSERVED :

Slice of cork resembled the structure of the honeycomb consisting of small compartments. Robert called these little compartments as cells.

CORK COMES FROM THE BARK OF THE

TREE

CORK SEEN UNDER THE MICROSCOPE OF HOOKE

STRUCTURE OF CELL

Cells come in all shapes and sizes. While most of the cells are spherical in shape, cells of various other shapes are also found. Most of the cells are microscopic in size, i.e. it is impossible to see them with naked eyes. Some cells are fairly large, e.g. a neuron in human body can be as long as 1 meter.

COMPARING CELLSnerve cells can be 1m long

human egg cell is no bigger than the dot on this i

human red blood cells is 1/10 the size of a human egg cell

bacterium are even smaller-8000 can fit inside a human egg cell

DIFFERENT CELLS

BONE CELLNERVE CELL FAT CELL

SPERM BLOOD CELL

OVUM

CELL TYPES

PROKARYOTIC CELLSno membrane bound

structures

EUKARYOTIC CELLSmembrane-bound

structures

UNICELLULAR ORGANISMS

ORGANISMS THAT HAVE A SINGLE CELL- PROKARYOTIC CELLS. AMOEBA

PARAMOECIUM CHLAMYDOMONAS

MULTICELLULAR ORGANISMS

ORGANISMS HAVING MORE THAN ONE CELL TO PERFORM VARIOUS FUNCTIONS- EUKARYOTIC CELLS.

ANIMALS

PLANTS

FUNGI

CELL WALL

found in plants, algae, fungi, most bacteria

tough, rigid outer coverings that protect the cell and give

it shape

plant cell walls are mainly made

of cellulose

what makes the cell walls rigid? Pectin and

lignin!

Protective layer around all cells

what does it do? regulate interactions between the cell and the environment

If a cell has a cell wall, then the cell membrane is inside of itfood particles and

some molecules enter and waste products leave through the cell membrane

water can move into and out of cell through the cell membrane

CELL MEMBRANE

CYTOPLASM

Gelatin like substance that fills cells which is constantly moving

Contains a framework called the cytoskeleton - this helps maintain or change the shape of the cell.

Cytoskeleton helps some cells move

cytoskeleton is made up of thin, hollow tubes of protein and thin, solid protein fibers

ORGANELLES contained within the

cytoplasmWhat do organelles do?

★process energy★manufacture substances needed by the cell

★move materials★act as storage sites★are surrounded by membranes★nucleus is usually the largest organelle

NUCLEUS

is surrounded by a membrane

directs all cell activities

materials enter and leave through the membrane

contains instructions for

everything in

the cell, which

are found on

DNA

a nucleolus is also within the nucleus

NUCLEUS

ENERGY-PROCESSING ORGANELLES

cells need energy to: ✤process food✤make new substances✤eliminate wastes✤communicate with each other

PLANTS๏food is made in green organelles called chloroplasts

๏contain green pigment chlorophyll

๏chlorophyll captures light energy that is used to make glucose

ANIMALS๏energy in food is stored until it is released by the mitochondria๏organelles where energy is released from the breakdown of food into carbon dioxide and water๏muscle cells are more active, so they contain more mitochondria

GOLGI BODIESproteins are made and sent to the Golgi bodies

Golgi bodies sort proteins and other cellular substances and package them into membrane-bound structures called vesicles vesicles deliver cellular

substances to areas inside the cellRefrigerator - cells have membrane-bound

spaces called vacuoles for temporary storage of materials (water, waste products, food, and other cellular materials)

RECYCLING ORGANELLESactive cells break down and recycle substances

lysosomes contain digestive chemicals that help break down food molecules, cell wastes, and worn-out parts

lysosome membrane keeps the chemicals from leaking into the cell

when a cell dies a lysosome’s membrane disintegrates, releasing digestive chemicals that quickly breakdown the cell’s contents

PRESENTED BY

LIPIKA BISWAS, TGT (SCIENCE), K.V. - BALLYGUNGE