cell- unit of life

Biology

Study of living organisms

Unity underlying diversity of life

Cellular organisation

Fundamental structural and functional unit of life

Cell

Unicellular organisms

Capable of independent existence

Anything less than a complete cell

Cannot ensure independent living

First observed and described a live cell

Anton Von Leeuwenhoek

Discovered nucleus

Robert Brown

Proposed that all plants are composed of cells

Matthias Schleiden (1838)

Reported presence of plasma membrane

Theodore Schwann (1839)

Presence of cell wall

Unique character of plant cells (as per Schwann)

Omnis cellula e cellula

Cells arise from pre-existing cells

Modified cell theory

Rudolf Virchow (1855)

All living organisms are composed of

Cells and products of cells

Cells lacking membrane-bound nucleus

Prokaryotic

Cells with membrane-bound nucleus

Eukaryotic

Semi-fluid matrix of cell

Cytoplasm

Main arena of cellular activities

Cytoplasm

Membrane-bound organelles absent in

Prokaryotes

Ribosomes are present in

Both prokaryotes and eukaryotes

Animal cell non-membrane organelle aiding division

Centrosome

Smallest cells

Mycoplasma (0.3 µm)

Size of bacteria

3–5 µm

Largest isolated single cell

Ostrich egg

Diameter of human RBC

~7.0 µm

Four basic shapes of bacteria

Bacillus, coccus, vibrio, spirillum

Genetic material in prokaryotes

Naked circular DNA

Extra-chromosomal DNA in bacteria

Plasmid

Plasmid confers

Antibiotic resistance

Specialised infolding of plasma membrane in prokaryotes

Mesosome

Three-layered prokaryotic envelope

Glycocalyx, cell wall, plasma membrane

Gram positive bacteria

Take up Gram stain

Loose glycocalyx

Slime layer

Thick glycocalyx

Capsule

Bacterial flagellum parts

Filament, hook, basal body

Ribosome size in prokaryotes

70S

Subunits of 70S ribosome

50S and 30S

Chain of ribosomes on mRNA

Polysome

Inclusion bodies

Reserve material storage

Gas vacuoles

Present in cyanobacteria

Eukaryotic ribosomes

80S

Subunits of 80S ribosome

60S and 40S

Fluid mosaic model proposed by

Singer and Nicolson (1972)

Major lipid of membrane

Phospholipid

Membrane movement property

Fluidity

Passive transport

No energy required

Movement of water across membrane

Osmosis

Energy dependent transport

Active transport

Example of active transport

Na+/K+ pump

Primary wall

Capable of growth

Secondary wall

Formed on inner side of primary wall