Introduction to cell

Dr. Ajith Sominanda (MBBS,MPhil,PhD) Senior Lecturer Department of Anatomy Faculty of Medicine Peradeniya

Outline of the lecture 1.

Origin of the life 2.

Characteristic features of living things 3.

The unit of the life: the cell 4.

Components of the cell and their functions 5.

Beyond the cell

1. Origin of the life

Origin of the universe occurred 15 billion years ago

Prebiotic chemistry and origin of the life ‘’Life could have arisen through chemistry’’ Charlse Darwin (probably)

Miller-Urey’s experiments on pre-biotic chemistry in 1953

Change of organic chemicals into ‘life’ substance  Chemically reducing conditions can form amino acids  Pre-biotic earth was low in oxygen (reducing atmosphere) and therefore amino acids could have formed with lightning or in the sea bed hydrothermal vents etc.

Archean chemistry of prebiotic era

Life could have come from outside rather than the chemical evolution on earth

Murchison meteorite , which fell in Australia. Amino acids found in the meteorite were apparently present in it when it fell.

The earlier most evidence of life on earth 3.5 billion years back Fossilized imprints of micro-organisms which resemble modern blue-green algae (cynobacteria)

The scientific definition An organized thing or a system capable of self 1. Growth 2. Synthesis and degradation of materials by utilizing or releasing energy Metabolism 3. Keep a balance of the activities and conditions Homeostasis 4. Response to the environmental stimuli 5. Reproduction

Antony van Leeuwenhoek (1632-1723) and the micro world

The visibility & the expansion of our understanding

Electron microscope & Ultra structure Hydrogen atom 0.1nm = 1 Å

The unit of the life: Cell

Differences between pro and eu Karyotic cells

Components of the eukaryotic cell         Cell membrane Cytoplasm Nucleus Endoplasmic reticulum Golgi apparatus Mitochondria Endosomes & Lysosomes Cytoskeleton

Cell membrane; the wall of the life

Nucleus - The control center of life A nerve cell Nucleus contains the genetic materials that control the cell growth, development & transfer informations to the next generation.

Eukaryotic nucleus is membrane bound and contains organized nucleic acid ( chromosome s)associated with nuclear proteins

Organelles      Membrane bound structures unique to eukaryotic cells Endoplasmic reticulum (Rough & Smooth) Mitochondria Golgi Endosomes and lysosomes

Endoplasmic reticulum (ER), Golgi apparatus & vescicles - The factory of life

Functions Transfer of information from nucleus to cytoplasm to synthesize molecules needed for cellular functions

Gene mRNA protein function

Origin of nucleus & ER

Mitochondrium – The Energy for living -

Origin of mitochondria

Endosomes & lysosomes – The (‘toilet’) recycler of life

the scavengers or recycling system Endo-lysosomal system Ingestion of materials Enclosed by parts of plasma membrane (Endosomes) Degradation by lysosomes expulsion

The support to the cell - Cytoskeleton

Cytoskeleton

Cell and its immediate environment, the extracellular matrix is in constant communication through receptors / mollecules

Cells and beyond Cells Tissues Organs systems

Terminology 1.

2.

3.

4.

5.

6.

7.

Archaebacteria Prebiotic era Prokaryotes Eukaryotes Symbiosis Cell membrane Cytoplasm 8.

9.

Nucleus Endoplasmic reticulum 10.

Golgi apparatus 11.

Mitochondria 12.

Endosomes & Lysosomes 13.

Cytoskeleton

Home work   Find a text book in histology, i.e. Basic Histology by Carlos Junqueira Read the first chapters on cytoplasm and nucleus and then list the structural features and functions of components of the cell

The END Thank you