2.  Scientific study of life.  Present era is most exciting in biology  Scientists are trying to solve biological puzzles like:  How a single microscopic cell develops into complex animals and plants?  How plants converts solar energy to chemical energy of food?  How human mind works?  How various forms of diverse life on earth evolve from first microbe?

3.  Evolution makes sense of everything we know about living organisms.  Organisms living on Earth are modified descendents of common ancestors  Biology is a quest, on ongoing inquiry about the nature of life.  Modern biology is as important as it is inspiring  Research breakthroughs in genetics and cell biology are transforming medicine and agriculture.  Molecular Biology is providing new tools to anthropology and criminal science(Forensics).  Neuroscience and evolutionary biology are reshaping psychology and sociology  New models in ecology are helping societies evaluate environmental issues i-e. causes and biological consequence of global warming.  That’s how biology weaves into the fabric of our culture more than before.  This is a better time to explore life.

4.  New properties emerge at each level in the biological hierarchy  Life can be studied at different levels from molecules to the entire living planet  The study of life can be divided into different levels of biological organization

8.  Cell is fundamental unit to biology as atom is to chemistry  All organisms are made of cells.  In the hierarchy of biological organization the cell is the simplest collection of matter that can live.  Single celled organisms are of diverse form  Complex organisms: Plants and animals are multicellular; ● Have many kinds of specialized cells ● These cell can be survive on their own ● Tissues and organs can not survive on their own either. Cell is a basic unit of structure and function.

9.  Various cells functions together or one after the other. i-e The contraction of muscle cells move your eyes as you read a sentence. When you decide to turn the next page, nerve cells transmit that decision from your brain to muscle cells of your hand.  Every thing an organism does occurs fundamentally at cellular level.  Life at cellular level arises from structural order, reinforcing the themes of emergent properties and correlation between structure and function. i-e The movement of an animal cell depends on an intricate interplay of the structure that make up a cellular skeleton.

11.  Interaction of organisms with their environment. Cells sense and respond to environmental fluctuations.  All cells are related by their descent from earlier cells. However they have been modified in many different ways during long evolutionary history of life on earth.  Although the cells differ substantially from each other they share certain common characteristics.

12.  A eukaryotic cell has membrane-enclosed organelles, the largest of which is usually the nucleus  By comparison, a prokaryotic cell is simpler and usually smaller, and does not contain a nucleus or other membrane-enclosed organelles  Bacteria and Archaea are prokaryotic; plants, animals, fungi, and all other forms of life are eukaryotic

15.  Theme: The continuity of life is based on heritable information in the form of DNA  Chromosomes contain most of a cell’s genetic material in the form of DNA (deoxyribonucleic acid)  DNA is the substance of genes  Genes are the units of inheritance that transmit information from parents to offspring

17.  Each chromosome has one long DNA molecule with hundreds or thousands of genes  DNA is inherited by offspring from their parents  DNA controls the development and maintenance of organisms  Each DNA molecule is made up of two long chains arranged in a double helix  Each link of a chain is one of four kinds of chemical building blocks called nucleotides

20.  Genes control protein production indirectly  DNA is transcribed into RNA then translated into a protein  An organism’s genome is its entire set of genetic instructions  The human genome and those of many other organisms have been sequenced using DNA sequencing machines.  Knowledge of a cell’s genes and proteins can be integrated using a systems approach

23.  Advances in systems biology at the cellular and molecular level depend on “High- throughput” technology, which yields enormous amounts of data -  Bioinformatics, which is the use of computational tools to process a large volume of data  Interdisciplinary research teams

36. Cell structure and Function