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  1. Cells Structure and functions By Priya tamang
  2. What is cell? • The cell is a structural and functional unit of all the living organisms, and it is also known as building blocks of life. • The human body is composed of trillions of cells, with their own specialized functions. • The term cell was first coined by Robert hook in 1965. • The cell is made up of water about two third of a cell, and rest is a mixture of molecules(protein, lipids, carbohydrates). • Cells covert the raw materials in the food into the molecules our body needs, using thousands of different metabolic reactions.
  3. Levels of Organization in Living Organisms • -Atoms (smallest unit of matter both living and non-living) • -Molecules (building blocks of matter composed of two or more atoms ) • -Organelles (parts of a cell that carry out a particular function or role and are made of molecules) • -Cell (is the smallest unit of life and the building block of all living organisms) • -Tissues (tissues are formed when cells combine to carry out a task. Muscles used to move your eyes are tissues) • -Organs (when two or more tissues combine and work together. Examples are the heart or stomach organs) • -Systems (Organs work together in systems, such as stomach, liver, and pancreas that work together in our digestive system) • -Organisms (Human beings are organisms that are composed of many systems)
  4. History • 1595 – Jansen credited with 1st compound microscope. • 1655 – Hooke described ‘cells’ in cork. • 1674 – Leeuwenhoek discovered protozoa. He saw bacteria some 9 years later. • 1833 – Brown descibed the cell nucleus in cells of the orchid. • 1838 – Schleiden and Schwann proposed cell theory. • 1840 – Albrecht von Roelliker realized that sperm cells and egg cells are also cells. • 1856 – N. Pringsheim observed how a sperm cell penetrated an egg cell. • 1858 – Rudolf Virchow (physician, pathologist and anthropologist) expounds his famous conclusion: omnis cellula e cellula, that is cells develop only from existing cells [cells come from preexisting cells] • 1857 – Kolliker described mitochondria. • 1879 – Flemming described chromosome behavior during mitosis. • 1883 – Germ cells are haploid, chromosome theory of heredity. • 1898 – Golgi described the golgi apparatus.
  5. • 1938 – Behrens used differential centrifugation to separate nuclei from cytoplasm. • 1939 – Siemens produced the first commercial transmission electron microscope. • 1952 – Gey and coworkers established a continuous human cell line. • 1955 – Eagle systematically defined the nutritional needs of animal cells in culture. • 1957 – Meselson, Stahl and Vinograd developed density gradient centrifugation in cesium chloride solutions for separating nucleic acids. • 1965 – Ham introduced a defined serum-free medium. Cambridge Instruments produced the first commercial scanning electron microscope. • 1976 – Sato and colleagues publish papers showing that different cell lines require different mixtures of hormones and growth factors in serum-free media. • 1981 – Transgenic mice and fruit flies are produced. Mouse embryonic stem cell line established. • 1995 – Tsien identifies mutant of GFP with enhanced spectral properties • 1998 – Mice are cloned from somatic cells. • 1999 – Hamilton and Baulcombe discover siRNA as part of post- transcriptional gene silencing (PTGS) in plants
  6. Cell theory • The cell theory describes the basic properties of all cells. • The three scientists that contributed to the development of cell theory are Matthias Schleiden, Theodor Schwann, and Rudolf Virchow. The cell theory states that:- • All living things are composed of one or more cells. • The cell is the basic unit of life. • All new cells arise from existing cells.
  7. Modern Cell Theory • All known living things are made up of cells. • The cell is structural & functional unit of all living things. • All cells come from pre-existing cells by division. (Spontaneous Generation does not occur). • Cells contains hereditary information which is passed from cell to cell during cell division. • All cells are basically the same in chemical composition. • All energy flow (metabolism & biochemistry) of life occurs within cells.
  8. BASIC
  10. Contain all the genetic information to produce new cells and controls all the chemical processes that take place in the cell. NUCLEUS
  11. Respiration takes place, glucose and oxygen are changed into energy. MITOCHONDRIA
  12. Cell membrane
  14. Type of cells • About 4.6 billion years ago, Earth was formed. In the earth's history, there was a very hostile and volcanic environment and is difficult to imagine any life being viable in those types of conditions. • It wasn't until the end of the Precambrian Era of the Geologic Time Scale when life began to form. • Several theories, about how life first came to be on Earth. These theories include the formation of organic molecules within what is known as the"Primordial Soup", life coming to Earth on asteroids (Panspermia Theory), or the first primitive cells forming in hydrothermal vents.
  15. Prokaryotic Cells • The simplest type of cells were most likely the first type of cells that formed on Earth. These are called prokaryotic cells. They have a cell membrane surrounding the cell, cytoplasm where all of the metabolic processes happen, ribosomes that make proteins, and a circular DNA molecule called a nucleoid where the genetic information is held. • They have a rigid cell wall that is used for protection. All are unicellular, meaning the entire organism is only one cell. • All are asexual, meaning they do not need a partner to reproduce. Most reproduce through a process called binary fission where basically the cell just splits in half after copying its DNA. This means that without mutations within the DNA, offspring are identical to their parent. • Archaea and Bacteria are prokaryotic organisms.
  16. Eukaryotic Cells • The other, much more complex, type of cell is called the eukaryotic cell. Like prokaryotic cells, they have cell membranes, cytoplasm, ribosomes, and DNA. • There are many more organelles within eukaryotic cells which include a nucleus to house the DNA, a nucleolus where ribosomes are made, rough endoplasmic reticulum for protein assembly, smooth endoplasmic reticulum for making lipids, Golgi apparatus for sorting and exporting proteins, mitochondria for creating energy, a cytoskeleton for structure and transporting information, and vesicles to move proteins around the cell. Some eukaryotic cells also have lysosomes or peroxisomes to digest waste, vacuoles for storing water or other things, chloroplasts for photosynthesis, and centrioles for splitting the cell during mitosis. • Cell walls can also be found surrounding some types of eukarotyic cells.
  17. • Most are multi-cellular. This allows the eukaryotic cells within the organism to become specialized. Through a process called differentiation, these cells take on characteristics and jobs that can work with other types of cells to create an entire organism. • There are a few unicellular eukaryotes as well. These sometimes have tiny hair-like projections called cilia to brush away debris and may also have a long thread-like tail called a flagellum for locomotion. • The third taxonomic domain is called the Eukarya Domain. • This domain includes all animals, plants, protists, and fungi. • Eukaryotes may use either asexual or sexual reproduction depending on the organism's complexity. • Sexual reproduction allows more diversity in offspring by mixing the genes of the parents to form a new combination and hopefully a more favorable adaptation for the environment.
  18. Difference between Prokaryotic cell and Eukaryotic cell
  19. Difference between plant cell and animal cell