Presentation on theme: "CELL Topics Cell structure Cell function Cellular organization"— Presentation transcript:
1CELL Topics Cell structure Cell function Cellular organization Cellular metabolism(by Dr. Amjad Ali Khan)
2IntroductionThe cell is the structural and functional basic unit of life.It was discovered by Robert Hooke and is the functional unit of all known living organisms.It is the smallest unit of life that is classified as a living thing, and is often called the building block of life.
3IntroductionSome organisms, such as most bacteria, are unicellular (consist of a single cell).Other organisms, such as humans, are multicellular.Humans have about 100 trillion or 1014 cells; a typical cell size is 10 µm (micrometer) and a typical cell mass is 1 nanogram.
4Types of Cells There are two types of cells: prokaryotic and eukaryoticProkaryotic cells are usually independent, while eukaryotic cells are often found in multicellular organisms.
5Prokaryotic CellThe prokaryote cell is simpler, and therefore smaller, than a eukaryote cell, lacking a nucleus and most of the other organelles of eukaryotes.Nuclear material of prokaryotic cell consist of a single chromosome which is in direct contact with cytoplasm. Here the undefined nuclear region in the cytoplasm is called nucleoid.
6On the outside, flagella and pili may be present On the outside, flagella and pili may be present. These facilitate the movement and communication between cells.Enclosing the cell is the cell envelope – generally consisting of a cell wall covering a plasma membrane
8Eukaryotic CellEukaryotic cells are far more advanced and complex than a Prokaryotic cell.Eukaryotic cell can be as much as 1000 times bigger in size than a prokaryotic cell.eukaryotic cells contain membrane-bound compartments (organelles) in which specific metabolic activities take place.
9Most important among these is a nucleus, a membrane bound compartment that contains DNA. This nucleus gives the eukaryote its name, which means "true nucleus.There are some differences in the structure and function of animal and plant cells. Though both cells are eukaryotic.
10In the cytoplasm the eukaryotic cell contains many organelles such as: MitochondriaEndoplasmic reticulum (rough and smooth)Golgi bodiesLysosomesPeroxisomesRibosomesChloroplast (found in plant cells)Vacuolecentriole
12Eukaryotic cell organelles There are several types of organelles in a cell.Some (such as the nucleus and golg apparatus) are typically solitary, while others (such as mitochondria, peroxisomes and lysosomes) can be numerous (hundreds to thousands).The cytosol is the gelatinous fluid that fills the cell and surrounds the organelles.
13NucleusThe cell nucleus is the most conspicuous organelle found in a eukaryotic cell. It contains the chromosomes,The nucleus is spherical and separated from the cytoplasm by a double membrane called the nuclear envelope.The nuclear envelope isolates and protects a cell's DNA
14The nucleolus is a specialized region within the nucleus where ribosome subunits are assembled. In prokaryotes, DNA processing takes place in thecytoplasm.
15MitochondriaMitochondria play a critical role in generating energy in the eukaryotic cell so it is also called “power house of a cell.Mitochondria are self-replicating organelles that occur in various numbers, shapes, and sizes in the cytoplasm of all eukaryotic cells.Mitochondria multiply by splitting in two.Respiration occurs in the cell mitochondria.
17Endoplasmic reticulum The endoplasmic reticulum (ER) is the transport network for molecules targeted for certain modifications and specific destinations.The ER has two forms: the rough ER, which has ribosomes on its surface and secretes proteins into the cytoplasm, and the smooth ER, which lacks them.
19Golgi apparatusThe primary function of the Golgi apparatus is to process and package the macromolecules such as proteins and lipids that are synthesized by the cell.It is particularly important in the processing of proteins for secretion.It consists of -cis and -trans faces
21RibosomesThe ribosome is a large complex of RNA and protein molecules.They each consist of two subunits, and act as an assembly line where RNA from the nucleus is used to synthesize proteins from amino acids.
22RibosomesRibosomes can be found either floating freely or bound to endoplas-mic reticulum in eukaryotes, or the cell membrane in prokaryotes).In prokaryotic cells 70S ribosomes are present while in eukaryotic cells 80S ribosomes are present
23LysosomesLysosomes contain digestive enzymes. They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria.These organelles (lysosomes and peroxisomes) are often called a "suicide bag" because of their ability to detonate and destroy the cell.
24VacuolesVacuoles store food and waste. Some vacuoles store extra water.The vacuoles of eukaryotic cells are usually larger in those of plants than animals.
25CentrioleIn animal cells, centrioles are short cylinders present near the nucleus.There is always one pair of centrioles near the nucleus.Before a cell divides, the centrioles duplicate.During cell division, the pair of centrioles separate so that each cell gets one pair of centrioles.
26The cytoskeletonSeveral types of filamentous proteins form a cytoskeleton that helps maintain the cell’s shape and either anchors the organelles or assists their movement.The cytoskeleton includes microtub-ules and actin filaments.
27MICROTUBULESMicrotubules are shaped like thin cylinders and are several times larger than actin filaments.Microtubules are made up of tubulin.Microtubules can assemble and dis-assemble.It is well known that during cell division, microtubules form spindle fibres, which assist the movement of chromosomes
28Cilia and FlagellaCilia and flagella are projections of cells that can move.Cilia are short (2-10µm) while flagella are longer about 200 µm.Cells that have these organelles are capable of self movement or moving material along the surface of the cell.
29Cellular metabolismCellular metabolism includes all the chemical reactions that occur in a cell.Quite often these reactions are organized in a metabolic pathways, which can be shown as:A B C D
30A B C DThe letters A,B,C,D are the reactants and products whereas 1,2,3 are the enzymes which take part in the reactions.Every reaction in a cell requires a specific enzyme
31Different types of enzymes present in a cell which act on different substrates are: Substrate EnzymeLipid lipasesProtein proteaseUrea ureaseMaltose maltaseLactose lactase
33Difference between prokaryotic and eukaryotic cell Typical organismsbacteria, archaeaplants, animals, fungiSize of cell1 – 10 µm10 – 100 µmType of nucleusNo real nucleusTrue nucleusCell organelles (mitochnodria, chloroplast, ER, golgi bodies, lysosomes etc)AbsentpresentRibosomes70S80SCell divisionBinary fissionMitosis and meiosisDNACircular , in cytoplasmIn chromosomes, in nucleus
34Difference and common between animal cell and plant cell StructureAnimal CellPlant cellCell membraneyesYesnucleusNucleolusRibosomesERGolgi bodiesCentriolesNoCell wallMitochnondriaChloroplastOne big vacuolecytoskeleton
36Cell theoryThe cell theory, first developed in 1839 by Schleiden and Schwann, states thatall organisms are composed of one or more cells,that all cells come from pre-existing cells,that vital functions of an organism occur within cells,
37Cell theoryand that all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.The word “Cell” was first coined by Robert Hooke in 1665