cell organisation .pptx

Cellular and molecular pharmacology
Mpharm (Pharmacology) 1st year, 1st semester

1. Structure And Function Of Cell And Its Organelles Genome Organization Chetana Pandurang Dakhare M.Pharm (Pharmacology) 1 st year

2. Cell Cell is defined as the structural and functional unit of life. The term cell has been derived from a Latin word cellula meaning a small compartment. The word cell was introduced by Robert Hooke and the first cell were observed in 1665 from a slice of cork. Cell are of two types prokaryotic and eukaryotic cells. Diameter – 2-10 µm.

3. Cell theory The german botanist M.J. Schleider and Theodor Schwann a zoologist (1839) established the cell theory in definite form. These two investigators postulated that the cell is the basic structural and functional unit in all living organisms. This simple, basic and formal biological generalization is known as cell theory or cell doctrine.

4. The modern version of cell theory states that: All living organisms are made up of cells It is the basic structural and functional unit of life It contain genetic information which is passed from cell to cell during cell division All cells arise from pre-existing cells ( Rudolf Virchow-1858 ) Cells are self duplicating and some cells are totipotent

5. Major structures present in a cell are : Cell wall Cell membrane Cytoplasm and its organelles Nucleus

6. Cell wall The protective semi transparent covering outside the cell membrane is called cell wall It is thick, strong, rigid and measures 0.1 nm to several nm thickness The chemical composition of the cell wall differs according to the cell type and function In higher plants it is made up of polysaccharides such as cellulose, pectin, lignin, hemicellulose, cutin and suberin Cell wall is absent in animal cell

7. FUNCTIONS: Cell wall provides rigidity, support and shape to the cell It protects the protoplasm against mechanical injury It also helps in the transport of material

8. Cell membrane All prokaryotic and eukaryotic cells have cell membrane. Thin liable elastic outermost structure which envelops the cell. Act as a boundary for cytoplasm and present beneath cell wall if present. But if cell wall is absent cell membrane is a outermost layer of cell. Fluid Mosaic Model :- The fluid mosaic model was proposed by singer & Nicholson (1972). According to this model, functionally distinct membranes, different protein sub-units are present in the highly viscous fluid matrix of phospholipid bilayer. The lipid bilayer is about 45Å.

9. Each phospholipid molecule in the lipid bilayers consists of two parts i)A head which is hydrophilic. ii)Tails which are hydrophobic. FUNCTIONS Cell membrane gives shape to the cell and protects cell from injury. It regulates the cellular semi-permeability,reabsorption,excretion and secretion. It contributes to the formation of various cell organelles within the cell. It also acts as selectively permeable membrane to allow only specific substance to go in & out of the cell.

10. Cytoplasm Cytosol or cytoplasm consists of jelly like colloidal,ground substance called cytoplasmic matrix The matrix shows streaming movement called cyclosis. The cytoplasmic matrix is composed of minerals, sugars, amino acids, tRNA, nucleotides,vitamins,proteins and enzymes. It accounts for almost 70% of the total cell volume. There are several types of organelles within a cell such as: i. Mitochondria ii. Endoplasmic reticulum iii.Golgi Apparatus iv. Lysosomes v. Ribosomes vi.Centrioles vii. Cytoskeleton viii. Vacuoles Each organelle is bounded by a lipid membrane and has specific functions

11. Mitochondria [ Mitos -Thread & Chondros - Granule] First observed by kolliker in 1850 as granular structures in striated muscles. Mitochondria are double membrane-bound organelles found in nearly all the eukaryotic cells. The average number of mitochondria in a cell varies from 50-5000. Shape:-Rod shaped or small spherical structures. Structure:- Length – 5-12µm Diameter – 0.5-1 µm. Mitochondria having two membrane: i)Outer membrane: is smooth & freely permeable to everthing present in cytoplasm. ii)Inner membrane: is folded in structure these foldings in the cavity are called as cristae. - Inner membrane is selectively permiable

12. Mitochondria are called as the power house of the cell. FUNCTIONS Power generating units of the cells. Important to maintain proper conc. Of calcium ions within the various compartments of the cell. Energy transduction through respiration. Responsible for thermogenesis iii) Matrix : The cavity of the mitochondrion filled with dense fluid known as the mitochondrial matrix. - Matrix shows presence of proteins, lipids, ribosomes, DNA molecule,RNA & certain other granules.

13. Endoplasmic Reticulum Network of tubular and flat vesicular structure in the cytoplasm. An extensive network of closed, flattened membrane-bounded sacs called cisternae. Space inside tubules is filled with endoplasmic matrix Endoplasmic Reticulum are of two types : i) Smooth Endoplasmic Reticulum ii) Rough Endoplasmic Reticulum

14. Difference between Smooth and Rough ER Smooth ER Ribosomes absent Site of synthesis of lipid & steroid hormones Mainly present in lipid forming cells of testis,glycogen storing cells of liver,adrenal cortex cells, muscle cells etc. Rough ER Contains ribosomes Site of protein synthesis, processing & packaging Mainly present in protein forming cells such as pancreatic acinar cells, goblet cells, antibody producing plasma cells,nissl’s granules of nerve cells etc.

15. FUNCTIONS Synthesis of proteins Protein segregation Unsaturation of fatty acid Muscle contraction ER is commonly known as sarcoplasmic reticulum in muscle fibers .

16. Golgi Apparatus Golgi apparatus was first described in 1898 by neurologist Camillo golgi in nervous tissue. Golgi apparatus is a collection of membrane enclosed sacs composed of four or more stacked layers of thin, flat enclosed vessels lying near the side of the nucleus. Consist of multiple discrete compartments. Consist of three functionally distinct regions: i) The cis golgi network ii) Golgi stack: which is divided into a) Medial b)Trans sub compartments iii) Trans golgi network

17. FUNCTIONS Wrapping & packaging department of the cell. Site of formation of lysosomes i.e. large irregular structures surrounded by membrane which are present in the cytoplasm. It adds certain carbohydrates to form glycoproteins, which play an important role in the association of the cells to form tissues. Synthesis of some complex lipids occurs in golgi apparatus.

18. Lysosomes Irregular structures surrounded by unit membrane. Diameter – 250-750nm More acidic than rest of the cytoplasm & external bacteria as well as worn out cell components are digested in them. The interior is kept acidic(Near pH 5.0)by the action of proton pump or H+ Lysosomes are cell hydrolases & they function best at the acidic pH.

19. FUNCTIONS Acts as a form of digestive system or the cell because enzymes present in it can digest essentially all macromolecules. Engulf worn out compartments of the cells in which they are located. Engulf exogenous substances e.g. bacteria & degrade them. When cell dies,lysosomal enzymes causes autolysis of the remanant,thats why lysosomes are called as suicidal bags.

20. Ribosomes Ribosomes were discovered and named by Palade. Present in all types of living cells i.e. prokaryotic or eukaryotic. Are granular organelles which do not have any enclosed membrane. Chemically they are composed of ribonucleoproteins. In eukaryotic cells ribosomes are found attached to the membrane of ER.& also scattered in cytoplasm,mitochondrial matrix. 150Å-250Å in diameter. Ribosomes are consists of two compartments a) RNA b) Ribosomal Proteins

21. FUNCTIONS Ribosomes are the sites of protein synthesis hence known as protein factories. Ribosomal RNA molecule possibly serve as a skeletal framework in the ribosomes. Ribosomes are also protective in function against the action of protein digesting enzymes.

22. Centrioles Centrioles are non-membranous cylindrical or rod-shaped micro-tubular structure. Normally found in animal cell. Present near the nucleus in a dense area of cytoplasmic material. Present within centrosomes in a pair of cylindrical structure called centrioles. Centrioles are the hub of protein called Tubulin. FUNCTIONS Help in spindle formation during cell division of the animal cell. Also helps in formation of basal bodies, flagella &spindle poles.

23. Cytoskeleton System of fibers that not only maintains the structure of the cell but also permit it to change shape & move The cytoskeleton is made up primarily of i) Microtubules- Cylindrical tubes,composed of subunits of the protein tubulin ii) Intermediate filaments- Are provide tensile strength for the cell. ex.keratin iii)Microfilaments-Fine thread like protein fibers .

24. FUNCTIONS Movement of chromosomes. cell movement. Processes that move secretion granules in the cell. Movement of proteins within the cell membrane.

25. Vacuoles Vacuoles are membrane bound fluid filled spaces present in an eukaryotic cell. Plant cells show two or three large & permanent vacuoles whereas in animal cells they are small & temporary. Vacuole is bound by single unit membrane called tonoplast. Vacuoles are filled with fluid called cell sap contains mineral salts, sugars, amino acids,proteins,esters,alkaloids waste products & water soluble pigments.

26. FUNCTIONS The contractile vacuoles are responsible for maintaining homeostasis. They are also specialized for osmoregulation & excretion e.g. paramecium These maintain the turgidity of the cell & help in maintaining a proper internal balance of cellular conatents .

27. NUCLEUS Robert Brown in 1831, discovered that nucleus is a constant part of the cell. It is the controlling centre of the cell. It contains the genetic material in the form of chromosome. The prokaryotic cells do not have true nucleus. Nucleus remains located in the centre,its position may change from time to time. Shape of the nucleus is spherical,ovoid or elongated,disc shaped. Structure: a typical interphase nucleus consists of nuclear envelope, nucleoplasm, nucleolus & chromatin material. 1] Nuclear envelope : seperates the nuclear material from the cytoplasm - it is concerned with nucleo -cytoplasmic exchange of the necessary materials.

28. - Nuclear envelope consists of nuclear membrane, perinuclear space , nuclear pores, annuli, central granule & fibrous lamina i)Nuclear membrane: Surrounded by two nuclear membrane. Outer nuclear membrane communicates with the endoplasmic reticulum. Inner nuclear membrane associated with dense material termed fibrous lamina attached to its inner surface. ii) Perinuclear space:The space between two nuclear membrane. It is filled with fluid similar to the fluid of ER. iii) Nuclear pores: Callon & Tomlin first observed the nuclear pores. The nuclear envelope is perforated by many apertures called nuclear pores. iv) Annuli: The nuclear pores are enclosed by an electron dense rings or cylinders called annuli v) Central granule: Present in the pore complex. It is not constant feature. vi) Fibrous Lamina: Present on inner surface of inner nuclear membrane.

29. 2] Nucleoplasm: Within the nuclear membrane is present a transparent semi-solid, granular & slightly acidophilic ground substance or matrix known as the nuclear sap or nucleoplasm. 3] Nucleolus: First discovered by Fontana. - It is a spherical , acidophilic body situated within the nucleus. 4] Chromatin Material: The nucleoplasm contains many thread like coiled & much elongated structures known as the chromatin. - Two types of chromatin materials have been recognized. i) Heterochromatin ii) Euchromatin

30. Summery

31. Genome Organization Introduction : ‘Gene’ are units of genetic information present on the DNA in the chromosome and chromatin. Genomics: The term genomic was coined by Thomas Roderick in 1986. - Genomic is the branch of molecular biology concerned with structure,function , evolution & mapping of genome and sequences.

32. Genome Genome is the complete set of genetic information in an organism. It provides all of the information the organism required to function. It consist complete set of DNA, including all of its gene The term genome was created in 1920 by Hans Winkler. The name ‘Genome’ is the blend of the words ‘gene’ and ‘chromosome’. The genome size is the total amount of DNA contained within one copy of a single genome.

33. Genome organization in prokaryotes & eukaryotes Prokaryotes Single chromosome + plasmids. Circular chromosome. Made only of DNA. Found in cytoplasm. Copies its chromosome & divides immediately afterwards Eukaryotes Many chromosomes. Linear chromosomes. Made of chromatin, a nucleoprotein.(DNA coiled around histone proteins) Copies chromosomes,then cell grows then goes through mitosis to organise chromosome in two equal groups.

34. Human genome Genetic material in human is stored in two organelles: Nucleus(About 3200mbp) & mitochondria (16.6kb). Human chromosomes are not of equal sizes the smallest chromosomes 21 & largest chromosome 1. Only a very small amount of human DNA is responsible for the differences among humans,indeed among all organisms. There are 3 billion base pairs present in human genome. Number of genes at least 100,000. Cost of sequence the first human genome was about $3 billion. And it took around 13 years to sequence the first human genome(from 2000-2013)

35. THANK YOU