CSU003 - Cell Biology Lecture 07 - Nucleic Acids and Proteins PDF

CSU003 – Cell Biology Lecture 07 – Nucleic acids and Proteins  Topics to be covered today 1.Introduction to Biochemical components 2. Biochemical composition – Definitions – types – Nucleic acids and proteins – Some examples 3. Homework ...

CSU003 – Cell Biology Lecture 07 – Nucleic acids and Proteins  Topics to be covered today 1.Introduction to Biochemical components 2. Biochemical composition – Definitions – types – Nucleic acids and proteins – Some examples 3. Homework  Proteins Proteins 1. Proteins are compounds of these element: carbon, hydrogen, oxygen, nitrogen sulphur and phosphorus. 2. Amino acids are the subunits of all proteins. 3. Each amino acids carries two functional group: a) A carboxyl group (- COOH) which is acidic and b) An amino group (-NH2) which is basic. COOH carboxyl group C NH2 amino group  Proteins Two amino acids can combine together to form a dipeptide by a condensation reaction between the carboxyl group of one and the amino group of the other. The resulting a bond liking the two amino acids that is called a peptide bond. H2O h O Peptide bond h cooh Hn condensation c n C C c c NH2 hooc nh2 hooc 3  Protein structure Long chains of amino acids are called polypeptides. A polypeptide is formed by the condensation reaction of many amino acids, with the removel of water. A polypeptide chain can also be hydrolysed, with the addition of water molecules to form individual amino acids Primary-linear sequence of amino acids Secondary structure- forming ahelixor pleated sheet. Tertiary structure- compact structure Quaternary structure- 2 or more tertiary structure Structures of protein the sequence of amino acid in a polypeptide  Secondary structure -the coiling and folding of polypeptide chain by hydrogen bonds  Tertiary structure -the overall three-dimensional shape of a polypeptide chain -examples: enzymes,hormones,antibodies,plasma protein  Quarternary structure -the combination of two or more tertiary polypeptides that makes up a protein -example : haemoglobin  Nucleic acids Are the largest and the most complex organic molecules. Friedrich Miescher who discovered nucleic acids in 1871 NUCLIEC ACIDS are macromolecules, found in all cells, which precipitate in the storage, transmission and translation of genetic information.  There are two types of nucleic acids, the ribose nucleic acid (RNA) and the deoxyribose nucleic acid (DNA), which on hydrolysis yield the sugar ribose and deoxyribose respectively.  Nucleic acids were first isolated from the cellular nucleus, hence the name. Nucleic acids are macromolecules, huge polymers with molecular masses of over 100 million.  Function of nucleic acids Functions of DNA (deoxyribonucleic acid): -DNA is a permanent storage place for genetic information. -DNA controls the synthesis of RNA (ribonucleic acid). -The sequence of nitrogenous bases in DNA determines the protein development in new cells. The function of the double helix formation of DNA is to ensure that no disorders occur. This is because the second identical strand of DNA that runs anti-parallel to the first is a back up in case of lost or destroyed genetic information. Ex. Down’s Syndrome or Sickle Cell Anemia.  Functions of RNA Functions of RNA (ribonucleic acid): -RNA is synthesized by DNA for the transportation of genetic information to the protein building apparatus in the cell. -RNA also directs the synthesis of new proteins using the genetic information it has transported. -mRNA (messenger ribonucleic acid) is used to transfer genetic information through plasma membranes  Nucleic acid Nucleotides Phosphoric acid Nucleosides Sugar Purine Pyrimidine base Ribose or Guanine and Cytosine, uracil deoxyribose Adenine or thymine  Kinds of nucleic acids DNA( deoxyribonucleic acid) –found only inside the nucleus of the cell. Contains the organism’s genetic information, including instructions for how to make proteins. RNA( ribonucleic acid) – found both inside and outside of the nucleus. Directs the building of proteins. -primarily concerned with the synthesis of protein. POLYPEPTIDES are the building blocks of nucleic acids.  DNA Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms. The main role of DNA molecules is the long-term storage of information and DNA is often compared to a set of blueprints, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules. The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information. Deoxyribose is present in the nucleic acid found in the yeast cell nuclei, while ribose is contained in the nucleic acid obtained from pancreas. – There are cases also were both of nucleic acids are found together. So that it is now definitely accepted that both the ribose and deoxyribose nucleic acids are found in plants and animals; and that while the deoxyribose type is found in the nucleic of the cells (white) the ribose type predominate in the cytoplasm  RNA Ribonucleic acid (RNA) functions in converting genetic information from genes into the amino acid sequences of proteins. The three universal types of RNA include transfer RNA (tRNA), messenger RNA (mRNA), and ribosomal RNA (rRNA). Messenger RNA acts to carry genetic sequence information between DNA and ribosomes, directing protein synthesis. Ribosomal RNA is a major component of the ribosome, and catalyzes peptide bond formation.  Transfer RNA serves as the carrier molecule for amino acids to be used in protein synthesis, and is responsible for decoding the mRNA. In addition, many other classes of RNA are now known.  Ribonucleic acid is found only in plants while the deoxyribonucleic acid is exclusive of animal products 1. Transfer RNA – 10 tO 15% Kinds of RNA -small, about 80 nucleotides long. -transport amino acids to site of protein synthesis. -exhibits extensive inter chain of bonding represent by clover leaf structure. 2) Ribosomal RNA – 75 to 80% -several kinds –variable in size -combines with proteins to form ribosome's, the site oh CHON synthesis. - molecules to be quite large. 3) Messenger RNA -variable size(its size varies with the size of CHON) -directs amino acids sequence of proteins - extent of it bonding is very little. - in most cells it constitutes not more than 5% to 10% of the total cellular RNA.  Properties of nucleic acids  Nucleic acids are insoluble in alcohol, slightly soluble in cold water, but readily dissolved in hot water and dilute alkalies, forming alkali salts. They are precipitated by HCL and by excess of acetic acid.  Feulgen Test differentiates the DNA from RNA, if the deoxyribose sugar is present, a rd color is produced with the dye. Ribose sugar do not exhibit this reaction. Hydrolysis of nucleic acids gives nucleotide, which can be considered the units that make up the polymer. A nucleotide consists of three parts:  1. Heterocyclic base  2. sugar  3. phosphoric acids  HETEROCYCLIC BASES Present in nucleic acids are divided into two types- PURINES and PYRIMIDINES. The two Purines present both DNA and RNA are adenine and guanine. The Pyrimidines cytosine is present in both DNA and RNA, whereas thymine is found in DNA only and Uracil is present in RNA only.  Pyrimidines Pyrimidines is a six-membered heterocyclic ring containing two nitrogen atom. Three important derivatives of Pyrimidine found in nucleic acids are thymine(2,4-dioxy-5- methylpyrimidine), cytosine(2-oxy-4-aminopyrimidine), and Uracil(2,4-dioxypyrimidines). Other important compound containing Pyrimidines are thiamin (vitamin B one).  Purines The Purines found in nucleic acids are derivatives of a substances, Purine, that does not occur naturally. As indicated by their structures, adenine is 6-amino-purine and guanine is 2-amino-6-oxypurine. Other Purine include caffeine and theophylline. Caffeine is a stimulant for the central nervous system and also a diuretic, and found in coffee and tea. Its chemical name is 1,3,7-trimethyl-2,6-dioxypurine. Theophylline, 1,3-dimethyl-2,6-dioxypurine, is found in tea and is used medically as a diuretic and for bronchial asthma.Uric acid is the end product of purine metabolism.  Nucleoproteins  Nucleoproteins are frankly acidic and are soluble in alkalies with which they form salt. They precipitated from their solutions by acetic acid -- are redissolved by dilute HCL. They are not coagulated by -- but exhibit the precipitation and color reactions characteristic of protein substances.  Their importance lies in the increasing evidence that they are closely associated with the chromosomes of the cells.  In the bacteria cells, substances have been demonstrated, which can transform one genetic type of bacteria into another genetic strain. They have been proven to be deoxyribonucleic acid  Nucleotides and Nucleosides Nucleotides are the building blocks of all nucleic acids. Nucleotides have a distinctive structure composed of three components covalently bound together: a nitrogen-containing "base" - either a pyrimidine (one ring) or purine (two rings) a 5-carbon sugar - ribose or deoxyribose a phosphate group  Nucleocytoplasmic ratio It is a ratio of the size (i.e., volume) of the nucleus of a cell to the size of the cytoplasm of that cell. The N:C ratio indicates the maturity of a cell, because as a cell matures the size of its nucleus generally decreases The proportion is usually constant for a specific cell type, and an increase is indicative of malignant neoplasms. Also called karyoplasmc ratio. Thank you Er. Rupak Nagraik School of Bioengineering and Food Technology Shoolini University Village Bhajol, Solan (H.P) 962598692(Mob No.) [email protected]  CSU-003 – Cell Biology Lecture 20 – Plastids  Topics to be covered today 1.Introduction – Definition, Occurrence and Discovery 2. Types of plastids – biogenesis –origin and evolution – Functions 3. Homework  Plastids Discovery: Term was given by Haeckel Occurrence: found in all plant cells and some protists On the basis of function and pigments plastids are of two types 1. Leucoplasts 2. Chromoplast 3. leucoplasts:- are largest colourless plastids and have no grana and photosynthetic pigment. Are found in those part of the body which are not exposed to sunlight. mainly involved in storage of food. 4. Chromoplast:- are pigmented include xanthophylls and carotenoids and found in those parts which are exposed to light. involved in photosynthesis, pollination or disprsal of seeds and fruits  Types of leucoplasts These are of three types on the basis of nature of food stored:- 1. Amylopasts:- store starch and are found in potato tubers and grains of wheat and rice 2. Aleuroplasts:- stores proteins and are found in maize grams 3. Elaiolasts:- stores fats and found in seeds of castor, mustard  Types of chromoplasts On the basis of pigments present, these are of three types:- 1. Chloroplast:- are green plastids and contain chlorophyll 2. Phaeoplasts:- are found in brown algae and contain xanthophyll and fucoxanthin 3. Rhodoplasts:- are found in red algae and contain red pigment phycoerythrin Origin and evolution of plastids Biogenesis of chloroplast Thank you Er. Rupak Nagraik School of Bioengineering and Food Technology Shoolini University Village Bhajol, Solan (H.P) 962598692(Mob No.) [email protected]  CSU-003 – Cell Biology Lecture 19 – Plant Cell Walls  Topics to be covered today 1.Introduction – Plant cell walls 2. Components – cellulose – matrix – lignin – plasmodesmata 3. Homework  Plant Cell Walls Many cells are surrounded by insoluble secreted macromolecules. Cells of bacteria, fungi and many protists and plants are surrounded by rigid cell walls which are integral part of the cell. The cell wall of plants is composed of cellulose, which is single most abundant polymer on the earth. The walls of plant cells must have sufficient tensile strength to withstand internal osmotic pressures of several times atmospheric pressure that result from the difference in solute concentration between the cell interior and external water.  Plant cell walls vary from 0.1 to several µm in thickness  Structural components of plant cell walls 1. Cellulose microfibrils:  Cellulose is linear polymer of glucose residues. The glucose residues are joined by ß(1-4) linkages. several chains then associate in parallel with one another to form 30nm diameter cellulose microfibrils.  Cellulose is also insoluble, chemically stable and relatively resistant to chemical and enzymatic attack  Cellulose microfibrils are synthesized by a plasma membrane bound enzyme complex called cellulose syntheses, which are encoded by a gene family named cellulose syntheses A  Structural components of plant cell walls 2. Matrix polysaccharides  Cellulose microfibrils are embedded in a matrix consisting of proteins and polysaccharides. The major polysaccharides of the matrix are synthesized by membrane bound enzymes in the Golgi apparatus and are delivered to the cell wall  Two major types of matrix polysaccharides are : hemicelluloses and pectins  Hemicelluloses are a heterogeneous group of highly branched polysaccharides that are hydrogen bonded to the surface of cellulose microfibrils.  Pectins are heterogeneous group of polysaccharides , containing acidic sugars such as galacturonic acid. These are gel forming components of matrix. It plays a role in forming connections between plant cells and establishing cell wall porosity.  Structural components of plant cell walls 3. Lignin  It is a phenolic polymer  Highly branched polymer of three simple phenolic alcohols- coniferyl alcohol, coumaryl alcohol and sinapyl alcohol- known as monolignols  Precursors of lignin are synthesized from phenylalanine are secreted to the wall  It is insoluble in water and most organic solvents  As lignin forms in the wall, it displaces water from the matrix and forms a hydrophobic network that bonds tightly to cellulose and prevents cell wall enlargement  Adds mechanical strength to cell walls and reduces the susceptibility of walls to attack by pathogens  Structural proteins  The cell walls contains several classes of structural proteins. These proteins usually classified accordingly to their predominant amino acid composition  Extensins, a major structural protein in the cell walls of higher plants, is a hydroxyproline rich glycoprotein  Cell walls also contain functional protein such as expansin, which causes ph- dependent extension and stress relaxation of cell walls  Plasmodesmata Are intracellular channels that connects plant cells Primary plasmodesmata are pores in the cell wall formed at Cytokinesis. Plasmodesmata interconnect cells into multicellular units called symplasts, within which signaling occurs. Plasmodesmata can open and close Their pore size can be increased by viruses. Plasmodesmata  Formation of plasmodesmata Primary plasmodesmata are formed when portions of the endoplasmic reticulum are trapped across the middle lamella as new cell wall is laid down between two newly divided plant cells and these eventually become the cytoplasmic connections between cells. Here the wall is not thickened further, and depressions or thin areas known as pits are formed in the walls. Pits normally pair up between adjacent cells. Plasmodesmata can also be inserted into existing cell walls between non-dividing cells (secondary plasmodesmata)  Structure of Plasmodesmata A. Plasmodesmatal plasma membrane A typical plant cell may have between 103 and 105 plasmodesmata connecting it with adjacent cells equating to between 1 and 10 per µm. Plasmodesmata are approximately 50-60 nm in diameter at the midpoint and are constructed of three main layers, the plasma membrane, the cytoplasmic sleeve, and the desmotubule. They can transverse cell walls that are up to 90 nm thick. The plasma membrane portion of the plasmodesma is a continuous extension of the cell membrane or plasmalemm and has a similar phospholipids bilayer structure Thank you Er. Rupak Nagraik School of Bioengineering and Food Technology Shoolini University Village Bhajol, Solan (H.P) 962598692(Mob No.) [email protected]  BT-201 – Cell Biology Lecture 18 – Nucleus  Topics to be covered today 1.Introduction – Nucleus 2. Structure and Function – Definitions – Parts – Functions – Some examples 3. Homework  Nucleus Definition: The nucleus ,also called the Director of the cell, is the most important part of the cell which directs and controls all the cellular functions Discovery: Discovered by Robert Brown Occurrence: absent in prokaryotes and present in all the eukaryotes except mature mammalian RBCs Position: nucleus is generally centric but is peripheral in adipocytes and basal in the columnar and gland cells. Number: Mostly the cells are monokaryotic but may be: Anucleate: with no nucleus (RBCs of mammalian) Binucleate: paramecium Multinucleate: voluntary muscle fibres  Nucleus Size: it also varies widely and depends upon : Nucleo-cytoplasmic index It is directly proportional to the number of chromosomes Chemical composition of Nucleus: Proteins = 80% DNA = 12% RNA = 5% Lipids = 3% Enzymes like polymerases are abundantly present and help in synthesis of DNA and RNA.  Ultrastructure of Nucleus Nucleus is seen to be formed of four components: A. Nuclear Membrane: Discovery: also called nuclear envelope or nucleolemma or Karyotheca was first discovered by Erclab Definition: it controls the Nucleo-cytoplasmic interactions and exchange of materials Structure:  It is bilayered envelope. Each membrane is about 90 A thick lipoproteinaceous and trilaminar. Outer membrane is studded with ribosomes on its cytoplasmic surface. Inner membrane is without ribosomes and is internally lined by electron dense material of protein fibres.  Two membranes are separated by a fluid –filed intermembranous perinuclear space  Ultrastructure of Nucleus Origin: it is formed by the fusion of ER elements during the Telophase of cell division Functions: Regulates the nucleo-cytoplasmic interactions Allows the passage of inorganic ions and small organic molecules Helps in Pinocytosis and Phagocytosis of large molecules Maintains the shape of nucleus Helps in dissolution and reformation of nuclear membrane during cell division Nuclear membrane forms annulated lamellae which forms cisternae of ER Allows the passage of ribosomal subunits ,RNAs and proteins through nuclear pores  Ultrastructure of Nucleus B. Nucleoplasm: Structure: It is transparent, homogeneous, semi fluid, colloidal ground substance present inside the nuclear membrane in which the nuclear chromatin and nucleoli are embedded. It is chemically formed of water, minerals, sugars, nucleotides, ribosomes, enzymes Functions:  Act as a nuclear skeleton and helps in maintaining the shape of nucleus  Is the site of enzyme activities  Helps in the formation of spindle proteins  Is the seat of synthesis of NAD, ATP, DNA,RNA and Ribosomal subunits  It supports nuclear chromatin and nucleoli  Ultrastructure of Nucleus C. Nucleolus: Discovery: first observed by Fontana Position: generally associated with nucleolar organizer origin (NOR) of the nucleolar chromosomes. Number: a diploid cell is with two nucleoli but there are 5 nucleoli in a somatic cell of man. Structure: A Nucleolus is a darkly stained granular naked organelle with no membranes.it is formed of four parts: Central and proteinaceous part called pars amorpha fibrillar zone and granular zone of ribonucleo proteinaceous fibrils and granules which collectively form nucleonema and outer nucleolar associated chromatin of nucleolar DNA and is again differentiated into peril-nucleolar and intranucleolar chromatin.  Ultrastructure of Nucleus Chemical composition: Nucleolus is mainly formed of RNA and non-histone acidic proteins. It is a storehouse of RNA Origin: A nucleolus is formed by Nucleolar DNA of the NOR Functions: It is seat of biogenesis of ribosomal RNA and also stores ribosomal RNA It plays important role in spindle formation during cell division It receives the ribosomal proteins from the cytoplasm, combines the ribosomal RNA and ribosomal proteins to form ribosomal subunits  Ultrastructure of Nucleus D. Nuclear Chromatin: Structure: A darkly stained networks of long and fine threads, called chromatin fibres.First reported by W. Flemming. During interphase ,the chromatin is differentiated into two parts: A. Heterochromatin: formed of thick regions which are more darkly stained than other areas. It is condensed DNA which is transcriptionally inactive and late replicating. Generally lies near the nuclear lamina. B. Euchromatin: it is true chromatin and is formed of thin , less darkly stained areas. It is with loose DNA which is transcriptionally active and early replicating During cell division, these chromatin fibres condense by spirilization and dehydration into number of rods, called Chromosomes.  Ultrastructure of Nucleus Functions of Nuclear Chromatin:  Chromatin fibres contain DNA which act as genetic material. It is estimated that a single human cell has about 6 billion base pairs of nucleotides constituting 2 meters long thread of DNA present in 23 pairs of chromosomes  These control the synthesis of structural as well as enzymatic proteins  The changes in DNA produce variations  Functions of Nucleus  Controls all the cellular functions  Controls the synthesis of structural proteins  Controls the cellular functions by controlling the synthesis of enzymatic proteins  Contains the genetic information for reproduction, development and behavior  Takes part in the formation of ribosomes  Induces genetic variations which helps in organic evolution  Controls cellular differentiation by regulating differential gene expression Thank you Er. Rupak Nagraik School of Bioengineering and Food Technology Shoolini University Village Bhajol, Solan (H.P) 962598692(Mob No.) [email protected]  BT-201 – Cell Biology Lecture 17 – Liposomes and Peroxysomes  Topics to be covered today 1.Introduction to Organelles – Definition, Occurrence and Discovery 2. Ultra structure and Function – Liposomes – Peroxysomes – Some examples 3. Homework  1. Liposomes Definition: It is well developed electron microscopic ,simple ,concentric bilayered vesicles in which an aqueous volume is entirely enclosed by a membranous lipid bilayered mainly composed of natural or synthetic phospholipids Discovery: Discovered by Bangham Structural main components are phospholipids and cholesterol  Phospholipids Phospholipids are amphipathic molecule i.e. having affinity for both aqueous and polar moieties , as they have a hydrophobic tail and hydrophobic head. The tail portion consist of 2 fatty acid chains having 10-24 carbon atoms and 0-6 double bonds in each chain The head or polar portion consist of phosphoric acid bound to a water soluble molecule  Cholesterol Cholesterol by itself do not form a bilayered structure, it act as fluidity buffer That means below phase transition temperature it makes the membrane less ordered and slightly more permeable while above phase transition temperature it makes the membrane more ordered and stable It inserts into membrane with hydroxyl group oriented towards aqueous surface and aliphatic chain aligned parallel to acyl chains in the center of bilayers. 4  2. Peroxysomes Definition: It is well developed electron microscopic single membrane bound small organelle Discovery: Discovered by Christian de Duve Occurrence: present in all eukaryotes Lack DNA and ribosomes It produces and consumed hydrogen peroxide Have an endosymbiotic origin similar to mitochondria Contain several oxidase enzymes that use molecular oxygen to oxidise organic substances. Also contain catalase enzyme.  Peroxysomes A major oxidative reaction carried out in Peroxysomes is the ß- oxidation Plays two main roles in plants- photorespiration and glyoxylate cycle Glyoxysomes is a specialized form of Peroxysomes in plants. Proteins that are required for Peroxysomes formation are peroxins 6 Thank you Er. Rupak Nagraik School of Bioengineering and Food Technology Shoolini University Village Bhajol, Solan (H.P) 962598692(Mob No.) [email protected]  CSU-003– Cell Biology Lecture 16 – Mitochondria, Chloroplast and Lysosomes  Topics to be covered today 1.Introduction to Organelles – Definition, Occurrence and Discovery 2. Ultra structure and Function – Mitochondria – Chloroplast – Lysosomes – Some examples 3. Homework  1. Mitochondria Definition: It is well developed electron microscopic tubular or rod-shaped organelles found in the cytoplasm of most cells and produces enzymes for the metabolic conversion of food to energy Discovery: Discovered by Kolliker Term was given by Benda Occurrence: absent in prokaryotes and present in all the eukaryotes except mature and old mammalian RBCs Are the second largest cellular structures Size and number depends upon the metabolic state of the cell In yeast=1 mitochondria Flight muscle cell of the insects= 500,00 per cell mitochondria Also known as power house of the cell  Mitochondria Mitochondria are responsible for converting nutrients into the energy-yielding molecule adenosine triphosphate (ATP) to fuel the cell's activities. This function, known as aerobic respiration, is the reason mitochondria are frequently referred to as the powerhouse of the cell Energy conversion The most prominent roles of mitochondria are to produce the energy currency of the cell, ATP, through respiration, and to regulate cellular metabolism. A dominant role for the mitochondria is the production of ATP, as reflected by the large number of proteins in the inner membrane for this task.  Ultra structure of Mitochondria A mitochondrion is formed of two limiting membranes and two chambers 1. Mitochondrial membranes Are two in number which forms an envelope. Outer membrane is with less proteins (50%) and is freely permeable while inner membrane is with more proteins(80%) and is semi permeable and act as a carrier. 4 Outer membrane is smooth while inner membrane is produced inwards into a number of folds called cristae which increases the surface area for respiration encloses the entire organelle, has a protein-to-phospholipids ratio similar to that of the eukaryotic plasma membrane Outer membrane contains large numbers of integral proteins called porins which allow molecules to freely diffuse from one side of the membrane to the other - The folding of the inner membrane that allows more surface area, enhancing its ability to produce ATP.  These are two in number 1. Outer or inter-membranous chamber or perimitochondrial 2. Mitochondrial space: lies between two membranes and about 6-8 nanometers. chambers It is filled with less denser medium formed of water, minerals, enzymes etc. Because the outer membrane is freely permeable to small molecules, the concentrations of small molecules such as ions and sugars in the intermembrane space is the same as the cytosol 2. Inner chamber: lies inside mitochondrial membrane and filled with granular mitochondrial matrix. and this matrix also contain 70S ribosomes. The matrix is the space enclosed by the inner membrane. It contains about 2/3 of the total protein in a mitochondrion. The matrix is important in the production of ATP with the aid of the ATP syntheses contained in the inner membrane.  Functions Known as ATP mills as these are sites for ATP formation through electron transport and oxidative phosphorylation Also the sites of thermiogenesis Those that perform the redox reactions of oxidative phosphorylation Specific transport proteins that regulate metabolite passage into and out of the matrix Protein import machinery Mitochondria fusion and fission protein  2. Chloroplast Definition: It is well developed electron microscopic organelles found in all plant cells and produces the sites for photosynthesis Discovery: Discovered by Anton Von Leeuwenhoek Term was given by Schimper Occurrence: most common type of plastids found in photosynthetic cells of leaves and green stem.also found in some protists. Absent in bacteria, cyanobacteria, fungi and animals Act as site for photosynthesis Have their own membrane and DNA Shape and number varies from species to species E.g. In spirogyra=1-16 chloroplast  In higher plants= 50  Ultra structure of Chloroplast A chloroplast is formed of limiting membranes, Stroma and Grana 1. Limiting membranes Are two in number , lipoproteinaceous and trilaminar in nature. Outer membrane has less proteins and is more permeable while inner membrane has more proteins and is semi- permeable. Between two membranes there is a fluid filled inter-membranous periplastidal space 2. Stroma or matrix Denser, colorless and granular ground substance present in inner membrane. Mainly formed of soluble proteins and also has 70S ribosomes, circular and naked DNA (plastidosome) It is a site of CO2 fixation and protein synthesis. Most common enzymatic protein is Rubisco  Ultra structure of Chloroplast 3. Grana Inner plastidial membrane of the chloroplast is invaginated to form a series of parallel membranous sheets called lamellae which forms a number of oval shaped closed sacs, called thylakoids. Thylakoids are structural and functional element of chloroplast. It contains all the requirements of light reactions e.g. pigments like chlorophyll, cartenoids, plastocyanin, etc. along the inner side of thylakoids membrane there are number of small rounded Para-crystalline bodies called quantasomes which can trap a mole of quantum light. There may be 40-80 Grana in per chloroplast. Chloroplast Thylakoids  Functions Are the sites of photosynthesis, also called kitchen of the cell These evolve oxygen for respiration for all the aerobes. These store starch in the proteinaceous bodies called pyrenoids in algal forms Its DNA contain 100 genes to synthesize proteins  3. Lysosomes Definition: It is well developed electron microscopic organelles, membrane bounded organelle, found in the cytoplasm of eukaryotic cells, which contains digestive enzymes Discovery: Discovered by Christian de Duve Occurrence: absent from prokaryotes but are present in all eukaryotic animal cells Generally spherical in shape but are irregular in plant root tip cells. in plant cell the same roles are performed by the vacuole most abundant in cells which are related with the enzymatic reactions such as liver cells pancreatic cells, kidney cells, spleen cells, leucocytes, macrophages etc Also known as suicidal bags.  Ultra structure of Lysosomes A chloroplast is formed of limiting membranes and matrix 1. Limiting membranes Is outer ,single layered, lipo protein and trilaminar unit membrane in nature. It keeps a limit on digestive enzymes 2. Matrix It is inner ,finely granular and highly heterogeneous ground substance inside the membrane. On the basis of nature of matrix lysosomes are of four types, so show polymorphism A. Primary lysosomes: have digestive enzyme in inactive form so called storage granules B. Secondary lysosomes: have digestive enzymes and ingest food. formed by fusion of primary lysosomes and endosomes.  Ultra structure of Lysosomes C. Autophagosomes: formed of primary lysosomes and some cell organelles like mitochondria, fragments of ER etc. during deficiency of food. D. Residual body: only lysosomes with undigested food. It is normally expelled out of the cell by exocytosis  The Secondary lysosomes contain engulfed materials and enzymes. The materials are progressively digested by the enzymes. So it is also called as digestive vacuole.  Chemical composition The primary function of lysosomes is degradation of extra and intra cellular material. For this purpose, lysosomes are filled with hydrolases. Which may contain about 40 varieties of enzymes. The lysosomal enzymes are classified into six main types namely. Proteases, which digest proteins. Lipase, which digests lipids. Amylase, which digest carbohydrates (e.g., sugars). Nucleases, which digest nucleic acids. phosphoric acid monoesters.  Functions Heterophagy. Program cell death. Autophagy. Autolysis. Fertilization. Chromosomal damage. 1. Heterophagy Heterophagy is the lysosomal digestion of extracellular materials by the process of endocytosis. Heterophagy are of two types namely Phagocytosis. Pinocytosis. 2. Program cell death Given their high levels of hydrolytic enzymes, lysosomes are potentially harmful to the cell. Partial and selective lysosomal membrane permeabilization (LMP) induces controlled cell death. LMP provokes the translocation of lysosomal contents to the cytoplasm. The proteases implicated in cell death are cathepsins that remain active at neutral pH, such as cathepsin B, CD, and cathepsin L. These proteases trigger and cascade the essential organelle of cell, which led to cell death 3. Autophagy Autophagy is a normal physiological process in the body that deals with destruction of cells in the body. It maintains homeostasis or normal functioning by protein degradation and turnover of the destroyed cell organelles for new cell formation.  4. Autolysis Autolysis refers to the digestion of own cells by the lysosomes. In autolysis, the lysosomes digests its own cell Autolysis occurs during amphibian metamorphosis, and insect metamorphosis etc. 5. Chromosomal Damage Due to the presence of DNase enzyme, lysosomes had an ability to attacks chromosome and cause chromosomal breakages. These breakages can leads to diseases like cancer etc 6. Fertilization During fertilization process, acrosome (giant lysosomes) of sperm head ruptures and releases enzymes on the surface of the egg. These enzymes digest the egg membrane and provide way for the entry of sperm nucleus into the egg Thank you Er. Rupak Nagraik School of Bioengineering and Food Technology Shoolini University Village Bhajol, Solan (H.P) 962598692(Mob No.) [email protected]  BT-201 – Cell Biology Lecture 13 – Endoplasmic Reticulum  Topics to be covered today 1.Introduction – Definition, Occurrence and Discovery 2. Types of ER – Molecular structure – Ultra structure – Functions of ERs 3. Homework  Endoplasmic Reticulum Definition: It is well developed electron microscopic network of interconnected cisternae, tubules and vesicles present throughout the cytoplasm, especially in the endoplasm Discovery: Term was given by Porter First observed by Garnier Ultra structure was given by Porter, Claude and Fullam Occurrence: absent in prokaryotes and present in all the eukaryotes except germinal cells and mature RBCs The ER often occupies most of the cytoplasm The ER varies in amount from cell to cell. In spermatocytes, it is represented by a few vacuoles only. The cells that are actively synthesizing proteins, such as liver and pancreatic cells and fibroblast, have abundant ER. Endoplasmic reticulum forms 30-60 % of the total membrane in a cell. PHYSICAL STRUCTURE The ER is 3-dimensional network of intracellular. It is formed of three types of element: 1-Cisternae 2-Tubules 3-Vesicles Cisternae- These are flattened , unbranched, sac-like element. They lie in stacks parallel to one another. They bear ribosomes on the surface that, therefore, appears rough. It contain glycoproteins named ribophorin-I & ribophorin-II that bind the ribosomes. Tubules- These are irregular branching element which form a network along with other element. These are often free of ribosome. Vesicles- These are oval and rounded ,vacuole like element. These are also free of ribosomes. All the element of ER freely communicates with one another, and contain a fluid called endoplasmic matrix, in the ER lumen. These matrix is different from cytoplasmic matrix outside the ER The ER may pass from one cell to another through the plasmodesmata in the form of desmotubules. Molecular structure The membrane of ER are composed of two layers of phospholipid molecules sandwiched by two layers of proteins molecules like other membrane in the cell wall. The space inside the tubules and vesicles is filled with a watery medium that is different from the fluid in the cytosol outside the ER. Their walls are constructed of lipid bilayers membranes that contains large amount of proteins , similar to the cell membrane. Types 1-Smooth endoplasmic reticulum (SER) 2-Rough endoplasmic reticulum (RER)  Smooth ER Smooth ER is an arrangement of tubules,vesicles and sacs. The size and structure of the SER varies between the cells. The SER can change within a cells lifetime to allow the cell to adapt to changes in its function and requirements. There are no ribosome’s attached to the membrane surface. The SER is connected to the nuclear envelope The network of the SER allows there to be enough surface area for the action or storage of key enzymes or the products of the enzymes. The SER is less stable. The SER is characteristic of cells in which synthesis of non-protein substances takes place.  ROUGH ENDOPLASMIC RETICULIM (RER) The surface of the RER is studded with ribosome, giving it a rough appearance. It mainly consists of cisternae. The membrane of the RER forms large double membrane sheets Which is located near and continuous with the outer layer of the nuclear envelope. RER is very imp. in the synthesis and packaging of proteins e:g, Russell’s bodies of plasma, nissel’s granules of nerve cell Binding site of the ribosome on the RER is the translocon. The ribosomes bound to the RER at any one time are not a stable part of this organelles structure Because ribosomes are constantly being bound and released from the membranes.  ROUGH ENDOPLASMIC RETICULIM (RER) Ribosomes only binds to the RER once a specific protein-nucleic acid complex forms in the cytosol. This special complex forms when a free ribosome begins translating the mRNA of a protein destined for the secretory pathway. The first 5-30 amino acid polymerized encode a single peptide, a molecular message that is recognized and bound by a single recognition particle (SRP). The ribosomes that become attached to the endoplasmic reticulum synthesize all trans membrane proteins. Most secreted proteins that are stored in the Golgi apparatus, lysosomes, and endosomes. Translation pauses and the ribosomes complex binds to the RER translocon  Protein Transport As proteins are formed in the endoplasmic reticulum, they are transported through the tubules toward proteins of the SER that lie nearest to Golgi apparatus. At this point, small transport vesicles composed of small envelopes of smooth ER continually break away and diffuse to the deepest layer of Golgi apparatus. Inside this vesicles are the synthesized proteins and other product from the ER present.  Transport vesicles They are surrounded by coating protein called COP I, COP II.(Coat Protein complex) COP II targets vesicles to the Golgi apparatus.Transport proteins from the RER to Golgi apparatus. This process is termed as anterograde transport. COP I transports proteins from the cis end of the Golgi complex back to the RER. This process is termed as retrograde transport.  FUNCTION OF RER- Surface for Ribosomes- The RER provides space and ribophorins for the attachment of ribosomes to itself. Surface for protein synthesis Formation of Glycoprotein- Linking of sugars to for glycoprotein starts in the RER and is completed in Golgi complex.  Synthesis of precursors- The RER produce enzyme precursors for the formation of lysosomes by Golgi Complex.  Smooth ER formation- The RER gives rise to the smooth ER by loss of ribosomes.  FUNCTION OF SER  The smooth endoplasmic reticulum lacks ribosomes and functions in lipid metabolism, carbohydrate metabolism, and detoxification and is especially abundant in mammalian liver and gonad cells. It also synthesizes phospholipids. Cells which secrete these products, such as those in the testes, ovaries, and skin oil glands have a great deal of smooth endoplasmic reticulum. Detoxification-The SER brings about detoxification in the liver , i.e., converts harmful materials(drugs, poisons) into harmless ones for excretion by the cell. (Cytochrome P450 brings out detoxification) Formation of organelles- The SER produces Golgi apparatus , lysosomes and vacuoles. It also carries out the attachment of receptors on cell membrane proteins and steroid metabolism The smooth endoplasmic reticulum also contains the enzyme glucose-6-phosphatase, which converts glucose-6-phosphate to glucose, a step in gluconeogenesis. Thank you Er. Rupak Nagraik School of Bioengineering and Food Technology Shoolini University Village Bhajol, Solan (H.P) 962598692(Mob No.) [email protected]  CSU-003 – Cell Biology Lecture 15 – Cytoskeleton Structures  Topics to be covered today 1.Introducing the learning environment – Syllabus, schedule, coursework 2. Introducing Intellectual property rights – Definitions – Importance of IPR – History of IPR – Some examples 3. Homework  Cytoskeleton It is an intracellular network of protein filaments present in the cytoplasm. Providing structural support to the cell, the cytoskeleton also functions in cell motility and regulation. The cytoskeleton is a network of fibers extending throughout the cytoplasm. It organizes the cell’s structures and activities, anchoring many organelles. It is composed of three types of molecular structures: Microtubules Microfilaments Intermediate filaments  Structural Support Mechanical support Maintains shape Fibers act like a geodesic dome to stabilize and balance opposing forces Provides anchorage for organelles Dynamic Dismantles in one spot and reassembles in another to change cell shape The cytoskeleton is a network of fibers extending throughout the cytoplasm. The cytoskeleton organizes the structures and activities of the cell. The cytoskeleton also plays a major role in cell motility. This involves both changes in cell location and limited movements of parts of the cell. The cytoskeleton interacts with motor proteins. In cilia and flagella motor proteins pull components of the cytoskeleton past each other. This is also true in muscle cells. Motor molecules also carry vesicles or organelles to various destinations along “monorails’ provided by the cytoskeleton. Interactions of motor proteins and the cytoskeleton circulates materials within a cell via streaming. Recently, evidence is accumulating that the cytoskeleton may transmit mechanical signals that rearrange the nucleoli and other structures. There are three main types of fibers in the cytoskeleton: microtubules, microfilaments, and intermediate filaments.  1.Microtubules Are hollow, cylindrical structure and about 25nm in diameter Present in all eukaryotic cells Plays main role in determination of cell shape and cellular motility Microtubule fibers are constructed of the globular protein, tubulin, and they grow or shrink as more tubulin molecules are added or removed They move chromosomes during cell division. Another function is as tracks that guide motor proteins carrying organelles to their destination Microtubules are the central structural supports in cilia and flagella. Both can move unicellular and small multicellular organisms by propelling water past the organism. If these structures are anchored in a large structure, they move fluid over a surface. For example, cilia sweep mucus carrying trapped debris from the lungs. Fig. 7.2 Cilia usually occur in large numbers on the cell surface. They are about 0.25 microns in diameter and 2-20 microns long. There are usually just one or a few flagella per cell. Flagella are the same width as cilia, but 10-200 microns long.  A flagellum has an undulatory movement. Force is generated parallel to the flagellum’s axis. Fig. 7.23a  Cilia move more like oars with alternating power and recovery strokes. They generate force perpendicular to the cilia’s axis. Fig. 7.23b In spite of their differences, both cilia and flagella have the same ultrastructure. Both have a core of microtubules sheathed by the plasma membrane. Nine doublets of microtubules arranged around a pair at the center, the “9 + 2” pattern. Flexible “wheels” of proteins connect outer doublets to each other and to the core. The outer doublets are also connected by motor proteins. The cilium or flagellum is anchored in the cell by a basal body, whose structure is identical to a centriole. Fig. 7.24  The bending of cilia and flagella is driven by the arms of a motor protein, dynein. – Addition to dynein of a phosphate group from ATP and its removal causes conformation changes in the protein. – Dynein arms alternately grab, move, and release the outer microtubules. – Protein cross-links limit sliding and the force is expressed as bending. Fig. 7.25  Microfilaments, the thinnest class of the cytoskeletal fibers, are solid rods of the globular protein actin. – An actin microfilament consists of a twisted double chain of actin subunits. Microfilaments are designed to resist tension. With other proteins, they form a three-dimensional network just inside the plasma membrane. Fig. 7.26 The shape of the microvilli in this intestinal cell are supported by microfilaments, anchored to a network of intermediate filaments. In muscle cells, thousands of actin filaments are arranged parallel to one another. Thicker filaments, composed of a motor protein, myosin, interdigitate with the thinner actin fibers. Myosin molecules walk along the actin filament, pulling stacks of actin fibers together and shortening the cell. Fig. 7.21a In other cells, these actin-myosin aggregates are less organized but still cause localized contraction. A contracting belt of microfilaments divides the cytoplasm of animals cells during cell division. Localized contraction also drives amoeboid movement. Pseudopodia, cellular extensions, extend and contract through the reversible assembly and contraction of actin subunits into microfilaments. Fig. 7.21b In plant cells (and others), actin-myosin interactions and sol-gel transformations drive cytoplasmic streaming. This creates a circular flow of cytoplasm in the cell. This speeds the distribution of materials within the cell. Fig. 7.21c Intermediate filaments, intermediate in size at 8 - 12 nanometers, are specialized for bearing tension. Intermediate filaments are built from a diverse class of subunits from a family of proteins called keratins. Intermediate filaments are more permanent fixtures of the cytoskeleton than are the other two classes. They reinforce cell shape and fix organelle location. Fig. 7.26 Thank you Er. Rupak Nagraik School of Bioengineering and Food Technology Shoolini University Village Bhajol, Solan (H.P) 962598692(Mob No.) [email protected]  BT-201 – Cell Biology Lecture 14 – Ribosomes  Topics to be covered today 1.Introduction – Definition, Occurrence and Discovery 2. Types of Ribosomes – Molecular structure – chemical composition – Functions 3. Homework  Ribosomes Definition: the ribosomes are large ribonucleo-protein particles attached either on RER or floating freely in the cytoplasm and are the sites for protein synthesis. Discovery: Term was given by Palade First observed by Claude Occurrence: found both in prokaryotes and eukaryotes In prokaryotes found in free form in cytoplasm whereas in eukaryotes found in two different forms : free and bound form Number of ribosomes depend upon the RNA content of the cell It consist of two major subunit. The smaller subunit reads the RNA, while larger sub unit, join amino acid to for polypeptide chain for protein synthesis. Protein = 25-40% RNA = 37-62%  Types of ribosomes On the basis of sedimentation coefficient( speed of sedimentation in centrifuge)these are of two types : 1. 70S Ribosomes in which larger subunit = 50 S (in Prokaryotes) smaller subunit = 30 S 2. 80S Ribosomes in which larger subunit = 60S smaller subunit = 40 S (in Eukaryotes)  50S= 23S and 5S 30S= 16S 60S = 28S, 5S, 5.8S 40S= 18S  Structure Each ribosome is formed of two unequal subunits which joins only on protein synthesis Larger subunits is in dome-shaped and is attached by glycoproteins called ribophorin. It also has two binding sites: Peptidyl site and Amino acyl site. These two sites are for attachment of charged tRNA Smaller subunit is ellipsoidal –shaped and fits as a cap on flat side of larger subunits. it has binding site for mRNA 4 Protein synthesis  Polyribosome's When many ribosomes (6-8) are attached at same mRNA strand ,it is called polysome or polyribosome. It is formed when a similar types of proteins are required. The no. of ribosomes attached on mRNA depends upon the length of mRNA The distance between adjacent ribosomes is of 90 nucleotides Association and disassociation of ribosomal subunits depends upon magnesium concentration.  Are called protein factories or engines of the Functions cell because these are sites of protein synthesis The process of translating mRNA into protein. Free ribosomes produces non-secretory proteins Bound ribosomes on RER synthesize secretory proteins e.g. enzymes for extracellular use e.g., pancreatic cells, liver cells and plasma cells Thank you Er. Rupak Nagraik School of Bioengineering and Food Technology Shoolini University Village Bhajol, Solan (H.P) 962598692(Mob No.) [email protected]  BT-201 – Cell Biology Lecture 12 – Bio membranes and Golgi bodies  Topics to be covered today 1.Introduction – Structure and function 2. Introduction to Golgi bodies – Definitions – Structure – Functions – Some examples 3. Homework  Plasma or cell membrane Every living cell is externally covered by a thin transparent , electron microscopic, elastic, regenerative and semipermeable membrane called cell membrane. Present in both prokaryotic and eukaryotic cells A peculiar function property of plasma membrane is its semipermeable nature DEFINATION The plasma membrane and all the membranes covering cell organelles present inside the cell have same ultrastructure and are collectively called Biomembranes because they play vital functions for a living cell. Primarily meant for exchange of materials between the cytoplasm and extracellular environment so maintains homeostasis inside the cell. Helps in the synthesis of many macromolecules, response of the cells to a variety of physical and chemical stimuli. Biochemical composition of cell membrane 3 Glycolipid and glycoprotein: Depending on the species and cell type, the carbohydrate content of the plasma membrane ranges between 2 and 10 percent by weight. Cholesterol and neutral lipid: Cholesterol and neutral lipid exist in the membranes of eukaryotic cells, and they are important to regulate the floatability and water permeability of plasma membrane. Liposome: Liposome can be manufactured in lab. Usually, 25 – 1000nm size in diameter liposome can be used to scientific research and clinical therapy. 4 Membrane proteins: 1. Peripheral membrane protein: Easy to be separated from membrane without membrane damaged. It is linked to membrane surface with a weak bond. 2. Integral membrane protein: It is a part of membrane structure and plays variety of functions. Isolate integral protein from cells: Use detergent, such as SDS and Triton. SDS causes protein molecules changed or damaged, but Triton does not usually.  Functions of Plasma Membrane  Protective barrier  Regulate transport in & out of cell (selectively permeable)  Allow cell recognition  Provide anchoring sites for filament of cytoskeleton  Provide a binding site for enzymes  Interlocking surfaces bind cells together (junctions) Contains the cytoplasm (fluid in cell). 6  Membrane Components Phospholipids Cholesterol. Proteins 7 Carbohydrates (glucose) (peripheral and integral)  2.Golgi Bodies Definition: It is well developed electron microscopic network composed of stacks of membrane-bound structures known as cisternae Discovery: discovered by Camilo Golgi First observed by George Occurrence: absent in prokaryotes and present in all the eukaryotes except mature RBCs Also called lipochondria or idiosome or Dalton complex Shape depends upon functional state of cell, so called pleomorphic organelle The primary function of the Golgi apparatus is to process and package macromolecules, such as proteins and lipids, after their synthesis. It is particularly important in the processing of proteins for secretion.  Structure of Golgi Bodies Golgi body is formed of three types of elements:1. Cisternae 2. Vacuoles 3. Vesicles 1.Cisternae: Also called flattened sacs or saccules or parallel membranes Elongated double layered, flat and curved components with swollen ends present one upon other Swollen ends of cisternae are called golgian vacuoles These are about 3-12 in animal cells and 10-20 in plant cells and certain protists  Structure of Golgi Bodies 2. Vacuoles: These are spherical components and lie towards the concave side of the cisternae 3. Vesicles: These are small sized components present along the convex surface of the cisternae Are of two types: Smooth vesicles(which contain secretory products of ER and Golgi body) and Coated vesicles( with rough surface and generally lie near the convex surface) Has a definite polarity. Its concave side is always directed towards the cell membrane and is called maturation face(trans-face) while its convex surface is towards the nucleus and is called formative phase( cis-face). It appears that materials are transports from cis to trans face by vesicles. Golgi Apparatus  Functions of Golgi Bodies It is involved in cell secretion, so is large sized in secretory cells It acts a condensation membrane and accumulates enzymes, mucus, hormones etc. and condenses the materials in secretory vesicles It helps in the formation of hormones e.g. thyroxin in thyroid gland cells It take part in cell plate formation during Cytokinesis in plant cells It helps in synthesis of pectic substances Helps in formation of primary lysosomes Takes part in vittelogenesis(yolk synthesis) Involved in biosynthesis of glycolipids and glycoproteins It participates in transformations of membranes and recycling of plasma membrane Also a component of intracellular transport , so called director of macromolecular traffic Thank you Er. Rupak Nagraik School of Bioengineering and Food Technology Shoolini University Village Bhajol, Solan (H.P) 962598692(Mob No.) [email protected]  CSU-003 – Cell Biology Lecture 11 – Solute Transport across membrane  Topics to be covered today 1.Introduction to membrane transport proteins 2. Types of transporters – Introduction – carriers involved in transport – Diagrams 3. Homework  Keywords 1. Solvent: (relatively large amount of a substance which is the dissolving medium; in the body is water). 2. Solute: (relatively small amount of a substance which is the dissolved substance and it dissolves in the solvent). 3. Solution: is a homogenous mixture of a solute in a solvent. 4. Concentration: of a solvent is the amount of solute dissolved in a specific amount of solution. 5. Concentration gradient: difference in the concentration of a solute on two sides of a permeable membrane. 6. Equilibrium: exact balance between 2 opposing forces. 7. Dynamic: continuous motion or movement.  Membrane Transport Proteins Many molecules must move back and forth from inside and outside of the cell Most cannot pass through without the assistance of proteins in the membrane bilayer Private passageways for select substances Each cell has membrane has a specific set of proteins depending on the cell 3  Membrane Permeability Size the smaller the particle, the more permeable small molecules (O2, CO2, H2O) can large molecules (protein, DNA) cannot Lipid Solubility YES: non-polar molecules (O2, cholesterol), NO: charged atoms/molecules (Na+, Cl-, HCO3-), large polar molecules (glucose) 4 Impermeable membranes Ions and hydrophilic molecules cannot easily pass through the hydrophobic membrane Small and hydrophobic molecules can Must know the list to the left  Major classes of proteins Carrier proteins – move the solute across the membrane by binding it on one side and transporting it to the other side Requires a conformation change Channel protein – small hydrophilic pores that allow for solutes to pass through Use diffusion to move across Also called ion channels when only ions moving  Transport- What does it mean? Highly selective filter which permits nutrients and leaves the waste products from the cell Maintain homeostasis Makes cytosol environment to different Plays an important role in cell to cell communication It detects chemical messengers arriving at the cell surface  Mechanism Of Transport 1. Active process  Primary transport  Secondary transport 2. Passive process  Simple diffusion  Facilitated diffusion  Osmosis  Bulk flow  Filtration Active vs. Passive Transport  Cell Flowchart Of Solute Transport Membrane Permeable Impermeable Selectively Permeable 1. Relative solubility of the 2. Size of the particle particle in Lipids Lipid- Lipid- Soluble Insoluble Size: Less than Size: more than 0.8nm in 0.8 nm diameter in diameter Permeate the Assisted Transport or Membrane: Carrier-mediated Protein Passive Transport Channel Transport (e.g. for NA+ , K+) Active Facilitated Diffusion Osmosis Transport Diffusion  1. Simple diffusion Diffusion is: 1. Passive. 2. Higher concentration to low concentration 3. Requires a concentration gradient. 4. Occurs until a dynamic equilibrium is reached. 5. Rapid over short distance, slow over long distance. 6. Increased at increased temperature. 7. Inversely related to molecular size, as molecular size increases the resistance. 8. Can occur in an open system or across a membrane. Factors that affect diffusion  2. Facilitated Diffusion Definition: the diffusion of lipid insoluble or water soluble substance across the membrane down their concentration gradients by aid of membrane proteins  (carrier or channel) Substances: K+, Na+, Ca2+, glucose, amino acid, urea etc.  3. Osmosis Definition: The diffusion of water down its concentration gradient (that is, an area of higher water concentration to an area of lower water concentration) thru a semi-permeable membrane is called Osmosis. Concept: Because solutions are always referred to in terms of concentration of solute, water moves by osmosis to the area of higher solute concentration. Despite the impression that the solutes are “pulling,” or attracting, water, osmosis is nothing more than diffusion of water down its own concentration gradient across the membrane.  Tonicity Tonicity - ability of a solution to affect fluid volume and pressure within a cell – depends on concentration and permeability of solute Isotonic solution – solution with the same solute concentration as that of the cytosol; normal saline Hypotonic solution – lower concentration of nonpermeating solutes than that of the cytosol (high water concentration) – cells absorb water, swell and may burst (lyse) Hypertonic solution – has higher concentration of nonpermeating solutes than that of the cytosol (low water concentration) – cells lose water + shrivel (crenate)  Osmosis and cells Important because large volume changes caused by water movement disrupt normal cell function Cell shrinkage or swelling Isotonic: cell neither shrinks nor swells Hypertonic: cell shrinks (crenation) Hypotonic: cell swells (lysis)  Endocytosis  It is a process by which the large number of particles are taken with forming the vesicle into the cell  It is classified into:  1. Phagocytosis  It is a process by which the large number of particles are engulfed into the cell.  2. Pinocytosis  It is a process by which the large number of particles which are soluble in water are taken into the cell  Bulk transport  The movement of large number of ions, molecules or particles that are dissolved or carried in a medium such as a fluid or air is called bulk flow.  Rate of Bulk transport is determined by the differences in hydrostatic pressure or air pressure. Eg: 1. Flow of blood within the vessels.  2.Movement of air into and out of the lungs.  Types of cellular transport Passive Transport Weeee!!! cell doesn’t use energy Diffusion high Facilitated Diffusion Osmosis low Active Transport cell does use energy This is gonna be hard work!! Protein Pumps Endocytosis Exocytosis high low  Active transport  Active transport is the transport of substances from a region of lower concentration to higher concentration using energy, usually in the form of ATP.  Examples: Na, K and Ca active transport.  1.sodium-potassium pump  2.Calcium pump  3.Potassium hydrogen pump  Need of Active Transport Active Transport needed for, 1. Maintaining the Chemical and Electrical Charge at rest. 2. Intake of Substances through gated Channels. 3. Collecting of ions with more concentration.  Active transport-Why?  Cells cannot rely solely on passive movement of substances across their membranes.  In many instances, it is necessary to move substances against their electrical or chemical gradient to maintain the appropriate concentrations inside of the cell or organelle.  Pumps involved in Active Transport 1.Sodium-potassium pump Found in many cells 2.Calcium pump Found in membrane of Sarcoplasmic reticulum 3.Potassium hydrogen pump Found in Gastrointestine cell membrane  Primary active transport  Primary active transport is the transport of substances uphill using energy (ATP hydrolysis)  It cause a conformational change that results in the transport of the molecule through the protein.  Eg. Na+-K+ pump.  Secondary active transport The transport of substances against a concentration gradient involving energy to establish a gradient across the cell membrane, utilizes the gradient to transport a molecule of interest up its concentration gradient. THE TRANSPORT MAY BE In the same direction (SYMPORT) In the opposite direction (ANTIPORT)  Carriers types process Carriers are transport proteins that binds ions and other molecules and then change their configuration moving the bound molecules from one side of cell membrane to the other. Types of carriers : 1.Uniporters 2.Symporters 3.Antiporters  Uniport The movement of a single Substance. It requires no energy from the cell. Examples. Simple diffusion. Facilitated diffusion.  Symport (co-transport) Transport of two substances using the energy produced by concentration difference developed by primary active transport Substances are moving in the same direction. Example: transport of amino acids, Glucose,  Anti-port (counter transport) In this process, the two substances move across the membrane in opposite directions. Example:  Exchange of H+ and Na+ in Renal tubule. Thank you Er. Rupak Nagraik School of Bioengineering and Food Technology Shoolini University Village Bhajol, Solan (H.P) 962598692(Mob No.) [email protected]