Cell Chemistry.pdf

PRB1016 BIOLOGY 1: CELL CHEMISTRY Maybelline Goh Boon Ling BSc Bio Industry (Plant Science) MSc Forestry (Tropical Forest Resource Management) Centre of Pre-University Studies University Malaysia Sarawak 2 LEARNING OBJECTIVES To explain the structure, properties and functions of wate...

PRB1016 BIOLOGY 1: CELL CHEMISTRY Maybelline Goh Boon Ling BSc Bio Industry (Plant Science) MSc Forestry (Tropical Forest Resource Management) Centre of Pre-University Studies University Malaysia Sarawak 2 LEARNING OBJECTIVES To explain the structure, properties and functions of water, carbohydrates, lipids, proteins and nucleic acids To explain the types and concepts of cellular transports: passive and active process. Cells, tissues and organs are composed of chemicals. The study of chemical compounds found in living systems and the reactions in which they take part is known as biochemistry. Chemical compounds are conventionally divided into organic and inorganic.  Organic Compounds Inorganic Compounds Organic compounds are characterised Inorganic compounds do not have by the presence of carbon atoms in carbon atoms in them them Organic compounds consists of They do not possess hydrogen or hydrogen, oxygen, carbon, and their oxygen and their derivatives other derivatives Organic compounds are mainly found These compounds are found in non- in most of the living things living things Examples of organic compounds The example for inorganic compounds includes fats, nucleic acids, sugars, includes non-metals, salts, metals, enzymes, proteins, and hydrocarbon acids, bases, substances which are fuels made from single elements WATER Water is the most common compound found in organisms. Water is the basis of life on our planet. It exists in different physical states – solid, liquid and gas – and makes up 70% of the surface of Earth, plus 65 – 90% of the weight of all living organisms. Water also plays an important role in all vital processes of living organisms. STRUCTURE OF WATER MOLECULES The water molecule, H2O, is composed of one oxygen atom and two hydrogen atoms. H in the water molecule are not arranged directly on opposite sides of oxygen atom, BUT at an angle of about 105 º. These atoms are bound covalently (by a covalent bond). In a water molecule, hydrogen carries a positive molecular charge, while oxygen carries a negative molecular charge. Thus, a water molecule is a ‘polar’ molecule, because it has both positive and negative poles. STRUCTURE OF WATER MOLECULES O can attract two nearby H from two other water molecules. A hydrogen bond is formed between the positively charged region of one molecule with the negatively charged region of the other molecules. Hydrogen bond considerably weaker than the covalent bond but it strong enough to keep water in a liquid state at ordinary temperatures. FORMS OF WATER Water is liquid at room temperature High boiling point : more energy required to heat the water Heat is needed to break the H bonds before increasing molecules movement PROPERTIES OF WATER 1. UNIVERSAL SOLVENT Water is regarded as the ‘general solvent’ or ‘universal solvent’ due to the polarity of its molecules. E.g. Sodium Chloride is added to water, the water molecules dissolve NaCl due to the partial charges on water molecule being attract to the Sodium ion and chloride ion. Water is a polar compound, good solvent for polar substances (e.g. sugars and alcohols) and ionic compounds (e.g. salts, acids and bases), which dissociate into their component ions. All the essential substances for living organisms (vitamins, salts, amino acids, gases, and glucose) transport inside their bodies in the form of solutes dissolved in water. These substances take part in metabolic reactions inside the cells. 2. VISCOSITY Low viscosity due to small size of the water molecule and the hydrogen bonding that can easily broken, enabling the molecules to slide over each other. In animals, water enables the blood plasma and lymph to flow easily in the circulatory system. 3. SPECIFIC HEAT CAPACITY Specific heat is the amount of heat required to increase the temperature of one gram of matter by 1 degree Celsius. Water has the highest specific heat on Earth due to the hydrogen bonds between its molecules. As a result of having high specific heat, water needs a great amount of energy to increase its temperature and loses a great amount of energy when its temperature decreases. This helps living organisms to have a constant temperature which is essential for the vital processes occurring within their bodies. Cells contain lots of water to keep their temperature constant. 4. LATENT HEAT OF VAPORISATION Latent heat of vaporization is a physical property of a substance. When a material in liquid state is given energy, it changes its phase from liquid to vapor; the energy absorbed in this process is called heat of vaporization. The heat of vaporization of water is about 2,260 kJ/kg, which is equal to 40.8 kJ/mol. The evaporation of water from the surface of the skin, when one sweats, gives rise to a cooling effect since the escaping molecules absorb the heat energy needed to change the water into vapor. 4. SURFACE TENSION Surface tension is the cohesion of the molecules on the surface of a fluid to occupy the least possible volume. The molecules at the surface of the water "stick together" to form a type of 'skin' on the water, strong enough to support very light objects. Insects that walk on water are taking advantage of this surface tension. Surface tension causes water to clump in drops rather than spreading out in a thin layer. It also allows water to move through plant roots and stems and the smallest blood vessels in your body - as one molecule moves up the tree root or through the capillary, it 'pulls' the others with it. 5. DENSITY Water expands when its temperature becomes less than 4◦C (instead of shrinking). This decreases its density and makes it float. In frozen lakes, we find ice on the surface, while we find liquid water underneath. This property is because of the hydrogen bonds between water molecules. This property is important because it enables living organisms to live in oceans and seas. Without this property, all oceans and seas will turn into ice, rather than just the surface. Surface freezing works as an insulator to prevent the rest of water from freezing CARBOHYDRATES Carbohydrates (also called saccharides) are molecular compounds made from just three elements: carbon, hydrogen and oxygen. Monosaccharides (e.g. glucose) and disaccharides (e.g. sucrose) are relatively small molecules. They are often called sugars. Other carbohydrate molecules are very large (polysaccharides such as starch and cellulose). Composed of carbon, hydrogen and oxygen atom in ratio 1:2:1, empirical formula (CH2O)n, Where n=3 or more. Large group of organic compound. CARBOHYDRATES 1. MONOSACCHARIDES Monosaccharides are the simplest carbohydrates and are often called single sugars. They are the building blocks from which all bigger carbohydrates are made. Monosaccharides have the general molecular formula (CH2O)n, where n can be 3, 5 or 6. They can be classified according to the number of carbon atoms in a molecule: n=3 trioses, e.g. glyceraldehyde n=5 pentoses, e.g. ribose and deoxyribose ('pent' indicates 5) n=6 hexoses, e.g. fructose, glucose and galactose ('hex' indicates 6) Monosaccharides containing the aldehyde group are classified as aldoses, and those with a ketone group are classified as ketoses. Aldoses are reducing sugars; ketoses are non-reducing sugars. CARBOHYDRATES 1. MONOSACCHARIDES If the carbonyl group (C=O) is at the end of a chain it is called an aldehyde If the carbonyl group is at the middle of a chain, it is called a ketone CARBOHYDRATES 1. MONOSACCHARIDES Group Name Type/composition Trioses (C3H6O3) Glyceraldehyde Aldose Sugar Dihydroxyacetone Ketose Sugar Pentose (C5H10O5) Ribose/Deoxyribose Aldose Sugar Ribulose Ketose Sugar Hexoses (C6H12O6) Glucose Aldose Sugar Galactose Aldose Sugar Fructose Ketose Sugar CARBOHYDRATES 1. MONOSACCHARIDES When Glucose forms a ring structure, it can do so in two different ways. If the OH at C1 is below the plane of the ring, it is called an α Glucose, if the OH at C1 is above the plane of the ring, it is called β Glucose. This difference in structure leads to a difference in properties. CARBOHYDRATES 2. DISACCHARIDES Formation by condensation of two monosaccharide units. The link formed between the two monosaccharide molecules is known as glycosidic bond. Disaccharides can also be hydrolysed, with presence of water to form monosaccharides. CARBOHYDRATES 2. DISACCHARIDES The three most important disaccharides are sucrose, lactose and maltose. They are formed from the a forms of the appropriate monosaccharides. Sucrose is a non-reducing sugar. Lactose and maltose are reducing sugars. Disaccharide Monosaccharides sucrose from α-glucose + α-fructose maltose from α-glucose + α-glucose α-lactose * from α-glucose + β-galactose * Lactose also exists in a beta form, which is made from β-galactose and β-glucose Disaccharides are soluble in water, but they are too big to pass through the cell membrane by diffusion. They are broken down in the small intestine during digestion to give the smaller monosaccharides that pass into the blood and through cell membranes into cells. CARBOHYDRATES 3. POLYSACCHARIDES 1. Large, complex carbohydrate molecule containing three or more monosaccharides. 2. Organisms use polysaccharides to store energy and hydrolysed as needed to provide sugar for cells. 3. Starch, glycogen and cellulose are made from glucose monomer. 4. Starch is carbohydrate found in plants, while glycogen is the form of carbohydrate storage found in animals. Cellulose is a structural carbohydrate found in plants. CARBOHYDRATES 3. POLYSACCHARIDES 1. Formation or synthesis of polysaccharides is known as polymerisation. 2. Production of a long chain polymer is a condensation process, water molecule is removed and glycosidic bond is formed. 3. Broken down by the hydrolysis process with help of specific enzymes for example amylase. CARBOHYDRATES 3. POLYSACCHARIDES (STARCH) 1. Starch is an example of a polysaccharide in plants 2. Plant cells store starch for energy 3. Potatoes and grains are major sources of starch in the human diet 4. Consists of many glucose monosaccharides linked together in both linear and branched forms. 5. Insoluble in water and serve as storage depots of glucose. 6. Plant convert excess glucose into starch for storage. CARBOHYDRATES 3. POLYSACCHARIDES (STARCH) 1. Mixture of amylose and amylopectin. 2. Amylose consists of straight chains with several hundred unit of glucose. 3. Amylopectin differ from amylose in that it is highly branched. There are several thousands of glucose residues in its molecule. CARBOHYDRATES 3. POLYSACCHARIDES (GLYCOGEN) 1. Glycogen is an example of a polysaccharide in animals 2. Animals store excess sugar in the form of glycogen 3. Glycogen is similar in structure to starch because BOTH are made of glucose monomers 4. Similar to amylopectin structure but the branches in glycogen shorter and more in number compare to amylopectin. 5. In the liver and muscles, the glycogen is broken down or reconverted into glucose when energy is needed, in a process called glycogenolysis. CARBOHYDRATES 3. POLYSACCHARIDES (CELLULOSE) 1. Cellulose is the most abundant organic compound on Earth. 2. It forms cable-like fibrils in the tough walls that enclose plants. 3. It is a major component of wood. 4. It is also known as dietary fibre. 5. Molecule is arranged in a straight and flip-flop manner. 6. No side chains or branches in cellulose such as those found in starch, allow linear molecules to lie close together. CARBOHYDRATES 1. Provide energy for life processes 2. Complete metabolism of glucose releases 686 kcal/mol 3. serving as precursors for building many polymers 4. storing short-term energy 5. providing structural building materials 6. Structure of cells and tissues 7. Act as extracellular binding or recognition sites, involved in recognition of hormones and neurotransmitters, cell-cell recognition. 33 LIPIDS 1. Lipid = a compound that is insoluble in water, but soluble in an organic solvent (e.g., ether, benzene, acetone, chloroform) 2. “lipid” is synonymous with “fat”, but also includes phospholipids, sterols, etc. 3. Store large amounts of energy, contain carbon, hydrogen and oxygen (small proportion). 4. There are 3 major classes of lipid which are triglycerides (fats and oils), phospholipids and steroids. LIPIDS TRIGLYCERIDES 1. In liquid state at room temperature called oils and in solid state in room temperature called fats. 2. Composed of 3 fatty acids and a glycerol (three backbone carbon). 3. Glycerol is trihydroxyl propane or polyhydroxyl alcohol. LIPIDS TRIGLYCERIDES 1. Condensation of glycerol and fatty acids leads to ester bonding in which triglyceride is formed (esterification process or dehydration). 2. Breakdown of fat is called a hydrolysis reaction, which fat is reconvert into glycerol and fatty acid. LIPIDS TRIGLYCERIDES LIPIDS TRIGLYCERIDES Importance of Lipid to Triglycerides 1. Fat provide concentrated energy especially for muscle activity in the heart and the respiratory system. 2. Fat are long-term food reserve found in adipose cells in mammals. 3. Fats insulate body from cold and provide padding for the internal organ. 4. Fat in diet carry essential fat soluble vitamins, namely A,D, E and K. LIPIDS FATTY ACIDS 1. Fatty acid are long unbranched chains of hydrocarbon with a carboxylic acid group (-COOH) at the end of each chain, giving acidic properties. 2. The backbone chains of fatty acids vary in length from 4-24 or more carbons. 3. -COOH group make fatty acid water soluble, chain length increase cause less water soluble. 4. Amphiphatic-containing both polar (water-soluble) and non-polar (not water-soluble) portions in its structure. LIPIDS FATTY ACIDS LIPIDS FATTY ACIDS 1. Can be saturated or unsaturated; essentials or nonessential; and cis or trans configuration. 2. Essential fatty acid in human cannot be manufactured and only can be derived from the diet such as linoleic (manufacture signaling molecules in the body) and linolenic acid (normal growth and development). 3. Non-essential fatty acid are those fatty acid that human body is able to produce in sufficient quantity. LIPIDS FATTY ACIDS Roles of fatty acids As building block of complex lipids. Manufacture and repair of cell membrane. Major sources of energy -major components of stored fat in the form of triglycerides. Vegetable oils and animal fats are mixtures of different types of fatty acids Vegetable oils such as groundnut oil, sunflower oil and olive oil –unsaturated triglycerides (liquid at room temperature). Animal fats –saturated fats. Essential fatty acids: linoleic, linolenic and arachidonic acids (cell membrane components) LIPIDS PHOSPHOLIPIDS 1. major constituents of all cell membranes 2. components of bile 3. anchor some proteins in membranes 4. signal mediators 5. components of lung surfactant 6. components of lipoproteins LIPIDS PHOSPHOLIPIDS Consists of a glycerol esterified to fatty acids and a phosphate group known as phosphatidic acid. The highly polar head and two long non-polar chains give the amphipatic nature. In cell membrane, the molecules are arranged in a bilayer where the polar head facing out while the non-polar tails face each other. LIPIDS STERIODS 1. Steriods are organic compounds that contain four ring of carbon atoms. 2. Like cholesterol, common component of animal cell membranes. 3. Many hormon such as estrogen, progesteron and testosteron are steroids produced from cholesterol. 4. Synthetic androgen (such as testosteron) is anabolic steroid classified as drugs, enhanced the transcription of gene to synthesised myofibril and increases the muscle mass. PROTEINS 1. Proteins are organic nitrogenous compounds formed of C H O & “N” 2. Proteins are the polymers of 20 naturally occurring amino acids 3. Amino acids are organic acids in which one H is replaced by NH3 usually at α carbon (next to COOH group) 4. All amino acids have in common central α carbon to which COOH & H & NH2 are attached α carbon is also attached to a side chain called R group which is different for each amino acid N and C terminals PROTEINS Amino acids are classified as 1. Nonpolar (hydrophobic) with hydrocarbon side chains. 2. Polar (hydrophilic) with polar or ionic side chains. 3. Acidic (hydrophilic) with acidic side chains. 4. Basic (hydrophilic) with –NH2 side chains. Amphoteric Properties Amino acids are amphoteric molecules have both basic and acidic group Zwitterions (dipolar molecules), have charged —NH3+ and COO- groups. Forms when both the —NH2 and the —COOH groups in an amino acid ionize in water. Has equal + and − charges at the isoelectric point (pI). PROTEINS ESSENTIAL AMINO ACID Cannot be synthesised in the body and must be included in the diet E.g : arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryphtophan, valine Sources: cereal grains (wheat, corn, rice, etc.) and legumes (beans,peanuts, etc.). NON ESSENTIAL AMINO ACID Can be synthesised from other amino acids in the body provided there is adequate total dietary protein. E.g :alanine, asparagine, aspartate, cysteine, glutamate, glutamine, glycine, proline, serine, tyrosine PROTEINS PROTEINS PEPTIDE BOND Polypeptides are a particular arrangement of amino acids synthesised into polymer by condensation reactions, form covalent bond called peptide bond. 2 chains of amino acid molecules are linked together by the peptide bond with removal of water molecule. PROTEINS LEVELS OF PROTEIN STRUCTURE Primary Structure of Proteins The particular sequence of amino acids. The backbone of a peptide chain or protein. PROTEINS LEVELS OF PROTEIN STRUCTURE The Secondary Structure of Protein The secondary structures of proteins indicate the three- dimensional spatial arrangements of the polypeptide chains. An alpha helix has A coiled shape held in place by hydrogen bonds between the amide groups and the carbonyl groups of the amino acids along the chain. Hydrogen bonds between the H of a –N-H group and the O of C=O of the fourth amino acid down the chain. PROTEINS LEVELS OF PROTEIN STRUCTURE The Secondary Structure of Protein Beta-pleated sheet A beta-pleated sheet is a secondary structure that Consists of polypeptide chains arranged side by side. Has hydrogen bonds between chains. Has R groups above and below the sheet. Is typical of fibrous proteins such as silk. PROTEINS LEVELS OF PROTEIN STRUCTURE The Tertiary Structure 1. The tertiary structure of a protein 2. Gives a specific three dimensional shape to the polypeptide chain. 3. Involves interactions and cross links between different parts of the peptide chain. 4. Is stabilized by Hydrophobic and hydrophilic interactions. Ionic Bond. Hydrogen bonds. Disulfide bonds. 5. The interactions of the R groups give a protein its specific three-dimensional tertiary structure. PROTEINS LEVELS OF PROTEIN STRUCTURE PROTEINS LEVELS OF PROTEIN STRUCTURE The Quaternary Structure 1. The quaternary structure 2. Is the combination of two or more tertiary units. 3. Is stabilized by the same interactions found in tertiary structures. 4. Of hemoglobin consists of two alpha chains and two beta chains. The heme group in each subunit picks up oxygen for transport in the blood to the tissues. PROTEINS DENATURATION Denaturation involves The disruption of bonds in the secondary, tertiary and quaternary protein structures. Heat and organic compounds that break apart H bonds and disrupt hydrophobic interactions. Acids and bases that break H bonds between polar R groups and disrupt ionic bonds. Heavy metal ions that react with S-S bonds to form solids. Agitation such as whipping that stretches peptide chains until bonds break. PROTEINS DENATURATION NUCLEIC ACID NUCLEOTIDE Nucleotide 1. Consists of three parts: base, pentose sugar (deoxyribose or ribose) and phosphoric acid unit. 2. Two type of nitrogenous base, pyrimidine and purines 3. Purines (adenine (A) and guanine (G)) larger than pyrimidines (cytosine (C), thymine (T) and uracil (U)) 4. The bond between the base and sugar is called N-glycosidic bond and the bond between pentose and the phosphates called phosphodiester bond. 5. Two type of nucleic acid DNA (A,G,C,T) and RNA (A,G,C,U) NUCLEIC ACID PENTOSE SUGAR 1. The two types of nucleic acids (DNA & RNA) differ in the type of pentose they contain. 2. Those containing the sugar ribose are called ribonucleic acids (RNA) 3. Those containing the sugar deoxyribose are called deoxyribonucleic acids (DNA) 4. Deoxyribose H-atom in carbon atom 2 5. Ribose -OH (hydroxyl) group in carbon atom 2 NUCLEIC ACID The Structure of DNA 1. Based on the work by James Watson and Francis Crick, consist of a double stranded structure, forming coil. 2. Composed of two polymer strands of nucleotides, the bases united by hydrogen bonds (A pair with T and C pair with G). 3. Two strands of a DNA molecule run in opposite direction or anti-parallel, one strand in a 5’-3’ arrangement and the other strand is in 3’-5’ arrangement. 4. Thymine -adenine pair interacts through two hydrogen bonds (T=A) Cytosine-guanine pair interacts through three hydrogen bonds (C=G) DNA is double stranded with the 2 strands held together by hydrogen bonds between complementary bases 5´ 3´ 5´ 3´ 5´ 3´ T A T A DNA is a double G C G C helix. C G CG T A A T T A A T C G C G G C G A T A T T A T A C G C G T A T A G C T A A T G C C G T A A T 3´Cartoon of 5´ 5´Cartoon of 3´ 5´ 3´ Space-filling model of base pairing double helix double helix NUCLEIC ACID The Structure of RNA 1. RiboNucleic Acid 2. Single stranded but can form secondary structure containing double stranded region 3. Similar to DNA, however the sugar group is ribose. 4. Contain bases Adenine, Cytosine, Guanine and Uracil instead of Thymine. 5. Single strand, there are three type of RNA: ribosomal RNA (rRNA), transfer RNA (tRNA) and messenger RNA (mRNA). NUCLEIC ACID Types of RNA 1. Messenger RNA is RNA that carries information from DNA to the ribosome sites of protein synthesis in the cell. 2. tRNA (transfer RNA) Transfer RNA is a small RNA chain of about 74 - 93 nucleotides that carries amino acids to the location of protein synthesis. 3. rRNA (ribosomal RNA) Ribosomal RNA is a component of the Ribosomes, the protein synthetic factories in the cell. Differences between RNA and DNA DNA RNA Double polynucleotide chain Single polynucleotide chain Large molecular mass Small molecular mass Double helix Single/ double helix Pentose sugar within deoxyribose Pentose sugar within ribose Bases A,T,C,G Bases A,U,C,G Chemically very stable Chemically less stable One basic form rRNA, tRNA and mRNA Exist permanently May exist temporarily for short period only PASSIVE TRANSPORT Transport of molecules/substances through a plasma membrane does not require energy. Molecules move from higher concentration until equilibrium is achieved. Three type of passive transport: diffusion, osmosis and facilitated diffusion. PASSIVE TRANSPORT DIFFUSION Diffusion can be defined as the net movement of molecules (or ions) from a region of their higher concentration to a region of their lower concentration down a diffusion gradient. passive (does not require energy) example:- oxygen diffuses from the lungs into the blood. PASSIVE TRANSPORT FCTORS THAT EFFECT THE RATE OF DIFFUSION The concentration gradient- The greater the differences in concentration between 2 regions of molecules or ions, the faster the rate of diffusion The area over which diffusion takes place- The larger the area, the faster the rate of diffusion The distance over which diffusion occurs- The shorter the distance, the faster the rate of diffusion Larger molecules such as glucose and amino acids cannot diffuse through the phospholipid bilayer. Can only cross the membrane by passing through hydrophilic channels created by protein molecules The rate of this diffusion depends on how many channels there are PASSIVE TRANSPORT FACILITATED DIFFUSION The transport of substances through plasma membrane with utilization of transport protein embedded in cell membrane. Transport protein is specific to certain molecule, has a specific binding site. Occur according to concentration gradient from higher to lower concentration region without using energy. Example of facilitated diffusion in the cell is transport glucose across the plasma membrane. Two types of protien involved: carrier protien (transport molecules) and channel protiens (transport ions).Transport rate increases with increasing concentration, until it reaches saturation. Specificity, follows concentration gradients. PASSIVE TRANSPORT FACILITATED DIFFUSION PASSIVE TRANSPORT OSMOSIS Water molecules 1. Solute + solvent = solution (sugar + water = sugar solution) 2. Separated by a partially permeable membrane 3. Defined as the passage of water from a region where it has a higher water potential to a region where it has a lower water potential through a partially permeable membrane. 1. Hypotonic solution-The solution has a higher water potential than the content of the cell. Water enters by osmosis therefore cell burst. 2. Hypertonic solution- The solution has lower water potential than the content of the cell. Water leaves the cell by osmosis therefore cell shrinks 3. Isotonic solution- Water potential of the cell equals that of the external solution. No net movement and cell remain normal. PASSIVE TRANSPORT OSMOSIS  Osmosis will occur from higher water potential to lower water potential until equilibrium achieved. When plant cells expose to distil water, osmosis will occur from distil water into the plant cells and plant cells become turgid. When expose to high concentration salt water, osmosis will occur from plant cells to the salt water and the plant will be plasmolysis (shrinkage of cytoplasm when water move out from the cell). In animal cells, when exposed to distil water, the cell will burst called haemolysis process. When exposed to high concentration salt, the cell will shrink and the process called creanation. ACTIVE TRANSPORT 1. Differs from passive transport 2. ATP is needed 3. Materials are moved against the concentration gradient (from lower to higher concentration) 4. Carrier protein molecules which act as ‘pumps’ are involved 5. Materials may be transported, either as molecule or in bulk as larger particles Mechanism of Active Transport Proteins accept the molecule or ions to be transported Change shape Using energy from ATP to carry the molecules or ions to the other side ACTIVE TRANSPORT CYTOLYSIS 1. In a process called cytolysis: 2 forms of cytolysis Endocytosis - bulk movement of material into the cell Exocytosis - bulk movement of material out of the cell 2. Endocytosis is the take in bulk material into the cell by using vesicle from membrane and divide into three: phagocytosis, pinocytosis and receptor-mediated Endocytosis. PHAGOCYTOSIS & PINOCYTOSIS 1. Phagocytosis is called cellular eating, involved take in solid substances/ organisms into the cell by infolding of plasma membrane. 2. Invagination is sac-like structure with substance inside it, will form vacuole such food vacuole and bud out from plasma into cytoplasm. 3. Vacuole then fuse with lysosomes that contain hydrolytic enzymes and content will be digested. 4. Amoeba and certain white blood cells perform phagocytosis. 5. Pinocytosis is known as cellular drinking, similar to phagocytosis but substance dissolve in liquid. 6. Plasma membrane infolded to form pinocytic channel and vesicles that bud off from the plasma membrane into the cytoplasm. 7. The liquid then transferred into cytosol. RECEPTOR MEDIATED ENDOCYTOSIS 1. Involves membrane receptors of tiny pits that formed by the invagination of the plasma membrane. 2. Outer surface of the membrane is coated with receptors. 3. Inner surface of the membrane is coated with a protien, clathrin.  EXOCYTOSIS 1. Reverse endocytosis, process used to export bulky material out of the cell. 2. Vesicles contain material such as enzyme move to plasma membrane, fused with the plasma membrane and release that enzymes out of the cells. THANK YOU AND THE END