STM 007 General Biology Module 10-11 Mitosis & Meiosis PDF

STM 007 | GENERAL BIOLOGY MODULE #10-11 “Mitosis & Meiosis” MITOSIS Purpose: Produces two genetically identical daughter cells. Used for growth, repair, and asexual reproduction. Phases: 1. Prophase:...

STM 007 | GENERAL BIOLOGY MODULE #10-11 “Mitosis & Meiosis” MITOSIS Purpose: Produces two genetically identical daughter cells. Used for growth, repair, and asexual reproduction. Phases: 1. Prophase: ○ Chromosomes condense and become visible. ○ Nuclear envelope breaks down. ○ Spindle fibers form. 2. Metaphase: ○ Chromosomes line up along the middle of the cell. ○ Spindle fibers attach to the centromeres of the chromosomes. 3. Anaphase: ○ Chromatids (sister chromosomes) are pulled apart to opposite sides of the cell. 4. Telophase: ○ Chromosomes begin to uncoil. ○ Nuclear envelope reforms around each set of chromosomes. ○ The cell starts to split. 5. Cytokinesis: ○ The cytoplasm divides, resulting in two separate daughter cells. MEIOSIS Purpose: Produces four genetically unique daughter cells with half the number of chromosomes. Used for sexual reproduction (sperm and eggs). Meiosis I: 1. Prophase I: ○ Chromosomes condense. ○ Homologous chromosomes pair up and exchange segments (crossing over). ○ Nuclear envelope breaks down. ○ Spindle fibers form. 2. Metaphase I: ○ Homologous pairs line up at the middle of the cell. 3. Anaphase I: ○ Homologous chromosomes are pulled apart to opposite sides of the cell. 4. Telophase I: ○ Chromosomes may uncoil slightly. ○ Nuclear envelope may reform. ○ The cell divides into two daughter cells. 5. Cytokinesis: ○ The cytoplasm divides, resulting in two cells. STM 007 | GENERAL BIOLOGY Meiosis II: (Similar to mitosis but without DNA replication beforehand) 1. Prophase II: ○ Chromosomes condense again. ○ Nuclear envelope breaks down if needed. ○ Spindle fibers form. 2. Metaphase II: ○ Chromosomes line up in the middle of each of the two cells. 3. Anaphase II: ○ Sister chromatids are pulled apart to opposite sides of each cell. 4. Telophase II: ○ Chromosomes begin to uncoil. ○ Nuclear envelopes reform around each set of chromosomes. ○ Cells begin to split. 5. Cytokinesis: ○ The cytoplasm divides in both cells, resulting in four genetically unique daughter cells. Key Differences: Mitosis: 1 division, 2 identical cells. Meiosis: 2 divisions, 4 unique cells with half the chromosome number. Meiosis I: 1. Prophase I: ○ Chromosomes: 46 (each chromosome is paired with its homologous chromosome, both having 2 chromatids) ○ Chromatids: 92 2. Metaphase I: ○ Chromosomes: 23 pairs (homologous chromosomes line up) ○ Chromatids: 92 (each pair consists of 4 chromatids) 3. Anaphase I: ○ Chromosomes: 46 (homologous chromosomes are pulled apart to opposite poles, but each chromosome still has 2 chromatids) ○ Chromatids: 92 4. Telophase I: ○ Chromosomes: 23 in each of the two new cells (still with 2 chromatids each) ○ Chromatids: 46 in each cell 5. Cytokinesis: ○ Chromosomes: 23 per daughter cell ○ Chromatids: 46 in each cell Meiosis II: 1. Prophase II: ○ Chromosomes: 23 in each cell (each chromosome has 2 chromatids) ○ Chromatids: 46 in each cell 2. Metaphase II: ○ Chromosomes: 23 in each cell (line up individually) ○ Chromatids: 46 in each cell 3. Anaphase II: ○ Chromosomes: 46 (sister chromatids are separated into individual chromosomes) ○ Chromatids: 46 in each cell STM 007 | GENERAL BIOLOGY 4. Telophase II: ○ Chromosomes: 23 in each of the four new cells (each with 1 chromatid) ○ Chromatids: 23 in each cell 5. Cytokinesis: ○ Chromosomes: 23 per daughter cell (total 4 cells) ○ Chromatids: 23 in each cell Summary: Meiosis halves the chromosome number from 46 to 23 and results in four genetically unique daughter cells, each with a single set of chromosomes and chromatids. MODULE #12 “GAMETOGENESIS: (SPERMATOGENESIS & OOGENESIS)” GAMETOGENESIS - Gametogenesis is the formation of sex cells or reproductive cells also known as gametes. It happens in primary sex organs called gonads. - The male gonad is called testis while in females is ovary which both contain primordial germ cells. - Primordial germ cells are the common origins of spermatozoa and oocytes, these cells are responsible for the production of gametes. Two components of gametogenesis: Spermatogenesis Oogenesis. Spermatogenesis- is the formation of sperm cells located in the seminiferous tubules of male gonads. - Seminiferous tubules are the site for germination, maturation and transportation of the sperm cells within the male testes. - The primordial germ cells produce cells which ultimately become sperm mother cells of spermatogonia. It is the most immature sperm cell that originated from a primordial germ cell. - Spermiogenesis is the transformation of spermatids into functional spermatozoa. The spermatogenesis produces four haploid cells at the end of the process. Oogenesis- is the formation of ovum located in the female gonad called ovary. This process happens inside the primordial germ cells and it starts from oogonium, the immature female germ cell. Through mitosis the oogonium gets converted into primary oocytes which are diploid cells (2n=46 chromosomes). MODULE #13 “THE STRUCTURE AND COMPONENTS OF PLASMA MEMBRANE” PLASMA MEMBRANE - is a thin semi-permeable membrane that surrounds the cytoplasm of a cell FUNCTIONS: protect the integrity of the interior of the cell by allowing certain substances into the cell, while keeping other substances out (selectively permeable) serves as a base of attachment for the cytoskeleton in some organisms and the cell wall in others serves to help support the cell and help maintain its shape STM 007 | GENERAL BIOLOGY regulate cell growth through the balance of endocytosis and exocytosis In exocytosis, vesicles containing lipids and proteins fuse with the cell membrane increasing cell size Animal cells, plant cells, prokaryotic cells, and fungal cells have plasma membranes. Internal organelles are also encased by membranes STRUCTURAL COMPONENTS OF PLASMA MEMBRANE: A. CELL MEMBRANE LIPIDS Phospholipids are lipid bilayer which is semi-permeable, allowing only certain molecules to diffuse across the membrane. Cholesterol molecules are selectively dispersed between membrane phospholipids. This helps to keep cell membranes from becoming stiff by preventing phospholipids from being too closely packed together. Cholesterol is not found in the membranes of plant cells. Glycolipids are located on cell membrane surfaces and have a carbohydrate sugar chain attached to them. They help the cell to recognize other cells of the body. B. CELL MEMBRANE PROTEINS Peripheral membrane proteins are exterior to and connected to the membrane by interactions with other proteins. Integral membrane proteins. Portions of these transmembrane proteins are exposed on both sides of the membrane. Structural proteins help to give the cell support and shape Receptor proteins help cells communicate with their external environment through the use of hormones, neurotransmitters, and other signaling molecules. Transport proteins, such as globular proteins, transport molecules across cell membranes through facilitated diffusion. Glycoproteins have a carbohydrate chain attached to them. They are embedded in the cell membrane and help in cell-to-cell communications and molecule transport across the membrane. MODULE #15 “INTRODUCTION TO PASSIVE TRANSPORT MECHANISM IN CELLS: SIMPLE AND FACILITATED DIFFUSION” PASSIVE TRANSPORT MECHANISM IN CELLS Transport Mechanism in Cell Membrane - The cell membrane is one of the great multi-taskers of biology. It provides structure for the cell, protects cellular contents from the environment, and allows cells to act as specialized units. - In cellular biology, membrane transport refers to the collection of mechanisms that regulate the passage of solutes such as ions and small molecules through biological membranes, which are lipid bilayers that contain proteins embedded in them. Transport means moving something from one area to another by passing through a gate or a membrane. - Types of membrane transport can be grouped into passive and active transport. Passive transport can be simple diffusion or facilitated diffusion. Active transport can be ion pumps, exocytosis and endocytosis. A. Simple Diffusion - In simple diffusion, small non-charged molecules or STM 007 | GENERAL BIOLOGY - Lipid soluble molecules pass between the phospholipids to enter or leave the cell, moving from areas of high concentration to areas of low concentration (they move down their concentration gradient). Oxygen and carbon dioxide and most lipids enter and leave cells by simple diffusion. What is diffusion? - Diffusion occurs when particles spread. They move from a region where they are in high concentration to a region where they are in low concentration, it happens when the particles are free to move. - Osmosis on the other hand is a type of diffusion where molecules of water are moving from a region of high-water concentration to a region of less water concentration by passing through a semipermeable membrane, a type of membrane selective to allow which substance will enter through it. Facilitated Diffusion - Facilitated diffusion uses transport proteins to move ions and other small molecules across the plasma membrane. - Channel proteins are water-filled transport proteins that transport proteins that open and close to allow substances to pass through. - Carrier proteins are transport proteins that change shape to open and close as substances diffuse across the membrane. MODULE #16 “THE ACTIVE TRANSPORT MECHANISM IN CELLS: SODIUM AND POTASSIUM PUMP AND BULK/VESICULAR TRANSPORT” What is active transport? - Active transport is the movement of molecules across a cell membrane from a region of their lower concentration to a region of their higher concentration-in the direction against some gradient or other obstructing factor (often a concentration gradient). - Active transport requires the assistance of a type of protein called a carrier protein, using energy supplied by ATP or Adenosine Triphosphate to affect the transport. How does the process of active transport work? - Those proteins do much of the work in active transport. They are positioned to cross the membrane so one part is on the inside of the cell and one part is on the outside. Only when they cross the bilayer are they able to move molecules and ions in and out of the cell. The membrane proteins are very specific. Bulk Transport Exocytosis Moves materials out of cell in vesicle Vesicle combines with plasma membrane Material is emptied to the outside Endocytosis Substances engulfed by being enclosed in a membranous vesicle 2 Types - Phagocytosis - cell eating - Pinocytosis - cell drinking STM 007 | GENERAL BIOLOGY What is Bulk/Vesicular Transport? - Most molecules, including proteins, are too large to pass directly through membranes. Instead, large molecules are loaded into small membrane-wrapped containers called vesicles. Vesicles are constantly forming - especially at the plasma membrane, the Endoplasmic Reticulum, and the Golgi. Once formed, vesicles deliver their contents to destinations within or outside of the cell. How are vesicles formed? - A vesicle forms when the membrane bulges out and pinches off. It travels to its destination then merges with another membrane to release its cargo. In this way proteins and other large molecules are transported without ever having to cross a membrane. Vesicular transport is the predominant mechanism for exchange of proteins and lipids between membrane-bound organelles in eukaryotic cells. - There are two types of vesicle transport, endocytosis and exocytosis. Both processes are active transport processes, requiring energy. Endocytosis is the case when a molecule causes the cell membrane to bulge inward, forming a vesicle. Difference between Endocytosis and Exocytosis - Endocytosis is the process of capturing a substance or particle from outside the cell by engulfing it with the cell membrane. The membrane folds over the substance and it becomes completely enclosed by the membrane. At this point a membrane-bound sac, or vesicle, pinches off and moves the substance into the cytosol. There are two main kinds of endocytosis. Phagocytosis, or cellular eating, occurs when the dissolved materials enter the cell. The plasma membrane engulfs the solid material, forming a phagocytic vesicle. Pinocytosis, or cellular drinking, occurs when the plasma membrane folds inward to form a channel allowing dissolved substances to enter the cell. When the channel is closed, the liquid is encircled within a pinocytic vesicle. Exocytosis describes the process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell. Exocytosis occurs when a cell produces substances for export, such as a protein, or when the cell is getting rid of a waste product or a toxin. Newly made membrane proteins and membrane lipids are moved on to the plasma membrane by exocytosis. MODULE #17 “THE STRUCTURES AND FUNCTIONS OF BIOLOGICAL MOLECULES: CARBOHYDRATES AND LIPIDS” I. CARBOHYDRATES - Carbohydrates are macronutrients and are one of the three main ways by which our body obtains its energy. They are called carbohydrates as they comprise carbon, hydrogen and oxygen at their chemical level. Carbohydrates are essential nutrients which include sugars, fibers and starches. They are found in grains, vegetables, fruits and in milk and other dairy products. They are the basic food groups which play an important role in a healthy life. The food containing carbohydrates are converted into glucose or blood sugar during the process of digestion by the digestive system. STM 007 | GENERAL BIOLOGY Our body utilizes this sugar as a source of energy for the cells, organs and tissues. The extra amount of energy or sugar is stored in our muscles and liver for further requirement. The term 'carbohydrate' is derived from a French term 'hydrate de carbone' meaning 'hydrate of carbon'. The general formula of this class of organic compounds is Cn(H2O)n. A. Classification of Carbohydrates The carbohydrates are further classified into simple and complex which is mainly based on their chemical structure and degree of polymerization. Simple Carbohydrates (Monosaccharides and Disaccharides) Simple carbohydrates have one or two sugar molecules. In simple carbohydrates, molecules are digested and converted quickly resulting in a rise in the blood sugar levels. They are abundantly found in milk products, beer, fruits, refined sugars, candies, etc. These carbohydrates are called empty calories, as they do not possess fiber, vitamins and minerals. Plants, being producers, synthesize glucose (C6H12O6) using raw materials like carbon dioxide and water in the presence of sunlight. This process of photosynthesis converts solar energy into chemical energy. Consumers feed on plants and harvest energy stored in the bonds of the compounds synthesized by plants. 1. Monosaccharides Glucose is an example of a carbohydrate monomer or monosaccharide. Other examples of monosaccharides include mannose, galactose, fructose, etc. The structural organization of monosaccharides is as follows (right side image). Monosaccharides may be further classified depending on the number of carbon atoms: (i) Trioses : These have three carbon atoms per molecule. (ii) Tetroses : These monosaccharides have four carbon atoms per molecule. 2. Disaccharides Two monosaccharides combine to form a disaccharide. Examples of carbohydrates having two monomers include- Sucrose, Lactose, Maltose, etc. Complex Carbohydrates (Polysaccharides) Complex carbohydrates have two or more sugar molecules; hence they are referred to as starchy foods. In complex carbohydrates, molecules are digested and converted slowly compared to simple carbohydrates. They are abundantly found in lentils, beans, peanuts, potatoes, peas, corn, whole-grain bread, cereals, etc. Polysaccharides are complex carbohydrates formed by the polymerization of a large number of monomers. Examples of polysaccharides include starch, glycogen, cellulose, etc. which exhibit extensive branching and are homopolymers - made up of only glucose units. 1. Starch is composed of two components- amylose and amylopectin. Amylose forms the linear chain and amylopectin is a much-branched chain. 2. Glycogen is called animal starch. It has a structure similar to starch, but has more extensive branching. 3. Cellulose is a structural carbohydrate and is the main structural component of the plant ceil wall. It is a fibrous polysaccharide with high tensile strength. In contrast to starch and glycogen, cellulose forms a linear polymer. STM 007 | GENERAL BIOLOGY B. Functions of Carbohydrates The main function of carbohydrates is to provide energy and food to the body and to the nervous system. Carbohydrates are known as one of the basic components of food, including sugars, starch, and fiber which are abundantly found in grains, fruits and milk products. Carbohydrates are also known as starch, simple sugars, complex carbohydrates and so on. It is also involved in fat metabolism and prevents ketosis. Inhibits the breakdown of proteins for energy as they are the primary source of energy. An enzyme by name amylase assists in the breakdown of starch into glucose, finally to produce energy for metabolism. C. Sources of Carbohydrates 1. Simple sugars are found in the form of fructose in many fruits. 2. Galactose is present in all dairy products. 3. Lactose is abundantly found in milk and other dairy products. 4. Maltose is present in cereal, beer, potatoes, processed cheese, pasta, etc. 5. Sucrose is naturally obtained from sugar and honey containing small amounts of vitamins and minerals. These simple sugars that consist of minerals and vitamins exist commonly in milk, fruits, and vegetables. Many refined and other processed foods like white flour, white rice, and sugar, lack important nutrients and hence, they are labeled "enriched." It is quite healthy to use vitamins, carbohydrates and all other organic nutrients in their normal forms. D. Carbohydrate Foods Eating too much sugar results in an abnormal increase in calories, which finally leads to obesity and in turn low calories leads to malnutrition. Therefore, a well-balanced diet needs to be maintained to have a healthy life. That is the reason a balanced diet is stressed so much by dietitians. II. LIPIDS - Lipids are organic compounds that contain hydrogen, carbon, and oxygen atoms, which form the framework for the structure and function of living cells. These organic compounds are nonpolar molecules, which are soluble only in nonpolar solvents and insoluble in water because water is a polar molecule. In the human body, these molecules can be synthesized in the liver and are found in oil, butter, whole milk, cheese, fried foods and also in some red meats. A. Properties of Lipids Lipids are a family of organic compounds, composed of fats and oils. These molecules yield high energy and are responsible for different functions within the human body. Listed below are some important characteristics of Lipids. 1. Lipids are oily or greasy nonpolar molecules, stored in the adipose tissue of the body. 2. Lipids are a heterogeneous group of compounds, mainly composed of hydrocarbon chains. 3. Lipids are energy-rich organic molecules, which provide energy for different life processes. 4. Lipids are a class of compounds characterized by their solubility in nonpolar solvents and insolubility in water. 5. Lipids are significant in biological systems as they form a mechanical barrier dividing a cell from the external environment known as the cell membrane. STM 007 | GENERAL BIOLOGY B. Lipid Structure Lipids are the polymers of fatty acids that contain a long, non-polar hydrocarbon chain with a small polar region. containing oxygen. The lipid structure is explained in the diagram (image in the right side). C. Classification of Lipids Monoglycerides or simple lipid - are storage lipids such as neutral fats and waxes. are storage Diglycerides/Triglycerides or Compound Lipid - phospholipids, glycolipids and lipoproteins Polyglycerides or Derived Lipids - the building blocks for simple and complex lipid such as fatty acids and alcohols, hydrocarbons, fat soluble vitamins A, D, E and K and sterols D. Types of Lipids Within these two major classes of lipids, there are numerous specific types of lipids, which are important to life, including fatty acids, triglycerides, glycerophospholipids, sphingolipids and steroids. These are broadly classified as simple lipids and complex lipids. Simple Lipids - Esters of fatty acids with various alcohols. i. Fats: Esters of fatty acids with glycerol. Oils are fats in the liquid state ii. Waxes: Esters of fatty acids with higher molecular weight monohydric alcohols Complex Lipids - Esters of fatty acids containing groups in addition to alcohol and fatty acid. i. Phospholipids: These are lipids containing, in addition to fatty acids and alcohol, phosphate groups. They frequently have nitrogen-containing bases and other substituents, e.g., in glycerophospholipids the alcohol is glycerol and in sphingophospholipids the alcohol is sphingosine. ii. Glycolipids (glycosphingolipids): Lipids containing a fatty acid, sphingosine and carbohydrate iii. Other complex lipids: Lipids such as sulfolipids and amino lipids. Lipoproteins may also be placed in this category. Precursor and Derived Lipids These include fatty acids, glycerol, steroids, other alcohols, fatty aldehydes, and ketone bodies, hydrocarbons, lipid-soluble vitamins, and hormones. Because they are uncharged, acylglycerols (glycerides), cholesterol, and cholesteryl esters are termed neutral lipids. These compounds are produced by the hydrolysis of simple and complex lipids. Some of the different types of lipids are described below in detail. i. Fatty Acids - Fatty acids are carboxylic acids (or organic acid), usually with long aliphatic tails (long chains), either unsaturated or saturated. a. Saturated fatty acids - Lack of carbon-carbon double bonds indicate that the fatty acid is saturated. The saturated fatty acids have higher melting points compared to unsaturated acids of the corresponding size due to their ability to pack their molecules together thus leading to a straight rod-like shape. b. Unsaturated fatty acids - Unsaturated fatty acid is indicated when a fatty acid has more than one double bond. - "Often, naturally occurring fatty acids possess an even number of carbon atoms and are unbranched." - On the other hand, unsaturated fatty acids contain a cis-double bond(s) which create a structural kink that disables them to group their molecules in straight rod-like shape. STM 007 | GENERAL BIOLOGY E. Functions of Lipid: Energy storage Serve as an important constituent of the structure of cells. Providing energy to produce hormones Insulates the body Protection of skin from drying up Buoyancy, it keeps one afloat Helps in food digestion F. Examples of Lipids There are different types of lipids. Some examples of lipids include butter, ghee, vegetable oil, cheese, cholesterol and other steroids, waxes, phospholipids, and fat-soluble vitamins. All these compounds have similar features, i.e. insoluble in water and soluble in organic solvents, etc. Waxes - Waxes are "esters" (an organic compound made by replacing the hydrogen with acid by an alkyl or another organic group) formed from long-alcohols and long-chain carboxylic acids. - Waxes are found almost everywhere. The fruits and leaves of many plants possess waxy coatings that can safeguard them from small predators and dehydration. - Fur of a few animals and the feathers of birds possess the same coatings serving as water repellants. Phospholipids - Membranes are primarily composed of phospholipids that are Phosphoacylglycerols. - Triacylglycerols and phosphoacylglycerols are the same, but, the terminal OH group of the phosphoacylglycerol is esterified with phosphoric acid in place of fatty acid which results in the formation of phosphatidic acid. - The name phospholipid is derived from the fact that phosphoacylglycerols are lipids containing a phosphate group Steroids - Our bodies possess chemical messengers known as hormones, which are basically organic compounds synthesized in glands and transported by the bloodstream to various tissues in order to trigger or hinder the desired process. - Steroids are a kind of hormone that is typically recognized by their tetracyclic skeleton, composed of three fused six-membered and one five-membered ring, as seen above. The four rings are assigned as A, B, C & D as observed in the shade blue, while the numbers in red indicate the carbons. Cholesterol - Cholesterol is a wax-like substance, found only in animal source foods. Triglycerides, LDL, HDL, VLDL are different types of cholesterol found in the blood cells. - Cholesterol is an important lipid found in the cell membrane. It is a sterol, which means that cholesterol is a combination of steroids and alcohol. In the human body, cholesterol is synthesized in the liver. - These compounds are biosynthesized by all living cells and are essential for the structural component of the cell membrane. - In the cell membrane, the steroid ring structure of cholesterol provides a rigid hydrophobic structure that helps boost the rigidity of the cell membrane. Without cholesterol, the cell membrane would be too fluid. STM 007 | GENERAL BIOLOGY - It is an important component of cell membranes and is also the basis for the synthesis of other steroids, including the sex hormones estradiol and testosterone, as well as other steroids such as cortisone and vitamin D. MODULE #18 “THE STRUCTURES AND FUNCTIONS OF BIOLOGICAL MOLECULES - PROTEINS” Proteins are any of a class of nitrogenous organic compounds that consist of large molecules composed of one or more long chains of amino acids and are an essential part of all living organisms, especially as structural components of body tissues such as muscle, hair, collagen, etc., and as enzymes and antibodies. Amino acids are the building blocks of proteins and these are classified as essential amino acids and non- essential amino acids. A. Types of Proteins Motility protein - allow movement of cells and their organelles Structural protein - provides support, strength and protection Enzymes - catalyze or speed up biochemical reactions in the body Transport protein - carry molecules from one place to another or across cell membranes Hormones-signaling between different cell types; stimulation or inhibiting functions Cell surface receptor - label cells for targets for hormones, viruses, growth factors, recognition of self- transmission of nerve impulse Neurotransmitter - signaling between neurons or brain cells Immunoglobulins - recognition of foreign substances that enters the body (antigen) Poisons/Toxins - chemicals for defense and capture of food such as snake venoms. B. Structure of Proteins Proteins are structured differently based on functions; it can be: 1. Primary protein structure with a long chain of monomers (single amino acid) connected by peptide, as it becomes a long chain, it is called polypeptide. 2. Secondary protein structure - the long chain of polypeptides folded and form into sheets or helices. 3. Tertiary protein structure resulted when chain interactions happen and it went to three-dimensional folding pattern 4. Quaternary protein structure combination of 4 chains polypeptides into a single unit such as the hemoglobin protein C. Functions of Proteins 1. Structural support for nails and hair, collagen and ligaments, skin, nails and hairs are waterproof because it is keratinized, it is made of proteins 2. Transporting molecule, proteins in the form of hemoglobin carry oxygen in the blood to different organs of the body, it means less hemoglobin less oxygen 3. Receiving and sending signals, messengers as hormones doing special functions 4. Brain and nerves functions by producing brain chemicals that allows us react faster 5. Movement muscles have proteins that allow movement these are actin and myosin 6. Defense against disease as antibodies fight viruses and bacteria 7. Catalyst/speed up of biochemical reactions in the body in the form of enzymes 8. Cellular construction especially growth and repair of cells and tissues and source of energy. STM 007 | GENERAL BIOLOGY D. What are enzymes? They are all proteins, which is one reason why we need protein in our diet. They are all biological catalysts. They speed up a reaction without being used up; this means they can be used over and over again. A small amount of enzyme can affect the change of a large amount of chemical. The way enzymes work is affected by temperature, pH and pressure. They can be denatured (destroyed) by excessive heat. The reactions are reversible. Enzymes are specific, that is they control only one reaction. So, maltase only acts on maltose, sucrase on sucrose etc. E. Types of Enzymes 1. Metabolic enzymes - Metabolic enzymes are intra-cellular (meaning, inside your cells), produced by the body to help the cells carry out a variety of functions and complex biochemical reactions related to its multiplication and replenishment. Examples of activities performed include breathing, talking, moving, thinking, breathing and maintenance of the immune system. Another important function of the enzyme is to neutralize poisons and carcinogens such as pollutants and tobacco smoke, changing them into less toxic forms that the body can eliminate. Did you know that sperm cells of male species have fertilizing enzymes, too? Yes! As soon as the sperm cell touch the egg cell, it will break the protective cover of egg cell and can bore a hole to let the sperm cell in and locked it, producing a fertilized egg cell, making it protected from other sperm cells and the fertilization process proceed uninterrupted: 2. Digestive enzymes Their main attribute is to convert food into nutrients; which are taken in by the bloodstream. - The digestive enzymes are produced by the body to break food substances into forms that can be absorbed and assimilated by the body. These are the enzymes primarily manufactured in the pancreas and intestine and to a lesser extent in the salivary glands and the stomach. In the digestive system enzymes break down large insoluble molecules (e.g., starch, proteins and fats) into small soluble molecules that can be absorbed into the blood from the small intestines. The main digestive enzymes are as listed below: If we don't have enough digestive enzymes, we can't break down our food-which means even though we're eating well, we aren't absorbing all that good nutrition. Other important enzymes are: Maltase - Converting complex sugars from grains Phytase - Helps with overall digestion, especially in producing the B vitamins into glucose Lactase - Digesting milk sugar (lactose) in dairy products Sucrase - Digesting most sugars And many more which are not highlighted here. There are around 45 important nutrients that are needed by the body. Without these 45 nutrients, the body cannot function properly and people must get them from outside sources. Nutrients, enzymes included, cooperate with each other and they act like catalysts; thus, they promote assimilation and absorption. Did you know that 90 percent of your digestion and absorption takes place in your small intestine? STM 007 | GENERAL BIOLOGY 3. Food enzymes - Food enzymes are ingested by the body through the raw food that we eat daily. When ingested, foods that contain enzymes provide us with digestive enzymes, elementary for our digestion. No enzymes will lead to problems...common conditions arising from lack of enzymes from the system Constipation slow movement of the bowels leading to colon cancer Bloating-gas is present in the digestive system and this is very uncomfortable. Heartburn - the painful feeling when stomach acid is going up the esophagus. Ulcers - the stomach wall has wounds and feels painful when eating or drinking. Allergies - uncomfortable reactions to foods and substances such as sea foods or odors. Lack of energy - feeling tired always even if you sleep all night. In general, the main benefits of enzymes are detoxification (to carry away waste that is toxic), purify the blood, digest food and deliver nutrients, balance cholesterol, feed the brain and optimize energy availability and production. All these serve to strengthen the immune system and boost your energy level.