Chemistry Notes PDF

Chemistry Terms Definition Anion A negatively charged ion has more electrons than protons. Cation A positively charged ion has more protons than electrons. Electrode...

Chemistry Terms Definition Anion A negatively charged ion has more electrons than protons. Cation A positively charged ion has more protons than electrons. Electrode Conductors that are used to make electrical contact with a non-metallic part of the circuit. Anode Electrode where oxidation occurs. Cathode Electrode where reduction occurs. Electrolyte A medium containing ions that are electrically conductive. Electrolysis The decomposition of a compound in the solution or ion the molten state brought about by the passage of electrical current through it. Insulator Materials that do not allow electricity to pass through them are called insulators. Conductor Conductors are the materials or substances which allow electricity to flow through them. In circuit (of battery), connect the positive terminal to the anode and the negative terminal to the cathode. Electrons travel from negative (-ve) to positive(+ve); From higher potential to lower potential Anode(+) attracts anions(-) and Cathode (-) attracts cations (+) Salts: Salt is an ionic compound that contains a cation (base) and an anion (acid). It is present in large quantities in seawater, where it is the main mineral constituent. Salt is essential for animal life and saltiness is one of the basic human tastes. Salt is an ionic compound that has a cation other than H+ and an anion other than OH– and is obtained along with water in the neutralization reaction between acids and bases. Eg: NaCl, CuCl2 etc. Acid + Base → Salt + water Salts are the ionic compounds made up with a metal and a nonmetal or polyatomic ions (other than H+ and OH-) Classification of Salts (Acid, Base, Salt): Acid ○ A substance that forms H+ ion when dissolved in water is called an acid. ○ A substance that dissociates almost completely when dissolved in water to form H+ ions is called a strong acid. ○ Eg. HCL, H2SO4, HNO3 ○ A substance partially dissolved in water to form H+ ions is called a weak acid. ○ Eg. CH3COOH, HCOOH ○ HCL is acidic only when it is dissolved in water (HCl(aq)) because it can then form H+ ions. ○ Acids present in animals and plants are called organic acids. ○ Acids produced artificially are called inorganic acids. Properties of Acids ○ Acids have pH values of below 7, have a sour taste (when edible) and are corrosive ○ Acids are substances that can neutralize a base, forming a salt and water ○ When acids are added to water, they form positively charged hydrogen ions (H+)  ○ The presence of H+ ions is what makes a solution acidic ○ Eg. Hydrochloric Acid HCl (aq)→H+(aq)+Cl- (aq) Base ○ A substance that forms OH- (Hydroxyl) ions is called a base. ○ A substance that dissociates almost completely when dissolved in water to form OH- ions is called a strong base. ○ Eg. NAOH, KOH ○ A substance that dissociates partially when dissolved in water to form OH- ions is called a weak base. ○ Eg. LIOH, ZNOH(2) Typical reactions of acids Acids and metals Only metals above hydrogen in the reactivity series will react with dilute acids. When acids react with metals they form a salt and hydrogen gas: Acid + Metal → Salt + Hydrogen The name of the salt is related to the name of the acid used, as it depends on the anion within the acid. Criss Cross Method: The criss-cross method is a way to write the formula for ionic compounds using the charges of the ions involved. Steps to Use the Criss-Cross Method: 1. Identify the Ions: Determine the cation (positive ion) and anion (negative ion) in the compound. 2. Write the Charges: Write down the charges of the cation and anion. For example, sodium (Na) has a charge of +1, and chloride (Cl) has a charge of -1. 3. Criss-Cross the Charges: Take the absolute value of the charge of each ion and criss-cross them to become the subscript for the other ion. 4. For Na⁺ and Cl⁻: The +1 from Na becomes the subscript for Cl, and the -1 from Cl becomes the subscript for Na. 5. Write the Formula: Write the formula using the new subscripts. If either subscript is 1, you usually omit it. In our example, NaCl is the formula. 6. Simplify if Necessary: If the subscripts can be simplified (e.g., if they are both multiples of a number), do that. But in simple cases like NaCl, no simplification is needed. Types of Salts: Acidic Salt: The salt formed by partial neutralization of a diprotic or a polyprotic acid is known as an acidic salt. These salts have ionizable H+ ion along with another cation. Mostly the ionizable H+ is a part of the anion. Some acid salts are used in baking. For eg. NaHSO4, KH2PO4 etc. Basic or Alkali Salt: A basic salt is the salt created when a strong base is partially neutralized by a weak acid. They break down into a basic solution when they are hydrolyzed. Because the conjugate base of the weak acid is produced in the solution when a basic salt is hydrolyzed. White lead (2PbCO3Pb(OH)2), for example. Double Salts: Double salt refers to salts that include more than one cation or anion. They are made through the crystallization of two distinct salts in the same ionic lattice. Potassium sodium tartrate (KNaC4H4O6.4H2O), commonly known as Rochelle salt, is a good example. Mixed Salts: A mixed salt is a salt that is made up of a fixed proportion of two salts that often share a similar cation or anion. CaOCl2, for example. Physical Properties of Salt: Compound Name: The common name given to a salt, which typically reflects its constituent ions or its source. For example, Sodium Chloride is commonly known as table salt. Molecular Formula: Represents the types and numbers of atoms in a molecule. For instance, Sodium Chloride has the molecular formula NaCl, indicating it consists of one sodium atom and one chlorine atom. Molecular Mass: The mass of one mole of a substance, measured in grams per mole (g/mol). For NaCl, the molecular mass is approximately 58.44 g/mol, derived from the atomic masses of sodium (22.99 g/mol) and chlorine (35.45 g/mol). Color: Salt contains traces of magnesium chloride, magnesium sulfate, magnesium bromide, and other minerals in its natural state. These impurities can cause the otherwise clear crystals to become yellow, red, blue, or purple in color.  Appearance: Solid salts, such as sodium chloride, have a translucent appearance. The apparent transparency or opacity is usually simply linked to the size difference between the individual monocrystals. The bigger crystals tend to be transparent, but the polycrystalline aggregates seem to be white powders, since light reflects from the grain boundaries (boundaries between the crystallites). Odor: Strong acid and strong base salts (“strong salts”) are non-volatile and frequently odorless, but weak acid and weak base salts can smell like the component ions’ conjugate acid (for example, vinegar and almonds) or conjugate base (for example, ammonium compounds such as ammonia). Taste: Different salts may elicit all five fundamental tastes, such as sweet (lead diacetate, which can induce lead poisoning if consumed), salty (sodium chloride), bitter (magnesium sulfate), sour (potassium bitartrate), and savory (monosodium glutamate) or umami (monosodium glutamate). Conductivity: Salts are insulators by nature and have a low conductivity. Salt solutions or molten salts conduct electricity. Liquified (molten) salts and solutions containing dissolved salts (such as sodium chloride in water) are referred to as electrolytes for this reason. Melting Point: Salts are known for having high melting points. Assume sodium chloride melts at 801 degrees Celsius. A few salts with low lattice energies are liquid at room temperature or close to it. Molten salts, which are generally mixes of ionic liquids, and salts, which usually retain organic cations, are the two types of salts. Cations or Anions: Salts are defined as compounds that include either a cation or an anion, and are therefore classified as salts in chemistry. Metals and Salts: The most basic salts are made up of one type of metal cation and one type of non-metal anion. On the right side of the periodic chart, there is a black stair-step line. Metals exist to the left of it, non-metals exist to the right, and a few atoms present on the steps (not aluminum) are termed metalloids or semimetals. Solubility in Water: Salt readily dissolves in water, forming a solution. The process involves the dissociation of salt into its constituent ions, which interact with water molecules, facilitating the separation of the ions and their distribution throughout the solution. Dissolution (Endothermic or Exothermic): The dissolution of salt in water is an endothermic process. During this process, energy is absorbed from the surroundings, resulting in a slight decrease in temperature of the solution as the ionic bonds in the salt are broken. Density: Density refers to the mass per unit volume of salt. Salt has a relatively high density, which results from its ionic structure, where ions are closely packed in a crystal lattice formation. pH: When dissolved in water, salt typically results in a neutral pH. This means that the solution does not exhibit acidic or basic properties, as the ions produced from the salt do not interact significantly with water to change its pH. Electrical Conductivity: Salt conducts electricity when dissolved in water or when melted due to the presence of free-moving ions. In its solid state, salt does not conduct electricity, as the ions are held in fixed positions within the crystal lattice. Boiling Point: The boiling point of salt is high, reflecting the strong ionic bonds that need significant energy to break. This property is important in processes that involve heating salt, such as in cooking or industrial applications. Chemical Properties of Salt: Dissociation: When dissolved in water, salts dissociate into their constituent ions, which can conduct electricity, making the solution an electrolyte. Reactivity: Salts can undergo various chemical reactions, including: ○ Double displacement reactions: When two salts react in solution to form a new salt and possibly a precipitate or gas. ○ Acid-base reactions: Certain salts can react with acids or bases. Precipitation: Many salts can form precipitates when mixed with solutions containing ions that lead to their insolubility. Hydrolysis: Some salts can undergo hydrolysis, where the ions react with water, leading to the formation of acidic or basic solutions. Water of Crystallization: Salts usually exist in their hydrated forms. This means that there is a certain number of water molecules associated with their lattice structures. This number varies from salt to salt owing to the type of crystals and spatial orientation. Not only does this water of crystallization change the structure of the anhydrous crystal, but it also affects the colors of the salts. The change in the crystal structure is accompanied by a change in properties such  as densities and refractive index etc. When a hydrated salt is heated, it drives off the water of crystallization, resulting in the formation of anhydrous salt. Adding water to the anhydrous salt reverses this process. An example is the hydrated copper sulfate CuSO4.5H2O (copper sulfate pentahydrate), which has a triclinic crystal structure and is blue in color. Upon heating the hydrated salt, anhydrous CuSO4 is formed which has an orthorhombic crystal structure and is a grayish-white powder. Osmosis, Cell Rupture, Density, Solubility: Osmosis: Osmosis is the process by which water moves from an area with a lot of water (or lower concentration of solutes, like salt or sugar) to an area with less water (or higher concentration of solutes) through a semipermeable membrane. This membrane allows water molecules to pass through but blocks larger molecules. Cell Rupture: Cell rupture in the context of salts typically refers to the breaking or damaging of cell membranes due to osmotic pressure changes caused by salt concentrations. When cells are exposed to high salt concentrations, water may leave the cell to balance the concentration gradient, leading to dehydration and potentially causing the cell to shrink and rupture. Density: In the context of salts, density refers to the mass of a salt per unit volume and plays a crucial role in both solid and solution forms. Different salts have distinct densities that can influence their behavior in mixtures, while the density of salt solutions changes with concentration; higher concentrations generally result in increased density. Solubility: Solubility refers to how well a salt can dissolve in a solvent, usually water, breaking into its ions. It's influenced by factors like temperature, the specific salt's characteristics, the presence of other ions (common ion effect), and the solution's pH. Solubility is typically expressed in molarity, indicating how many moles of salt can dissolve in a liter of solution. Salt and Electricity: Salt and electricity are closely connected because salt can help conduct electricity when dissolved in water. 1. Solid Salt: In solid form, salt doesn’t conduct electricity because the ions (charged particles) are locked in place within the crystal structure. 2. Dissolved Salt: When salt (like table salt, sodium chloride) dissolves in water, it breaks into its ions – sodium (Na⁺) and chloride (Cl⁻). These free ions in the water can move around, allowing electric current to flow through the solution. This is why salty water can conduct electricity. So, while pure water is a poor conductor of electricity, adding salt increases conductivity because the ions help carry the electric charge. This is why salty water can be dangerous with electricity nearby. Salt and Health: Table Salt: A refined salt primarily made of sodium chloride, often iodized to prevent iodine deficiency, supporting thyroid function and fluid balance. Sea Salt: Harvested from evaporated seawater, it retains trace minerals like magnesium and calcium, which may offer additional health benefits. Himalayan Pink Salt: Rich in over 80 trace minerals, this salt is believed to help with hydration and pH balance, while adding a subtle flavor to dishes. Kosher Salt: Coarse and flaky, kosher salt is prized for its ability to season food evenly and is often used in cooking for its mild flavor. Black Salt (Kala Namak): This mineral-rich salt is commonly used in Ayurvedic medicine and is known for its unique flavor and potential digestive benefits.  Fleur de Sel: A delicate sea salt harvested from the surface of seawater, it adds a gourmet touch to dishes and contains various trace minerals. Soluble and Insoluble Salts: Soluble salts: are salts that dissolve easily in water, breaking apart into ions. Examples of soluble salts include table salt (sodium chloride) and potassium nitrate. When these salts are mixed with water, they disperse completely, creating a clear solution. Insoluble salts: do not dissolve well in water and usually form a solid that settles at the bottom, called a precipitate. Examples of insoluble salts include calcium carbonate (found in chalk) and silver chloride. Even if you try mixing them in water, they’ll stay as solids and won’t dissolve. In short: Soluble salts: dissolve in water to form clear solutions. Insoluble salts: do not dissolve in water and often form a visible solid. Electrical Conductivity: Electrical conductivity is a material's ability to let electricity flow through it. Some materials, like metals, have high conductivity, so they allow electricity to pass easily. Others, like rubber or plastic, have low conductivity and don't let electricity flow through them well. It’s like how some things are better at carrying heat – here, it's about carrying electric current. Polarity: Polarity refers to the distribution of electrical charge within a molecule, which can result in regions of partial positive and negative charges. It arises from differences in electronegativity between atoms: Polar Molecules: Have uneven distribution of charge, leading to distinct positive and negative ends (e.g., water, H₂O). Nonpolar Molecules: Have even distribution of charge and do not have charged ends (e.g., oil, methane). Polarity affects how substances interact with each other, influencing solubility, boiling points, and chemical reactions. Polar substances tend to dissolve well in other polar substances, while nonpolar substances dissolve in nonpolar solvents. Molecular Mass: Molecular mass is the total mass of all the atoms in a molecule. It's calculated by adding up the atomic masses of each atom in the molecule, usually measured in atomic mass units (amu or u). To calculate molecular mass, follow these steps: 1. Identify the Chemical Formula: Determine the formula of the compound (e.g., H₂O, CO₂). 2. List Atomic Masses: Use the periodic table to find the atomic mass of each element in the compound. This is typically given in atomic mass units (amu). 3. Multiply by the Number of Atoms: For each element in the formula, multiply its atomic mass by the number of times it appears in the formula. 4. Sum the Values: Add together all the individual masses calculated in the previous step. Example: Water (H₂O) 1. Each hydrogen (H) atom has an atomic mass of approximately 1 amu, and there are 2 hydrogen atoms. 2. Oxygen (O) has an atomic mass of about 16 amu. The molecular mass of water is calculated as: (2 X 1) + 16 = 18 amu So, the molecular mass of H₂O is 18 amu. Mole: A mole is defined as the amount of a substance that contains exactly 6.02214076 × 1023 'elementary entities' of the given substance of some chemical unit, be it atoms, molecules, ions, or others. The number 6.02214076 × 1023 is popularly known as the Avogadro constant and is often denoted by the symbol 'NA'. Molar Mass: Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It represents the mass of 6.022 × 1023 molecules or atoms of that substance, which is known as Avogadro's number. To calculate the molar mass of a compound: 1. Identify the chemical formula: For example, water (H₂O) consists of hydrogen and oxygen. 2. Determine the atomic masses: You can find these values on the periodic table: Hydrogen (H) ≈ 1.01 g/mol Oxygen (O) ≈ 16.00 g/mol 3. Count the number of each type of atom:  In H₂O, there are 2 hydrogen atoms and 1 oxygen atom. Calculate the contribution of each element: For hydrogen: 2 × 1.01 g/mol = 2.02 g/mol For oxygen: 1 × 16.00 g/mol =16.00 4. Add the contributions together: Molar mass of H₂O = 2.02 g/mol + 16.00 g/mol = 18.02 g/mol So, the molar mass of water is approximately 18.02 g/mol. Apply the same steps for any other compound. Molar Solutions: A molar solution is a solution that contains a specific number of moles of a solute per liter of solution. It’s usually expressed in molarity (M), which is the concentration in moles per liter (mol/L). Formula for Molar Solutions The general formula to calculate the mass of salts needed for a molar solution is: Mass of salt (g) = Molarity (M) × Volume (L) × Molar mass (MW) Mass of salt = M × V × MW How to Calculate 1. Determine Molarity (M): This is the concentration you want, in mol/L. 2. Determine Volume (V): This is the total volume of the solution you’re preparing, in liters (L). 3. Find Molar Mass (Mw): This is the molar mass of the solute (salt), in g/mol. 4. Calculate Mass: Substitute into the formula: For example, you want to make a 0.5 L of a 1 M of NaCl solution, molar mass of NaCl is 58.5 g/mol: Mass of NaCL (g) = 1 mol/l × 0.5 L × 58.8 g/mol = 29.25 g So, you would need 29.25 grams of NaCl to make this solution. Polyatomic Ions: Polyatomic ions are groups of atoms that stick together and have an electric charge. Unlike single-atom ions (like sodium or chloride), polyatomic ions have multiple atoms bonded together that act as a single unit with a positive or negative charge. For example, the sulfate ion (SO₄²⁻) has four oxygen atoms and one sulfur atom bonded together, carrying a charge of -2. These ions are common in chemistry and play a big role in forming various compounds, like in baking soda and fertilizers. Chemical and Physical Change: Chemical change: This is when a substance transforms into a completely different substance with new properties. This happens because the chemical bonds change, and new ones form. Signs of chemical change include color change, gas production (bubbles), temperature change, or formation of a solid (precipitate). Examples are burning wood, rusting iron, or baking a cake. Physical change: On the other hand, doesn’t change the substance itself—only its form or state. In a physical change, the appearance may change, but the molecules stay the same, so it’s often reversible. Examples include melting ice, dissolving sugar in water, or cutting paper. In short: Chemical Change: New Substance, Hard to reverse. Physical Change: Same Substance, Just looks different, Usually reversible. Preparing Soluble Salts: Electrolysis of Salt Solution: The metal plates immersed in the electrolyte are called electrodes. The electrode connected with the positive terminal of the battery is called anode. And the electrode connected with the negative terminal of the battery is called cathode PANIC(Positive anode negative is cathode) Pure water cannot undergo electrolysis because the ions are not free to move and so we add acid which catalyzes the formation of ions. (generally h2so4 is used) Only hydrogen or metal can be found on cathode. Gas is found on the anode side. Batteries and Salts: Salt is beneficial in batteries primarily as an electrolyte, which facilitates the movement of ions essential for battery operation. Salt solutions conduct ions, allowing charge flow between the anode and cathode. Additionally, saltwater batteries are generally safer than traditional options, as they are less flammable and less toxic, making them more environmentally friendly. The use of abundant and inexpensive materials, like sodium, can also help reduce manufacturing costs. Furthermore, salt-based batteries can offer greater stability and longer life cycles in certain conditions, enhancing their overall performance. Lithium Battery: Lightweight with high energy density, lithium batteries are popular in portable electronics and electric vehicles. They offer long life and minimal self-discharge but require careful management. Lead Acid Battery: An older rechargeable battery made of lead and sulfuric acid, commonly used in cars. They are cost-effective but heavy and have a shorter lifespan compared to newer technologies. Rechargeable Battery: Designed for multiple uses, these batteries can be restored through charging. They include lithium-ion, NiCd, and NiMH, and are eco-friendly and cost-effective over time. Nickel-Metal Hydride (NiMH) Battery: A rechargeable battery using nickel and hydrogen, NiMH batteries have higher capacity than NiCd and are used in hybrid vehicles and portable devices, though they may have a shorter lifespan than lithium-ion. Coin Battery: Small, round batteries used in low-drain devices like watches and calculators. Available in various chemistries, they are compact and reliable but typically non-rechargeable. Electrolytic Cell: Has one beaker Is non spontaneous, needs a battery Two metal plates or metal rods (electrodes) are required We provide current by connecting a battery (Electrical to Chemical) The is an anode on the +ve side and a cathode on the -ve side. The metal that has to be coated on other metal than that will be the anode. Eg. If silver has to be coated over Iron then, Silver (Ag) will be at the Anode and Iron(Fe) will be at the Cathode. Anode is Positive and Cathode is Negative  The solution remains neutral Salt bridge is not required in the cell, because the solution remains neutral (no net charge is developed) NOTE: To determine the Anode, think about what should get consumed, Eg: in electrorefining, in the case of pure and impure copper, the impure copper will be the anode since it should be consumed to be able to refine pure copper. Galvanic Cell: Has two beakers Is spontaneous, does not need a battery Two metal plates or metal rods (electrodes) are required Has a bulb We draw current (Chemical to Electrical) For the solution in the beaker you can take any salt but it should be of the respective electrode. Eg. If the electrode is Zinc, then Zinc Chloride, Zinc Nitrate, Zinc Carbonate etc. can be taken but if the electrode is Copper, then Copper Chloride, Copper Nitrate, Copper Carbonate etc. can be taken. The metal that has the least reactivity will attract the electrons. In other words, the metal that has the higher reactivity will lose the electrons. The metal that attracts the electrons, its ions will gain the electrons. The metal that has the higher reactivity will form anode of the galvanic cell. The one that gains the elections is negative, and the one that loses the electrons is positive. Anode is Negative and Cathode is Positive The solution develops a net charge in both the solutions, hence salt bridge is required. The solution at Anode will become positive because it loses electrons The solution at Cathode will become negative because it gains electrons The salt bridge is used to maintain electrical neutrality inside the circuit of a galvanic cell. The Salt bridge acts as an electrical connection between two half cells. The Salt bridge prevents the diffusion of solution from one cell to the other. The salts from the salt bridge bonds with the salts in the beakers to neutralize the solutions. As a salt bridge, the salt bridge is usually made up of Potassium Chloride, Sodium Chloride (it should not be the same as used in the cell). Physics Variable Denote Unit Charge Q C / coulomb Electric Current I A / ampere Time t s / seconds Number of Electrons n – Charge of an Electron e − 1. 602 × 10 19  Charge of a Proton p (Not every time) + 1. 602 × 10 19 Voltage V V / volts Energy / Work Done E/W J / joules Static Electricity: All matter is made up of atoms that consist of three types of smaller particles; negatively charged electrons, positively charged protons, and neutral neutrons. Normally, the electrons and protons in an atom balance out, which is why most matter you come across is electrically neutral. But electrons are tiny and almost insignificant in mass, and rubbing or friction can give loosely bound electrons enough energy to leave their atoms and attach to others, migrating between different surfaces. When this happens, the first object is left with more protons than electrons and becomes positively charged, while the one with more electrons accumulates a negative charge. This situation is called a charge imbalance, or net charge separation. Static electricity occurs when two or more bodies come into contact and separate again. Static electricity does not allow the flow of electrons. Static electricity only takes place in an insulator. But nature tends towards balance, so when one of these newly charged bodies comes into contact with another material, the mobile electrons will take the first chance they get to go where they're most needed, either jumping off the negatively charged object, or jumping onto the positively charged one in an attempt to restore the neutral charge equilibrium. And this quick movement of electrons, called static discharge, is what we recognize as that sudden spark. This process doesn't happen with just any objects. Otherwise you'd be getting zapped all the time. Conductors like metals and salt water tend to have loosely bound outer electrons, which can easily flow between molecules. On the other hand, insulators like plastics, rubber and glass have tightly bound electrons that won't readily jump to other atoms. Static build-up is most likely to occur when one of the materials involved is an insulator. When you walk across a rug, electrons from your body will rub off onto it, while the rug's insulating wool will resist losing its own electrons. Although your body and the rug together are still electrically neutral, there is now a charge polarization between the two. And when you reach to touch the door knob, Zap! The metal door knob's loosely bound electrons hop to your hand to replace the electrons your body has lost. When it happens in your bedroom, it's a minor nuisance. But in the great outdoors, static electricity can be a terrifying, destructive force of nature. In certain conditions, charge separation will occur in clouds. We don't know exactly how this happens. It may have to do with the circulation of water droplets and ice particles within them. Regardless, the charge imbalance is neutralized by being released towards another body, such as a building, the Earth, or another cloud in a giant spark that we know as lightning. Applications: Lightning: A metal rod placed on top of a building to protect it from a lightning strike is known as a lightning conductor. This conductor is struck first in lightning without hitting the building directly, preventing fire or electrocution. It provides a harmless and easy path for the lightning energy to pass into the ground without damaging the structure of the buildings. Grounding for Fuel Transportation Electrostatic Spray Painting Electrostatic Precipitator Photocopier Conductors Flow of Electric Current: Electric Current is the flow of electric charge. Conventional current (I): Conventional current is believed to flow from positive to negative terminal  − Electron current (𝑒 ): Electron current flows from negative to positive terminal Convectional current - A to B Electron current - B to A Charge (Q): The state of having excess or deficit of electrons as compared to the proton is called charge. There are two kinds of charge, +ve (less electrons) and -ve (more electrons). Charge is measured in coulombs (C). One coulomb is defined as: The charge is carried by an electric current of one ampere in one second. Charge is a scalar quantity Electrons have a negative charge Protons have a positive charge Like charges repel each other and attract opposite ones In neutral (i.e. uncharged) atoms and objects the number of electrons and the number of protons are equal Electric Current: The rate of flow of electrons in a conductor. The SI Unit of electric current is the Ampere (A). Voltage / Electric Potential Difference: The work done on moving a charge from one point to another in a conductor. The SI unit of Voltage is volt (V). Direct Current (DC) and Alternating Current (AC): Direct Current Alternating Current The current flows in the single direction with steady The electric charge flow changes its direction voltage. (Unidirectional flow of charges) periodically. (Bi-directional flow of charges)  No frequency or has zero frequency Frequency is 50 or 60 Hz, depending on the country Transmitting DC over long distances is a bit difficult AC is preferred for long distances because it is and expensive cheaper and easier to transmit. Source: Batteries & Solar cells Source: Power plants & Generators Applications: Laptops, Smartphones etc Applications: Homes, appliances and Businesses DC is often preferred for powering electronic devices AC is more efficient for transmitting electricity over because it provides a more stable and predictable long distances due to reduced power loss compared current flow. to DC. Unlike alternating current, the In alternating current, the flow of direct current does not electric charge flow change periodically. The current changes its direction electricity flows in a single periodically. AC is the direction in a steady voltage. The most commonly used major use of DC is to supply and most-preferred power to electrical devices and electric power for also to charge batteries. household equipment, Examples include mobile phone office, buildings, etc. batteries, flashlights, flat-screen television and electric Alternating current can be identified in a waveform vehicles. DC has the combination of a plus and a called a sine wave. In other words, it can be referred minus sign, a dotted line or a straight line. Everything to as a curved line. These curved lines represent that runs on a battery and uses an AC adapter while electric cycles and are measured per second. The plugging into a wall or uses a USB cable for power measurement is read as Hertz (Hz). AC is used in relies on DC. Examples would be cellphones, electric powerhouses and buildings because generating and vehicles, flashlights, flat-screen TVs (AC goes into the transporting AC across long distances is relatively TV and is converted into DC). easy. AC is capable of powering electric motors which are used in refrigerators, washing machines, etc Circuit Symbols: Part of the Circuit Function Symbol Battery Combination of electric cells Electric Cell Current flow from positive to negative Ammeter Measures electric current, connected in series Ohmmeter Measures electrical resistance Multimeter Measure various electrical properties, including voltage, current, and resistance.  Voltmeter Measures electrical / potential voltage. Connected in parallel. Galvanometer Measure electric current’s direction and intensity Bulb Light source, for example LED light & tubelight Rheostat / Variable Resistance can be changed Resistor Open Key Closed Key An electrical component that can open or close a circuit, which means it can interrupt or divert the Open Switch flow of electricity Closed Switch Resistor: A passive electrical component with two terminals that are used for either limiting or regulating the flow of electric current in electrical circuits. The main purpose of the resistor is to reduce the current flow and to lower the voltage in any particular portion of the circuit. Advantages of a Resistor: Current Regulation: Resistors control the flow of electric current, ensuring circuits function correctly. Protection of Components: Resistors prevent damage to sensitive components by limiting current. They protect against short circuits and overheating. Safety: Resistors enhance the safety of electrical systems by preventing potential hazards. Circuit Stability: They improve the overall stability and reliability of electronic devices. Cost-Effectiveness: Resistors are affordable and widely available, making them practical for various applications. Advancements in Technology: Modern resistors are designed to minimize energy loss and improve efficiency. Disadvantages of a Resistor: Energy Dissipation: Resistors convert electrical energy into heat, leading to inefficiencies and energy loss. Reduced Efficiency: The energy loss from resistors impacts the overall efficiency of electrical systems. Design Complexity: Resistors can add unnecessary complexity to circuit design and maintenance. Environmental Impact: Energy inefficiency and waste associated with resistors have environmental consequences. Alternatives: Smart Integrated Circuits (ICs) and digital control systems offer more efficient current regulation without the drawbacks of resistors. Sustainability: Moving towards more sustainable and efficient technologies is essential for future development. Factors Affecting Resistance Temperature: As the temperature of a conductor increases, its resistance typically rises. This happens because higher temperatures cause the atoms in the material to vibrate more, which interferes with the flow of electrons. Increased resistance at higher temperatures means that less current can flow for the same voltage, which can lead to overheating and energy loss. This makes it crucial to choose materials that maintain stable resistance under varying temperatures, especially in high-heat environments. Material: Different materials have different levels of resistance. Metals like copper and silver have low resistance, allowing electricity to flow easily, while insulating materials like rubber have high resistance, restricting current flow. Resistance of the Conductor: Resistance directly affects the current flow in a conductor according to Ohm's law (I = V/R), where 'I' is the current, 'V' is the voltage, and 'R' is the resistance. Higher resistance means lower current flow for a given voltage. Conductors with higher resistance tend to generate more heat as the energy lost due to resistance is converted into heat. It is crucial to select conductive materials with low resistance for applications where efficiency and minimal energy loss are essential. Cross Sectional Area: The larger the cross-sectional area of the conductor, the lower its resistance to current flow. A larger area provides more space for electrons to move, reducing the likelihood of collisions and resistance. A conductor with a larger cross-sectional area can handle more current with less resistance. This property is essential for power transmission lines and busbars, which need to carry high current loads with minimal loss due to resistance. Length of the Conductor: The longer the conductor, the higher its resistance to the flow of current. This is because electrons encounter more resistance and collisions with atoms as they travel through a longer path. A longer conductor will have a lower current flow compared to a shorter one, assuming the voltage remains constant. This is why long electrical wires are generally not ideal for transmitting electricity over long distances, as they would lead to significant energy losses due to increased resistance. Ohm's Law: Ohm’s Law states that the voltage across a conductor is directly proportional to the current flowing through the conductor, provided all the physical conditions and temperature remains constant. As the potential difference (voltage) increases the current also increases, given that the temperature remains constant. OR At constant temperature voltage is directly proportional to current. V = IR : Mathematical way of Ohm’s law Where, R is the resistance, I is the Current , T is the temperature Electric Power & Energy: Electric Power Electric Energy The rate at which work is done by a source in The total work done by a source of emf maintaining an electric current through a circuit is (electromagnetic field) in maintaining an electric called the electric power of a circuit. current for a given time is called the electric energy of the circuit. Electric Power: P Electric Energy: W S.I Unit is Watt(W) SI Unit is Joule(J) P= 𝑡 𝑊 W = 𝑃𝑡  W = work done T = time taken V = potential difference I = current that flows through the circuit for time t Series & Parallel Circuits: Series Circuit Parallel Circuit The same amount of current flows through all the The current flowing through each component components. combines to form the current flow through the source. In an electrical circuit, components are arranged in a In an electrical circuit, components are arranged line. parallel to each other. When resistors are put in a series circuit, the voltage When resistors are put in a parallel circuit, the voltage across each resistor is different even though the across each of the resistors is the same. Even the current flow is the same through all of them. polarities are the same. If one component breaks down, the whole circuit will Other components will function even if one component burn out. breaks down, each has its own independent circuit If Vt is the total voltage then it is equal to V1 + V2 + V3 If Vt is the total voltage then it is equal to V1 = V2 = V3 Right Hand Thumb Rule: The right hand rule states that to determine the direction of the magnetic force on a positive moving charge, point your right thumb in the direction of the current flow and the direction of the fingers curling shows the direction of the magnetic field. On reversing the direction of current, the magnetic field will also be reversed. Electromagnets: An electromagnet is a type of magnet created by electric current. Unlike a regular magnet, which is always "on," an electromagnet only becomes magnetic when electricity flows through it. You can make a basic electromagnet by wrapping a coil of wire around a metal core (like an iron nail) and connecting the wire to a battery. The electric current running through the wire generates a magnetic field, making the metal core act like a magnet. When you disconnect the battery, the magnetism disappears. Faraday's Law: Faraday's law of electromagnetic induction states that a change in the magnetic field through a loop of wire induces an electromotive force (EMF) and, consequently, an electric current in the wire. The magnitude of the induced EMF is directly proportional to the rate of change of magnetic flux through the loop. This law forms the basis of electric power generation, transformers, and many other electrical devices. Application of Electromagnets: Motors and Generators: They make devices like fans and washing machines work by turning electricity into motion (motors) or turning motion into electricity (generators). Electric Bells: The ringing sound in an electric bell uses an electromagnet to make a hammer hit the bell. Magnetic Cranes: Used in junkyards, electromagnets can pick up heavy metal objects when electricity flows and drop them by cutting off the electricity. MRI Machines: In hospitals, powerful electromagnets help make images of the inside of the body. Difference between Electromagnetism and Electromagnets? Electromagnetism is the branch of physics that studies the relationship between electric and magnetic fields, showing how electric currents create magnetic fields and vice versa. It’s a fundamental force behind many natural and technological processes. An electromagnet, on the other hand, is a physical device that uses this principle. It’s a coil of wire, often wrapped around a piece of iron, that becomes magnetic when an electric current flows through it. So, while electromagnetism is the science explaining the interaction, an electromagnet is an application of that science, used in things like electric motors, cranes, and MRI machines. Homopolar Motor: A homopolar motor is a direct current (DC) electric motor which produces constant circular motion. Flemings’ Left Hand Rule: used for determining the direction of the induced current in electric motors. Thumb: Direction of force or motion of coil Forefinger: Direction of magnetic field Middle finger: Direction of induced current in Deflection in Magnets: When you change the direction of the electric current, you are effectively changing the orientation of the magnetic field near the compass. As a result, the compass needle will respond by deflecting or swinging to align itself with the new direction of the magnetic field. The compass needle will align itself with the magnetic field lines produced by the current-carrying wire. The specific orientation of the needle will depend on the direction of the current and the relative position of the compass with respect to the wire. How will the deflection of the compass get affected if the current in the wire is increased? Magnetic field produced by the current-carrying wire: ○ A magnetic compass is made by using magnetized iron and that iron points towards the pole of the earth. ○ When another magnet is brought near, the compass will basically point on towards the other magnet as its magnetic strength is known to be stronger than the earth’s magnetic strength. ○ When a current-carrying wire is brought close to a magnetic compass then there will be a deflection in the magnetic compass due to the magnetic field formation. ○ The magnetic field around a wire carrying an electric current will form concentric circles around the wire. Affected on the magnetic field if the current in the wire is increased: ○ The deflection will tend to increase when the current in the wire is increased. ○ The strength of the magnetic field is directly proportional to the magnitude of the electric current through the wire. ○ When a current-carrying wire is brought close to a magnetic compass then there will be a deflection in the magnetic compass due to the magnetic field formation.  ○ The deflection increases with the increased current in the wire because the magnetic force is directly proportional to the magnetic field strength. ○ Thus, we can say that the stronger the current, the stronger the magnetic force acting on the needle of the magnet. Hence, if the current is increased in the conductor then the deflection of the compass needle increases, this is because the strength of the magnetic field varies directly as the magnitude of the electric current or the current passing through the wire. Magnetic Fields: A region in which a magnetic pole experiences a force. Magnetic field around a bar magnet: 1. The magnetic field is strongest at the poles. Therefore, the magnetic field lines are closer together at the ends of the magnets. 2. The magnetic field becomes weaker as the distance from the magnet increases. Therefore, the magnetic field lines get further apart Electric Motor: Electric motors convert electrical energy into mechanical energy. The type of energy conversion that occurs in an electric motor is from electrical energy (supplied by the flow of current) to mechanical energy (rotational motion). Direction of Electric Current: ○ When an electric current flows through a conductor (such as a coil) in the presence of a magnetic field, it experiences a force. ○ The direction of the electric current is crucial in determining the direction of the force. Magnetic Field Lines: ○ The coil is placed in a magnetic field, typically created by a permanent magnet or an electromagnet. ○ Magnetic field lines run from the north pole to the south pole outside the magnet. Force Acting on the Coil: ○ The force acting on the coil is described by Fleming's Left-Hand Rule. ○ Fleming's Left-Hand Rule states that if you point your thumb in the direction of the force (motion), your index finger in the direction of the magnetic field, and your middle finger in the direction of the current, then the force acting on the conductor will be perpendicular to both the magnetic field and the current direction. ○ This rule helps determine the direction of rotation in an electric motor. Variables: Current (I): The amount of current flowing through the coil affects the strength of the magnetic field and, consequently, the force experienced by the coil. Magnetic Field (B): The strength of the magnetic field in which the coil is placed influences the force acting on the coil. Stronger magnetic fields generally result in more powerful motors hence the more force to rotate. Number of Turns in the Coil (N): The number of turns in the coil is a factor in determining the overall force experienced by the coil. More turns can enhance the effectiveness of the motor hence the more force to rotate. Length of the Conductor (l): The length of the coil's conductor is another variable that affects the force. Longer conductors may experience more significant forces. Electric Generator: This is an electric machine that converts mechanical energy into electrical energy. The electric generators work on the principle of electromagnetic induction. Electric generators, also known as dynamos, are electric machines that convert mechanical energy into electrical energy. Electric generators work on the principle of Electromagnetic induction. Variables:  ○ Generator Speed: The rotational speed of the generator's rotor can affect the frequency and voltage of the generated current. Typically, higher speeds result in higher frequencies and voltages for AC generators. ○ Magnetic Field Strength: The strength of the magnetic field within the generator affects the induction of electric current. Greater field strength often leads to higher current output. ○ Number of Turns in the Coil: In generators with coils (like in alternators), the number of turns in the coil can impact the current generated. More turns generally result in higher current output. ○ Material, Cross-section and length of the wire of the coil. Flemings’ Right Hand Rule: Used for determining the direction of induced current in electric generators. Thumb: Direction of force or motion of coil Forefinger: Direction of magnetic field Middle finger: Direction of induced current in Biology DNA: Deoxyribonucleic Acid or DNA, is a molecule that carries genetic information in living organisms. It is a long, double-stranded polymer made up of repeating units called nucleotides. DNA is essential for the storage, transmission, and expression of genetic information. DNA Structure: 1. Nucleotides: DNA is composed of nucleotides, which are the building blocks of the molecule. Each nucleotide consists of three main components: A phosphate group A deoxyribose sugar molecule One of four nitrogenous bases: adenine (A), thymine (T), cytosine (C), or guanine (G). 2. Base Pairing: The structure of DNA is a double helix, with two long chains of nucleotides running in opposite directions. Adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G) through hydrogen bonds. This complementary base pairing is crucial for the stability of the DNA molecule. 3. Antiparallel Strands: The two chains in a DNA double helix run in opposite directions, referred to as antiparallel. One strand has a 5' (five-prime) end, and the other has a 3' (three-prime) end. This arrangement is important for DNA replication. 4. Sugar-Phosphate Backbone: The sugar and phosphate groups form the backbone of the DNA molecule, while the nitrogenous bases project inward, forming base pairs. Function of DNA: 1. Genetic Information Storage: DNA serves as the primary repository of genetic information in all living organisms. It contains the instructions for the development, functioning, and reproduction of organisms. 2. Transmission of Genetic Information: DNA is passed from one generation to the next during reproduction. It ensures the continuity of genetic traits from parents to offspring. 3. Protein Synthesis: DNA carries the genetic code that directs the synthesis of proteins, which are essential for the structure and function of cells. The process of protein synthesis involves two main steps: transcription and translation. Transcription: The DNA code is transcribed into a complementary RNA molecule called messenger RNA (mRNA) in the cell's nucleus. Translation: The mRNA is then translated into a specific sequence of amino acids to form a protein. 4. Regulation of Gene Expression: DNA plays a crucial role in regulating when and how genes are expressed. Gene expression can be controlled by various mechanisms, including transcription factors and epigenetic modifications. Structure of a DNA Molecule: Extended DNA, or deoxyribonucleic acid, is the molecule that contains the instructions for the growth and development of all organisms It consists of two strands of DNA wound around each other in what is called a double helix Location of DNA: In human cells, molecules of DNA are densely packed into thread-like structures called chromosomes in the nucleus. There are 23 pairs of chromosomes in the nucleus of each human cell. Each chromosome contains one very long DNA molecule. To allow it to fit in the nucleus, the DNA molecule is coiled around proteins called histones and folded many times. Base Pairs: The two strands in DNA are held together by hydrogen bonding between the bases. DNA bases always pair in the same way: A with T and C with G. The double-stranded molecule is twisted into a double helix shape resembling a twisted ladder. Nucleotide: Every nucleotide is made of three components: a phosphate group, a deoxyribose sugar, and a nitrogen-containing base. Nucleotides are all identical except for their base. DNA has four different bases, known as adenine, thymine, cytosine, and guanine. Bases are often referred to by the letters A, T, C, and G. All nucleotides contain the same phosphate and deoxyribose sugar, but differ from each other in the base attached There are four different bases, Adenine (A), Cytosine (C), Thymine (T) and Guanine (G) The bases on each strand pair up with each other, holding the two strands of DNA in the double helix The bases always pair up in the same way:  ○ Adenine always pairs with Thymine (A-T) ○ Cytosine always pairs with Guanine (C-G) The phosphate and sugar section of the nucleotides form the ‘backbone’ of the DNA strand (like the sides of a ladder) and the base pairs of each strand connect to form the rungs of the ladder The DNA helix is made from two strands of DNA held together by hydrogen bonds It is this sequence of bases that holds the code for the formation of proteins RNA: RNA is a ribonucleic acid that helps in the synthesis of proteins in our body. This nucleic acid is responsible for the production of new cells in the human body. It is usually obtained from the DNA molecule. RNA resembles the same as that of DNA, the only difference being that it has a single strand unlike the DNA which has two strands and it consists of an only single ribose sugar molecule in it. Hence is the name Ribonucleic acid. RNA is also referred to as an enzyme as it helps in the process of chemical reactions in the body. Functions of RNA: Facilitate the translation of DNA into proteins Functions as an adapter molecule in protein synthesis Serves as a messenger between the DNA and the ribosomes. They are the carrier of genetic information in all living cells Promotes the ribosomes to choose the right amino acid which is required in building up new proteins in the body. Types of RNA: tRNA – Transfer RNA: The transfer RNA is held responsible for choosing the correct protein or the amino acids required by the body in-turn helping the ribosomes. It is located at the endpoints of each amino acid. This is also called as soluble RNA and it forms a link between the messenger RNA and the amino acid. rRNA – Ribosomal RNA: The rRNA is the component of the ribosome and are located within the cytoplasm of a cell, where ribosomes are found. In all living cells, the ribosomal RNA plays a fundamental role in the synthesis and translation of mRNA into proteins. The rRNA is mainly composed of cellular RNA and is the most predominant RNA within the cells of all living beings. mRNA – Messenger RNA: This type of RNA functions by transferring the genetic material into the ribosomes and passing the instructions about the type of proteins required by the body cells. Based on the functions, these types of RNA are called the messenger RNA. Therefore, the mRNA plays a vital role in the process of transcription or during the protein synthesis process. In RNA, Adenine (A) pairs with Uracil (U), and Guanine (G) pairs with Cytosine (C). Codons: A gene is a segment or sequence of DNA responsible for expressing characters. Genes are more commonly thought of as units for heredity, such as the gene for brown eyes or the genes responsible for being tall or having high blood pressure. DNA, and consequently genes, is passed from a father to his offspring through his sperm, and from a mother to her offspring through her egg. Children have a 50-50 mix of DNA from their parents. Humans have about 25,000 genes. DNA stores the information of characters, using the genetic code, a triplet code of nucleotide bases known as codon. DNA Replication: 1. DNA replication is the process by which DNA makes a copy of itself during cell division. 2. The first step in DNA replication is to 'unzip' the double helix structure of the DNA molecule. 3. The two separated strands will act as templates for making the new strands of DNA. 4. The nitrogen bases are added to each strand. 5. The new strands are proofread to make sure no mistakes are made while copying. 6. Two new DNA are made and then are winded into a Double helix. Problems in replication 1. If there is a problem during the replication process, then there are chances that certain nitrogen bases may change, causing a change in the DNA. 2. These changes can lead to differences in the DNA from generation to generation. 3. These mutations can be beneficial or can be harmful. Transcription: Transcription is when the DNA in a gene is copied to produce a translated message in the form of mRNA (messenger RiboNucleic Acid). RNA is in structure and properties to DNA, but it only has a single strand of bases and instead of the base thymine(T), RNA has a base called uracil (U). The DNA is transcribed to mRNA to code for a specific protein, whereas the DNA has codes for all proteins. For each protein a new mRNA is produced. Translation: The mRNA after its production reaches the Ribosomes to make proteins. The mRNA is translated here in the form of codons and is read in 3 letters at a time like you did in the activity. For each codon, one amino acid corresponding to it is added. Some amino acids will have multiple possible codons as there are only 20 amino acids and 64 potential combinations of codons. The tRNA(transfer RNA) reads mRNA until it reaches something known as stop codon. Once a stop codon comes it stops adding amino acids and the protein is produced. Protein Synthesis: Protein synthesis is the process by which cells create proteins, essential for numerous biological functions. It occurs in two main stages: transcription and translation. During transcription, DNA in the nucleus is converted into messenger RNA (mRNA) by the enzyme RNA polymerase. This mRNA then travels to the ribosome in the cytoplasm, where translation takes place. In translation, transfer RNA (tRNA) molecules bring specific amino acids to the ribosome, which reads the mRNA sequence in codons (three-nucleotide segments). The ribosome links the amino acids together in the correct order, forming a polypeptide chain that eventually folds into a functional protein, vital for cell structure and function. Mutation: A mutation is a permanent change in a DNA sequence. Mutations change the numbers, types, or order of base pairs (A, T, G, and C). They occur during cell division, when the DNA is copying itself, through a process called replication. Causes of Mutation: DNA copying mistakes made during cell division, exposure to ionizing radiation, exposure to chemicals called mutagens, or infection by viruses. Germline mutations occur in the eggs and sperm and can be passed onto offspring, while somatic mutations occur in body cells and are not passed on. Types of Mutation (Small & Large Scale): Small Scale Mutations: Affect DNA at the molecular level by changing the normal sequence of nucleotides base pairs. Occur during the process of DNA replications (either meiosis or mitosis) Types of Small Scale Mutations Substitution Deletion Insertion Substitutions occur when a Deletion is the removal of a Addition of a nucleotide to the DNA nucleotide is replaced with a nucleotide from the DNA sequence. sequence. Addition of even a single different nucleotide in the DNA Removal of even a single nucleotide to a gene alters every sequence. This type of mutation nucleotide from a gene alters every codon after the mutation. only affects the codon for a single codon after the mutation. amino acid.  Effects of Small Scale Mutations Silent Mutations Missense Mutations Nonsense Mutations The nucleotide is replaced, but the The codon now results in a different The codon now results in a “stop” codon still produces the same amino acid, which may or may not command, truncating the protein at amino acid. significantly alter the protein’s the location where the mutated function. codon is read; this almost always leads to a loss of protein functionality. Large Scale Mutations: Affect entire portions of the chromosome Some large-scale mutations affect only single chromosomes, other occur across non-homologous pairs Entire genes or sets of genes are altered rather than only single nucleotides of the DNA Mutations involving multiple chromosomes are likely to occur in meiosis, during the prophase l. Large Scale Mutation Inversion Insertion Translocation Single Chromosome Mutation Multiple Chromosome Mutation Multiple nonhomologous chromosome mutation The complete reversal of one or One or more gene(s) removed from more gene(s) within a one chromosome and inserted into Chromosomes swap one or more chromosome; the genes are another non-homologous gene(s) with another chromosome present, but the order is backwards chromosome can occur by an error from the parent chromosome. during the prophase I of meiosis when the chromosomes are swapping genes to increase diversity. Deletion Duplications Nondisjunction Single Chromosome Mutation Single Chromosome Mutation Does not involve any errors in DNA replication or crossing-over. The loss of one or more gene(s) The addition of one or more Mutations occur during the from the parent chromosome. gene(s) that are already present in anaphase and telophase when the the chromosome. chromosomes are not separated correctly into the new cells. Common nondisjunctions are missing or extra chromosomes  Effects of Large Scale Mutations Effects of large-scale mutations are more obvious than those of small-scale mutations Duplication of multiple genes causes those genes to be overexpressed while deletions result in missing or incomplete genes Mutations that change the order of the genes on the chromosome—such as deletions, inversions, insertions and translocations—result in genes that are close together When certain genes are positioned closely together, they may encode for a “fusion protein” A fusion protein is a protein that would not normally exist but is created by a mutation in which two genes were combined The new proteins give cells a growth advantage, leading to tumors and cancer Often, large-scale mutations lead to cells that are not viable. The cell dies due to the mutation Sex linked chromosomal disorder: Sex-linked chromosomal disorders are genetic conditions caused by mutations on the sex chromosomes, primarily the X and Y chromosomes. These disorders are often inherited in specific patterns due to the differences in how males (XY) and females (XX) inherit and express these genes. Down Syndrome: Down syndrome is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is typically associated with physical growth delays, characteristic facial features and mild to moderate intellectual disability. The parents of the affected individual are typically genetically normal. The extra chromosome occurs by chance. Hemophilia: A disorder that affects the blood's ability to clot, primarily affecting males since the gene is located on the X chromosome. Women can be carriers and may have mild symptoms. Duchenne Muscular Dystrophy (DMD): A severe form of muscular dystrophy caused by mutations in the dystrophin gene on the X chromosome, leading to progressive muscle degeneration. Color Blindness: Often inherited as an X-linked trait, leading to difficulty distinguishing certain colors, more commonly seen in males. Allele: A gene is a short length of DNA found on a chromosome that codes for a particular characteristic (expressed by the formation of different proteins) Alleles are variations of the same gene. ○ As we have two copies of each chromosome, we have two copies of each gene and therefore two alleles for each gene ○ One of the alleles is inherited from the mother and the other from the father ○ This means that the alleles do not have to ‘say’ the same thing ○ For example, an individual has two copies of the gene for eye color but one allele could code for brown eyes and one allele could code for blue eyes The observable characteristics of an organism (seen just by looking - like eye color, or found – like blood type) is called the phenotype The combination of alleles that control each characteristic is called the genotype Alleles can be dominant or recessive  ○ Dominant Alleles: Think of these as strong instructions. If an organism has one dominant allele and one recessive allele for a trait, the dominant allele usually "wins" and determines the trait expressed. ○ Recessive Alleles: These are like quieter instructions. They only determine the trait if an organism has two of them. If an organism has two recessive alleles, traits associated with the recessive allele will be expressed. Alleles work together to create a unique genetic code for each individual, shaping their physical and sometimes even behavioral characteristics. This diversity is the essence of genetic variation and inheritance. ○ If there is only one recessive allele, it will remain hidden and the dominant characteristic will show. If the two alleles of a gene are the same, we describe the individual as being homozygous (homo → same) An individual could be homozygous dominant (having two copies of the dominant allele), or homozygous recessive (having two copies of the recessive allele) If the two alleles of a gene are different, we describe the individual as being heterozygous (hetero → different) Punnett Square: 1. Determine the genotype of the parent organism and write down the cross: a. In case of Thalassemia as both the parents are carriers so the thalassemia gene is recessive as it is not expressed in the parents but they do carry the mutated gene. b. Hence the mutated genes can be denoted as small letter t and the normal dominant gene can be represented as capital T. c. The parents genotype is: Mom: Tt Dad: Tt Tt × Tt 2. Draw a punnett square: a. Draw a punnett square and and "split" the letters of the genotype for each parent & put them "outside" the p-square b. Parent's genotype: Mom: Tt Dad: Tt Tt × Tt 3. Determine the possible genotypes and phenotype of the offspring by filling in the p-square: a. Summarize result either in ratio or in percentage b. Genotypic Ratio – TT : Tt : tt ; 1 : 2 : 1 c. Phenotypic Ratio – Thalassemic : Non Thalassemic ; 1:3 Genotype: A genotype is the genetic makeup of an organism – the specific set of genes it carries. It’s like an organism’s genetic blueprint, which includes all the DNA that influences its traits, such as eye color, height, or risk of certain diseases. The genotype is represented by pairs of alleles (versions of a gene) that an individual inherits from their parents. For instance, if a gene for eye color has alleles for brown (B) and blue (b), a person’s genotype could be BB, Bb, or bb. While genotype refers to the genetic code itself, phenotype is the actual physical expression of these genes (like having brown or blue eyes). The environment can also influence how the genotype is expressed in the phenotype. Phenotype: A phenotype is the visible traits or characteristics of an organism, like appearance or behavior. For example, having brown eyes is a phenotype resulting from specific genes and environmental factors. While genotype refers to the genetic code itself, phenotype is the actual physical expression of these genes (like having brown or blue eyes). The environment can also influence how the genotype is expressed in the phenotype. DNA Fingerprinting: DNA fingerprinting, also known as DNA profiling or genetic fingerprinting, is a forensic technique used to identify individuals based on their unique DNA patterns. It involves the analysis of specific regions of an individual's DNA, such as short tandem repeats (STRs) or variable number tandem repeats (VNTRs). By comparing the DNA patterns from a sample, such as blood or hair, to a known reference sample, like that of a suspect, DNA fingerprinting can determine whether the two samples are from the same individual or related individuals. GMO’s: GMOs are organisms whose genetic material has been altered using genetic engineering techniques. These alterations can involve the insertion of genes from one species into another to confer specific traits or characteristics, such as resistance to pests, herbicides, or enhanced nutritional content. GMOs are commonly used in agriculture, and they can be plants, animals, or microorganisms engineered for various purposes, including improved crop yields, reduced pesticide use, and increased food production. Human Genome Project: Human genome sequencing is the process of determining the complete DNA sequence of an individual's genome. It involves identifying and sequencing all the genes and non-coding regions in an individual's DNA. The Human Genome Project, completed in 2003, was a monumental effort to map and sequence the entire human genome. This technology has paved the way for personalized medicine, genetic research, and understanding the genetic basis of various diseases. Cloning: Cloning is a biotechnological process that creates genetically identical copies of an organism. There are several methods of cloning, including reproductive cloning, which produces a genetic copy of an entire organism, and therapeutic cloning, which creates embryonic stem cells for medical purposes. Reproductive cloning has been used to clone animals, such as Dolly the sheep, while therapeutic cloning holds potential for regenerative medicine and the treatment of various diseases. Genetic Testing(23&me): Genetic testing involves looking for changes in: 1. Genes: Gene tests study DNA sequences to identify variations (mutations) in genes that can cause or increase the risk of a genetic disorder. Gene tests can be narrow or large in scope, analyzing an individual DNA building block (nucleotide), one or more genes, or all of a person’s DNA (which is known as their genome). 2. Chromosomes: Chromosomal genetic tests analyze whole chromosomes or long lengths of DNA to see if there are large genetic changes, such as an extra copy of a chromosome, that cause a genetic condition. 3. Proteins: Biochemical genetic tests study the amount or activity level of proteins or enzymes; abnormalities in either can indicate changes to the DNA that result in a genetic disorder. Genetic testing is voluntary. Because testing has benefits as well as limitations and risks, the decision about whether to be tested is a personal and complex one. A geneticist or genetic counselor can help by providing information about the pros and cons of the test and discussing the social and emotional aspects of testing. Gene Therapy: Gene therapy is a medical approach aimed at treating or preventing genetic and acquired diseases by modifying or replacing faulty genes. This involves introducing healthy genes into a patient's cells to correct genetic defects or enhance the body's ability to fight disease. Gene therapy has shown promise in treating various genetic disorders and is a growing field in the realm of personalized medicine. Genetic Engineering: Genetic engineering is a biotechnological process that involves altering the genetic material of an organism. This can include adding, removing, or modifying specific genes to change how an organism develops or functions. Techniques like CRISPR, gene cloning, and recombinant DNA technology are commonly used in genetic engineering. Duchenne Muscular Dystrophy: Duchenne Muscular Dystrophy (DMD) is a genetic disorder characterized by progressive muscle degeneration and weakness. It primarily affects boys and is caused by a mutation in the dystrophin gene, which is essential for muscle function. Symptoms typically appear in early childhood, often between the ages of 2 and 6, and may include difficulty walking, frequent falls, and trouble climbing stairs. As the disease progresses, muscle weakness spreads to other parts of the body, leading to complications such as respiratory issues and heart problems. Muscle Proteins: Muscle proteins are proteins that help muscles contract, maintain structure, and enable movement. The two main types are actin and myosin: Actin Filaments: Actin forms thin, rope-like filaments in the muscle. It provides the "track" along which myosin moves to generate a contraction. Actin filaments are attached to Z-lines, which mark the boundaries of muscle units called sarcomeres. Myosin Filaments: Myosin forms thicker filaments with "heads" that can bind to specific sites on actin. These myosin heads use energy (from ATP) to latch onto and "pull" the actin filaments, sliding them toward the center of the sarcomere. This pulling action shortens the sarcomere, causing the muscle to contract. Dystrophin: Dystrophin is a large protein that links the cytoskeleton of muscle cells to the extracellular matrix, providing structural stability. It plays a critical role in maintaining muscle integrity, and its deficiency is associated with muscular dystrophy.