Microscope History and Usage

• Here are your study notes:

The Microscope

• Hans & Zacharias Janssen were father and son Dutch spectacle makers who put several lenses in a tube.
• Janssen's microscope used 3 sliding tubes (46cm extended & 5cm diameter).
• The Janssen microscope had a magnification of 3x (closed) and 9x (extended).
• Anton van Leeuwenhoek was a Dutch draper and scientist.
• Leeuwenhoek ground and polished 550 lenses to make a lens tube with 270x magnification.
• Leeuwenhoek observed bacteria & yeast, life inside water drops, and circulation of blood in capillaries.
• Robert Hooke furthered Anton's work and published micrographia.

Wet Mount Slide Preparation

• A wet mount suspends a specimen in a drop of liquid between a slide and cover slip.
• Steps for preparation: 1. Add a drop of water to a slide 2. Place specimen in the water 3. Place the edge of a coverslip so it touches the edge of the water 4. Slowly lower the coverslip to prevent air bubbles.

Calculating Magnification

• Magnification equals the total enlargement of an object.
• Magnification uses the unit: x
• Total magnification = Ocular lens x Objective lens

Micrographs

• Micrographs will always have an indication of the size of object.
• Micrographs are in the form of a scale bar or magnification in the caption.

Calculating Size with Magnification

• Size = Measured Length / Magnification
• Example Calculation: Size = 80mm / 90,000x = 0.00089mm = 0.89 μm (x1000)

Calculating Size with Scale Bar

• Size = (Measured length x Value on scale line) / Measured Length of scale line
• Example calculation: Size = (83mm x 100 μm) / 32 mm = 259.38 μm = 0.26 mm

Compound Light Microscope Parts

• Eyepiece/Ocular Lens: The lens you look through.
• Body Tube: Connects the eyepiece to the objective lenses.
• Rotating Nose Piece: Holds multiple objective lenses and rotates to change magnification.
• Arm: Supports the body tube and connects it to the base.
• Objective Lens: Lenses with different magnifications.
• Stage: Supports the slide.
• Stage Clips: Hold the slide firmly in place.
• Coarse Focus Knob: Raises and lowers the stage to focus the image.
• Fine Focus Knob: Raises and lowers the stage slightly for fine focusing.
• Base: Supports the microscope.

Chemistry of Life

• An Atom is the smallest particle of matter.
• A Molecule is made up of 2+ atoms chemically combined.
• An Element is a type of atom and a substance in purest form.
• A Compound is 2+ atoms/elements chemically combined.

Organic/Inorganic Compounds

• Organic Compounds: Contain carbon, hydrogen, and oxygen; are living, large, and complex (e.g., fats, proteins).
• Inorganic Compounds: Are non-living, elements and simple molecules (e.g., water, minerals).

Carbohydrates

• Atoms: C, H, O
• Ratio: 1:2:1
• Monomers: saccharides

Monosaccharides

• Simple sugars (e.g., glucose, fructose, galactose).

Disaccharides

• Double sugars.
• Composed of two monomers.
• Sucrose is made of glucose & fructose.
• Lactose is galactose & glucose.
• Maltose is glucose & glucose.

Polysaccharides

• Large, complex sugars with a large number of monomers.
• Starch is for sugar storage in plants.
• Glycogen is for sugar storage in animals.
• Cellulose makes up the cell wall.

Biological Importance of Carbohydrates

• Provide energy through glucose in respiration.
• Storage of energy (glycogen & starch).
• Structural component of the primary cell wall (cellulose).

Sugar Facts

• Fructose is the sweetest sugar.
• Brain sugar: galactose.
• Grape sugar: glucose.
• Cane and table sugar: sucrose.
• Fruit sugar: fructose.
• Milk sugar: lactose.
• Blood sugar: glucose.

Lipids

• Atoms: C, H, O
• Large molecules made of 3 fatty acids and a glycerol.
• Triglycerides (e.g. Phospholipid, cholesterol) are composed of a glycerol molecule and three fatty acids.

Fats: Saturated

• Saturated fats originate from animal sources.
• Saturated fats are solid at room temperature.
• Saturated fats are unhealthy in large amounts and increase cholesterol levels in the blood.

Fats: Unsaturated

• Unsaturated fats come from plant and animal sources.
• Unsaturated fats are liquid at room temperature.
• Unsaturated fats are 'healthier' and help lower cholesterol in blood.

Biological Importance of Lipids

• Reserve energy (breaking down of lipids = energy).
• Shock absorber.
• Protection of organs (e.g., kidney/heart).
• Structural component of cell membrane (e.g., phospholipids).
• Insulator.
• Some hormones are made of fat.

Proteins

• Atoms: C, H, O, N (P, S)
• Enzymes are proteins and some hormones.
• Monomers are amino acids.
  • A polypeptide chain of 1-49 amino acids.
  • A protein is a chain of 50+ amino acids is bonded.
  • 1 = monomer
  • 2+ = polymer
• Humans have 20 different types of amino acids.

Biological Importance of Proteins

• Growth of cells.
• Repairs damaged and replaces old cells.
• Enzymes and some hormones are made of proteins.
• Structural component of cell membrane.
• Component of chromosomes.
• Balances pH.
• Forms antibodies.

Enzymes

• Proteins that control chemical reactions needed for functioning of a cell.
• Biological catalysts speed up/cause reactions without being used up and can be used over and over again.
• Enzyme shape is important.

Anabolic Processes

• Synthesis by building up complex molecules in living organisms from simpler ones.
• Enzyme + Substrates = Product

Catabolic Enzymatic Reaction

• Breakdown of complex substances into simpler molecules.
• Enzyme + Substrates = Product

Metabolism

• Chemical processes that occur within a living organism to maintain life.

Enzyme Characteristics: Sensitivity to Temperature

• Increased temperature breaks peptide bonds between amino acids.
• Enzymes become denatured, losing function and shape.
• Enzymes inactivate and human enzymes have an optimum temperature of 37°C.

Enzyme Characteristics: Sensitivity to pH

• Increased or decreased pH denatures enzymes.
• Pepsin (stomach -> proteins) has an optimum pH of 1.5-2 (acidic).
• Amylase (saliva -> starch) has an optimum pH of 7 (neutral).
• Trypsin (small intestine -> proteins) has an optimum pH of 9 (alkaline).

Lock and Key Hypothesis

• Each enzyme can act on one specific substrate.
• An active site has a specific shape that must fit perfectly or a substrate will not react.

Enzymes in Everyday Life: Washing Powders

• Added to washing powders & detergents to ensure stains are broken down biochemically.
• Proteases and lipases are the most often used.
• They hydrolyze protein and fat stains.

Enzymes in Everyday Life: Making Beer

• Amylase is used to hydrolyze starch into sugars.
• Yeast uses sugars in anaerobic processes to ferment beer through anaerobic respiration/alcoholic fermentation.

Enzymes in Everyday Life: Making Cheese

• Rennin is used to coagulate milk protein and then matured by bacteria.

Enzymes in Everyday Life: Making Fruit Juice

• Cellulase and pectinase used to hydrolyze plant cell walls to clarify juice.

Nucleic Acids

• Atoms: C, H, O, N, P
• Linear (chain-like) molecules
• Monomers are nucleotides which include a sugar, phosphate group, & nitrogenous base.

Types of Nucleic Acids: Ribonucleic Acid (RNA)

• Ribose sugar.
• Single strand.
• Responsible for protein synthesis.
• Located in the nucleolus, ribosomes, and cytoplasm.

Types of Nucleic Acids: Deoxyribonucleic Acid (DNA)

• Deoxyribose sugar.
• Double strand.
• Controls all functions.
• Located in chromatin network in the nucleus.

Biological Importance of Nucleic Acids

• DNA controls all functions of the cell and carries hereditary characteristics.
• RNA is responsible for protein synthesis.

Vitamins

• Vitamin A: Leafy green vegetables and carrots promote night vision. Deficiency: Night blindness.
• Vitamin B1: Wholewheat bread & grains, oats provides energy. Deficiency: Beri-Beri: Weight loss, pain, weakness, impaired sensory perception.
• Vitamin C: Citrus fruits and strawberries has a strong immune system. Deficiency: Scurvy: anaemia, swollen & bleeding gums, swollen legs, rough scaly skin.
• Vitamin D: Fatty fish, exposure to sun (UV rays cause sun to turn cholesterol into D) is required for absorption of calcium. Deficiency: Rickets: softening/weakening of bones in children.
• Vitamin E: Nuts & seeds, leafy green vegetables are antioxidants and scavenge 'free radicals'. Deficiency: Nerve problems.

Free Radicals

• Unstable molecules are produced during normal cell metabolism.
• Build up in cells and cause damage to molecules (e.g., DNA, lipids, proteins).
• Contribute to cardiovascular & inflammatory diseases, cataracts, cancer, & ageing.
• Antioxidants are chemicals that interact with and neutralise free radicals. They prevent free radical-induced tissue damage.

Water

• Water is an inorganic compound with the formula H2O.
• Water is vital to survival.

Functions of Water

• Water transports medium to carry dissolved food to cells and remove metabolic waste to excretory organs.
• All chemical reactions occur in water, making it a universal solvent.
• Water regulates body temperature.
• Water forms hydrostatic skeletons in invertebrates.
• Water lubricates joints.
• Water breaks down large substances into smaller substances (hydrolysis).

Minerals: micro-elements

• Micro-elements (trace elements) are needed in small amounts.
• Functions of micro-elements.
• Deficiency diseases of micro-elements.

Iron

• Iron builds haemoglobin in red blood cells for transport of oxygen and carbon dioxide.
• Deficiency in iron leads to Anaemia: not enough healthy red blood cells or haemoglobin to carry oxygen, tiredness, shortness of breath, weakness.

Iodine

• Normal functioning of thyroid gland (produces thyroxine hormone).
• Plays a role in metabolism, heart & muscles function, brain development & maintenance of bone.
• Goitre is a symptom of iodine deficiency: lump or swelling at the front of the neck.

Macro-elements

• Needed in large amounts.
  • Calcium: Building strong bones & teeth - Deficiency leads to Rickets.
  • Phosphorous: Part of energy compound ATP, builds strong bones - Deficiency can cause muscle & nerve dysfunction.
  • Sodium: Nerve impulse transmission, builds strong bones - Deficiency can cause Coma & seizure.
  • Potassium: Nerve impulse transmission - Deficiency leads to muscle weakness & fatigue.

Minerals in the Environment: Eutrophication

• Fertilisers contain nitrates & phosphates.
• Fertiliser added to the soil increases yield.
• Phosphates & nitrates are washed away by rain, causing leaching.
• Nitrates & phosphates stimulate algae growth.
• Algae covers the entire surface of water = algal bloom.

Algal Bloom

• Algal Bloom results in a block of sunlight for the plants.
• No photosynthesis occurs.
• Fish & water organisms suffocate due to lack of oxygen.
• Decomposing bacteria breaks down dead matter and further uses up oxygen.
• Ecosystem is damaged/destroyed.

Preventing Eutrophication

• Using biodegradable & phosphate-free cleaning agents & detergents.
• Laws regulating the dumping of wastewater.
• Using organic fertiliser.

Active & Passive Transport Terms

• Concentration gradient: difference in concentration, molecules go down the gradient (high to low).
• Selectively permeable: membrane that allows certain substances through (e.g., cell membrane).

Passive Transport

• Movement from high to low concentration continues until equilibrium is reached.
• Does not require energy/carrier.
• Sometimes uses carrier/channel proteins (e.g., osmosis & diffusion).

Diffusion

• The movement of solutes from high concentration to low concentration continues until equilibrium.
• Increased Temperature will lead to increased Diffusion (Kinetic energy).
• No energy is required.

Practical for Diffusion

• A demonstration of the process of diffusion.
• Apparatus: potassium permanganate crystals, large funnel, 500ml beaker, 500ml water.
• Method: 1. Fill beaker with water and allow movement to stop. 2. Place large funnel into water, touching bottom of beaker. Drop a few small crystals through straw. Remove funnel carefully. 3. Observe size of area covered by pot. Perma. from beginning, after 5 min, after 20 min.
• Molecules of potassium permanganate diffuse from high concentration to low concentration.

Osmosis

• Movement of water molecules across a semi-permeable membrane continues until equilibrium.

Osmosis Application

• In Hypotonic solutions the cell swells, decreases solutes, and increases H2O (Endosmosis).
• In Isotonic solutions there is no net loss or gain.
• In Hypertonic solutions the cell wilts, increases solutes, and decreases H2O (Exosmosis).
• Cell wall prevents hypotonic plant cells from bursting
• Hypotonic solutions: 'Hypo' = less, less solute outside, more water inside.
• Hypertonic solutions: 'Hyper' = more, more solute outside, less water inside.

Practical for Osmosis

• Aim: Demonstrate the process of osmosis
• Apparatus: thistle funnel dialysis membrane (semi-permeable), beaker, water, strong sugar solution, retort stand and clamp.
• Method: 1. Set up investigation per diagram (A) 2. Record observations
• Water molecules move from a high water concentration in the beaker through the selectively permeable membrane into the thistle funnel with a low water concentration via osmosis.

Active Transport

• Movement of substances against the concentration gradient requires energy (ATP) and a protein carrier.
• ATP (Adenosine triphosphate).
• ATP = energy currency of cell.
• Cell respiration = increased ATP.
• Uses energy = ATP.