1.
Microscopy 00:34
● Resolution is the minimum distance at which two objects can be distinguished as
separate. 01:41
● Magnification is how many times larger the image appears compared to the actual object.
02:03
● Light (Optical) Microscopes: 00:40
○ Poor resolution due to the wavelength of light.
○ Can view living samples and produce color images.
● Transmission Electron Microscopes (TEM): 01:03
○ High magnification and resolution.
○ Electrons pass through the specimen, creating a 2D image of internal structures.
○ Samples must be very thin and in a vacuum.
● Scanning Electron Microscopes (SEM): 01:10
○ Electrons bounce off the surface, creating a 3D image of the surface.
○ Samples are coated and placed in a vacuum.
● Laser Scanning Confocal Microscopes: 01:24
○ High resolution and 3D imaging using laser light.
● Slide Preparation Techniques: 02:09
○ Dry Mount: Thin slices or whole specimens viewed with a cover slip.
○ Wet Mount: Specimens in water or stain, covered with a cover slip.
○ Squash Slide: Wet mount squashed to create a thin layer of cells.
○ Smear Slide: Sample smeared across the slide for viewing (e.g., blood cells).
● Eyepiece Graticule Calibration: 03:55
○ An eyepiece graticule is a scale in the microscope eyepiece used to measure
objects.
○ A stage micrometer (a slide with a ruler) is used to calibrate the eyepiece
graticule at different magnifications.
○ Each division on the stage micrometer is typically 10 micrometers.
○ Calibration involves aligning the eyepiece graticule and stage micrometer scales
and calculating the value of one eyepiece graticule division.
● Magnification Calculation: 06:34
○ Magnification = Image Size / Real Object Size
○ Unit conversions (mm to μm) are often required (multiply mm by 1000 to get μm).
● Staining Techniques: 07:13
○ Staining enhances visibility of cell components.
○ Differential staining uses multiple stains to color different parts of the cell.
○ Examples: Crystal violet, methylene blue (positive stains), Nigrosin, Congo red
(negative stains).
● Scientific Drawings: 08:18
○ Use pencil, include a title, state magnification, label key features, annotate cell
components, use solid lines (no shading), and horizontal label lines.
○ Aim is to show size, location, and proportion.2. Cell Structure 12:50
● Eukaryotic Cells: 13:02
○ Contain membrane-bound organelles.
○ Examples: animal, plant, and fungal cells.
○ Key organelles and their functions:
■ Nucleus: 13:21 Contains DNA, site of replication and transcription.
■ Flagella: 14:15 Mobility (not in all eukaryotic cells).
■ Cilia: 14:36 Hair-like projections for movement or sensory functions.
■ Centrioles: 15:04 Involved in spindle fiber formation during cell division.
■ Cytoskeleton: 15:34 Provides mechanical strength and support.
■ Endoplasmic Reticulum (ER): 16:09
■ Rough ER: Protein synthesis (has ribosomes).
■ Smooth ER: Lipid and carbohydrate synthesis.
■ Golgi Apparatus: 16:50 Modifies and packages proteins and lipids.
■ Lysosomes: 17:52 Contain digestive enzymes for breaking down
materials.
■ Mitochondria: 18:38 Site of aerobic respiration and ATP production.
■ Ribosomes: 19:21 Protein synthesis (80S in eukaryotes).
■ Chloroplasts: 20:02 (Plant cells) Site of photosynthesis.
■ Cell Wall: 20:33 (Plant and fungal cells) Provides structural support.
■ Plasma Membrane: 21:03 Controls what enters and exits the cell.
● Protein Production and Secretion: 21:47
○ Polypeptide chains are synthesized on the rough ER (ribosomes).
○ They move to the Golgi apparatus for modification and packaging into vesicles.
○ Vesicles transport proteins to the cell surface membrane for exocytosis.
● Prokaryotic Cells: 22:52
○ Smaller than eukaryotic cells.
○ Lack membrane-bound organelles.
○ Have 70S ribosomes.
○ DNA is circular and free in the cytoplasm (no nucleus).
○ Cell wall made of peptidoglycan.
○ May have plasmids, a capsule, and flagella.
3. Biological Molecules 25:41
● Contain carbon.
● Carbohydrates, lipids, proteins, and nucleic acids.
● Ions: 26:01 Important roles (e.g., calcium, sodium, potassium, chloride, phosphate).
● Water: 26:50
○ Polar molecule due to uneven charge distribution.
○ Forms hydrogen bonds.
○ Important solvent, transport medium, coolant (high specific heat capacity and
latent heat of vaporization), and provides habitats.
● Monomers and Polymers: 32:18
○ Monomers are small units that bind together to form polymers.
○ Examples:
■ Glucose (monomer) forms starch, cellulose, and glycogen (polymers).
■ Amino acids (monomer) form proteins (polymer).
■ Nucleotides (monomer) form DNA and RNA (polymers).
● Carbohydrates: 33:08
○ Contain carbon, hydrogen, and oxygen.
○ Monosaccharides: Single sugar units (glucose, fructose, galactose, ribose).
○ Disaccharides: Two sugar units joined by a glycosidic bond (sucrose, maltose,
lactose).
○ Polysaccharides: Many sugar units (starch, cellulose, glycogen).
○ Condensation Reaction: 37:41 Joins two molecules together by removing a water
molecule.
○ Hydrolysis Reaction: 37:53 Splits a molecule by adding a water molecule.
○ Starch: 39:35 (Plants) Storage of glucose (amylose and amylopectin).
○ Cellulose: 41:44 (Plants) Structural support (beta glucose).
○ Glycogen: 42:40 (Animals) Storage of glucose.
● Lipids: 43:34
○ Non-polar, insoluble in water.
○ Made of fatty acids and glycerol.
○ Triglycerides: 44:05 Three fatty acids attached to glycerol (energy storage).
○ Phospholipids: 44:05 Two fatty acids and a phosphate group attached to glycerol
(cell membranes).
○ Saturated Fatty Acids: 45:23 Have only single bonds.
○ Unsaturated Fatty Acids: 45:28 Have at least one double bond.
○ Cholesterol: 47:40 (Sterol) Embedded in cell membranes to regulate fluidity.
● Proteins: 48:10
○ Polymers made of amino acids.
○ Amino Acid Structure: Central carbon, amine group, carboxyl group, hydrogen,
and R group (variable).
○ Protein Structure:
■ Primary: Sequence of amino acids.
■ Secondary: Folding into alpha helices or beta-pleated sheets (hydrogen
bonds).
■ Tertiary: Further folding into a 3D shape (hydrophobic/hydrophilic
interactions, hydrogen bonds, ionic bonds, disulfide bonds).
■ Quaternary: More than one polypeptide chain.
○ Fibrous Proteins: 51:24 Long, twisted strands (collagen, keratin, elastin).
○ Globular Proteins: 51:53 Spherical shape (enzymes, antibodies, some hormones,
hemoglobin, pepsin, insulin).
4. Biochemical Tests 54:47
● Starch: Add iodine solution (orange-brown to blue-black).
● Reducing Sugars: Add Benedict's solution and heat (blue to green/yellow/orange/brick
red).
● Non-Reducing Sugars: 55:35 Boil with hydrochloric acid, neutralize with alkali, then add
Benedict's solution and heat (blue to green/yellow/orange/brick red).
● Proteins: Add biuret solution (blue to purple).
● Lipids: Emulsion test (dissolve in ethanol, add water, white emulsion forms).
● Colorimetry: 57:21 Use a colorimeter to measure the absorbance or transmission of light
through a sample.
● Biosensors: 58:06 Use immobilized DNA or protein to detect specific molecules.
● Chromatography: 58:30 Separates molecules based on their solubility in a solvent.
○ Retention Factor (Rf): Distance moved by solute / Distance moved by solvent.
5. Nucleotides and Nucleic Acids 60:21
● Nucleotides: Monomers of nucleic acids (DNA and RNA).
○ Nitrogenous Bases:
■ Purines: (two rings) Adenine (A) and Guanine (G).
■ Pyrimidines: (one ring) Cytosine (C), Thymine (T) (DNA), and Uracil (U)
(RNA).
○ Pentose Sugar: Ribose (RNA) or deoxyribose (DNA).
○ Phosphate Group.
● Base Pairing: A with T (or U in RNA), G with C.
● Phosphodiester Bond: 61:42 Bond between adjacent nucleotides in a nucleic acid chain.
● ATP (Adenosine Triphosphate): 62:17 Energy currency of the cell.
● DNA (Deoxyribonucleic Acid): 64:08
○ Double helix structure.
○ Stores genetic information.
○ DNA Precipitation: 65:45 Homogenize cells, filter, add salt, add protease, add
ice-cold ethanol.
● RNA (Ribonucleic Acid): 66:34
○ mRNA (messenger RNA): Carries genetic code from DNA to ribosomes.
○ rRNA (ribosomal RNA): Component of ribosomes.
○ tRNA (transfer RNA): Transports amino acids to ribosomes during protein
synthesis.
● DNA Replication: 69:10
○ Semi-conservative: Each new DNA molecule contains one original strand and
one new strand.
○ DNA Helicase: Unwinds the DNA double helix.
○ DNA Polymerase: Adds nucleotides to the new DNA strand.
● Genetic Code Properties: 72:14
○ Degenerate: Amino acids are coded for by more than one triplet of bases.
○ Universal: The same triplet of bases codes for the same amino acid in all
organisms.
○ Non-overlapping: Each base is part of only one codon.
● Protein Synthesis: 74:04
○ Transcription: 75:50 mRNA is created from a DNA template in the nucleus.
○ Translation: 77:05 mRNA is used to create a polypeptide chain on a ribosome in
the cytoplasm.
○ Introns: Non-coding sequences in a gene that are removed from mRNA.
○ Exons: Coding sequences in a gene.
○ Start and Stop Codons: Initiate and terminate translation.
6. Enzymes 78:20
● Biological catalysts made of globular proteins.
● Active Site: 78:25 Specific shape that binds to the substrate.
● Lower activation energy of reactions.
● Lock and Key Hypothesis: 79:51 (Older model) Enzyme and substrate are perfectly
complementary.
● Induced Fit Hypothesis: 80:43 (Current model) Enzyme active site changes shape to fit
the substrate.
● Factors Affecting Enzyme Activity:
○ Temperature: 82:35 Increases rate up to an optimum, then denatures the
enzyme.
○ pH: 83:50 Enzymes have optimal pH ranges.
○ Enzyme Concentration: 84:45 Increases rate up to a point of saturation.
○ Substrate Concentration: 84:50 Increases rate up to a point of saturation.
● Enzyme Inhibitors: 86:27
○ Competitive Inhibitors: 86:32 Similar in shape to the substrate and bind to the
active site.
○ Non-Competitive Inhibitors: 88:24 Bind to the enzyme at a site other than the
active site (allosteric site), changing its shape.
○ End-Product Inhibition: 89:27 The product of a reaction inhibits the enzyme.
● Coenzymes, Cofactors, and Prosthetic Groups: 90:13 Non-protein molecules required for
enzyme activity.
● Precursor Activation: 91:12 Enzymes are activated by a cofactor.
7. Biological Membranes 91:54
● Composed of a phospholipid bilayer.
● Fluid Mosaic Model: 92:10 Describes the structure and movement of components in the
membrane.
● Membrane Proteins:
○ Extrinsic (Peripheral): On the surface.
○ Intrinsic (Integral): Span the membrane (channel and carrier proteins).
● Cholesterol: 93:41 Regulates membrane fluidity.
● Factors Affecting Membrane Permeability:
○ Temperature: 94:07 High temperatures increase fluidity and can denature
proteins.
○ Solvents: 95:00 Organic solvents dissolve lipids, increasing permeability.
● Membrane Transport:
○ Simple Diffusion: 95:33 Movement down a concentration gradient (no ATP
required).
○ Facilitated Diffusion: 96:08 Movement down a concentration gradient with the
help of channel or carrier proteins (no ATP required).
○ Osmosis: 96:45 Movement of water down a water potential gradient across a
partially permeable membrane.
○ Active Transport: 98:33 Movement against a concentration gradient (ATP
required).
○ Endocytosis: 99:39 Bulk transport of molecules into the cell (phagocytosis and
pinocytosis).
○ Exocytosis: {timestamp:100:33} Bulk transport of molecules out of the cell.
8. Cell Division, Diversity, and Organization {timestamp:100:58}
● Cell Cycle: Interphase (G1, S, G2), nuclear division (mitosis or meiosis), cytokinesis.
● Mitosis: {timestamp:102:43} Creates two genetically identical diploid cells (growth, tissue
repair, asexual reproduction).
○ Stages: Prophase, Metaphase, Anaphase, Telophase (PMAT).
○ Cytokinesis: {timestamp:105:04} Division of the cytoplasm.
○ Mitotic Index: {timestamp:107:06} Number of cells in mitosis / Total number of
cells.
● Meiosis: {timestamp:107:56} Creates four genetically different haploid daughter cells
(sexual reproduction).
○ Two rounds of division (Meiosis I and Meiosis II).
○ Crossing Over: {timestamp:108:55} Exchange of genetic material between
homologous chromosomes.
○ Independent Assortment: {timestamp:110:02} Random alignment of homologous
chromosomes during metaphase I.
● Cellular Organization: {timestamp:111:30}
○ Cells -> Tissues -> Organs -> Organ Systems -> Organism
● Specialized Cells: {timestamp:111:49} (e.g., epithelial cells, red blood cells, sperm cells,
xylem vessels, phloem sieve tubes, root hair cells).
● Tissues: {timestamp:112:34} (e.g., squamous epithelium, ciliated epithelium, muscle
tissue, cartilage,
