Comprehensive Study Notes (Biology: Units, Microscopy, Biochemistry, Cells, and Homeostasis)

Metric system, measurements, and conversions

Length, weight, volume, and temperature units:
- Length: meter (m)
- Mass/weight: gram (g)
- Volume: liter (L)
- Temperature: degree Celsius (°C)
Metric conversions to know:
- 1\text{ m} = 100\text{ cm}
- 1\text{ cm} = 10\text{ mm}
- 1\text{ km} = 1000\text{ m}
- 1\text{ kg} = 1000\text{ g}
- 1\text{ g} = 1000\text{ mg}
Tools: Measure length, weight, volume, and temperature using provided tools.

Microscope anatomy, function, and magnification

Parts and functions:
- Eyepiece (Ocular Lens): the lens you look through, usually 10× magnification.
- Objective Lenses: usually 3–4 lenses with different magnifications (e.g., 4×, 10×, 40×, 100×). They magnify the specimen.
- Revolving Nosepiece (Turret): holds objective lenses and allows rotation between them.
- Stage: flat platform where the slide sits.
- Stage Clips: hold the slide in place on the stage.
- Light Source (Illuminator): provides light through the specimen.
- Diaphragm (Iris or Disc Diaphragm): controls the amount of light reaching the specimen.
- Coarse Adjustment Knob: moves the stage up/down quickly for rough focus.
- Fine Adjustment Knob: sharpens focus with small adjustments.
- Arm: supports the tube and connects to the base; used to carry the microscope.
- Base: bottom support structure.
Body tube: connects eyepiece to objective lenses and maintains distance between them.
Calculating total magnification:
- M{total} = M{ocular} \times M_{objective}
- Example: ocular 10× and objective 45× → M_{total} = 10 \times 45 = 450\times
- Common objective powers: 4×, 10×, 40×, 100× (often with oil immersion at 100×).

Biochemistry basics: dehydration synthesis and hydrolysis

Dehydration synthesis (condensation): builds polymers from monomers by removing a water molecule, creating a covalent bond; requires energy.
- General reaction: \text{monomer} + \text{monomer} \rightarrow \text{polymer} + H_2O
Hydrolysis: breaks polymers into monomers by adding a water molecule; releases energy (in a sense, the bond is broken with water).
- General reaction: \text{polymer} + H2O \rightarrow \text{monomer}1 + \text{monomer}_2 \,(\text{and possibly other products})

Biochemical tests and molecule characteristics

Proteins
- Test for proteins: not specified in transcript (typical lab test is the Biuret test, but not detailed here).
Carbohydrates: characteristics and structure
- General features: organic molecules made of C, H, O in a roughly 1:2:1 ratio.
- Monomers: monosaccharides (e.g., glucose, fructose, galactose).
- Dimers: disaccharides (e.g., sucrose, lactose).
- Polysaccharides: multiple monosaccharides (e.g., starch, cellulose in plants; glycogen in animals).
- Primary functions: energy provision and storage; structural support in some polymers.
Test for starches
- Test mentioned but not described in transcript (iodine test is common in practice, but not detailed here).
Controls and data interpretation for proteins and starches
- Positive controls: described as part of the experimental design (not detailed in transcript).
- Negative controls: described as part of the experimental design (not detailed in transcript).
- Positive results: indicate presence of the target (protein or starch) in the data supplied on the exam.
- Negative results: indicate absence.

Lipids: characteristics and tests

Lipids: diverse, mostly nonpolar and hydrophobic; do not have traditional monomers.
- Common building blocks: fatty acids and glycerol (e.g., triglycerides: three fatty acids attached to one glycerol).
- Functions: long-term energy storage, membrane structure (phospholipids), signaling molecules (steroids/hormones).
Test for lipids: described but not detailed in transcript.

Cells: prokaryotic vs eukaryotic; overview of organelles

Prokaryotic cells
- Simpler, smaller; no nucleus or membrane-bound organelles.
- DNA located in nucleoid region; typically unicellular (bacteria, archaea).
Eukaryotic cells
- More complex, larger; true nucleus enclosed by a membrane.
- Contain membrane-bound organelles: mitochondria, endoplasmic reticulum, Golgi apparatus, etc.; plants, animals, fungi, protists.
Shared features (both)
- Plasma membrane, cytoplasm, ribosomes.
- Eukaryotes have compartmentalization; prokaryotes do not.

Animal cell organelles and functions (as listed/outlined in the transcript)

Nucleus: control center; contains DNA; regulates gene expression and directs all cell activities (growth, metabolism, reproduction).
Nucleolus: inside nucleus; produces ribosomes essential for protein synthesis.
Cell membrane (plasma membrane): flexible barrier; controls entry/exit; maintains homeostasis.
Cytoplasm: jelly-like fluid; site of many metabolic reactions; surrounds organelles.
Mitochondria: powerhouses; generate ATP via cellular respiration.
Ribosomes: synthesize proteins; free-floating or attached to rough ER.
Rough Endoplasmic Reticulum (Rough ER): has ribosomes; synthesizes and transports proteins.
Smooth Endoplasmic Reticulum (Smooth ER): lacks ribosomes; lipid synthesis, detoxification, calcium storage.
Golgi Apparatus: modifies, sorts, and packages proteins and lipids for transport.
Lysosomes: contain digestive enzymes; break down waste, old organelles, and foreign invaders.
Centrioles: organize microtubules during cell division (mitosis and meiosis).
Other: ribosomes (again listed as part of protein synthesis), cytoplasm, mitochondria, etc.

Plant cell organelles and plant-specific features

Plant-specific organelles/features listed:
- Cell Wall: rigid outer layer of cellulose; provides structural support, protection, and maintains shape.
- Chloroplasts: contain chlorophyll; perform photosynthesis (convert light, CO2, and water into glucose and O2).
- Large Central Vacuole: large, fluid-filled sac; stores water, nutrients, waste; helps maintain turgor pressure for rigidity.
Shared organelles with animal cells include: nucleus, nucleolus, mitochondria, ribosomes, ER (rough and smooth), Golgi, cytoplasm, cell membrane, etc.
Some plant cells may have lysosome-like structures (lytic vacuoles) that act similarly to lysosomes in animal cells.

Plant vs. animal cell differences (summary)

Organelles unique to plant cells:
- Cell wall
- Chloroplasts
- Large central vacuole
Organelles unique to animal cells:
- Lysosomes
- Centrioles
Common organelles: nucleus, nucleolus, ribosomes, mitochondria, ER, Golgi, cytoplasm, plasma membrane, etc.
Rationale: plants rely on photosynthesis (chloroplasts) and need rigid structure (cell wall and central vacuole) for turgor; animals rely on lysosomal digestion and centrioles for cell division.

Diffusion and osmosis; movement of water and solutes

Diffusion: passive movement of particles from high concentration to low concentration until equilibrium.
Factors affecting diffusion rate by medium type:
- Gas: fastest diffusion due to high kinetic energy and large spaces between particles.
- Liquid: slower than gas; particles closer together and move less freely.
- Solid: slowest; tightly packed; particles vibrate in place.
- Overall: Gas > Liquid > Solid in diffusion speed.
Osmosis: type of passive transport; movement of water across a semipermeable membrane from area of low solute concentration (more water) to high solute concentration (less water).
- Water moves toward higher solute concentration to balance solute/water concentrations.
- No energy required; occurs through the membrane (water passes; many solutes do not).
- Role in maintaining cell shape and homeostasis; examples: pure water vs saline environments.

Osmotic tonicity terms and effects

Tonicity: describes solute concentration relative to the inside of a cell and predicts water movement by osmosis.
Isotonic: solution with solute concentration equal to the cell interior; no net water movement; cell size remains the same.
Hypotonic: solution with lower solute concentration (more water) than inside the cell; water enters the cell; potential swelling or bursting.
Hypertonic: solution with higher solute concentration (less water) than inside the cell; water exits the cell; cell shrinks.
Crenation (in animal cells): shrinking/shriveling of an animal cell in a hypertonic solution due to water loss.
Hemolysis (in animal cells): bursting of red blood cells in a hypotonic solution due to excess water entry.
Turgor pressure (in plant cells): pressure exerted by central vacuole against the cell wall when the cell fills with water in a hypotonic environment; keeps plant cells firm and upright.
Plasmolysis (in plant cells): cytoplasm and vacuole shrink as the cell loses water in a hypertonic environment; plasma membrane pulls away from cell wall; plant wilts.

Determining tonicity and pH concepts

How to determine tonicity from data: tonicity describes water movement in osmosis; assess whether solution will make a cell gain, lose, or maintain water.
pH scale: measures acidity/basicity of a solution; 0–14 scale.
- <7: acidic (more H⁺ ions)
- =7: neutral
- >7: basic/alkaline (more OH⁻ ions)
- Logarithmic scale: each change by 1 unit represents a tenfold change in H⁺ or OH⁻ concentration.
- Importance: many biological processes require specific pH ranges.
Buffers and their role in pH balance:
- Buffers resist changes in pH by neutralizing small amounts of added acid or base.
- They help maintain homeostasis in biological systems, enabling enzymes and reactions to function near optimal pH.
- Example: blood bicarbonate buffer keeps pH around ~7.4.

Diagram-based notes on organelles (labeling and comparisons)

Common organelles listed across diagrams:
- Nucleus, Nucleolus, Nuclear envelope, Nuclear pore, Chromatin
- Cytoplasm, Cell membrane (plasma membrane), Cell wall (plants), Secretory vesicle
- Mitochondrion, Golgi apparatus, Ribosomes, Endoplasmic Reticulum (rough and smooth)
- Chloroplasts (plants), Vacuole (central in plants), Lysosome, Peroxisome (not explicitly listed but often included in diagrams)
- Centrioles, Microtubules
Note on labeling nuances:
- Cell membrane vs Plasma membrane: synonyms; both refer to the same structure.
- Plants may have lytic vacuoles that act like lysosomes.
- Plants possess chloroplasts, cell walls, and large central vacuoles not present in animal cells.
- Animal cells possess lysosomes and centrioles not typically present in plant cells.

Quick recap: key differences and practical implications

Structure-function alignment:
- Plant cells: cell wall, chloroplasts, large central vacuole support photosynthesis and structural integrity.
- Animal cells: lysosomes and centrioles support digestion and cell division.
Transport concepts:
- Diffusion vs osmosis: diffusion moves solutes; osmosis moves water.
- Tonicity determines water flow direction; improper tonicity can lead to crenation, hemolysis, or plasmolysis.
pH and buffers:
- Biological systems rely on stable pH; buffers maintain this stability to preserve enzyme activity and cellular processes.
Laboratory interpretation (controls and data):
- Positive/negative controls are essential to interpret presence/absence of proteins, starch, and other biomolecules.
- Data interpretation involves comparing results to controls and determining whether the target is present.

Formulas and explicit numerical notes (LaTeX)

Unit conversions:
- 1\text{ m} = 100\text{ cm}
- 1\text{ cm} = 10\text{ mm}
- 1\text{ km} = 1000\text{ m}
- 1\text{ kg} = 1000\text{ g}
- 1\text{ g} = 1000\text{ mg}
Magnification:
- M{total} = M{ocular} \times M_{objective}
- With M{ocular} = 10\times, M{objective} = 45\times → M_{total} = 10 \times 45 = 450\times
Dehydration synthesis:
- \text{monomer} + \text{monomer} \rightarrow \text{polymer} + H_2O
Hydrolysis:
- \text{polymer} + H_2O \rightarrow \text{monomer} + \text{monomer} + \dots
pH concepts (illustrative):
- pH scale is logarithmic; a change of one unit corresponds to a tenfold change in H⁺ concentration.