Untitled Flashcards Set

3. Counting Monomer Units in Polysaccharides

A polysaccharide consists of repeating monosaccharide units linked by glycosidic bonds.

Example:

• Starch is made up of thousands of glucose units.

• To count the monomers in a polysaccharide, break it down into its repeating monosaccharide components.

4. Identifying Polar and Nonpolar Molecules

• Polar molecules have an unequal charge distribution due to electronegative atoms (like oxygen and nitrogen). They dissolve well in water.

  • Example: Carbohydrates, water, alcohols (-OH groups make them polar)

• Nonpolar molecules have an equal charge distribution, meaning no strong charge separation. They do not dissolve in water (hydrophobic).

  • Example: Lipids, oils, hydrocarbons (C-H bonds make them nonpolar)

6. Identifying Hexoses and Pentoses

• Hexoses (6-carbon sugars) → C₆H₁₂O₆

  • Examples: Glucose, Fructose, Galactose

• Pentoses (5-carbon sugars) → C₅H₁₀O₅

  • Examples: Ribose, Deoxyribose (found in DNA & RNA)

Hexoses have six carbon atoms, while pentoses have five carbon atoms.

Amino Acids

1. Recognizing Amino Acids

   • Amino acids are the building blocks of proteins.

   • They contain an amino group (-NH₂), a carboxyl group (-COOH), and a unique R-group (side chain).

   • Examples:

     • Glycine (Gly, G) – The simplest amino acid, with just a hydrogen (-H) as its R-group.

     • Alanine (Ala, A) – Has a methyl group (-CH₃) as its R-group.

2. General Structure of an Amino Acid

    H   H   O 

    |   |   || 

    N—C—C 

    |   |   | 

    H   R   OH 

1.  

   • Amino group (-NH₂)

   • Carboxyl group (-COOH)

   • Hydrogen atom (-H)

   • Variable R-group (determines properties)

2. Classifying Amino Acids

   • Polar (hydrophilic): Serine, Threonine

   • Nonpolar (hydrophobic): Glycine, Alanine

   • Charged:

     • Positively charged (basic): Lysine, Arginine

     • Negatively charged (acidic): Aspartate, Glutamate

3. Dipeptide vs. Polypeptide

   • Dipeptide = Two amino acids linked by a peptide bond.

   • Polypeptide = Three or more amino acids forming a protein chain.

4. Counting Amino Acids

   • Each amino acid has one amine (-NH₂) and carboxyl (-COOH) group.

   • Count peptide bonds to determine the number of amino acids in a chain.

5. N-terminus vs. Carboxyl Terminus

   • N-terminus: The amino end (-NH₂) (beginning of the chain).

   • C-terminus: The carboxyl end (-COOH) (end of the chain).

Lipids

1. Recognizing Lipids

   • Lipids are hydrophobic (nonpolar) molecules used for energy storage, membrane structure, and signaling.

   • They do not dissolve in water.

2. Types of Lipids

   • Steroids: Four fused rings (e.g., cholesterol, testosterone).

   • Phospholipids: Form cell membranes (hydrophilic head + hydrophobic tails).

   • Mono- & Triglycerides: Energy storage molecules made of glycerol + fatty acids.

3. Saturated vs. Unsaturated Fats

   • Saturated fats: No double bonds (solid at room temperature).

   • Unsaturated fats: Have one or more double bonds (liquid at room temperature).

4. Formation and Breakdown of Mono & Triglycerides

   • Formation: Glycerol + Fatty Acids → Triglyceride + Water (dehydration synthesis).

   • Breakdown: Triglyceride + Water → Glycerol + Fatty Acids (hydrolysis).

Nucleic Acids

1. Monomer Unit: Nucleotide

   • Nucleic acids (DNA & RNA) are made of nucleotides.

2. Three Parts of a Nucleotide

   • Phosphate group (-PO₄³⁻)

   • Sugar (deoxyribose in DNA, ribose in RNA)

   • Nitrogenous base (A, T, C, G, U in RNA)

3. 3’ and 5’ Ends of DNA

   • 3’ end: Has a free OH group on the sugar.

   • 5’ end: Has a free phosphate group.

4. Purines vs. Pyrimidines

   • Purines (double-ringed): Adenine (A), Guanine (G).

   • Pyrimidines (single-ringed): Cytosine (C), Thymine (T, in DNA), Uracil (U, in RNA).

5. Base Pairing and Hydrogen Bonds

   • A pairs with T (or U in RNA) – 2 hydrogen bonds.

   • C pairs with G – 3 hydrogen bonds.

Lab 5 – Microscope and Cells

Microscope

1. Parts of a Microscope and Their Functions

• Ocular Lens (Eyepiece): Magnifies the image, usually 10x.

• Objective Lenses: Provide different levels of magnification (4x, 10x, 40x, 100x).

• Stage: Holds the slide in place.

• Stage Clips: Secure the slide.

• Coarse Focus Knob: Moves the stage up and down for rough focus.

• Fine Focus Knob: Adjusts sharpness for precise focusing.

• Light Source: Provides illumination.

• Diaphragm: Controls the amount of light entering the lens.

2. Difference Between Magnification and Resolution

• Magnification: How much larger an object appears compared to its actual size.

• Resolution (Resolving Power): The ability to distinguish two close points as separate. Higher resolution = clearer details.

3. Calculating Magnification

Total Magnification=Ocular Magnification×Objective Magnification\text{Total Magnification} = \text{Ocular Magnification} \times \text{Objective Magnification}Total Magnification=Ocular Magnification×Objective Magnification

• Example: Ocular lens (10x) × Objective lens (40x) = 400x total magnification

4. Depth of Field

• The thickness of the sample that remains in focus at one time.

• Higher magnification = shallower depth of field (fewer layers in focus at once).

Cells: Plant vs. Animal Cells

1. Identifying Plant vs. Animal Cells

2. Organelles in Eukaryotic Cells

3. Measuring Cell Size Using a Micrometer

• Use an ocular micrometer (etched scale in the eyepiece) and compare it to the stage micrometer (known scale on slide).

• Calibration formula: Cell Size=Ocular UnitsCalibration Factor (µm per unit)\text{Cell Size} = \frac{\text{Ocular Units}}{\text{Calibration Factor (µm per unit)}}Cell Size=Calibration Factor (µm per unit)Ocular Units​

• Example: If a cell is 5 ocular units and 1 unit = 2 µm, the cell size is: 5×2=10 µm5 \times 2 = 10 \text{ µm}5×2=10 µm

4. Importance of Determining Cell Size

• Distinguishes between cell types (bacteria vs. eukaryotic cells).

• Helps in diagnosing diseases (e.g., cancer cells tend to have abnormal sizes).

• Essential for scaling experiments (e.g., drug testing on cells).

• Understanding growth and development in organisms.

1. Definitions of Diffusion and Osmosis

• Diffusion: The movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached.

• Osmosis: The diffusion of water across a selectively permeable membrane from an area of lower solute concentration (higher water concentration) to an area of higher solute concentration (lower water concentration).

2. Factors Affecting Diffusion Rate

1. Temperature – Higher temperature increases diffusion speed.

2. Molecule Size – Smaller molecules diffuse faster than larger ones.

3. Concentration Gradient – A steeper gradient leads to faster diffusion.

4. Membrane Permeability – More permeable membranes allow faster diffusion.

5. Surface Area – Larger surface area increases diffusion rate.

3. Isotonic, Hypotonic, and Hypertonic Solutions

4. How Concentration Affects the Rate of Movement

• Higher concentration gradients = faster diffusion and osmosis.

• As equilibrium approaches, movement slows down.

5. Importance to Living Systems

• Maintains Homeostasis – Cells regulate water and solute balance.

• Nutrient and Waste Transport – Diffusion moves oxygen and nutrients into cells while removing waste (e.g., CO₂ diffusion in lungs).

• Prevents Cell Damage – Extreme osmosis can cause cell bursting or shrinking, affecting function.

6. Plant vs. Animal Cells in Osmosis