Unit 2 Test Makeup Part 1 (Study Guide)

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Polarity of Water Molecule [Explain how the polarity of a water molecule contributes to its ability to act as the universal solvent and facilitate life processes.]

The water molecule has a partially negative oxygen and partially positive hydrogen ends, allowing it to dissolve polar molecules and ionic compounds.

Surface Area to Volume Ratio [Why does a cell's necessity to maintain a large surface area-to-volume ratio restrict the maximum size a cell can achieve?]

A large surface area-to-volume ratio allows efficient nutrient uptake and waste removal. As a cell grows, volume increases faster than surface area, limiting how large the cell can become.

Prokaryotic Cells vs. Eukaryotic Cells [Identify two major structural differences between prokaryotic and eukaryotic cells, other than the presence of a nucleus.]

Membrane-bound organelles: Eukaryotes have organelles like mitochondria and ER; prokaryotes do not.

Genetic material organization: Eukaryotic DNA is linear and in multiple chromosomes; prokaryotic DNA is usually a single circular chromosome.

Endosymbiotic Theory Evidence [Describe two pieces of evidence that support the Endosymbiotic Theory for the origin of mitochondria and chloroplasts.]

Mitochondria and chloroplasts have their own circular DNA and ribosomes, and possess a double membrane structure.

Free Ribosomes vs. Bound Ribosomes [Compare the function and location of free ribosomes versus ribosomes bound to the Rough Endoplasmic Reticulum (RER).]

Free ribosomes in the cytoplasm make proteins for use inside the cell, while RER-bound ribosomes make proteins for secretion, membranes, or other organelles.

Golgi Apparatus Functions [ Explain the main functions of the Golgi apparatus (or Golgi complex) in modifying and sorting proteins.]

The Golgi apparatus modifies, sorts, and packages proteins for transport to various destinations.

Lysosomes [Describe the primary function of a lysosome and explain why its contents are typically acidic]

Lysosomes act as the waste disposal and recycling center of the cell, containing digestive enzymes that are optimal in an acidic environment.

Amphipathic Nature of Phospholipids

Phospholipids have hydrophilic heads and hydrophobic tails, leading to the formation of a lipid bilayer in aqueous environments.

Fluid Mosaic Model

A fluid mosaic refers to the plasma membrane's structure, which consists of a variety of molecules embedded in a fluid lipid bilayer.

Cholesterol's Role in Membranes

Cholesterol stabilizes cell membranes at different temperatures, reducing fluidity at high temperatures and preventing solidification at low temperatures.

Selective Permeability of Plasma Membrane

The plasma membrane is selectively permeable, allowing small nonpolar molecules like oxygen to pass while repelling larger, charged molecules.

Simple Diffusion vs. Facilitated Diffusion

Simple diffusion occurs without membrane proteins for small nonpolar molecules, while facilitated diffusion involves specific membrane proteins for larger or charged molecules.

Hypotonic Solutions and Red Blood Cells

In a hypotonic solution, water moves into red blood cells, causing them to swell and potentially burst.

Water Potential

Water potential measures the free energy of water, with solute addition lowering its potential and making it more negative.

Turgor Pressure

Turgor pressure is maintained in plant cells by the cell wall resisting swelling in a hypotonic environment.

Primary Active Transport Example

The sodium-potassium pump moves Na+ out and K+ into the cell, requiring ATP because it transports ions against their concentration gradients.

Cotransport

Cotransport uses the energy from an ion's concentration gradient generated by primary active transport to move another molecule against its gradient.

Exocytosis vs. Endocytosis

Exocytosis moves materials out of the cell, while endocytosis moves materials into the cell, both requiring energy and vesicle formation.

Osmosis

Osmosis is the movement of water through a selectively permeable membrane from areas of high water concentration to low water concentration.

Isotonic Concentration for Potato Cells

The isotonic concentration of sucrose solution for potato cells is around 0.25 M where there's no net mass change.

Impact of Distilled Water on Potato Cells

Transferring potato cubes from a 0.6 M sucrose solution to 0.0 M results in water moving into the cells, causing them to swell.

Structure of Plasma Membrane

The plasma membrane is a phospholipid bilayer with embedded proteins, allowing selective movement of substances, including water through aquaporins.

Endomembrane System Path [Trace the path of a protein that is destined for secretion outside the cell, beginning with its synthesis on the RER.]

secreted protein is synthesized on the rough endoplasmic reticulum (RER) then transported via vehicles to the golgi apparatus for modification and sorting.