Cell Geometry & Math
As a spherical cell increases in size, Because of this mathematical relationship, its surface area-to-volume ratio does this.
What is decreases (or gets smaller)?
This structural model describes the plasma membrane as flexible and composed of different floating molecules,such as proteins, cholesterol, and carbohydrates,that can float around within the bilayer.
What is the Fluid Mosaic Model?
Movement of molecules across a membrane down their concentration gradient without any energy input from the cell.
What is passive transport (or simple diffusion / facilitated diffusion)?
Placing an animal cell into this type of solution causes water to move out of the cell, leading to cell shrinkage or crenation.
What is a hypertonic solution?
These two energy-producing organelles are membrane-bound, but are NOT part of the endomembrane system
What are mitochondria and chloroplasts? (they are not derived from other organelles, and so no exchange components via vesicles, they are independent)
This structural adaptation, commonly found on intestinal epithelial cells, increases plasma membrane surface area without significantly altering total cell volume.
What are microvilli (or membrane folds/invaginations)?
Small, nonpolar molecules like O2 and CO2 cross the plasma membrane freely via simple diffusion, while these types of particles cannot pass without assistance.
What are ions (+/-) or large polar molecules (e.g., glucose, proteins)?
Water-specific transport proteins that allow water molecules to bypass the hydrophobic interior of the phospholipid bilayer.
What are aquaporins?
Plant cells placed in a hypotonic solution do not burst because water entering the central vacuole pushes the plasma membrane against the cell wall, creating this pressure
What is turgor pressure?
these membrane-bound sacs contain hydrolytic enzymes and maintain a distinct internal environment to digest large molecules without destroying the rest of the cell.
What are lysosomes or Peroxisomes?
A spherical cell has a diameter of 6μm. Using the sphere surface area formula and volume formula, this is the cell's simplified surface area-to-volume ratio (Calculate)
SA = (4pi r^2)
V+ (4/3)(Pi)(r^3)
What is 1:1
At colder temperatures, cholesterol prevents the plasma membrane from becoming too rigid by preventing these structures from packing together too tightly.
What are phospholipids (or saturated fatty acid tails)?
Unlike open channel proteins, these transport proteins undergo a unique conformational change (shape change) to move specific molecules like glucose across the membrane.
What are carrier proteins?
Water will always move spontaneously from areas of this type of water potential to areas of this type of water potential.
What is higher (less negative) to lower (more negative) water potential?
All organelles in the endomembrane system such as the nuclear envelope, ER, and Golgi evolved through this specific process where the outer cell membrane folded inward.
What is Infolding Theory (invagination)?
when a cell increases in size, its volume increases much faster than its surface area, causing this crucial ratio to drop and limiting diffusion efficiency.
What is the surface area-to-volume (SA/V) ratio?
Fatty acid tails with double bonds create kinks that prevent close packing, making the plasma membrane more fluid. These are known by this chemical name.
What are unsaturated fatty acids?
In active transport, animal cells use ATP to pump these two ions in opposite directions across the membrane to establish a chemical and electrical gradient.
What are sodium (NA+) and potassium (K+)?
The ionization constant (i) in the solute potential formula PSI = -iCRT equals this number for NaCl because it dissociates.
What is 2?
peroxisomes maintain a isolated, membrane-bound compartment specifically to perform this function
What is detoxification (or breaking down toxic substances)?
microvilli on intestinal cells, as well as specific flattened, elongated, or spiraled bacterial cell shapes (like Spirilla or Cocci), as structural adaptations that serve this primary evolutionary purpose
What is maintaining a high surface area-to-volume ratio for efficient material exchange?
the plasma membrane maintains selective permeability because its phospholipid bilayer acts as a barrier to most particles, ensuring that internal cell and organelle contents remain seperated from this.
What is the external environment?
When cells need to move extremely large molecules across the membrane, simple and facilitated diffusion are insufficient; instead, the cell uses energy to form or fuse vesicles during these two broad processes.
What are endocytosis and exocytosis?
When calculating solute potential using Psi_s = -iCRT, temperature (T) must be in Kelvin. If a experiment is conducted at a room temperature of 20 degree C, this is the numerical value that must be plugged into the formula for T
What is 293 K?
this endosymbiotic double-membrane organelle preserve evidence of two distinct evolutionary origins: their outer membrane matches the host eukaryotic cell membrane, while their inner membrane is unique. What are the two organelles
Mitochondria or chloroplast