Membrane Transport and Cell Organelles

Comprehensive flashcards covering membrane transport mechanisms (passive, active, bulk), cellular organelles (nucleus, ER, Golgi, lysosomes, peroxisomes, energy organelles), and the three main elements of the cytoskeleton.

What are the two defining characteristics of passive processes in membrane transport?

They do not require expenditure of cellular energy and substances move down their concentration gradient.

How does simple diffusion differ from facilitated diffusion?

Simple diffusion requires no transport protein for small, nonpolar molecules, while facilitated diffusion requires a transport protein for ions or polar molecules.

What is osmosis?

The movement of water across a semipermeable membrane.

What is the difference between primary and secondary active transport?

Primary active transport uses energy from ATP directly, while secondary active transport uses an energy source from the movement of another substance.

Define symport and antiport in active transport.

Symport involves two substances moved in the same direction, while antiport involves two substances moved in opposite directions.

What are the three types of endocytosis identified in the transcript?

a) Phagocytosis ("cell eating"), b) Pinocytosis ("cell drinking"), and c) Receptor-mediated endocytosis.

What is the function of exocytosis?

Exocytosis uses vesicles to transport macromolecules out of the cell.

Describe Phagocytosis based on the notes.

It is "cell eating" where a particle is engulfed by extending a pseudopodium to form a food vacuole.

Describe Pinocytosis based on the notes.

It is "cell drinking" where the cell "gulps" ECF solutes and forms a coated vesicle.

What are the primary functions of the nucleus?

It is the storehouse for the cell's genetic information and the site for RNA synthesis.

How do molecules pass through the nuclear envelope?

Small molecules and ions can passively diffuse through nuclear pores, but large proteins and RNA require active transport.

What are the distinct roles of the Rough ER and the Smooth ER?

Rough ER is associated with ribosomes and produces proteins (including those for secretion); Smooth ER lacks ribosomes and is the primary site of lipid synthesis.

What functions are performed by Peroxisomes?

They degrade lipids, synthesize lipids, detoxify alcohols, and signal immune cells.

What are the major roles of the Golgi apparatus?

It modifies and sorts proteins and lipids moving to final destinations, and it synthesizes carbohydrates.

What is the function of Lysosomes?

They degrade damaged or unneeded macromolecules, recycle organic compounds, and are involved in apoptosis ("programmed cell death").

What is the difference between Mitochondria and Chloroplasts regarding energy?

Mitochondria harness energy from sugars and convert it into ATP; Chloroplasts capture energy from sunlight and convert it into sugars.

What is the composition and function of Microfilaments?

They are made of actin monomers in a double helix. They provide cell shape, support, allow movement by crawling, and assist in cell division (cytokinesis).

What is the composition and function of Microtubules?

They are hollow tubes formed from $ext{\alpha}$ and $ext{\beta}$ tubulin dimers. They provide cell shape, enable movement via cilia/flagella, and segregate chromosomes during cell division.

Regarding the dynamic nature of microtubules and microfilaments, how do the ends differ?

The plus ($+\text{}$) end assembles quickly, and the minus ($-\text{}$) end assembles slowly.

Name the motor proteins that move cargo along microtubule tracks and their directions.

Kinesin moves cargo toward the $+\text{}$ end, and Dynein moves cargo toward the $-\text{}$ end.

What is the role of Intermediate Filaments?

They provide mechanical strength and structural support to cells; they are composed of diverse protein subunits depending on the cell type.

What disease is associated with mutations in intermediate filaments found in keratinocytes?

Epidermolysis Bullosa, where the skin is fragile and easily blisters.