Mod. 18

Which situations involve a cell using endocytosis?

1. A cell wraps a portion of its membrane around a droplet of nutrient-rich water and brings the droplet inside the cell. 2. A free-living single-celled organism engulfs a smaller single-celled organism and uses the smaller organism as a food source. 3. LDL cholesterol attaches to cell membrane proteins, triggering the membrane to fold around the cholesterol and bring it into the cell.

Exocytosis is one of the processes living organisms use to move molecules. Choose all the examples of exocytosis.

1. A nerve cell releases peptides used as messengers into the extracellular space. 2. A single-celled eukaryotic organism excretes digestive waste into the surrounding water. 3. Pancreatic cells release digestive enzymes into the small intestine.

Select the statements that accurately describe endocytosis.

1. The cell expends energy to transport materials into the cytosol. 2. The cell membrane invaginates and pinches off, creating a vesicle within the cell.

Exocytosis is a type of cellular transport that allows materials to move across the plasma membrane of a cell. Which of the statements describe properties of exocytosis?

1.Exocytosis secretes materials from the cell through the fusion of a vesicle with the plasma membrane. 2.Exocytosis is the primary method of transporting large molecules out of the cell.

uniporter

A protein allows glucose to flow into a cell down its concentration gradient.

antiporter

A protein moves one Ca2 out of the cell and three Na into the cell.

symporter

A protein moves one H ion and one K ion out of the cell.

need help from protein to cross the membrane

glucose, amino acids, potassium ions and sodium chloride

active transport

movement of solutes out of the cell against their concentration gradient using membrane proteins

simple diffusion

movement of solutes out of the cell directly through the plasma membrane

facilitated diffusion

movement of solutes out of the cell down their concentration gradient using membrane proteins

bulk transports

movements of contents of transport vesicles out of the cell by exocytosis

Specialized cells can identify specific targets for ingestion and engulf proteins, debris, and other cells. What is the term for the cellular ingestion of large particles or cells?

phagocytosis

One way that cells engulf material from the environment is by ingesting solutes in the aqueous environment and enclosing them in intracellular vesicles. What is the name of this method of ingestion?

pinocytosis

Plasma membranes are selectively permeable (semipermeable), meaning that

the membrane permits the transport of only certain substances.