Set 2: Nutritional Types & Transport Processes

How do chemoheterotrophs obtain organic nutrients?

They obtain nutrients from other organisms.

What are the two main categories of chemoheterotrophs?

• saprobes

• parasites

What is the energy source of chemoheterotrophs: saprobes?

They feed on dead organic matter

What is the energy source of chemoheterotrophs: parasites?

They feed on a living host

Describe the parasite: ectoparasite

Lives on the outside of its host.

Describe the parasite: Endoparasite

Lives inside the host's body

Describe the parasite: Intracellular parasite

Lives inside the host's cells.

Describe the parasite: Obligate parasite and give an example

Cannot survive outside a living host.

Ex: Mycobacterium leprae (leprosy) or Treponema pallidum (syphilis).

What is passive diffusion, and what types of molecules typically move across the membrane this way?

• Passive diffusion is the overall direction (they spread out) of substances, where it’s moving down the concentration gradient without energy input.

• Small, non-polar molecules like O₂, CO₂, and H₂O move this way.

How does osmosis differ from simple diffusion?

Osmosis is the specific passive movement of water across a selectively permeable membrane.

What determines the osmotic relationship between a cell and its environment?

The osmotic relationship is determined by the concentration of solutions on either side of the cytoplasmic membrane (tonicity).

For molecules that cannot use passive diffusion (like ions and large molecules), what two main transport processes can a cell use?

• facilitated diffusion

• active transport

Name a type of protein involved in the first process facilitated diffusion.

using channel or carrier proteins

What is endocytosis?

Endocytosis is a process where the cell membrane engulfs large materials or liquids to bring them into the cell.

What are the 2 primary forms of endocytosis?

• phagocytosis

• pinocytosis

What is phagocytosis?

The pseudopodium will swallow large, solid material —> phagosome (food vacuole

What is pinocytosis?

pseudopodiums will swallow liquids or molecules in solution —> vesicle (cytoplasm)