bio 2.5

These flashcards cover key concepts related to the structure and function of cell membranes and cell walls, including membrane permeability, transport proteins, and the composition of cell walls.

What are the main components of the cell membrane according to the fluid mosaic model?

The cell membrane is composed of phospholipids, proteins, steroids, and carbohydrates.

What does amphipathic mean in the context of phospholipids?

Amphipathic means that phospholipids have both hydrophobic (water-repelling) and hydrophilic (water-attracting) properties.

What types of molecules can pass freely across the cell membrane?

Small non-polar molecules such as nitrogen, oxygen, and carbon dioxide can pass freely.

What is the role of channel proteins in the cell membrane?

Channel proteins act as hydrophilic tunnels that allow specific target molecules to pass through the membrane.

What do carrier proteins do in the cell membrane?

Carrier proteins span the membrane and change shape to move target molecules from one side to the other.

Why can small polar molecules like water pass through the cell membrane?

Small polar molecules can pass through the cell membrane in minimal amounts due to their size.

What is the function of a cell wall in plant cells?

Cell walls provide structural support, protect against rupture, and help maintain cell shape.

What are plasma desmodemes and their function?

Plasma desmodemes are small holes between plant cells that allow the transfer of nutrients, waste, and ions.

What is the composition of plant cell walls?

Plant cell walls are primarily made up of cellulose, a polysaccharide.

What is chitin and where is it found?

Chitin is a complex carbohydrate found in the cell walls of fungi.

What is peptidoglycan and its role in prokaryotes?

Peptidoglycan is a polymer of sugars and amino acids that make up the cell walls of prokaryotes.

Why do animal cells not have cell walls?

Animal cells lack cell walls and rely on the cell membrane for structural integrity.

What is selective permeability?

Selective permeability refers to the ability of the cell membrane to allow certain substances to pass while blocking others.

What kind of substances require help to cross the cell membrane?

Hydrophilic substances, such as large polar molecules and ions, require transport proteins to cross the cell membrane.

What examples of small non-polar molecules can cross the cell membrane freely?

Examples include nitrogen, oxygen, and carbon dioxide.

How do transport proteins assist in cellular transport?

Transport proteins facilitate the movement of molecules that cannot freely pass through the membrane.

What is the significance of the bilayer formation of phospholipids in aqueous solutions?

The bilayer formation is essential for creating a barrier that separates the internal cellular environment from the external environment.

What does it mean for a membrane to be described as a 'fluid mosaic model'?

The 'fluid mosaic model' describes the cell membrane as a flexible layer made of various molecules, resembling a mosaic.

What role do carbohydrates play in the cell membrane?

Carbohydrates serve as recognition sites for cell communication and interactions.

How can cell walls act as a barrier while still being permeable?

Cell walls can have small openings that allow certain molecules to pass through while providing structural support.