AP Bio Units 2 Topics : 3,4,5 Cell Size, Plasma Membrane, and Membrane Permiability

Flashcards covering key vocabulary related to cell size, plasma membrane structure, fluidity, components (phospholipids, proteins, carbohydrates), and plant cell features (cell wall, plasmodesmata).

SA:V ratio

The ratio of surface area to volume, a high ratio in small cells optimizes material exchange, while a low ratio in large cells decreases efficiency.

Small cell characteristics

Possess a high SA:V ratio, which optimizes the exchange of materials at the plasma membrane.

Large cell characteristics

Have a lower SA:V ratio, leading to reduced efficiency in material exchange, increased cellular demand for resources, and decreased rate of heat exchange.

Phospholipid

A primary component of the plasma membrane, an amphipathic molecule composed of a hydrophilic head and two hydrophobic tails.

Hydrophilic Head

The water-loving component of a phospholipid, often containing a phosphate group and glycerol, oriented towards aqueous environments.

Hydrophobic Tail

The water-fearing component of a phospholipid, composed of hydrocarbon chains, facing inwards away from aqueous environments.

Plasma Membrane

A selectively permeable boundary primarily composed of phospholipids, separating the internal cell environment from the external environment.

Amphipathic

A descriptor for molecules, like phospholipids, that possess both hydrophilic (water-loving) and hydrophobic (water-fearing) regions.

Selective Permeability

The ability of the plasma membrane to regulate which substances can enter and exit the cell.

Fluid Mosaic Model

A model describing the cell membrane as a fluid structure with various proteins and other macromolecules embedded in or associated with a phospholipid bilayer.

Fluid (membrane property)

Refers to the membrane's characteristic of being held together by weak hydrophobic interactions, allowing phospholipids and proteins to move and shift.

Mosaic (membrane property)

Refers to the membrane's composition of many different macromolecules, including various proteins, lipids, and carbohydrates.

Unsaturated hydrocarbon tails

Kinked phospholipid tails that prevent tight packing, helping to maintain membrane fluidity, especially at low temperatures.

Cholesterol (membrane)

A lipid embedded in the membrane that helps maintain fluidity by reducing movement at high temperatures and reducing tight packing of phospholipids at low temperatures.

Integral proteins

Proteins that are embedded into the lipid bilayer, also known as transmembrane proteins, and are amphipathic.

Transmembrane proteins

Another term for integral proteins, indicating they span across the entire lipid bilayer.

Peripheral proteins

Proteins that are not embedded into the lipid bilayer but are loosely bonded to the surface of the membrane.

Membrane Carbohydrates

Molecules (glycolipids and glycoproteins) found on the cell membrane surface that are important for cell-to-cell recognition.

Glycolipids

Carbohydrates bonded to lipids, found on the external surface of the plasma membrane.

Glycoproteins

Carbohydrates bonded to proteins, found on the external surface of the plasma membrane.

Cell wall

An extracellular structure found in plant cells (not animal cells) composed of cellulose, providing shape, structure, protection, and regulating water intake for the cell.

Plasmodesmata

Hole-like structures in plant cell walls filled with cytosol that connect adjacent plant cells, facilitating material exchange and communication.

Ose ending

Always carbs

Ase ending

Always proteins

Nine ending

Always nucleic acids