Mastering the Microscopic: Cell Structure, Function, and Transport

Surface Area-to-Volume Ratio (SA:V)

The ratio that compares the surface area of a cell to its volume, impacting efficiency in material exchange.

Higher SA:V ratio

Characteristic of smaller cells that allows them to exchange materials more efficiently than larger cells.

Prokaryotes

Single-celled organisms that lack a nucleus and membrane-bound organelles, belonging to Domains Bacteria and Archaea.

Eukaryotes

Organisms whose cells contain a nucleus and membrane-bound organelles, belonging to Domain Eukarya.

Nucleus

The membrane-bound organelle in eukaryotic cells that contains DNA.

Ribosomes

Cell structures responsible for protein synthesis, present in both prokaryotic and eukaryotic cells.

Endomembrane System

A network of membranes that compartmentalizes the cell and facilitates the synthesis and transport of proteins.

Mitochondria

Organelles known as the powerhouses of the cell, where cellular respiration occurs, producing ATP.

Chloroplasts

Organelles in plant cells where photosynthesis takes place.

Lysosomes

Membrane-bound organelles containing hydrolytic enzymes for digestion and waste recycling within cells.

Vacuoles

Storage organelles in cells, significantly larger in plant cells, that maintain turgor pressure.

Phospholipid Bilayer

A double layer of phospholipids that makes up the plasma membrane, with hydrophilic heads and hydrophobic tails.

Fluid Mosaic Model

The concept that describes the plasma membrane as a flexible combination of lipids and proteins.

Osmosis

The diffusion of water across a semipermeable membrane from high water potential to low water potential.

Hypotonic Solution

A solution with a lower solute concentration compared to the inside of the cell, causing cells to swell.

Hypertonic Solution

A solution with a higher solute concentration compared to the inside of the cell, causing cells to shrink.

Isotonic Solution

A solution where the solute concentration is equal inside and outside the cell, resulting in no net movement of water.

Turgor Pressure

The pressure exerted by the fluid in a central vacuole against the cell wall, maintaining cell structure.

Active Transport

Movement of molecules against their concentration gradient, requiring energy (ATP).

Passive Transport

Movement of molecules down their concentration gradient without the use of energy.

Exocytosis

The process where vesicles fuse with the plasma membrane to release their contents outside the cell.

Endocytosis

The process by which cells internalize substances from the extracellular environment by engulfing them in vesicles.

Cotransport

A process in which the movement of one substance against its concentration gradient is coupled with the movement of another down its gradient.

Endosymbiotic Theory

The theory that explains the origin of eukaryotic cells as a result of symbiosis between prokaryotic cells.

Compartmentalization

The division of cellular functions into separate regions within a eukaryotic cell, enhancing efficiency.

Glycolipids and Glycoproteins

Carbohydrates attached to lipids and proteins that serve as ID tags for cell-to-cell recognition.

Sodium-Potassium Pump

An example of active transport that moves sodium and potassium ions across the plasma membrane.

Aquaporins

Channel proteins that facilitate the transport of water across the plasma membrane.

Solute Potential

The potential of a solution to attract water, determined by solute concentration.

Pressure Potential

The physical pressure within a cell that impacts water potential.

Fluidity of Membrane

The degree to which lipids and proteins in the plasma membrane can move freely, influenced by the presence of cholesterol.

Free Ribosomes

Ribosomes that float freely in the cytosol, synthesizing proteins for use within the cell.

Bound Ribosomes

Ribosomes attached to the rough endoplasmic reticulum, synthesizing proteins for export or membrane insertion.

Central Vacuole

A large vacuole in plant cells that stores water, nutrients, and waste, playing a key role in maintaining turgor pressure.

Rough Endoplasmic Reticulum (RER)

A type of endoplasmic reticulum studded with ribosomes, involved in the synthesis of proteins.

Smooth Endoplasmic Reticulum (SER)

A type of endoplasmic reticulum that synthesizes lipids, detoxifies poisons, and stores calcium.

Golgi Complex

An organelle that modifies, sorts, and packages proteins for secretion or delivery to other organelles.

Cristae

Folded inner membrane structures of mitochondria that increase the surface area for chemical reactions.

Stroma

The fluid part of chloroplasts where the Calvin cycle takes place.

Thylakoids

Membrane-bound structures within chloroplasts where light-dependent reactions of photosynthesis occur.

Cell Membrane Structure

Made up of phospholipids, proteins, cholesterol, and carbohydrates, contributing to selective permeability.

Autophagy

The process by which a cell recycles its own components through the action of lysosomes.

Cell Signaling

How cells communicate and transmit signals to each other, often involving membrane receptors.

Cell Wall

A rigid outer layer found in plants, fungi, and bacteria that provides structural support and protection.

Protein Sorting

The process of directing newly synthesized proteins to their appropriate location within or outside the cell.

Chemical Reactions in Organelles

The location-specific biochemical processes that occur within the various compartments of eukaryotic cells.