Unit 2 - Cell Structure and Function

Plasma Membrane

A selectively permeable barrier that surrounds all cells and regulates the movement of substances in and out of the cell.

Cytoplasm

The gel-like substance inside the cell that contains all the subcellular components.

Chromosomes

Structures within the cell that contain genetic information in the form of DNA.

Ribosomes

Cellular structures responsible for protein synthesis.

Endosymbiont theory

The theory that proposes that eukaryotic cells evolved from a symbiotic relationship between different types of prokaryotic cells.

Prokaryotes

Single-celled organisms that lack a nucleus and membrane-bound organelles.

Eukaryotes

Organisms whose cells have a nucleus and membrane-bound organelles.

Plant cell specific organelles:

Chloroplasts

Organelles responsible for photosynthesis in plant cells.

Central vacuole

A large fluid-filled organelle in plant cells that stores water, nutrients, and waste products.

Cell wall

A rigid outer layer that provides support and protection to plant cells.

Plasmodesmata

Channels that connect the cytoplasm of adjacent plant cells, allowing for communication and transport.

Animal cell specific organelles:

Lysosomes

Organelles responsible for the breakdown of macromolecules and cellular waste.

Centrosomes with centrioles

Organelles involved in organizing the cell's microtubules and cell division.

Flagella

Motility structures composed of microtubules that allow for cell movement.

Cell junctions

Structures that allow cells to adhere, interact, and communicate with each other.

Tight junctions

Junctions that tightly seal the plasma membranes of adjacent animal cells, preventing leakage of extracellular fluid.

Gap junctions

Junctions that allow for the passage of small molecules and ions between adjacent animal cells, facilitating cell communication.

Desmosomes

Junctions that anchor cells together using intermediate filaments, providing mechanical strength.

Endoplasmic reticulum (ER)

An organelle involved in the synthesis, modification, and transport of proteins and lipids.

Smooth endoplasmic reticulum

ER involved in lipid synthesis, carbohydrate metabolism, and detoxification.

Rough endoplasmic reticulum

ER studded with ribosomes that synthesize and secrete proteins.

Nucleus

The organelle that contains the cell's DNA and controls cellular activities.

Nuclear envelope

A double membrane that surrounds the nucleus, separating it from the cytoplasm.

Nucleolus

A region within the nucleus responsible for the production of ribosomes.

Chromatin

The complex of DNA and proteins that make up chromosomes.

Golgi apparatus

An organelle involved in sorting, modifying, and shipping proteins.

Mitochondrion

The organelle responsible for cellular respiration and energy production.

Peroxisome

A metabolic compartment involved in the breakdown of fatty acids and detoxification.

Cytoskeleton

A network of protein filaments that provides structural support and facilitates cell movement.

Microfilaments

Filaments involved in cell shape changes and cell division in animal cells.

Intermediate filaments

Filaments involved in maintaining cell shape and anchoring organelles.

Microtubules

Filaments involved in cell motility, chromosome movement, and organelle transport.

Fluid mosaic model

A model that describes the structure of the cell membrane as a fluid bilayer of phospholipids with embedded proteins, carbohydrates, and cholesterol.

Amphipathic

Molecules that have both hydrophilic and hydrophobic regions.

Facilitated diffusion

The passive transport of molecules across a membrane with the help of transport proteins.

Active transport

The movement of molecules across a membrane against their concentration gradient, requiring energy in the form of ATP.

Tonicity

The relative concentration of solutes inside and outside of a cell.

Osmoregulation

The control of water balance and solute concentrations within a cell or organism.