Chapter 4 Biology Ikenna Opara

Cell Theory

States that all organisms are composed of one or more cells, which are the basic units of life.

Factors that limit cell size

Surface area, temperature, and concentration gradient of diffusing substances limit cell size.

Prokaryotic Cells

Unicellular organisms that lack a nucleus and reproduce by binary fission.

Eukaryotic Cells

Cells that have a nucleus, are larger and more complex, and contain membrane-bound organelles.

Nucleus

The organelle that stores genetic information and regulates gene expression in eukaryotic cells.

Ribosomes

Cellular structures composed of rRNA and proteins that synthesize proteins.

Endomembrane System

A group of membranes and organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins.

Mitochondria

Organelles that metabolize sugar to generate ATP, known as the powerhouse of the cell.

Chloroplasts

Organelles in plant cells that use light energy to produce ATP and synthesize sugars through photosynthesis.

Endosymbiotic Theory

The theory explaining the origin of mitochondria and chloroplasts as being engulfed prokaryotic cells.

Cytoskeleton

A network of fibers that provides structural support and aids in cell movement.

Actin Filaments

Component of the cytoskeleton that aids in cell crawling and contraction.

Microtubules

Cytoskeletal components that facilitate vesicle transport within cells.

Extracellular Matrix (ECM)

A collection of extracellular molecules secreted by cells for structural and biochemical support.

Tight Junctions

Cell junctions that connect plasma membranes of adjacent cells, forming a barrier.

Adhesive Junctions

Cell junctions that anchor the cytoskeleton of one cell to another.

Gap Junctions

Communicating junctions that allow ions and small molecules to pass between adjacent animal cells.

Plasmodesmata

Transport structures that connect adjacent plant cells.

Rough ER

Endoplasmic reticulum studded with ribosomes that synthesizes proteins.

Smooth ER

Endoplasmic reticulum that synthesizes lipids and detoxifies substances.

Vacuole

The largest organelle in plant cells, aiding in maintaining water balance.

Peroxisome

An organelle that contains enzymes to break down fatty acids and detoxify.

Cell Movement

Movement facilitated by actin filaments, flagella, and cilia.