Cell biology

Eukaryotic Cells

Cells characterized by the presence of a nucleus housing DNA in chromatin form, containing membrane-bound organelles.

Prokaryotic Cells

Cells lacking a true nucleus; DNA is concentrated in a nucleoid region, without membrane-bound organelles.

Nucleus

The control center of the cell that houses most of the cell's genetic material (DNA).

Cytoplasm

The contents outside of the nucleus that include organelles and cytosol.

Ribosomes

Molecular machines responsible for protein synthesis, composed of ribosomal RNA (rRNA) and proteins.

Endoplasmic Reticulum (ER)

A network of membranous tubules involved in protein and lipid synthesis, with rough (ribosomes present) and smooth types.

Golgi Apparatus

Organelle that sorts, modifies, and packages proteins and lipids for transport.

Lysosomes

Organelles containing digestive enzymes that break down waste materials and cellular debris.

Chloroplasts

Organelles that conduct photosynthesis in plants and algae, converting light energy into chemical energy.

Mitochondria

Organelles known as the powerhouses of the cell, generating ATP through cellular respiration.

Cytoskeleton

A network of protein filaments that provides structural support to the cell and facilitates intracellular transport.

Flagella

Long, hair-like structures used for locomotion, composed of microtubules arranged in a '9+2' structure.

Desmosomes

Junctions between cells providing mechanical strength, acting as spot welds.

Plasmodesmata

Specialized junctions in plant cells allowing direct cytoplasmic exchange between adjacent cells.

Passive Transport

Transport of substances across the cell membrane without energy, occurring down a concentration gradient.

Active Transport

Requires energy to move substances against their concentration gradient, from low to high concentration.

Osmosis

The net movement of water across a semi-permeable membrane from an area of lower solute concentration to higher concentration.

Tonicity

The ability of an extracellular solution to influence the movement of water in or out of a cell by osmosis.

Hypertonic Solution

A solution with a higher solute concentration outside the cell, causing the cell to shrink.

Hypotonic Solution

A solution with a lower solute concentration outside the cell, causing the cell to swell.

Isotonic Solution

A solution where the solute concentration is equal inside and outside the cell, maintaining stable cell volume.