Unit 2 Notes: Cell Structure and Functions

Cell structures and functions

Cell Theory

All living things are composed of one or more cells; a cell is the basic unit of life; all cells come from preexisting cells.

Prokaryotic Cells

Cells without a nucleus; includes Archaea and Bacteria.

Eukaryotic Cells

Cells with a nucleus and membrane-bound organelles, including fungi, protists, plants, and animals.

Plasma Membrane

A semi-permeable membrane that allows the passage of oxygen, nutrients, and waste in/out of the cell.

Endomembrane System

A system that includes the synthesis and transport of proteins, lipid movement, and detoxification processes.

Nuclear Envelope

A double layer of membranes with pores that allows movement in and out of the nucleus.

Ribosomes

Cell structures that carry out protein synthesis, consisting of rRNA and proteins.

Smooth ER

Type of endoplasmic reticulum that synthesizes lipids and detoxifies drugs, not covered in ribosomes.

Rough ER

Type of endoplasmic reticulum covered in ribosomes, produces secretory proteins.

Golgi Apparatus

Organelles that modify, store, and ship proteins received from the ER.

Lysosomes

Organelles that contain digestive enzymes to break down waste and cellular debris.

Vesicles

Tiny sacs made of lipid bilayer that transport materials within or out of the cell.

Mitochondria

Organelles that serve as the site of cellular respiration, generating ATP from fats and sugars.

Chloroplasts

Organelles in plants that conduct photosynthesis, containing chlorophyll and thylakoids.

Cell Wall

A rigid structure made of cellulose that protects plant cells and helps maintain shape.

Passive Transport

Movement of substances across a membrane without the use of energy, following the concentration gradient.

Active Transport

The pumping of solutes across a membrane against the concentration gradient, requiring energy (ATP).

Osmosis

The diffusion of water across a selectively permeable membrane from a region of lower solute concentration to higher.

Tonicity

The ability of a solution to cause a cell to gain or lose water, related to solute concentration.

Isotonic Solution

A solution with equal solute concentration, resulting in no net movement of water.

Hypertonic Solution

A solution with a higher solute concentration, causing a cell to lose water and shrink.

Hypotonic Solution

A solution with a lower solute concentration, causing a cell to gain water and potentially swell.

Osmoregulation

The ability of organisms to maintain water balance and control solute concentration.

Fluid Mosaic Model

A depiction of the plasma membrane as a mosaic of diverse protein molecules suspended in a fluid phospholipid bilayer.

Simple Diffusion

The movement of molecules from high to low concentration without the use of energy.

Facilitated Diffusion

Transport of substances across a membrane via proteins, following the concentration gradient.

Cytoskeleton

A network of fibers that helps maintain cell shape, enables movement, and organizes cell contents.

Endosymbiont Theory

The theory that eukaryotic cells originated through the engulfing of prokaryotic cells, leading to a mutualistic relationship.