Biology, Chap. #4 : A Tour of the Cell

Cell Theory

All living things are composed of cells and that all cells come from other cells

Prokaryotic Cells

Basteria and archaea

Eukaryotic Cells

Protists, fungi, plants, and animals

Plasma membrane

Forms a boundary between a living cells and its suroundings and controls the traffic of materials into and out of the cell.

Membrane are made out of

Phospholipids are the main components. It has two distinct regions: a negatively charged/hydrophilic phosphate group (head) and two nonpolar, hydrophobic fatty acid tails


Carrying genes made of DNA


Tiny structures that make proteins according to instructions from the genes


The entire region between the nucleus and the plasma membrane


The region in a prokaryotic cells where the DNA is coiled up


Long projections that may propel the prokaryotic cell through its liquid environment. Present in sperm cells in eukaryotic cells


Membrane-bound structures perform specific functions in the cell

Cellular Metabolism

Chemical activities of the cell


Contains most of the cells DNA and controls the cell's activities by directing protein synthesis.


A complex of proteins and DNA

Nuclear Envelope

A double membrane perforated with protein-lined pores that control the flow of materials into ando out of the nucleus


The site where a special type of RNA called ribosomal RNA (rRNA) is synthesized according to the instructions in the DNA

Endomembrane system

Includes the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and the plasma membrane


sacs made of membrane, helps with the transfer of membrane segments

Endoplasmic Reticulum (ER)

Extensive network of flattened sacs and tubules. The membranes are continuous with the nuclear envelope

Smooth ER

Synthesis of lipids, including oils, phospholipids, and steroids. Helps to process drugs and other potentially harmful substances. Stores calcium.

Rough ER

Makes more membrane, phospholipids are made by enzymes. Has ribosomes attached to its surface.


Short chains of sugars are often linked to the polypeptide.

Transport vesicle

Packaged molecules ready for export from the ER

Golgi apparatus

Consists of flattened sacs stracked on top of each other. Performs several functions in close partnership with the ER. Receives and modifies products manufactured by the ER. Vesicles on the other side bud off and travel to other sites.


Consists of digestive enzymes enclosed in a membranous sac. The enzymes are made by rough ER and then transferred to the Golgi apparatus for further procesing.


Membranous sacs that have a variety of functions

Central Vacuole

Helps a cell grow in size by absorbing water and enlarging, and it can store vital chemicals or waste products


An organelle that is not part of the endomembrane system but, is involved in various metabolic finctions. Including the breakdown of fatty acids to be used as fuel and the detoxification of alcohol and other harmful substances.


Organelles that carry out cellular respiration in nearly all eukaryotic cells, converting the chemical energy of foods such as sugars to the chemical energy of a molecule called ATP

Intermembrane space

The narrow region between the inner and outer membranes.

Mitochondrial matrix

Enclosed by the inner membrane, contains the mitochondrial DNA and ribosomes, as well as many enzymes that catalyze some of the reactions of cellular repiration.


photosynthesizing organelles of all photosynthetic eukaryotes.


Thick fluid inside the inner membrane that contains the chloroplast DNA and ribosomes as well as many enzymes


A network of interconnected sacs inside the chloroplast


A stack of thylakoids


Proposes that mitochondria and chloroplasts were formerly small prokaryotes that began living within another cell


Network of protein fibers, extending thoughout the cytoplasm of a cell


Solid rods composed mainly of globular proteins called actin, arranged in a twisted double chain.

Intermediate filaments

Made of various fibrous proteins and have a ropelike structure. Reinforce cell shape and to anchor certain organelles.


Hollow tubes composed of globular proteins called tubulins


Come in pairs and are within the centrosome


Short, numerous appendages that propel protists

Basal Body

Nine microtubule triplets arranged in a ring. Act as a foundation for microtubule assembly from tubulin subunits.

Extracellular Matrix (ECM)

A product of animal cells. The layer helps hold cells together in tissues and protects and supports the plasma membrane


Span the membrane, attaching on the other side to proteins connected to microfilaments of the cytoskeleton

Tight junctions

Forming continuous seals around cells, they pervent leakage of extracellular fluid across a layer of epithelial cells

Anchoring junctions

Function like rivets, fastening cells together into strong sheets. Intermediate filaments made of sturdy keratin proteins anchor these junctions in the cytoplasm

Gap junctions

Channels that allow small molecules to flow through proteinlined pores between neighboring cells.

Cell Wall

Rigid extracellular structure not only protects the cell but provides the skeletal support and keeps plants upright on land.


Channels between adjacent plant cells, form a circulatory and communication system connecting the cells in plant tissues.