Organelles

Ribosomes

• made of RNA and proteins; larger in eukaryotes but still present in prokaryotes

• site of translation/polypeptide synthesis

Cytoskeleton

• Scaffolding within the cytoplasm

• Provides internal structure and mediates intracellular transport

Plasma membrane

• Phospholipid belayer embedded with proteins

• Semi-permeable and selective barrier surrounding the cell

Nucleus

• Eukaryotic only

• Double membrane structure with pores; inner nucleolus

• Stores genetic material as chromatin; nucleolus is site of ribosome assembly

Endoplasmic Reticulum

• A membrane network that may be bare (smooth) or studded with ribosomes (rough)

• Transports materials between organelles (smooth: lipids, rough: proteins)

Golgi Apparatus

• An assembly of vesicles and folded membranes located near the cell membrane

• Involved in the sorting, storing, modification, and export of secretory products

Mitochondrion

• Double membrane structure

• Site of aerobic respiration/ATP production

Peroxisome

• Membranous sac containing a variety of catabolic enzymes

• Catalyses breakdown of toxi substances (like H2O2) and other metabolites

Centrosome

• Microtubule organizing center

• Radiating microtubules form spindle fibers and contribute to cell division

Chloroplast

• PLANT CELLS ONLY

• Double membrane structure with internal stacks of membranous discs a called thylakoids

• Site of photosynthesis

Large vacuole

• PLANT ONLY

• Fluid filled internal cavity surrounded by a membrane

• Maintains hydrostatic pressure

Cell Wall

• PLANT ONLY

• External outer covering made of cellulose

• provides support and mechanical strength; prevents excess water

Lysosome

• ANIMAL CELLS ONLY

• Membranous sacs filled with hydrolytic enzymes

• Breakdown/hydrolysis of macromolecules