ULTRASTRUCTURE OF CELLSFOR THE 2016 IB SYLLABUS

www.ibscrewed.org

PROKARYOTIC CELL

• Single-celled prokaryotic cells have a very simple structure

• All the DNA and other chemicals of life float freely in the cytoplasm: there are no organelles

• There is no compartmentalisation

• They divide by binary fission

DRAWING PROKARYOTES

• Example:

• The most important elements are: cell wall, pili and flagella, plasma membrane, cytoplasm, 70S ribosomes and naked loop of DNA

EUKARYOTIC CELLS

• Eukaryotic cells have a compartmentalised structure, with membrane-bound organelles

• They often join together to form multicellular organisms

• Eukaryotes are usually larger than prokaryotes

DRAWING EUKARYOTES

• Example:

• The most important elements are: plasma membrane, cytoplasm, 80S ribosomes, nucleus, mitochondria, some other organelles

PROKARYOTES VS. EUKARYOTES

• Both have: cell membranes, DNA, ribosomes, metabolism, and cytoplasm

• Differences include: prokaryotes have cell walls (and eukaryotic plant cells), eukaryotes have histone-bound DNA, prokaryotic DNA is in a single loop, eukaryotic DNA is found in chromosomes

ELECTRON MICROSCOPES

• Electron microscopes have much higher resolution than light microscopes

• They are used to take images of the ultrastructure of cells