Ultrastructure

Topic 1.2

Essential idea: Eukaryotes have a much more complex cell structure than prokaryotes.

Understandings

1.2.U1 The prokaryotic cell

prokaryote cell

1.2.U2 The eukaryotic cell

eukaryote cell

1.2.U3 Electron microscopes have a much higher resolution than light microscopes.

Light microscopes use light to illuminate specimens while an electron microscope uses a beam of electrons to illuminate specimens. The resolution (the level of image detailing) is the main difference between these two microscopes.

Definition of resolution

Comparison of an image under a light microscope, a scanning electron microscope and an transmission electron microscope

Light microscopes have a resolution within the visible light spectrum of 400-700 nanometers.
Electron microscopes use a more shorter wavelenght of 2-12 picometers.

Comparison of an image under light vs electron microscope

Applications

Structure an exocrine gland

Electromicrograph of an exocrine cells

1.2.A1 Structure and function of organelles within an exocrine cell of the pancreas

Electromicrograph of an exocrine cells

1.2.A1 Structure and function of organelles within the palisade mesophyll of the leaf

Electromicrograph of an exocrine cells

Summary - Function of organelles: exocrine cell and leaf cell

Organelle Function
nucleus site of transcription of DNA into mRNA.
mitochondrion site of aerobic respiration producing ATP.
rough endoplasmic reticulum proteins are synthesized by ribosomes, packaged into vesicles and sent to the Golgi apparatus.
Golgi apparatus proteins are processed for export from the cell.
vesicle memebrane-bound organelle that contains zymogens which are released into the duct.
cell wall extracellular component that is NOT an organelle, bowever, gives support and prevents bursting of the cell.
chloroplast site of photosynthesis.
vacuole surrounded by a membrane to hold materials and wastes which functions to maintain the proper pressure within the plant cells to provide structure and support for the growing plant.

1.2.A2 Prokaryotes divide by binary fission

Binary fission in prokaryotes

Skills

1.2.S1 Drawing the ultrastructure of prokaryotic cells based on electron micrographs

Prokaryotic cells have a simple cell structure without compartmentalization.
Can you identify the different organelles in a typical prokaryotic cell?
Placing your mouse pointer on the figure below will reveal the organelles and the function of each organelle.

prokaryote

1.2.S2 Drawing the ultrastructure of eukaryotic cells based on electron micrographs

Eukaryotic cells have a compartmentalized cell structure. Can you identify the different organelles in a typical eukaryotic cell?
Placing your mouse pointer on the figure below will reveal the organelles and the function of each organelle.

eukaryote

1.2.S3 Interpretation of electron micrographs to identify organelles and deduce the function of specialized cells

Can you identify the organelles found in the cell shown below?

What is the function of this specialized cell?

Place your mouse on the figure for information about the cell.

Epithelial cell in the small intestine
Back to top of page

Valid XHTML 1.0 Strict Valid CSS!