1.2 Ultrastructure of cells Understanding: Prokaryotes have simple cell structure without compartments Eukaryotes have a compartmentalized cell structure Prokaryotes divide by binary fission Electron microscopes have a much higher resolution that light microscopes Applications: The structure and function of organelles within exocrine gland cells of the pancreas The structure and function of organelles within palisade mesophyll cells of the leaf Nature of science: Developments in scientific research follow improvements in apparatus: the invention of electron microscopes led to greater understanding of cell structure Skills: Drawing the ultrastructure of prokaryotic cells based on electron micrographs Drawing the ultrastructure of eukaryotic cells based on electron micrographs Interpretation of electron micrographs to identify organelles and deduce the function of specialised cells

Vs.

Surface area to volume ratio Smaller cells have a larger surface area compared to their volume. Whereas larger cells have smaller surface area compared to their volume

Surface area to volume ratio Chihuahua Husky Who will freeze first?

Surface area to volume ratio Larger cells have less surface area to bring in the materials that the cell needs, and to get rid of waste. Smaller cells have lots of surface area compared to their volume to do this. Therefore this limits the size of cells Reactions inside the cytoplasm would not work well otherwise

Cell size Larger animals do not just have just a few large cells in them, they have many small cells.

How do we get from… This… (A simple animal cell) To this… (A human)

Cells Many multicellular organisms start as a single cell, made from sexual reproduction. This cell can reproduce at a rapid rate. But then we are just a pile of the same cells…

The possibilities are endless…

Differentiation Every cell has - An entire set of genes Instructions to develop into any type of cell Cells just use the genes they need for their pathway Once on a pathway they are committed

Differentiation Some cells have greatly reduced ability to reproduce after specializing Nerve cells & muscle cells However some can reproduce throughout their life Skin cells

Stem cells Retain their ability to divide and differentiate into various cell types.

Stem cell research What are stem cells Give examples of how stem cells can be used (Stargardt’s disease and leukemia) Sources of stem cells (Embryonic, cord blood or adult) How stem cell research has progressed – how may local, cultural and religious traditions impact stem cell research in different countries Arguments for and against stem cell research Your own thoughts/opinions on the matter

Eukaryotes vs Prokaryotes Create a poster in pairs Prokaryote and eukaryote. For each cell: Drawing and labels What each organelle does Examples of that type of cell How they divide Summarise the similarities and differences between them Make them as beautiful as possible so I can put them on the wall! THEN: Draw and explain the structure and function of organelles within exocrine gland cells of the pancreas and within the palisade mesophyll cells of the leaf