Robert Hooke first discovered the cell in 1665 (cork cells), but not till 19th Century when Schann & Schleiden (1839) & then Virchow (1858) suggested that cells were the basic unit of life. Before this spontaneous generation believed.
Transmission EM = electron beam travels through the sectionScanning EM = electron beam bounces off surface (that has been fixed by coating with gold) higher resolution
Genetics - 01 A closer look at cells
01. A closer look at cells.
Saint Ignatius College Geelong
KEY KNOWLEDGE & SKILLS
Outline the cell theory.
Compare prokaryotic and eukaryotic cells at light
and electron microscope levels.
List the specialised parts of cells and describe their
State the main differences between plant and
All living things are made of
All cells come from pre-existing
Cells are the basic building
blocks of all life.
Holds true for all
To the more
To understand life you need to understand how cells
Even though cells are specialised for many different
purposes, they share some common features.
They all have a similar cell structure.
They all perform similar basic functions.
They are all made up of ‘the molecules of life’.
LOOKING AT CELLS.
Magnify up to 1000-2000 times.
Magnify up to 2 million times.
Transmission v scanning electron
Magnification to molecular level!
Cells can be classified into two major types based on
their level of cell structure.
(pro = before; karyotic = a nucleus).
Small, primitive cells.
Lack membrane-bound organelles.
Have a single circular DNA chromosome.
In addition, can also have several small circles of DNA
Have a cell wall.
e.g. bacteria & cyanobacteria.
(eu= with; karyotic = a nucleus).
More advanced & usually larger than prokaryotic cells.
Contain membrane-bound organelles.
Distinct nucleus and other organelles.
e.g. plants, animals, fungi, protista.
Plasma membrane Controls entry of substances into and out of the cell.
Nucleus Contains genetic material and controls cellular
Mitochondrion Involved in the energy transformations that release
energy for the cell.
Endoplasmic reticulum A network of intracellular membranes forming
channels through which proteins are moved.
Golgi apparatus Packages the protein into vesicles for transport
across the plasma membrane and out of the cell.
Ribosomes Sites of protein synthesis. [Also found in
Lysosome Membrane bound vesicles containing digestive
Vacuole Membrane bound organelle. In plants – usually
large and help maintain water balance within the cell
and provide turgidity. In animals – usually smaller
and involved in intracellular digestion or water
Cilia & flagellum Involved with movement.
Chloroplasts Site of photosynthesis.
Centrioles Points of attachment for the spindle fibres during
Electron micrograph of a liver cell (x9000)
Source: Walpole et al. (2011)
PLANT V ANIMAL CELLS.
PLANT V ANIMAL CELLS.
All plant cells contain a cell wall outside the plasma
membrane. Made of cellulose. Provides structural
support and is permeable to most substances.
Animal cells do not have a cell wall.
Chloroplasts are often found in plants, but never in
Vacuoles can be found in both plant and animal
cells, In plant cells, often large and play key role in
maintaining osmotic balance. In animal cells, never
Centrioles are only found in animal cells.
THE INNER LIFE OF A CELL.