Download Introduction to Cells

Do Now: Think-Pair-Share
What do we have in common with bacteria
living in our body ?
Microscope observations of organisms led to the
discovery of cells.
• 1665 – Robert Hook used the first microscope to discover
structures he called ‘cells’
• Ten years later , Anton van Leeuwenhoek used a more
powerful microscope to observe living organisms in
pond water.
• It took 150 years of improving the microscopes and
compiling the observations made by different scientists
to come up with
• Cell Theory :
• All living things are made of one or more cells
• Cells are the basic units of structure and function in
living organisms
• All cells arise from existing cells
Contributors to the Cell Theory – Theodor Schwann,
Rudolph Virchow, and Matthias Schleiden
Cells vary in size and shape. A cell’s shape reflects the
cell’s function.
Cells in Human Body
Cell size is limited by a cell’s surface area-to –volume ratio. Cells
with greater surface area – to – volume ratio (smaller cells) can
exchange substances more efficiently.
All cells share the following features :
• Cell membrane
• Cytoplasm
• Ribosomes
All cells are divided into Prokaryotic cells and
Eukaryotic cells.
Prokaryotic cells
• Very simple in their organization
• Have cell walls (some have capsule surrounding the cell wall)
• Small in size 1-15 µm
• Believed to appear 3.5 billion years ago
• Do not have nucleus or membrane-bound organelles
Examples all bacterial cells
Eukaryotic cells
• Complex organization
• Can carry out more functions
• First appeared 1.5 billion years ago
• Have nucleus
• Have many different membrane-bound organelles