Biology- Life is Cellular 3.1

Which are the main points of the cell theory?

• Cells are the basic units of structure and function in living things.

• New cells are produced from existing cells.

• All living things are made up of cells.

The invention of which instrument allowed scientists to discover cells?

microscope

Josey wants to look at the cells of an onion under a light microscope. She peels off a thin, transparent layer of onion and places it on a microscope slide. Josey places the sample on the microscope stage, looks through the eyepiece, and adjusts the stage to focus the image. However, she is unable to see any details of the cells.

Which solution could possibly help Josey to see the onion cells in detail?

Josey should apply a stain, such as iodine, to her sample.

Light Microscope

• Use a beam of light to produce magnified images

• can be used to examine living cells and tissue

Electron Microscope

• Use a beam of electrons to produce magnified images

• can be used to examine DNA

What kind of cell is this?

Prokaryotic cell

Highlights of a Prokaryotic cell

• Contains DNA

• Are surrounded by a cell membrane

• Were the first photosynthetic organisms on Earth

Highlights of a Eukaryotic cell

• Contains DNA

• Are surrounded by a cell membrane

• Contain nuclei

• Can be specialized for specific tasks in multicellular organisms