CellsCellsCh. 13

Guiding questions:

• What is a cell and how do you think it functions?

• How are cells like factories or cities?

• What is this

picture about?

Background Information:Every living thing on Earth is made up of cells.

Cells keep living things organized. Some organisms, like bacteria, are only as big as a single cell.

In an organism as complex as a human, there is no way you we could do everything we do and be just a single cell. We must have many different, and many different kinds of cells.

Background Information:

One of the main functions of cells is to organize the body. We have brain cells, stomach cells, bone cells, and many other types of cells. They all do special jobs to help our bodies function the way they are supposed to. Although the cells in our bodies do many different jobs, they all contain similar parts called organelles.

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Background Information:

In the same way there are different kinds of cells inside us, different organisms have different types of cells. Trees have different cells than us and so do dogs and cockroaches. Each of those cells is different in some way. Every cell has a special job to do.

Cell Explorers

It’s hard to believe, but there was a time when we didn’t know anything about cell structure. In fact, the word cell (from the Latin word for chamber, cello) wasn’t used as a biological term until 1665. That’s when Robert Hooke, an English-born scientist, looked at a thin slice of a cork plant under a compound microscope he had built himself. Hooke noticed small holes surrounded by walls and named these tiny pores cells. After that, scientists believed cells were found only in plants.

But in 1839, Matthias Schleiden and Theodor Schwann, both German scientists, shared their scientific findings with one another. Schleiden had been studying plant cells and Schwann had been studying animal structures. Together, they compared plant and animal structures and found that the structures were very similar—too similar to be accidental.

They concluded that cells are the basic building blocks for both plants and animals. In 1858, Rudolf Virchow took Schleiden’s and Schwann’s theory and stated it simply: all cells come from other cells. This remains known as the cell theory.

Throughout the mid-1800s and into the 1900s, scientists continued to discover more and more about cells thanks in part to Gregor Mendel’s study of genetics, Friedrich Miescher’s discovery of nuclein (which later became known as DNA), and James Watson’s findings about DNA’s structure. Although many amazing discoveries have happened in recent years, including genetic engineering and gene therapy, all of it is because of the work of those early cell explorers.

Reading questions:

1. How important was Hooke’s homemade microscope to the discovery of the plant cell? Explain.

2. Restate the cell theory in your own words.

3. Why do you think it took almost 200 years for scientists to formulate the cell theory?

Answer ch. 13 sec.1 questions

How do we pronounce the organelles?

Background Information:

All cells have some things in common. If you were to look inside of a cell, you would be able to see all of the organelles that are labeled in this drawing of a cell

Micro-journeyto the

plant cell

Cell Organelles and their functions

Animal Cells

Plant Cells

Plant Cells

Parts and functions of an animal

cell

Back to the essential question:

2 cell types• Living cells are divided into two types -

procaryotic and eucaryotic (sometimes spelled prokaryotic and eukaryotic). This division is based on internal complexity.

• What analogies can you come up with to What analogies can you come up with to help you remember the difference? help you remember the difference? (analyze the next two slides)(analyze the next two slides)

Eucaryotic:

• The cells of protozoa (in Greek proto = first and zoa = animals), higher plants and animals that are highly structured.

• These cells have a nucleus.

• “Eu” “you”

Procaryotic:

• (pro-KAR-ee-oht) from Old Greek pro- before + karyon nut or kernel (referring to the cell nucleus)

• Do not have a nucleus

• Usually bacteria

Cell Animation / Video

• http://www.cellsalive.com/cells/cell_model.htm (identification game)

• http://www.brainpop.com/science/livingsystems/cellstructures/ (quizes)

• http://multimedia.mcb.harvard.edu/ (advanced look)

Cell model project questions:

Questions & Conclusions:

1. Why do we often depend on models? Why are models useful when discussing cells?

2. How is your model like a real cell?

3. How is it different?

4. What are some limitations of models in general?

5. How are the plant and animal cell models different?