The Sensational Single Cell

All organisms (whether single-celled or multicellular) need to cope with certain fundamental challenges. This unit examines the curious case of an ubiquitous single-celled organism: yeast. A story about self-replicating robots, a comic about yeast cells in bread dough, and an activity with live yeast cells producing carbon dioxide gas introduce students to life at its most basic level: the cell. Along the way, students repeatedly encounter different approaches to understanding a cell's four essential functions. With a doubling population, yeast growth also provides a model for exponential growth and cancer.

Activities

Scene: Biology in the Bakery

Trey shows his friends Vanessa, Sarah, and Tim how to bake bread, giving a quick lesson on the single-celled organism, yeast, that makes it possible.

Duration: Approximately 50 minutes

Reading: Dr. Otto and the Four Fatal Flaws

Students join Dr. Otto as he builds cell-like robots that make copies of themselves in this illustrated story. The eight-part story provides a model for a cell's four essential functions: storing and passing on operating instructions; getting energy; obtaining building materials; and disposing of waste.

Duration: Approximately 50 minutes

Interactive: Zooming in on Yeast

Students discover the internal workings of a yeast cell in this simulation related to a cell's four essential functions: storing and passing on operating instructions; getting energy; obtaining building materials; and disposing of waste. In this interactive animation of yeast cells, students can toggle four basic functions on and off to see what happens.

Duration: Approximately 45 minutes

Reading: Rise of the Yeast Cells

Students learn more about the cell biology of single-celled organisms—and of bread baking!—in this whimsical comic. The four-page explainer shows yeast cells getting energy, obtaining building materials, disposing of waste, and storing and following inheritable instructions. And they also crack jokes.

Duration: Approximately 50 minutes

Lab: The Bread Necessities of Life

What are the "bread necessities of life"? Students compare two mixtures that yield carbon dioxide as an output: yeast, sugar, and water vs. vinegar and baking soda. Students also grow colonies of yeast under different conditions.

Duration: Approximately 50 minutes

Writing: Science-Fiction Science—Grey Goo

Students explore exponential growth and its relationship to cancer, then discuss why the world isn't covered by the grey goo of self-reproducing organisms (or robots).

Duration: Approximately 50 minutes

Teacher Tune-ups

• Why do traditional cell modeling activities fail?
• What do scientists mean when they say the cell is the basic unit of life?
• Why do biologists study yeast?
• How do cells do the things they do?
• What does it mean for something to be alive?

Student View of Visuals and Activities

Some teachers prefer to have students view the slides and other visual assets in this unit directly instead of projecting them in class. Below is a web page to share with students with links to some of same items that are within in the teacher lesson plans, but without the explanatory text for the teacher.

 

• Student Links to Unit L5 Slides and Other Visuals

cell

noun – the smallest, most basic unit of a living organism able to make a copy of itself

We have trillions of cells in our bodies.

divide

verb — to split something into two or more parts

One “parent” cell divides into two independent “daughter” cells.

multiply

verb — to increase the amount, degree or number of something; to breed or generate

Yeast cells multiply every three hours or so.

fungus

noun – an organism like yeast, mold, or mushrooms that gets its nutrition from an outside source

A fungus is not an animal or plant; fungi are a kingdom onto themselves.

individual

noun – a single, separate person or thing

Individual cells cannot survive on their own, except for unicellular organisms.

reproduction

noun – making a copy of something; making another generation of individuals

Reproduction creates the next generations of a population.

separate

adjective — apart from others; not attached to or connected to

Yeast cells can survive in separate containers.

exponential

adjective — quickly growing; having a rapid rate of change

A line graph of exponential growth makes the shape of a hockey stick.

microscopic

adjective — so tiny it can only be seen with great magnification, as with a microscope

I never saw a microscopic creature before we used a microscope in science class.

nucleus

noun – the core of some cells, containing genetic material and surrounded by a membrane

An atom has a nucleus, and so does a cell. It's a word that means the core.

nutrient

noun – a source of building materials and energy, like food

A plant that does not get all the nutrients it needs will die.

fuel

noun – an energy source that feeds a living thing

Sugars are a basic fuel for many cells.

process

noun – a series of events producing a result

Photosynthesis is a process in which plants convert light energy into chemical energy.

matter

noun – substances and materials

Matter makes up everything in the universe.