Cell Differentiation

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Objective

SWBAT to develop an argument supported by evidence for how our body is a system of interacting subsystems composed of groups of cells.

Big Idea

Developing students’ understanding of the essential biology understanding of the relationship between form and function.

Engage

5 minutes

To Engage students, I show the following pictures and ask them to analyze them to develop a common connection amongst them.  The idea that I'm hoping to elicit is the intricate relationship between structure and function in both living and non-living things.  Structure and Function is a NGSS crosscutting concepts: (The way in which an object or living thing is shaped and its substructure determine many of its properties and functions).  

In this screencast, I explain my approach to teaching the CCC Structure and Function. 

In life science this crosscutting concept is encountered throughout the curriculum especially when talking about cell structure.  In addition structure and function is used in variety of engineering fields to increase efficiency. 

  • Crosscutting concepts have value because they provide students with connections and intellectual tools that are related across the differing areas of disciplinary content and can enrich their application of practices and their understanding of core ideas. 
  1. Analyze each picture carefully individually and then as a collection.
  2. Is there anything in common  between all pictures (i.e. a relationship)? If yes please explain.
  3. Can you think of any other pictures that can be added to this collection that have the same relationship?

 

Explore

20 minutes

To further explore the relationship between structure and function I have students visit The Cell Image Library.  

The Cell: An Image Library™ is a freely accessible, easy-to-search, public repository of reviewed and annotated images, videos, and animations of cells from a variety of organisms, showcasing cell architecture, intracellular functionalities, and both normal and abnormal processes. The purpose of this database is to advance research, education, and training, with the ultimate goal of improving human health. 

Students are given The Cell: An Image Library to complete.  In this assignment student are instructed to research 5 cell types. These cells will be explored in more detail later in the semester.

My students are fortunate to have a visiting doctoral candidate scientist, whose focus is cochlear implants. This gives meaning to the study of auditory hair cells as it helps us to understand his research purpose and work.  Students are required to search The Cell Image Library database and write each cell's description, cell type, cellular components, and complete a detailed sketch of each cell. 

Explain

15 minutes

After students have explored the diversity of cells, I ask students to begin to consider, "Why are there so many different type of cells, with different shapes and functions?"  

To explain this further, I show students the Cellular Differentiation video.  It does a great job in demonstrating that all living things come from one cell that that multiplies and divides to create a multicellular organism and along the way cells differentiate to become specialized cells.  

Guiding questions that I give students are:

1)  From how many cells do we come from?

2)  How do we become multicellular organisms?

3)  What's the name of the process that results in cells becoming specialized to do complete specific jobs?

4)  Write and describe two type of cells shown in video.

5)  A group of cell forms ______________ which group together to form _____________.

 

In addition, this video reinforces the concept of cellular organization (cells-tissues-organs-organ systems-organisms). I make sure to repeatedly show students the image below to reinforce that cells are important because they are our building blocks. (LS1-3 - the body is a system of interacting subsystems composed of groups of cells).

 

 

After discussing both video and the graphic above, students read a small excerpt from an NIH website Inside the Cell Chapter 3: On the Job: Cellular SpecialtiesThis reading explains how cells are "fitted" to their role by being genetically customized (LS1.A: Structure and Function - In multicellular organisms, the body is a system of multiple interacting subsystems. These subsystems are groups of cells that work together to form tissues and organs that are specialized for particular body functions.) For example, red blood cells are shaped like lozenges so they can float easily through the bloodstream.

Elaborate

10 minutes

To elaborate on our form-function cellular investigation,  students read a neuron article.  This text discusses research being conducted on mice that is showing evidence that new neurons have the ability to buffer the brains of mice against stress and depressive symptoms.  

Students are required to answer the following text-dependent questions (RI-7.1 - Cite several pieces of textual evidence to support analysis of what the text says explicitly as well as inferences drawn from the text.):

1)  According to the article, what is unique about the hippocampus?

2)  What strong evidence has Jason Snyder found that makes a connection between neurogenesis and depression?

3)  How did the treatment with valganciclovir aid Snyder in finding evidence for his claim that neurogenesis can buffer stress and depressive symptoms in mice.

4)  Read the passage below, what do you think the author means by "behavioural* despair"?

"Their behaviour also changed. Without the ability to create new neurons, the stressed mice were less likely to enter an unfamiliar area to retrieve a piece of food, even if they were very hungry. And when they were placed in a cylinder of water, they gave up swimming more quickly and floated motionless, a supposed sign of “behavioural despair”. Again, the mice only behaved differently if they were stressed; under normal circumstances, they were indistinguishable from their peers. "

5)  According to the article, it's too early to say that this research can lead to better treatments for depressions.  Why so?

 

behavioural - British English spelling of behavioral

Evaluate

5 minutes

To close, I assess student learning using this Exit Slip.  It covers the following topics:  

  • the relationship between structure/function
  •  cell specialization
  • cellular organization  

 

Students use evidence from lessons activities to complete exit slip. (SP-7 Engaging in Argument from Evidence, specifically "Use an oral and written argument supported by evidence to support or refute an explanation or a model for a phenomenon.")