This slide is the first in the Inheritance and Adaptations CELL.

______________________________________________

This slide simply poses the question, “Have you ever wondered how brothers and sisters look a little like each other?”

• Students may have their own stories about how a neighbor always confuses them with their sibling or times they have heard comments like, “You can sure tell they are related!”
• Explain to students that this CELL is designed to explore the science of genetics. During the Investigations, students will explore the genetic information that is contained in cells, determine how parents pass information to their offspring, and come to understand how changes in this information can affect individuals as well as entire populations over time.

Ask students:  How is the human body organized?  Can you give some examples of this organization? Students should indicate that the human body is organized into different systems.  The circulatory, respiratory, and digestive systems are examples of this organization.

Ask students:  How are the systems of the body organized?  Can you give some examples of this organization? Students should indicate that the systems of the body are organized into different parts or organs.  The heart, veins, and arteries are examples of organs that are organized into the circulatory system.

______________________________________________

This slide can help direct a discussion about tissues and cells. Explain to students that smaller parts (cells) join together to create larger parts (tissues, organs, systems). 

• Ask students to locate Problem1 on their Scientist Data Record.
• Explain that problem 1 shows a simple concept map.  The concept map shows the word “cells” in the center.
• Ask students to list five different tissues found in the human body that are made up of many cells.
• Allow several student volunteers to share their answers with the class.
• An example of a filled-in chart is shown below.

______________________________________________

This slide shows the organizational hierarchy of the circulatory system.

• Point out the arteries, veins, atria, and ventricles of the heart. If necessary, write these terms on the board.
• Point out the nucleus, membrane, and cytoplasm of the cells. If necessary, write these terms on the board.
• Direct students to copy the heart, tissue, and individual cells from this slide to Problem 2 in their Scientist Data Records.

______________________________________________

Now, narrow the focus of the discussion by asking students to recall what they know about the organization of cells.

Direct students to draw the plant cell and the animal cell in Problems 3 and 4 of their Scientist Data Records.

Ask students:  Which cell is a plant cell?  Which cell is an animal cell?  How can you tell which one is which? Students should indicate that the plant cell is on the top and the animal cell is on the bottom.  The plant cell has a large vacuole, chloroplasts, and a cell wall.

Encourage student volunteers to name some of the parts of the animal cell and plant cell:

Write the names of these parts on the board and instruct students to label their drawings accordingly. If students did not know the components of the cells be sure to point out:

• the nucleus, mitochondria, cytoplasm and cell membrane on the animal cell.
• the vacuole, chloroplasts, mitochondria, cell membrane and cell wall in the plant cell.

Ask students:  Can you name some of the parts that animal cells and plant cells have in common?  Can you name some of the parts that are different? Student answers may vary.  Examples of cell parts that are similar in animal and plant cells are the cell membrane, nucleus, and cytoplasm. Plant cells contain a cell wall, chloroplasts, and a very large vacuole, but animal cells lack these parts.

Ask students:  How do you think each type of cell gets its own unique characteristics? Student answers may vary.  Encourage students to realize that each cell contains information that gives each cell its unique characteristics.

Ask students:  Which part of the cell holds the information that gives each cell its unique characteristics? Student answers may vary.  Encourage students to realize that the information found in each cell is contained inside the nucleus of that cell.

Ask students:  Think about breaking open the nucleus of a cell.  What do you think would be inside of the nucleus?  Allow several student volunteers to share their answers. Student answers may vary.

______________________________________________

Ask students:  Think about breaking open the nucleus of a cell.  What do you think would be inside of the nucleus?  Allow several student volunteers to share their answers. Student answers may vary.

Direct students to follow the pathway of organization:

The nucleus of each cell contains several pairs of chromosomes. Each pair is different from the other pairs.

• Each chromosome is made up of DNA that is wrapped around a molecule called a protein.
• If the chromosomes are unwound or stretched out, you would find long strands of DNA.
• DNA (deoxyribonucleic acid) contains all of the genetic information for every cell.
• Each strand of DNA contains many genes.

______________________________________________

This is another diagram of the organization of genes on the DNA molecule. The DNA is wrapped up with proteins. Removal of the proteins yields purified DNA. 

Notice that the DNA molecule is long and stringy. Students may remember this graphic during Investigation 1 lab, as the isolated DNA from onion cells will likely have a stringy, viscous texture.

Finally, notice that the four bases that hold the DNA molecule are shown in this slide as well. The four bases in DNA are:

• Adenine
• Cytosine
• Guanine
• Thymine

______________________________________________

In Investigation 1 lab, students will isolate DNA from an onion. This slide simply shows the major materials that will be used in the lab. In addition, a small amount of sand will be added to the mortar to help to grind and break the onion cells in the extraction solution. 

The detergent in the extraction solution helps solubilize the cell membranes.

______________________________________________

DNA Extraction from Onion (First steps):

1. The onion is chopped with a scalpel and transferred to a mortar and pestle with extraction solution.
2. The mixture is ground with the addition of a small amount of sand.
3. The ground suspension is transferred to a funnel cover with a coffee filter.
4. The filtrate is used in the next step shown on the following slide.

______________________________________________

DNA Extraction from Onion (next steps):

1. The filtered suspension (filtrate) of ground onion in extraction solution is transferred to a 15 ml centrifuge (Falcon) tube.
2. Rubbing alcohol (isopropanol) is added.
3. The cap is tightly screwed on the centrifuge tube and the tube is then inverted several times to mix the contents.
4. After mixing, the mixture is allowed to stand for a moment as whitish-color “globs” or strands of DNA become apparent.

______________________________________________